Merge pull request #193 from nathanielmanistaatgoogle/python-introduction

Bring the rest of Python RPC Framework into GRPC.

63 files changed, 9610 insertions, 2 deletions

diff --git a/src/python/_framework/base/__init__.py b/src/python/_framework/base/__init__.py
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/src/python/_framework/base/__init__.py
diff --git a/src/python/_framework/base/exceptions.py b/src/python/_framework/base/exceptions.py
new file mode 100644
index 0000000000..b8f4752184
--- /dev/null
+++ b/src/python/_framework/base/exceptions.py
@@ -0,0 +1,34 @@
+# Copyright 2015, Google Inc.
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+"""Exceptions defined and used by the base layer of RPC Framework."""
+
+
+class NoSuchMethodError(Exception):
+  """Indicates that an operation with an unrecognized name has been called."""
diff --git a/src/python/_framework/base/interfaces.py b/src/python/_framework/base/interfaces.py
new file mode 100644
index 0000000000..de7137cbf7
--- /dev/null
+++ b/src/python/_framework/base/interfaces.py
@@ -0,0 +1,229 @@
+# Copyright 2015, Google Inc.
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+"""Interfaces defined and used by the base layer of RPC Framework."""
+
+# TODO(nathaniel): Use Python's new enum library for enumerated types rather
+# than constants merely placed close together.
+
+import abc
+
+# stream is referenced from specification in this module.
+from _framework.foundation import stream  # pylint: disable=unused-import
+
+# Operation outcomes.
+COMPLETED = 'completed'
+CANCELLED = 'cancelled'
+EXPIRED = 'expired'
+RECEPTION_FAILURE = 'reception failure'
+TRANSMISSION_FAILURE = 'transmission failure'
+SERVICER_FAILURE = 'servicer failure'
+SERVICED_FAILURE = 'serviced failure'
+
+# Subscription categories.
+FULL = 'full'
+TERMINATION_ONLY = 'termination only'
+NONE = 'none'
+
+
+class OperationContext(object):
+  """Provides operation-related information and action.
+
+  Attributes:
+    trace_id: A uuid.UUID identifying a particular set of related operations.
+  """
+  __metaclass__ = abc.ABCMeta
+
+  @abc.abstractmethod
+  def is_active(self):
+    """Describes whether the operation is active or has terminated."""
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def add_termination_callback(self, callback):
+    """Adds a function to be called upon operation termination.
+
+    Args:
+      callback: A callable that will be passed one of COMPLETED, CANCELLED,
+        EXPIRED, RECEPTION_FAILURE, TRANSMISSION_FAILURE, SERVICER_FAILURE, or
+        SERVICED_FAILURE.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def time_remaining(self):
+    """Describes the length of allowed time remaining for the operation.
+
+    Returns:
+      A nonnegative float indicating the length of allowed time in seconds
+      remaining for the operation to complete before it is considered to have
+      timed out.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def fail(self, exception):
+    """Indicates that the operation has failed.
+
+    Args:
+      exception: An exception germane to the operation failure. May be None.
+    """
+    raise NotImplementedError()
+
+
+class Servicer(object):
+  """Interface for service implementations."""
+  __metaclass__ = abc.ABCMeta
+
+  @abc.abstractmethod
+  def service(self, name, context, output_consumer):
+    """Services an operation.
+
+    Args:
+      name: The name of the operation.
+      context: A ServicerContext object affording contextual information and
+        actions.
+      output_consumer: A stream.Consumer that will accept output values of
+        the operation.
+
+    Returns:
+      A stream.Consumer that will accept input values for the operation.
+
+    Raises:
+      exceptions.NoSuchMethodError: If this Servicer affords no method with the
+        given name.
+      abandonment.Abandoned: If the operation has been aborted and there no
+        longer is any reason to service the operation.
+    """
+    raise NotImplementedError()
+
+
+class Operation(object):
+  """Representation of an in-progress operation.
+
+  Attributes:
+    consumer: A stream.Consumer into which payloads constituting the operation's
+      input may be passed.
+    context: An OperationContext affording information and action about the
+      operation.
+  """
+  __metaclass__ = abc.ABCMeta
+
+  @abc.abstractmethod
+  def cancel(self):
+    """Cancels this operation."""
+    raise NotImplementedError()
+
+
+class ServicedIngestor(object):
+  """Responsible for accepting the result of an operation."""
+  __metaclass__ = abc.ABCMeta
+
+  @abc.abstractmethod
+  def consumer(self, operation_context):
+    """Affords a consumer to which operation results will be passed.
+
+    Args:
+      operation_context: An OperationContext object for the current operation.
+
+    Returns:
+      A stream.Consumer to which the results of the current operation will be
+        passed.
+
+    Raises:
+      abandonment.Abandoned: If the operation has been aborted and there no
+        longer is any reason to service the operation.
+    """
+    raise NotImplementedError()
+
+
+class ServicedSubscription(object):
+  """A sum type representing a serviced's interest in an operation.
+
+  Attributes:
+    category: One of FULL, TERMINATION_ONLY, or NONE.
+    ingestor: A ServicedIngestor. Must be present if category is FULL.
+  """
+  __metaclass__ = abc.ABCMeta
+
+
+class End(object):
+  """Common type for entry-point objects on both sides of an operation."""
+  __metaclass__ = abc.ABCMeta
+
+  @abc.abstractmethod
+  def operation_stats(self):
+    """Reports the number of terminated operations broken down by outcome.
+
+    Returns:
+      A dictionary from operation outcome constant (COMPLETED, CANCELLED,
+        EXPIRED, and so on) to an integer representing the number of operations
+        that terminated with that outcome.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def add_idle_action(self, action):
+    """Adds an action to be called when this End has no ongoing operations.
+
+    Args:
+      action: A callable that accepts no arguments.
+    """
+    raise NotImplementedError()
+
+
+class Front(End):
+  """Clientish objects that afford the invocation of operations."""
+  __metaclass__ = abc.ABCMeta
+
+  @abc.abstractmethod
+  def operate(
+      self, name, payload, complete, timeout, subscription, trace_id):
+    """Commences an operation.
+
+    Args:
+      name: The name of the method invoked for the operation.
+      payload: An initial payload for the operation. May be None.
+      complete: A boolean indicating whether or not additional payloads to be
+        sent to the servicer may be supplied after this call.
+      timeout: A length of time in seconds to allow for the operation.
+      subscription: A ServicedSubscription for the operation.
+      trace_id: A uuid.UUID identifying a set of related operations to which
+        this operation belongs.
+
+    Returns:
+      An Operation object affording information and action about the operation
+        in progress.
+    """
+    raise NotImplementedError()
+
+
+class Back(End):
+  """Serverish objects that perform the work of operations."""
+  __metaclass__ = abc.ABCMeta
diff --git a/src/python/_framework/base/interfaces_test.py b/src/python/_framework/base/interfaces_test.py
new file mode 100644
index 0000000000..6eb07ea505
--- /dev/null
+++ b/src/python/_framework/base/interfaces_test.py
@@ -0,0 +1,299 @@
+# Copyright 2015, Google Inc.
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+"""Abstract tests against the interfaces of the base layer of RPC Framework."""
+
+import threading
+import time
+
+from _framework.base import interfaces
+from _framework.base import util
+from _framework.foundation import stream
+from _framework.foundation import stream_testing
+from _framework.foundation import stream_util
+
+TICK = 0.1
+SMALL_TIMEOUT = TICK * 50
+STREAM_LENGTH = 100
+
+SYNCHRONOUS_ECHO = 'synchronous echo'
+ASYNCHRONOUS_ECHO = 'asynchronous echo'
+IMMEDIATE_FAILURE = 'immediate failure'
+TRIGGERED_FAILURE = 'triggered failure'
+WAIT_ON_CONDITION = 'wait on condition'
+
+EMPTY_OUTCOME_DICT = {
+    interfaces.COMPLETED: 0,
+    interfaces.CANCELLED: 0,
+    interfaces.EXPIRED: 0,
+    interfaces.RECEPTION_FAILURE: 0,
+    interfaces.TRANSMISSION_FAILURE: 0,
+    interfaces.SERVICER_FAILURE: 0,
+    interfaces.SERVICED_FAILURE: 0,
+    }
+
+
+def _synchronous_echo(output_consumer):
+  return stream_util.TransformingConsumer(lambda x: x, output_consumer)
+
+
+class AsynchronousEcho(stream.Consumer):
+  """A stream.Consumer that echoes its input to another stream.Consumer."""
+
+  def __init__(self, output_consumer, pool):
+    self._lock = threading.Lock()
+    self._output_consumer = output_consumer
+    self._pool = pool
+
+    self._queue = []
+    self._spinning = False
+
+  def _spin(self, value, complete):
+    while True:
+      if value:
+        if complete:
+          self._output_consumer.consume_and_terminate(value)
+        else:
+          self._output_consumer.consume(value)
+      elif complete:
+        self._output_consumer.terminate()
+      with self._lock:
+        if self._queue:
+          value, complete = self._queue.pop(0)
+        else:
+          self._spinning = False
+          return
+
+  def consume(self, value):
+    with self._lock:
+      if self._spinning:
+        self._queue.append((value, False))
+      else:
+        self._spinning = True
+        self._pool.submit(self._spin, value, False)
+
+  def terminate(self):
+    with self._lock:
+      if self._spinning:
+        self._queue.append((None, True))
+      else:
+        self._spinning = True
+        self._pool.submit(self._spin, None, True)
+
+  def consume_and_terminate(self, value):
+    with self._lock:
+      if self._spinning:
+        self._queue.append((value, True))
+      else:
+        self._spinning = True
+        self._pool.submit(self._spin, value, True)
+
+
+class TestServicer(interfaces.Servicer):
+  """An interfaces.Servicer with instrumented for testing."""
+
+  def __init__(self, pool):
+    self._pool = pool
+    self.condition = threading.Condition()
+    self._released = False
+
+  def service(self, name, context, output_consumer):
+    if name == SYNCHRONOUS_ECHO:
+      return _synchronous_echo(output_consumer)
+    elif name == ASYNCHRONOUS_ECHO:
+      return AsynchronousEcho(output_consumer, self._pool)
+    elif name == IMMEDIATE_FAILURE:
+      raise ValueError()
+    elif name == TRIGGERED_FAILURE:
+      raise NotImplementedError
+    elif name == WAIT_ON_CONDITION:
+      with self.condition:
+        while not self._released:
+          self.condition.wait()
+      return _synchronous_echo(output_consumer)
+    else:
+      raise NotImplementedError()
+
+  def release(self):
+    with self.condition:
+      self._released = True
+      self.condition.notify_all()
+
+
+class EasyServicedIngestor(interfaces.ServicedIngestor):
+  """A trivial implementation of interfaces.ServicedIngestor."""
+
+  def __init__(self, consumer):
+    self._consumer = consumer
+
+  def consumer(self, operation_context):
+    """See interfaces.ServicedIngestor.consumer for specification."""
+    return self._consumer
+
+
+class FrontAndBackTest(object):
+  """A test suite usable against any joined Front and Back."""
+
+  # Pylint doesn't know that this is a unittest.TestCase mix-in.
+  # pylint: disable=invalid-name
+
+  def testSimplestCall(self):
+    """Tests the absolute simplest call - a one-packet fire-and-forget."""
+    self.front.operate(
+        SYNCHRONOUS_ECHO, None, True, SMALL_TIMEOUT,
+        util.none_serviced_subscription(), 'test trace ID')
+    util.wait_for_idle(self.front)
+    self.assertEqual(1, self.front.operation_stats()[interfaces.COMPLETED])
+
+    # Assuming nothing really pathological (such as pauses on the order of
+    # SMALL_TIMEOUT interfering with this test) there are a two different ways
+    # the back could have experienced execution up to this point:
+    # (1) The packet is still either in the front waiting to be transmitted
+    # or is somewhere on the link between the front and the back. The back has
+    # no idea that this test is even happening. Calling wait_for_idle on it
+    # would do no good because in this case the back is idle and the call would
+    # return with the packet bound for it still in the front or on the link.
+    back_operation_stats = self.back.operation_stats()
+    first_back_possibility = EMPTY_OUTCOME_DICT
+    # (2) The packet arrived at the back and the back completed the operation.
+    second_back_possibility = dict(EMPTY_OUTCOME_DICT)
+    second_back_possibility[interfaces.COMPLETED] = 1
+    self.assertIn(
+        back_operation_stats, (first_back_possibility, second_back_possibility))
+    # It's true that if the packet had arrived at the back and the back had
+    # begun processing that wait_for_idle could hold test execution until the
+    # back completed the operation, but that doesn't really collapse the
+    # possibility space down to one solution.
+
+  def testEntireEcho(self):
+    """Tests a very simple one-packet-each-way round-trip."""
+    test_payload = 'test payload'
+    test_consumer = stream_testing.TestConsumer()
+    subscription = util.full_serviced_subscription(
+        EasyServicedIngestor(test_consumer))
+
+    self.front.operate(
+        ASYNCHRONOUS_ECHO, test_payload, True, SMALL_TIMEOUT, subscription,
+        'test trace ID')
+
+    util.wait_for_idle(self.front)
+    util.wait_for_idle(self.back)
+    self.assertEqual(1, self.front.operation_stats()[interfaces.COMPLETED])
+    self.assertEqual(1, self.back.operation_stats()[interfaces.COMPLETED])
+    self.assertListEqual([(test_payload, True)], test_consumer.calls)
+
+  def testBidirectionalStreamingEcho(self):
+    """Tests sending multiple packets each way."""
+    test_payload_template = 'test_payload: %03d'
+    test_payloads = [test_payload_template % i for i in range(STREAM_LENGTH)]
+    test_consumer = stream_testing.TestConsumer()
+    subscription = util.full_serviced_subscription(
+        EasyServicedIngestor(test_consumer))
+
+    operation = self.front.operate(
+        SYNCHRONOUS_ECHO, None, False, SMALL_TIMEOUT, subscription,
+        'test trace ID')
+
+    for test_payload in test_payloads:
+      operation.consumer.consume(test_payload)
+    operation.consumer.terminate()
+
+    util.wait_for_idle(self.front)
+    util.wait_for_idle(self.back)
+    self.assertEqual(1, self.front.operation_stats()[interfaces.COMPLETED])
+    self.assertEqual(1, self.back.operation_stats()[interfaces.COMPLETED])
+    self.assertListEqual(test_payloads, test_consumer.values())
+
+  def testCancellation(self):
+    """Tests cancelling a long-lived operation."""
+    test_consumer = stream_testing.TestConsumer()
+    subscription = util.full_serviced_subscription(
+        EasyServicedIngestor(test_consumer))
+
+    operation = self.front.operate(
+        ASYNCHRONOUS_ECHO, None, False, SMALL_TIMEOUT, subscription,
+        'test trace ID')
+    operation.cancel()
+
+    util.wait_for_idle(self.front)
+    self.assertEqual(1, self.front.operation_stats()[interfaces.CANCELLED])
+    util.wait_for_idle(self.back)
+    self.assertListEqual([], test_consumer.calls)
+
+    # Assuming nothing really pathological (such as pauses on the order of
+    # SMALL_TIMEOUT interfering with this test) there are a two different ways
+    # the back could have experienced execution up to this point:
+    # (1) Both packets are still either in the front waiting to be transmitted
+    # or are somewhere on the link between the front and the back. The back has
+    # no idea that this test is even happening. Calling wait_for_idle on it
+    # would do no good because in this case the back is idle and the call would
+    # return with the packets bound for it still in the front or on the link.
+    back_operation_stats = self.back.operation_stats()
+    first_back_possibility = EMPTY_OUTCOME_DICT
+    # (2) Both packets arrived within SMALL_TIMEOUT of one another at the back.
+    # The back started processing based on the first packet and then stopped
+    # upon receiving the cancellation packet.
+    second_back_possibility = dict(EMPTY_OUTCOME_DICT)
+    second_back_possibility[interfaces.CANCELLED] = 1
+    self.assertIn(
+        back_operation_stats, (first_back_possibility, second_back_possibility))
+
+  def testExpiration(self):
+    """Tests that operations time out."""
+    timeout = TICK * 2
+    allowance = TICK  # How much extra time to
+    condition = threading.Condition()
+    test_payload = 'test payload'
+    subscription = util.termination_only_serviced_subscription()
+    start_time = time.time()
+
+    outcome_cell = [None]
+    termination_time_cell = [None]
+    def termination_action(outcome):
+      with condition:
+        outcome_cell[0] = outcome
+        termination_time_cell[0] = time.time()
+        condition.notify()
+
+    with condition:
+      operation = self.front.operate(
+          SYNCHRONOUS_ECHO, test_payload, False, timeout, subscription,
+          'test trace ID')
+      operation.context.add_termination_callback(termination_action)
+      while outcome_cell[0] is None:
+        condition.wait()
+
+    duration = termination_time_cell[0] - start_time
+    self.assertLessEqual(timeout, duration)
+    self.assertLess(duration, timeout + allowance)
+    self.assertEqual(interfaces.EXPIRED, outcome_cell[0])
+    util.wait_for_idle(self.front)
+    self.assertEqual(1, self.front.operation_stats()[interfaces.EXPIRED])
+    util.wait_for_idle(self.back)
+    self.assertLessEqual(1, self.back.operation_stats()[interfaces.EXPIRED])
diff --git a/src/python/_framework/base/packets/__init__.py b/src/python/_framework/base/packets/__init__.py
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/src/python/_framework/base/packets/__init__.py
diff --git a/src/python/_framework/base/packets/_cancellation.py b/src/python/_framework/base/packets/_cancellation.py
new file mode 100644
index 0000000000..49172d1b97
--- /dev/null
+++ b/src/python/_framework/base/packets/_cancellation.py
@@ -0,0 +1,64 @@
+# Copyright 2015, Google Inc.
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+"""State and behavior for operation cancellation."""
+
+from _framework.base.packets import _interfaces
+from _framework.base.packets import packets
+
+
+class CancellationManager(_interfaces.CancellationManager):
+  """An implementation of _interfaces.CancellationManager."""
+
+  def __init__(
+      self, lock, termination_manager, transmission_manager, ingestion_manager,
+      expiration_manager):
+    """Constructor.
+
+    Args:
+      lock: The operation-wide lock.
+      termination_manager: The _interfaces.TerminationManager for the operation.
+      transmission_manager: The _interfaces.TransmissionManager for the
+        operation.
+      ingestion_manager: The _interfaces.IngestionManager for the operation.
+      expiration_manager: The _interfaces.ExpirationManager for the operation.
+    """
+    self._lock = lock
+    self._termination_manager = termination_manager
+    self._transmission_manager = transmission_manager
+    self._ingestion_manager = ingestion_manager
+    self._expiration_manager = expiration_manager
+
+  def cancel(self):
+    """See _interfaces.CancellationManager.cancel for specification."""
+    with self._lock:
+      self._termination_manager.abort(packets.Kind.CANCELLATION)
+      self._transmission_manager.abort(packets.Kind.CANCELLATION)
+      self._ingestion_manager.abort()
+      self._expiration_manager.abort()
diff --git a/src/python/_framework/base/packets/_constants.py b/src/python/_framework/base/packets/_constants.py
new file mode 100644
index 0000000000..8fbdc82782
--- /dev/null
+++ b/src/python/_framework/base/packets/_constants.py
@@ -0,0 +1,32 @@
+# Copyright 2015, Google Inc.
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+"""Private constants for the package."""
+
+INTERNAL_ERROR_LOG_MESSAGE = ':-( RPC Framework (Base) internal error! :-('
diff --git a/src/python/_framework/base/packets/_context.py b/src/python/_framework/base/packets/_context.py
new file mode 100644
index 0000000000..be390364b0
--- /dev/null
+++ b/src/python/_framework/base/packets/_context.py
@@ -0,0 +1,99 @@
+# Copyright 2015, Google Inc.
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+"""State and behavior for operation context."""
+
+import time
+
+# _interfaces and packets are referenced from specification in this module.
+from _framework.base import interfaces as base_interfaces
+from _framework.base.packets import _interfaces  # pylint: disable=unused-import
+from _framework.base.packets import packets  # pylint: disable=unused-import
+
+
+class OperationContext(base_interfaces.OperationContext):
+  """An implementation of base_interfaces.OperationContext."""
+
+  def __init__(
+      self, lock, operation_id, local_failure, termination_manager,
+      transmission_manager):
+    """Constructor.
+
+    Args:
+      lock: The operation-wide lock.
+      operation_id: An object identifying the operation.
+      local_failure: Whichever one of packets.Kind.SERVICED_FAILURE or
+        packets.Kind.SERVICER_FAILURE describes local failure of customer code.
+      termination_manager: The _interfaces.TerminationManager for the operation.
+      transmission_manager: The _interfaces.TransmissionManager for the
+        operation.
+    """
+    self._lock = lock
+    self._local_failure = local_failure
+    self._termination_manager = termination_manager
+    self._transmission_manager = transmission_manager
+    self._ingestion_manager = None
+    self._expiration_manager = None
+
+    self.operation_id = operation_id
+
+  def set_ingestion_and_expiration_managers(
+      self, ingestion_manager, expiration_manager):
+    """Sets managers with which this OperationContext cooperates.
+
+    Args:
+      ingestion_manager: The _interfaces.IngestionManager for the operation.
+      expiration_manager: The _interfaces.ExpirationManager for the operation.
+    """
+    self._ingestion_manager = ingestion_manager
+    self._expiration_manager = expiration_manager
+
+  def is_active(self):
+    """See base_interfaces.OperationContext.is_active for specification."""
+    with self._lock:
+      return self._termination_manager.is_active()
+
+  def add_termination_callback(self, callback):
+    """See base_interfaces.OperationContext.add_termination_callback."""
+    with self._lock:
+      self._termination_manager.add_callback(callback)
+
+  def time_remaining(self):
+    """See interfaces.OperationContext.time_remaining for specification."""
+    with self._lock:
+      deadline = self._expiration_manager.deadline()
+    return max(0.0, deadline - time.time())
+
+  def fail(self, exception):
+    """See interfaces.OperationContext.fail for specification."""
+    with self._lock:
+      self._termination_manager.abort(self._local_failure)
+      self._transmission_manager.abort(self._local_failure)
+      self._ingestion_manager.abort()
+      self._expiration_manager.abort()
diff --git a/src/python/_framework/base/packets/_emission.py b/src/python/_framework/base/packets/_emission.py
new file mode 100644
index 0000000000..b4be5eb0ff
--- /dev/null
+++ b/src/python/_framework/base/packets/_emission.py
@@ -0,0 +1,126 @@
+# Copyright 2015, Google Inc.
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+"""State and behavior for handling emitted values."""
+
+# packets is referenced from specifications in this module.
+from _framework.base.packets import _interfaces
+from _framework.base.packets import packets  # pylint: disable=unused-import
+
+
+class _EmissionManager(_interfaces.EmissionManager):
+  """An implementation of _interfaces.EmissionManager."""
+
+  def __init__(
+      self, lock, failure_kind, termination_manager, transmission_manager):
+    """Constructor.
+
+    Args:
+      lock: The operation-wide lock.
+      failure_kind: Whichever one of packets.Kind.SERVICED_FAILURE or
+        packets.Kind.SERVICER_FAILURE describes this object's methods being
+        called inappropriately by customer code.
+      termination_manager: The _interfaces.TerminationManager for the operation.
+      transmission_manager: The _interfaces.TransmissionManager for the
+        operation.
+    """
+    self._lock = lock
+    self._failure_kind = failure_kind
+    self._termination_manager = termination_manager
+    self._transmission_manager = transmission_manager
+    self._ingestion_manager = None
+    self._expiration_manager = None
+
+    self._emission_complete = False
+
+  def set_ingestion_manager_and_expiration_manager(
+      self, ingestion_manager, expiration_manager):
+    self._ingestion_manager = ingestion_manager
+    self._expiration_manager = expiration_manager
+
+  def _abort(self):
+    self._termination_manager.abort(self._failure_kind)
+    self._transmission_manager.abort(self._failure_kind)
+    self._ingestion_manager.abort()
+    self._expiration_manager.abort()
+
+  def consume(self, value):
+    with self._lock:
+      if self._emission_complete:
+        self._abort()
+      else:
+        self._transmission_manager.inmit(value, False)
+
+  def terminate(self):
+    with self._lock:
+      if not self._emission_complete:
+        self._termination_manager.emission_complete()
+        self._transmission_manager.inmit(None, True)
+        self._emission_complete = True
+
+  def consume_and_terminate(self, value):
+    with self._lock:
+      if self._emission_complete:
+        self._abort()
+      else:
+        self._termination_manager.emission_complete()
+        self._transmission_manager.inmit(value, True)
+        self._emission_complete = True
+
+
+def front_emission_manager(lock, termination_manager, transmission_manager):
+  """Creates an _interfaces.EmissionManager appropriate for front-side use.
+
+  Args:
+    lock: The operation-wide lock.
+    termination_manager: The _interfaces.TerminationManager for the operation.
+    transmission_manager: The _interfaces.TransmissionManager for the operation.
+
+  Returns:
+    An _interfaces.EmissionManager appropriate for front-side use.
+  """
+  return _EmissionManager(
+      lock, packets.Kind.SERVICED_FAILURE, termination_manager,
+      transmission_manager)
+
+
+def back_emission_manager(lock, termination_manager, transmission_manager):
+  """Creates an _interfaces.EmissionManager appropriate for back-side use.
+
+  Args:
+    lock: The operation-wide lock.
+    termination_manager: The _interfaces.TerminationManager for the operation.
+    transmission_manager: The _interfaces.TransmissionManager for the operation.
+
+  Returns:
+    An _interfaces.EmissionManager appropriate for back-side use.
+  """
+  return _EmissionManager(
+      lock, packets.Kind.SERVICER_FAILURE, termination_manager,
+      transmission_manager)
diff --git a/src/python/_framework/base/packets/_ends.py b/src/python/_framework/base/packets/_ends.py
new file mode 100644
index 0000000000..baaf5cacf9
--- /dev/null
+++ b/src/python/_framework/base/packets/_ends.py
@@ -0,0 +1,408 @@
+# Copyright 2015, Google Inc.
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+"""Implementations of Fronts and Backs."""
+
+import collections
+import threading
+import uuid
+
+# _interfaces and packets are referenced from specification in this module.
+from _framework.base import interfaces as base_interfaces
+from _framework.base.packets import _cancellation
+from _framework.base.packets import _context
+from _framework.base.packets import _emission
+from _framework.base.packets import _expiration
+from _framework.base.packets import _ingestion
+from _framework.base.packets import _interfaces  # pylint: disable=unused-import
+from _framework.base.packets import _reception
+from _framework.base.packets import _termination
+from _framework.base.packets import _transmission
+from _framework.base.packets import interfaces
+from _framework.base.packets import packets  # pylint: disable=unused-import
+from _framework.foundation import callable_util
+
+_IDLE_ACTION_EXCEPTION_LOG_MESSAGE = 'Exception calling idle action!'
+
+_OPERATION_OUTCOMES = (
+    base_interfaces.COMPLETED,
+    base_interfaces.CANCELLED,
+    base_interfaces.EXPIRED,
+    base_interfaces.RECEPTION_FAILURE,
+    base_interfaces.TRANSMISSION_FAILURE,
+    base_interfaces.SERVICER_FAILURE,
+    base_interfaces.SERVICED_FAILURE,
+    )
+
+
+class _EasyOperation(base_interfaces.Operation):
+  """A trivial implementation of base_interfaces.Operation."""
+
+  def __init__(self, emission_manager, context, cancellation_manager):
+    """Constructor.
+
+    Args:
+      emission_manager: The _interfaces.EmissionManager for the operation that
+        will accept values emitted by customer code.
+      context: The base_interfaces.OperationContext for use by the customer
+        during the operation.
+      cancellation_manager: The _interfaces.CancellationManager for the
+        operation.
+    """
+    self.consumer = emission_manager
+    self.context = context
+    self._cancellation_manager = cancellation_manager
+
+  def cancel(self):
+    self._cancellation_manager.cancel()
+
+
+class _Endlette(object):
+  """Utility for stateful behavior common to Fronts and Backs."""
+
+  def __init__(self, pool):
+    """Constructor.
+
+    Args:
+      pool: A thread pool to use when calling registered idle actions.
+    """
+    self._lock = threading.Lock()
+    self._pool = pool
+    # Dictionary from operation IDs to ReceptionManager-or-None. A None value
+    # indicates an in-progress fire-and-forget operation for which the customer
+    # has chosen to ignore results.
+    self._operations = {}
+    self._stats = {outcome: 0 for outcome in _OPERATION_OUTCOMES}
+    self._idle_actions = []
+
+  def terminal_action(self, operation_id):
+    """Constructs the termination action for a single operation.
+
+    Args:
+      operation_id: An operation ID.
+
+    Returns:
+      A callable that takes an operation outcome for an argument to be used as
+        the termination action for the operation associated with the given
+        operation ID.
+    """
+    def termination_action(outcome):
+      with self._lock:
+        self._stats[outcome] += 1
+        self._operations.pop(operation_id, None)
+        if not self._operations:
+          for action in self._idle_actions:
+            self._pool.submit(callable_util.with_exceptions_logged(
+                action, _IDLE_ACTION_EXCEPTION_LOG_MESSAGE))
+          self._idle_actions = []
+    return termination_action
+
+  def __enter__(self):
+    self._lock.acquire()
+
+  def __exit__(self, exc_type, exc_val, exc_tb):
+    self._lock.release()
+
+  def get_operation(self, operation_id):
+    return self._operations.get(operation_id, None)
+
+  def add_operation(self, operation_id, operation_reception_manager):
+    self._operations[operation_id] = operation_reception_manager
+
+  def operation_stats(self):
+    with self._lock:
+      return dict(self._stats)
+
+  def add_idle_action(self, action):
+    with self._lock:
+      if self._operations:
+        self._idle_actions.append(action)
+      else:
+        self._pool.submit(callable_util.with_exceptions_logged(
+            action, _IDLE_ACTION_EXCEPTION_LOG_MESSAGE))
+
+
+class _FrontManagement(
+    collections.namedtuple(
+        '_FrontManagement',
+        ('reception', 'emission', 'operation', 'cancellation'))):
+  """Just a trivial helper class to bundle four fellow-traveling objects."""
+
+
+def _front_operate(
+    callback, work_pool, transmission_pool, utility_pool,
+    termination_action, operation_id, name, payload, complete, timeout,
+    subscription, trace_id):
+  """Constructs objects necessary for front-side operation management.
+
+  Args:
+    callback: A callable that accepts packets.FrontToBackPackets and delivers
+      them to the other side of the operation. Execution of this callable may
+      take any arbitrary length of time.
+    work_pool: A thread pool in which to execute customer code.
+    transmission_pool: A thread pool to use for transmitting to the other side
+      of the operation.
+    utility_pool: A thread pool for utility tasks.
+    termination_action: A no-arg behavior to be called upon operation
+      completion.
+    operation_id: An object identifying the operation.
+    name: The name of the method being called during the operation.
+    payload: The first customer-significant value to be transmitted to the other
+      side. May be None if there is no such value or if the customer chose not
+      to pass it at operation invocation.
+    complete: A boolean indicating whether or not additional payloads will be
+      supplied by the customer.
+    timeout: A length of time in seconds to allow for the operation.
+    subscription: A base_interfaces.ServicedSubscription describing the
+      customer's interest in the results of the operation.
+    trace_id: A uuid.UUID identifying a set of related operations to which this
+      operation belongs. May be None.
+
+  Returns:
+    A _FrontManagement object bundling together the
+      _interfaces.ReceptionManager, _interfaces.EmissionManager,
+      _context.OperationContext, and _interfaces.CancellationManager for the
+      operation.
+  """
+  lock = threading.Lock()
+  with lock:
+    termination_manager = _termination.front_termination_manager(
+        work_pool, utility_pool, termination_action, subscription.category)
+    transmission_manager = _transmission.front_transmission_manager(
+        lock, transmission_pool, callback, operation_id, name,
+        subscription.category, trace_id, timeout, termination_manager)
+    operation_context = _context.OperationContext(
+        lock, operation_id, packets.Kind.SERVICED_FAILURE,
+        termination_manager, transmission_manager)
+    emission_manager = _emission.front_emission_manager(
+        lock, termination_manager, transmission_manager)
+    ingestion_manager = _ingestion.front_ingestion_manager(
+        lock, work_pool, subscription, termination_manager,
+        transmission_manager, operation_context)
+    expiration_manager = _expiration.front_expiration_manager(
+        lock, termination_manager, transmission_manager, ingestion_manager,
+        timeout)
+    reception_manager = _reception.front_reception_manager(
+        lock, termination_manager, transmission_manager, ingestion_manager,
+        expiration_manager)
+    cancellation_manager = _cancellation.CancellationManager(
+        lock, termination_manager, transmission_manager, ingestion_manager,
+        expiration_manager)
+
+    transmission_manager.set_ingestion_and_expiration_managers(
+        ingestion_manager, expiration_manager)
+    operation_context.set_ingestion_and_expiration_managers(
+        ingestion_manager, expiration_manager)
+    emission_manager.set_ingestion_manager_and_expiration_manager(
+        ingestion_manager, expiration_manager)
+    ingestion_manager.set_expiration_manager(expiration_manager)
+
+    transmission_manager.inmit(payload, complete)
+
+    returned_reception_manager = (
+        None if subscription.category == base_interfaces.NONE
+        else reception_manager)
+
+    return _FrontManagement(
+        returned_reception_manager, emission_manager, operation_context,
+        cancellation_manager)
+
+
+class Front(interfaces.Front):
+  """An implementation of interfaces.Front."""
+
+  def __init__(self, work_pool, transmission_pool, utility_pool):
+    """Constructor.
+
+    Args:
+      work_pool: A thread pool to be used for executing customer code.
+      transmission_pool: A thread pool to be used for transmitting values to
+        the other side of the operation.
+      utility_pool: A thread pool to be used for utility tasks.
+    """
+    self._endlette = _Endlette(utility_pool)
+    self._work_pool = work_pool
+    self._transmission_pool = transmission_pool
+    self._utility_pool = utility_pool
+    self._callback = None
+
+    self._operations = {}
+
+  def join_rear_link(self, rear_link):
+    """See interfaces.ForeLink.join_rear_link for specification."""
+    with self._endlette:
+      self._callback = rear_link.accept_front_to_back_ticket
+
+  def operation_stats(self):
+    """See base_interfaces.End.operation_stats for specification."""
+    return self._endlette.operation_stats()
+
+  def add_idle_action(self, action):
+    """See base_interfaces.End.add_idle_action for specification."""
+    self._endlette.add_idle_action(action)
+
+  def operate(
+      self, name, payload, complete, timeout, subscription, trace_id):
+    """See base_interfaces.Front.operate for specification."""
+    operation_id = uuid.uuid4()
+    with self._endlette:
+      management = _front_operate(
+          self._callback, self._work_pool, self._transmission_pool,
+          self._utility_pool, self._endlette.terminal_action(operation_id),
+          operation_id, name, payload, complete, timeout, subscription,
+          trace_id)
+      self._endlette.add_operation(operation_id, management.reception)
+      return _EasyOperation(
+          management.emission, management.operation, management.cancellation)
+
+  def accept_back_to_front_ticket(self, ticket):
+    """See interfaces.End.act for specification."""
+    with self._endlette:
+      reception_manager = self._endlette.get_operation(ticket.operation_id)
+    if reception_manager:
+      reception_manager.receive_packet(ticket)
+
+
+def _back_operate(
+    servicer, callback, work_pool, transmission_pool, utility_pool,
+    termination_action, ticket, default_timeout, maximum_timeout):
+  """Constructs objects necessary for back-side operation management.
+
+  Also begins back-side operation by feeding the first received ticket into the
+  constructed _interfaces.ReceptionManager.
+
+  Args:
+    servicer: An interfaces.Servicer for servicing operations.
+    callback: A callable that accepts packets.BackToFrontPackets and delivers
+      them to the other side of the operation. Execution of this callable may
+      take any arbitrary length of time.
+    work_pool: A thread pool in which to execute customer code.
+    transmission_pool: A thread pool to use for transmitting to the other side
+      of the operation.
+    utility_pool: A thread pool for utility tasks.
+    termination_action: A no-arg behavior to be called upon operation
+      completion.
+    ticket: The first packets.FrontToBackPacket received for the operation.
+    default_timeout: A length of time in seconds to be used as the default
+      time alloted for a single operation.
+    maximum_timeout: A length of time in seconds to be used as the maximum
+      time alloted for a single operation.
+
+  Returns:
+    The _interfaces.ReceptionManager to be used for the operation.
+  """
+  lock = threading.Lock()
+  with lock:
+    termination_manager = _termination.back_termination_manager(
+        work_pool, utility_pool, termination_action, ticket.subscription)
+    transmission_manager = _transmission.back_transmission_manager(
+        lock, transmission_pool, callback, ticket.operation_id,
+        termination_manager, ticket.subscription)
+    operation_context = _context.OperationContext(
+        lock, ticket.operation_id, packets.Kind.SERVICER_FAILURE,
+        termination_manager, transmission_manager)
+    emission_manager = _emission.back_emission_manager(
+        lock, termination_manager, transmission_manager)
+    ingestion_manager = _ingestion.back_ingestion_manager(
+        lock, work_pool, servicer, termination_manager,
+        transmission_manager, operation_context, emission_manager)
+    expiration_manager = _expiration.back_expiration_manager(
+        lock, termination_manager, transmission_manager, ingestion_manager,
+        ticket.timeout, default_timeout, maximum_timeout)
+    reception_manager = _reception.back_reception_manager(
+        lock, termination_manager, transmission_manager, ingestion_manager,
+        expiration_manager)
+
+    transmission_manager.set_ingestion_and_expiration_managers(
+        ingestion_manager, expiration_manager)
+    operation_context.set_ingestion_and_expiration_managers(
+        ingestion_manager, expiration_manager)
+    emission_manager.set_ingestion_manager_and_expiration_manager(
+        ingestion_manager, expiration_manager)
+    ingestion_manager.set_expiration_manager(expiration_manager)
+
+  reception_manager.receive_packet(ticket)
+
+  return reception_manager
+
+
+class Back(interfaces.Back):
+  """An implementation of interfaces.Back."""
+
+  def __init__(
+      self, servicer, work_pool, transmission_pool, utility_pool,
+      default_timeout, maximum_timeout):
+    """Constructor.
+
+    Args:
+      servicer: An interfaces.Servicer for servicing operations.
+      work_pool: A thread pool in which to execute customer code.
+      transmission_pool: A thread pool to use for transmitting to the other side
+        of the operation.
+      utility_pool: A thread pool for utility tasks.
+      default_timeout: A length of time in seconds to be used as the default
+        time alloted for a single operation.
+      maximum_timeout: A length of time in seconds to be used as the maximum
+        time alloted for a single operation.
+    """
+    self._endlette = _Endlette(utility_pool)
+    self._servicer = servicer
+    self._work_pool = work_pool
+    self._transmission_pool = transmission_pool
+    self._utility_pool = utility_pool
+    self._default_timeout = default_timeout
+    self._maximum_timeout = maximum_timeout
+    self._callback = None
+
+  def join_fore_link(self, fore_link):
+    """See interfaces.RearLink.join_fore_link for specification."""
+    with self._endlette:
+      self._callback = fore_link.accept_back_to_front_ticket
+
+  def accept_front_to_back_ticket(self, ticket):
+    """See interfaces.RearLink.accept_front_to_back_ticket for specification."""
+    with self._endlette:
+      reception_manager = self._endlette.get_operation(ticket.operation_id)
+      if reception_manager is None:
+        reception_manager = _back_operate(
+            self._servicer, self._callback, self._work_pool,
+            self._transmission_pool, self._utility_pool,
+            self._endlette.terminal_action(ticket.operation_id), ticket,
+            self._default_timeout, self._maximum_timeout)
+        self._endlette.add_operation(ticket.operation_id, reception_manager)
+      else:
+        reception_manager.receive_packet(ticket)
+
+  def operation_stats(self):
+    """See base_interfaces.End.operation_stats for specification."""
+    return self._endlette.operation_stats()
+
+  def add_idle_action(self, action):
+    """See base_interfaces.End.add_idle_action for specification."""
+    self._endlette.add_idle_action(action)
diff --git a/src/python/_framework/base/packets/_expiration.py b/src/python/_framework/base/packets/_expiration.py
new file mode 100644
index 0000000000..772e15f08c
--- /dev/null
+++ b/src/python/_framework/base/packets/_expiration.py
@@ -0,0 +1,158 @@
+# Copyright 2015, Google Inc.
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+"""State and behavior for operation expiration."""
+
+import time
+
+from _framework.base.packets import _interfaces
+from _framework.base.packets import packets
+from _framework.foundation import later
+
+
+class _ExpirationManager(_interfaces.ExpirationManager):
+  """An implementation of _interfaces.ExpirationManager."""
+
+  def __init__(
+      self, lock, termination_manager, transmission_manager, ingestion_manager,
+      commencement, timeout, maximum_timeout):
+    """Constructor.
+
+    Args:
+      lock: The operation-wide lock.
+      termination_manager: The _interfaces.TerminationManager for the operation.
+      transmission_manager: The _interfaces.TransmissionManager for the
+        operation.
+      ingestion_manager: The _interfaces.IngestionManager for the operation.
+      commencement: The time in seconds since the epoch at which the operation
+        began.
+      timeout: A length of time in seconds to allow for the operation to run.
+      maximum_timeout: The maximum length of time in seconds to allow for the
+        operation to run despite what is requested via this object's
+        change_timout method.
+    """
+    self._lock = lock
+    self._termination_manager = termination_manager
+    self._transmission_manager = transmission_manager
+    self._ingestion_manager = ingestion_manager
+    self._commencement = commencement
+    self._maximum_timeout = maximum_timeout
+
+    self._timeout = timeout
+    self._deadline = commencement + timeout
+    self._index = None
+    self._future = None
+
+  def _expire(self, index):
+    with self._lock:
+      if self._future is not None and index == self._index:
+        self._future = None
+        self._termination_manager.abort(packets.Kind.EXPIRATION)
+        self._transmission_manager.abort(packets.Kind.EXPIRATION)
+        self._ingestion_manager.abort()
+
+  def start(self):
+    self._index = 0
+    self._future = later.later(self._timeout, lambda: self._expire(0))
+
+  def change_timeout(self, timeout):
+    if self._future is not None and timeout != self._timeout:
+      self._future.cancel()
+      new_timeout = min(timeout, self._maximum_timeout)
+      new_index = self._index + 1
+      self._timeout = new_timeout
+      self._deadline = self._commencement + new_timeout
+      self._index = new_index
+      delay = self._deadline - time.time()
+      self._future = later.later(
+          delay, lambda: self._expire(new_index))
+
+  def deadline(self):
+    return self._deadline
+
+  def abort(self):
+    if self._future:
+      self._future.cancel()
+      self._future = None
+    self._deadline_index = None
+
+
+def front_expiration_manager(
+    lock, termination_manager, transmission_manager, ingestion_manager,
+    timeout):
+  """Creates an _interfaces.ExpirationManager appropriate for front-side use.
+
+  Args:
+    lock: The operation-wide lock.
+    termination_manager: The _interfaces.TerminationManager for the operation.
+    transmission_manager: The _interfaces.TransmissionManager for the
+      operation.
+    ingestion_manager: The _interfaces.IngestionManager for the operation.
+    timeout: A length of time in seconds to allow for the operation to run.
+
+  Returns:
+    An _interfaces.ExpirationManager appropriate for front-side use.
+  """
+  commencement = time.time()
+  expiration_manager = _ExpirationManager(
+      lock, termination_manager, transmission_manager, ingestion_manager,
+      commencement, timeout, timeout)
+  expiration_manager.start()
+  return expiration_manager
+
+
+def back_expiration_manager(
+    lock, termination_manager, transmission_manager, ingestion_manager,
+    timeout, default_timeout, maximum_timeout):
+  """Creates an _interfaces.ExpirationManager appropriate for back-side use.
+
+  Args:
+    lock: The operation-wide lock.
+    termination_manager: The _interfaces.TerminationManager for the operation.
+    transmission_manager: The _interfaces.TransmissionManager for the
+      operation.
+    ingestion_manager: The _interfaces.IngestionManager for the operation.
+    timeout: A length of time in seconds to allow for the operation to run. May
+      be None in which case default_timeout will be used.
+    default_timeout: The default length of time in seconds to allow for the
+      operation to run if the front-side customer has not specified such a value
+      (or if the value they specified is not yet known).
+    maximum_timeout: The maximum length of time in seconds to allow for the
+      operation to run.
+
+  Returns:
+    An _interfaces.ExpirationManager appropriate for back-side use.
+  """
+  commencement = time.time()
+  expiration_manager = _ExpirationManager(
+      lock, termination_manager, transmission_manager, ingestion_manager,
+      commencement, default_timeout if timeout is None else timeout,
+      maximum_timeout)
+  expiration_manager.start()
+  return expiration_manager
diff --git a/src/python/_framework/base/packets/_ingestion.py b/src/python/_framework/base/packets/_ingestion.py
new file mode 100644
index 0000000000..ad5ed4cada
--- /dev/null
+++ b/src/python/_framework/base/packets/_ingestion.py
@@ -0,0 +1,440 @@
+# Copyright 2015, Google Inc.
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+"""State and behavior for ingestion during an operation."""
+
+import abc
+import collections
+
+from _framework.base import exceptions
+from _framework.base import interfaces
+from _framework.base.packets import _constants
+from _framework.base.packets import _interfaces
+from _framework.base.packets import packets
+from _framework.foundation import abandonment
+from _framework.foundation import callable_util
+from _framework.foundation import stream
+
+_CREATE_CONSUMER_EXCEPTION_LOG_MESSAGE = 'Exception initializing ingestion!'
+_CONSUME_EXCEPTION_LOG_MESSAGE = 'Exception during ingestion!'
+
+
+class _ConsumerCreation(collections.namedtuple(
+    '_ConsumerCreation', ('consumer', 'remote_error', 'abandoned'))):
+  """A sum type for the outcome of ingestion initialization.
+
+  Either consumer will be non-None, remote_error will be True, or abandoned will
+  be True.
+
+  Attributes:
+    consumer: A stream.Consumer for ingesting payloads.
+    remote_error: A boolean indicating that the consumer could not be created
+      due to an error on the remote side of the operation.
+    abandoned: A boolean indicating that the consumer creation was abandoned.
+  """
+
+
+class _EmptyConsumer(stream.Consumer):
+  """A no-operative stream.Consumer that ignores all inputs and calls."""
+
+  def consume(self, value):
+    """See stream.Consumer.consume for specification."""
+
+  def terminate(self):
+    """See stream.Consumer.terminate for specification."""
+
+  def consume_and_terminate(self, value):
+    """See stream.Consumer.consume_and_terminate for specification."""
+
+
+class _ConsumerCreator(object):
+  """Common specification of different consumer-creating behavior."""
+  __metaclass__ = abc.ABCMeta
+
+  @abc.abstractmethod
+  def create_consumer(self, requirement):
+    """Creates the stream.Consumer to which customer payloads will be delivered.
+
+    Any exceptions raised by this method should be attributed to and treated as
+    defects in the serviced or servicer code called by this method.
+
+    Args:
+      requirement: A value required by this _ConsumerCreator for consumer
+        creation.
+
+    Returns:
+      A _ConsumerCreation describing the result of consumer creation.
+    """
+    raise NotImplementedError()
+
+
+class _FrontConsumerCreator(_ConsumerCreator):
+  """A _ConsumerCreator appropriate for front-side use."""
+
+  def __init__(self, subscription, operation_context):
+    """Constructor.
+
+    Args:
+      subscription: The serviced's interfaces.ServicedSubscription for the
+        operation.
+      operation_context: The interfaces.OperationContext object for the
+        operation.
+    """
+    self._subscription = subscription
+    self._operation_context = operation_context
+
+  def create_consumer(self, requirement):
+    """See _ConsumerCreator.create_consumer for specification."""
+    if self._subscription.category == interfaces.FULL:
+      try:
+        return _ConsumerCreation(
+            self._subscription.ingestor.consumer(self._operation_context),
+            False, False)
+      except abandonment.Abandoned:
+        return _ConsumerCreation(None, False, True)
+    else:
+      return _ConsumerCreation(_EmptyConsumer(), False, False)
+
+
+class _BackConsumerCreator(_ConsumerCreator):
+  """A _ConsumerCreator appropriate for back-side use."""
+
+  def __init__(self, servicer, operation_context, emission_consumer):
+    """Constructor.
+
+    Args:
+      servicer: The interfaces.Servicer that will service the operation.
+      operation_context: The interfaces.OperationContext object for the
+        operation.
+      emission_consumer: The stream.Consumer object to which payloads emitted
+        from the operation will be passed.
+    """
+    self._servicer = servicer
+    self._operation_context = operation_context
+    self._emission_consumer = emission_consumer
+
+  def create_consumer(self, requirement):
+    """See _ConsumerCreator.create_consumer for full specification.
+
+    Args:
+      requirement: The name of the Servicer method to be called during this
+        operation.
+
+    Returns:
+      A _ConsumerCreation describing the result of consumer creation.
+    """
+    try:
+      return _ConsumerCreation(
+          self._servicer.service(
+              requirement, self._operation_context, self._emission_consumer),
+          False, False)
+    except exceptions.NoSuchMethodError:
+      return _ConsumerCreation(None, True, False)
+    except abandonment.Abandoned:
+      return _ConsumerCreation(None, False, True)
+
+
+class _WrappedConsumer(object):
+  """Wraps a consumer to catch the exceptions that it is allowed to throw."""
+
+  def __init__(self, consumer):
+    """Constructor.
+
+    Args:
+      consumer: A stream.Consumer that may raise abandonment.Abandoned from any
+        of its methods.
+    """
+    self._consumer = consumer
+
+  def moar(self, payload, complete):
+    """Makes progress with the wrapped consumer.
+
+    This method catches all exceptions allowed to be thrown by the wrapped
+    consumer. Any exceptions raised by this method should be blamed on the
+    customer-supplied consumer.
+
+    Args:
+      payload: A customer-significant payload object. May be None only if
+        complete is True.
+      complete: Whether or not the end of the payload sequence has been reached.
+        May be False only if payload is not None.
+
+    Returns:
+      True if the wrapped consumer made progress or False if the wrapped
+        consumer raised abandonment.Abandoned to indicate its abandonment of
+        progress.
+    """
+    try:
+      if payload:
+        if complete:
+          self._consumer.consume_and_terminate(payload)
+        else:
+          self._consumer.consume(payload)
+      else:
+        self._consumer.terminate()
+      return True
+    except abandonment.Abandoned:
+      return False
+
+
+class _IngestionManager(_interfaces.IngestionManager):
+  """An implementation of _interfaces.IngestionManager."""
+
+  def __init__(
+      self, lock, pool, consumer_creator, failure_kind, termination_manager,
+      transmission_manager):
+    """Constructor.
+
+    Args:
+      lock: The operation-wide lock.
+      pool: A thread pool in which to execute customer code.
+      consumer_creator: A _ConsumerCreator wrapping the portion of customer code
+        that when called returns the stream.Consumer with which the customer
+        code will ingest payload values.
+      failure_kind: Whichever one of packets.Kind.SERVICED_FAILURE or
+        packets.Kind.SERVICER_FAILURE describes local failure of customer code.
+      termination_manager: The _interfaces.TerminationManager for the operation.
+      transmission_manager: The _interfaces.TransmissionManager for the
+        operation.
+    """
+    self._lock = lock
+    self._pool = pool
+    self._consumer_creator = consumer_creator
+    self._failure_kind = failure_kind
+    self._termination_manager = termination_manager
+    self._transmission_manager = transmission_manager
+    self._expiration_manager = None
+
+    self._wrapped_ingestion_consumer = None
+    self._pending_ingestion = []
+    self._ingestion_complete = False
+    self._processing = False
+
+  def set_expiration_manager(self, expiration_manager):
+    self._expiration_manager = expiration_manager
+
+  def _abort_internal_only(self):
+    self._wrapped_ingestion_consumer = None
+    self._pending_ingestion = None
+
+  def _abort_and_notify(self, outcome):
+    self._abort_internal_only()
+    self._termination_manager.abort(outcome)
+    self._transmission_manager.abort(outcome)
+    self._expiration_manager.abort()
+
+  def _next(self):
+    """Computes the next step for ingestion.
+
+    Returns:
+      A payload, complete, continue triplet indicating what payload (if any) is
+        available to feed into customer code, whether or not the sequence of
+        payloads has terminated, and whether or not there is anything
+        immediately actionable to call customer code to do.
+    """
+    if self._pending_ingestion is None:
+      return None, False, False
+    elif self._pending_ingestion:
+      payload = self._pending_ingestion.pop(0)
+      complete = self._ingestion_complete and not self._pending_ingestion
+      return payload, complete, True
+    elif self._ingestion_complete:
+      return None, True, True
+    else:
+      return None, False, False
+
+  def _process(self, wrapped_ingestion_consumer, payload, complete):
+    """A method to call to execute customer code.
+
+    This object's lock must *not* be held when calling this method.
+
+    Args:
+      wrapped_ingestion_consumer: The _WrappedConsumer with which to pass
+        payloads to customer code.
+      payload: A customer payload. May be None only if complete is True.
+      complete: Whether or not the sequence of payloads to pass to the customer
+        has concluded.
+    """
+    while True:
+      consumption_outcome = callable_util.call_logging_exceptions(
+          wrapped_ingestion_consumer.moar, _CONSUME_EXCEPTION_LOG_MESSAGE,
+          payload, complete)
+      if consumption_outcome.exception is None:
+        if consumption_outcome.return_value:
+          with self._lock:
+            if complete:
+              self._pending_ingestion = None
+              self._termination_manager.ingestion_complete()
+              return
+            else:
+              payload, complete, moar = self._next()
+              if not moar:
+                self._processing = False
+                return
+        else:
+          with self._lock:
+            if self._pending_ingestion is not None:
+              self._abort_and_notify(self._failure_kind)
+            self._processing = False
+            return
+      else:
+        with self._lock:
+          self._abort_and_notify(self._failure_kind)
+          self._processing = False
+          return
+
+  def start(self, requirement):
+    if self._pending_ingestion is not None:
+      def initialize():
+        consumer_creation_outcome = callable_util.call_logging_exceptions(
+            self._consumer_creator.create_consumer,
+            _CREATE_CONSUMER_EXCEPTION_LOG_MESSAGE, requirement)
+        if consumer_creation_outcome.return_value is None:
+          with self._lock:
+            self._abort_and_notify(self._failure_kind)
+            self._processing = False
+        elif consumer_creation_outcome.return_value.remote_error:
+          with self._lock:
+            self._abort_and_notify(packets.Kind.RECEPTION_FAILURE)
+            self._processing = False
+        elif consumer_creation_outcome.return_value.abandoned:
+          with self._lock:
+            if self._pending_ingestion is not None:
+              self._abort_and_notify(self._failure_kind)
+            self._processing = False
+        else:
+          wrapped_ingestion_consumer = _WrappedConsumer(
+              consumer_creation_outcome.return_value.consumer)
+          with self._lock:
+            self._wrapped_ingestion_consumer = wrapped_ingestion_consumer
+            payload, complete, moar = self._next()
+            if not moar:
+              self._processing = False
+              return
+
+          self._process(wrapped_ingestion_consumer, payload, complete)
+
+      self._pool.submit(
+          callable_util.with_exceptions_logged(
+              initialize, _constants.INTERNAL_ERROR_LOG_MESSAGE))
+      self._processing = True
+
+  def consume(self, payload):
+    if self._ingestion_complete:
+      self._abort_and_notify(self._failure_kind)
+    elif self._pending_ingestion is not None:
+      if self._processing:
+        self._pending_ingestion.append(payload)
+      else:
+        self._pool.submit(
+            callable_util.with_exceptions_logged(
+                self._process, _constants.INTERNAL_ERROR_LOG_MESSAGE),
+            self._wrapped_ingestion_consumer, payload, False)
+        self._processing = True
+
+  def terminate(self):
+    if self._ingestion_complete:
+      self._abort_and_notify(self._failure_kind)
+    else:
+      self._ingestion_complete = True
+      if self._pending_ingestion is not None and not self._processing:
+        self._pool.submit(
+            callable_util.with_exceptions_logged(
+                self._process, _constants.INTERNAL_ERROR_LOG_MESSAGE),
+            self._wrapped_ingestion_consumer, None, True)
+        self._processing = True
+
+  def consume_and_terminate(self, payload):
+    if self._ingestion_complete:
+      self._abort_and_notify(self._failure_kind)
+    else:
+      self._ingestion_complete = True
+      if self._pending_ingestion is not None:
+        if self._processing:
+          self._pending_ingestion.append(payload)
+        else:
+          self._pool.submit(
+              callable_util.with_exceptions_logged(
+                  self._process, _constants.INTERNAL_ERROR_LOG_MESSAGE),
+              self._wrapped_ingestion_consumer, payload, True)
+          self._processing = True
+
+  def abort(self):
+    """See _interfaces.IngestionManager.abort for specification."""
+    self._abort_internal_only()
+
+
+def front_ingestion_manager(
+    lock, pool, subscription, termination_manager, transmission_manager,
+    operation_context):
+  """Creates an IngestionManager appropriate for front-side use.
+
+  Args:
+    lock: The operation-wide lock.
+    pool: A thread pool in which to execute customer code.
+    subscription: A base_interfaces.ServicedSubscription indicating the
+      customer's interest in the results of the operation.
+    termination_manager: The _interfaces.TerminationManager for the operation.
+    transmission_manager: The _interfaces.TransmissionManager for the
+      operation.
+    operation_context: A base_interfaces.OperationContext for the operation.
+
+  Returns:
+    An IngestionManager appropriate for front-side use.
+  """
+  ingestion_manager = _IngestionManager(
+      lock, pool, _FrontConsumerCreator(subscription, operation_context),
+      packets.Kind.SERVICED_FAILURE, termination_manager, transmission_manager)
+  ingestion_manager.start(None)
+  return ingestion_manager
+
+
+def back_ingestion_manager(
+    lock, pool, servicer, termination_manager, transmission_manager,
+    operation_context, emission_consumer):
+  """Creates an IngestionManager appropriate for back-side use.
+
+  Args:
+    lock: The operation-wide lock.
+    pool: A thread pool in which to execute customer code.
+    servicer: A base_interfaces.Servicer for servicing the operation.
+    termination_manager: The _interfaces.TerminationManager for the operation.
+    transmission_manager: The _interfaces.TransmissionManager for the
+      operation.
+    operation_context: A base_interfaces.OperationContext for the operation.
+    emission_consumer: The _interfaces.EmissionConsumer for the operation.
+
+  Returns:
+    An IngestionManager appropriate for back-side use.
+  """
+  ingestion_manager = _IngestionManager(
+      lock, pool, _BackConsumerCreator(
+          servicer, operation_context, emission_consumer),
+      packets.Kind.SERVICER_FAILURE, termination_manager, transmission_manager)
+  return ingestion_manager
diff --git a/src/python/_framework/base/packets/_interfaces.py b/src/python/_framework/base/packets/_interfaces.py
new file mode 100644
index 0000000000..5f6c0593d0
--- /dev/null
+++ b/src/python/_framework/base/packets/_interfaces.py
@@ -0,0 +1,269 @@
+# Copyright 2015, Google Inc.
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+"""Package-internal interfaces."""
+
+import abc
+
+# base_interfaces and packets are referenced from specification in this module.
+from _framework.base import interfaces as base_interfaces  # pylint: disable=unused-import
+from _framework.base.packets import packets  # pylint: disable=unused-import
+from _framework.foundation import stream
+
+
+class TerminationManager(object):
+  """An object responsible for handling the termination of an operation."""
+  __metaclass__ = abc.ABCMeta
+
+  @abc.abstractmethod
+  def is_active(self):
+    """Reports whether or not the operation is active.
+
+    Returns:
+      True if the operation is active or False if the operation has terminated.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def add_callback(self, callback):
+    """Registers a callback to be called on operation termination.
+
+    If the operation has already terminated, the callback will be called
+    immediately.
+
+    Args:
+      callback: A callable that will be passed one of base_interfaces.COMPLETED,
+        base_interfaces.CANCELLED, base_interfaces.EXPIRED,
+        base_interfaces.RECEPTION_FAILURE, base_interfaces.TRANSMISSION_FAILURE,
+        base_interfaces.SERVICER_FAILURE, or base_interfaces.SERVICED_FAILURE.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def emission_complete(self):
+    """Indicates that emissions from customer code have completed."""
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def transmission_complete(self):
+    """Indicates that transmissions to the remote end are complete."""
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def ingestion_complete(self):
+    """Indicates that customer code ingestion of received values is complete."""
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def abort(self, kind):
+    """Indicates that the operation must abort for the indicated reason.
+
+    Args:
+      kind: A value of packets.Kind indicating operation abortion.
+    """
+    raise NotImplementedError()
+
+
+class TransmissionManager(object):
+  """A manager responsible for transmitting to the other end of an operation."""
+  __metaclass__ = abc.ABCMeta
+
+  @abc.abstractmethod
+  def inmit(self, emission, complete):
+    """Accepts a value for transmission to the other end of the operation.
+
+    Args:
+      emission: A value of some significance to the customer to be transmitted
+        to the other end of the operation. May be None only if complete is True.
+      complete: A boolean that if True indicates that customer code has emitted
+        all values it intends to emit.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def abort(self, kind):
+    """Indicates that the operation has aborted for the indicated reason.
+
+    Args:
+      kind: A value of packets.Kind indicating operation abortion.
+    """
+    raise NotImplementedError()
+
+
+class EmissionManager(stream.Consumer):
+  """A manager of values emitted by customer code."""
+  __metaclass__ = abc.ABCMeta
+
+  @abc.abstractmethod
+  def set_ingestion_manager_and_expiration_manager(
+      self, ingestion_manager, expiration_manager):
+    """Sets two other objects with which this EmissionManager will cooperate.
+
+    Args:
+      ingestion_manager: The IngestionManager for the operation.
+      expiration_manager: The ExpirationManager for the operation.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def consume(self, value):
+    """Accepts a value emitted by customer code.
+
+    This method should only be called by customer code.
+
+    Args:
+      value: Any value of significance to the customer.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def terminate(self):
+    """Indicates that no more values will be emitted by customer code.
+
+    This method should only be called by customer code.
+
+    Implementations of this method may be idempotent and forgive customer code
+    calling this method more than once.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def consume_and_terminate(self, value):
+    """Accepts the last value emitted by customer code.
+
+    This method should only be called by customer code.
+
+    Args:
+      value: Any value of significance to the customer.
+    """
+    raise NotImplementedError()
+
+
+class IngestionManager(stream.Consumer):
+  """A manager responsible for executing customer code."""
+  __metaclass__ = abc.ABCMeta
+
+  @abc.abstractmethod
+  def set_expiration_manager(self, expiration_manager):
+    """Sets the ExpirationManager with which this object will cooperate."""
+
+  @abc.abstractmethod
+  def start(self, requirement):
+    """Commences execution of customer code.
+
+    Args:
+      requirement: Some value unavailable at the time of this object's
+        construction that is required to begin executing customer code.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def consume(self, payload):
+    """Accepts a customer-significant value to be supplied to customer code.
+
+    Args:
+      payload: Some customer-significant value.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def terminate(self):
+    """Indicates the end of values to be supplied to customer code."""
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def consume_and_terminate(self, payload):
+    """Accepts the last value to be supplied to customer code.
+
+    Args:
+      payload: Some customer-significant value (and the last such value).
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def abort(self):
+    """Indicates to this manager that the operation has aborted."""
+    raise NotImplementedError()
+
+
+class ExpirationManager(object):
+  """A manager responsible for aborting the operation if it runs out of time."""
+  __metaclass__ = abc.ABCMeta
+
+  @abc.abstractmethod
+  def change_timeout(self, timeout):
+    """Changes the timeout allotted for the operation.
+
+    Operation duration is always measure from the beginning of the operation;
+    calling this method changes the operation's allotted time to timeout total
+    seconds, not timeout seconds from the time of this method call.
+
+    Args:
+      timeout: A length of time in seconds to allow for the operation.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def deadline(self):
+    """Returns the time until which the operation is allowed to run.
+
+    Returns:
+      The time (seconds since the epoch) at which the operation will expire.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def abort(self):
+    """Indicates to this manager that the operation has aborted."""
+    raise NotImplementedError()
+
+
+class ReceptionManager(object):
+  """A manager responsible for receiving packets from the other end."""
+  __metaclass__ = abc.ABCMeta
+
+  @abc.abstractmethod
+  def receive_packet(self, packet):
+    """Handle a packet from the other side of the operation.
+
+    Args:
+      packet: A packets.BackToFrontPacket or packets.FrontToBackPacket
+        appropriate to this end of the operation and this object.
+    """
+    raise NotImplementedError()
+
+
+class CancellationManager(object):
+  """A manager of operation cancellation."""
+  __metaclass__ = abc.ABCMeta
+
+  @abc.abstractmethod
+  def cancel(self):
+    """Cancels the operation."""
+    raise NotImplementedError()
diff --git a/src/python/_framework/base/packets/_reception.py b/src/python/_framework/base/packets/_reception.py
new file mode 100644
index 0000000000..a2a3823d28
--- /dev/null
+++ b/src/python/_framework/base/packets/_reception.py
@@ -0,0 +1,394 @@
+# Copyright 2015, Google Inc.
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+"""State and behavior for packet reception."""
+
+import abc
+
+from _framework.base.packets import _interfaces
+from _framework.base.packets import packets
+
+
+class _Receiver(object):
+  """Common specification of different packet-handling behavior."""
+  __metaclass__ = abc.ABCMeta
+
+  @abc.abstractmethod
+  def abort_if_abortive(self, packet):
+    """Aborts the operation if the packet is abortive.
+
+    Args:
+      packet: A just-arrived packet.
+
+    Returns:
+      A boolean indicating whether or not this Receiver aborted the operation
+        based on the packet.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def receive(self, packet):
+    """Handles a just-arrived packet.
+
+    Args:
+      packet: A just-arrived packet.
+
+    Returns:
+      A boolean indicating whether or not the packet was terminal (i.e. whether
+        or not non-abortive packets are legal after this one).
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def reception_failure(self):
+    """Aborts the operation with an indication of reception failure."""
+    raise NotImplementedError()
+
+
+def _abort(
+    category, termination_manager, transmission_manager, ingestion_manager,
+    expiration_manager):
+  """Indicates abortion with the given category to the given managers."""
+  termination_manager.abort(category)
+  transmission_manager.abort(category)
+  ingestion_manager.abort()
+  expiration_manager.abort()
+
+
+def _abort_if_abortive(
+    packet, abortive, termination_manager, transmission_manager,
+    ingestion_manager, expiration_manager):
+  """Determines a packet's being abortive and if so aborts the operation.
+
+  Args:
+    packet: A just-arrived packet.
+    abortive: A callable that takes a packet and returns an operation category
+      indicating that the operation should be aborted or None indicating that
+      the operation should not be aborted.
+    termination_manager: The operation's _interfaces.TerminationManager.
+    transmission_manager: The operation's _interfaces.TransmissionManager.
+    ingestion_manager: The operation's _interfaces.IngestionManager.
+    expiration_manager: The operation's _interfaces.ExpirationManager.
+
+  Returns:
+    True if the operation was aborted; False otherwise.
+  """
+  abort_category = abortive(packet)
+  if abort_category is None:
+    return False
+  else:
+    _abort(
+        abort_category, termination_manager, transmission_manager,
+        ingestion_manager, expiration_manager)
+    return True
+
+
+def _reception_failure(
+    termination_manager, transmission_manager, ingestion_manager,
+    expiration_manager):
+  """Aborts the operation with an indication of reception failure."""
+  _abort(
+      packets.Kind.RECEPTION_FAILURE, termination_manager, transmission_manager,
+      ingestion_manager, expiration_manager)
+
+
+class _BackReceiver(_Receiver):
+  """Packet-handling specific to the back side of an operation."""
+
+  def __init__(
+      self, termination_manager, transmission_manager, ingestion_manager,
+      expiration_manager):
+    """Constructor.
+
+    Args:
+      termination_manager: The operation's _interfaces.TerminationManager.
+      transmission_manager: The operation's _interfaces.TransmissionManager.
+      ingestion_manager: The operation's _interfaces.IngestionManager.
+      expiration_manager: The operation's _interfaces.ExpirationManager.
+    """
+    self._termination_manager = termination_manager
+    self._transmission_manager = transmission_manager
+    self._ingestion_manager = ingestion_manager
+    self._expiration_manager = expiration_manager
+
+    self._first_packet_seen = False
+    self._last_packet_seen = False
+
+  def _abortive(self, packet):
+    """Determines whether or not (and if so, how) a packet is abortive.
+
+    Args:
+      packet: A just-arrived packet.
+
+    Returns:
+      One of packets.Kind.CANCELLATION, packets.Kind.SERVICED_FAILURE, or
+        packets.Kind.RECEPTION_FAILURE, indicating that the packet is abortive
+        and how, or None, indicating that the packet is not abortive.
+    """
+    if packet.kind is packets.Kind.CANCELLATION:
+      return packets.Kind.CANCELLATION
+    elif packet.kind is packets.Kind.EXPIRATION:
+      return packets.Kind.EXPIRATION
+    elif packet.kind is packets.Kind.SERVICED_FAILURE:
+      return packets.Kind.SERVICED_FAILURE
+    elif packet.kind is packets.Kind.RECEPTION_FAILURE:
+      return packets.Kind.SERVICED_FAILURE
+    elif (packet.kind in (packets.Kind.COMMENCEMENT, packets.Kind.ENTIRE) and
+          self._first_packet_seen):
+      return packets.Kind.RECEPTION_FAILURE
+    elif self._last_packet_seen:
+      return packets.Kind.RECEPTION_FAILURE
+    else:
+      return None
+
+  def abort_if_abortive(self, packet):
+    """See _Receiver.abort_if_abortive for specification."""
+    return _abort_if_abortive(
+        packet, self._abortive, self._termination_manager,
+        self._transmission_manager, self._ingestion_manager,
+        self._expiration_manager)
+
+  def receive(self, packet):
+    """See _Receiver.receive for specification."""
+    if packet.timeout is not None:
+      self._expiration_manager.change_timeout(packet.timeout)
+
+    if packet.kind is packets.Kind.COMMENCEMENT:
+      self._first_packet_seen = True
+      self._ingestion_manager.start(packet.name)
+      if packet.payload is not None:
+        self._ingestion_manager.consume(packet.payload)
+    elif packet.kind is packets.Kind.CONTINUATION:
+      self._ingestion_manager.consume(packet.payload)
+    elif packet.kind is packets.Kind.COMPLETION:
+      self._last_packet_seen = True
+      if packet.payload is None:
+        self._ingestion_manager.terminate()
+      else:
+        self._ingestion_manager.consume_and_terminate(packet.payload)
+    else:
+      self._first_packet_seen = True
+      self._last_packet_seen = True
+      self._ingestion_manager.start(packet.name)
+      if packet.payload is None:
+        self._ingestion_manager.terminate()
+      else:
+        self._ingestion_manager.consume_and_terminate(packet.payload)
+
+  def reception_failure(self):
+    """See _Receiver.reception_failure for specification."""
+    _reception_failure(
+        self._termination_manager, self._transmission_manager,
+        self._ingestion_manager, self._expiration_manager)
+
+
+class _FrontReceiver(_Receiver):
+  """Packet-handling specific to the front side of an operation."""
+
+  def __init__(
+      self, termination_manager, transmission_manager, ingestion_manager,
+      expiration_manager):
+    """Constructor.
+
+    Args:
+      termination_manager: The operation's _interfaces.TerminationManager.
+      transmission_manager: The operation's _interfaces.TransmissionManager.
+      ingestion_manager: The operation's _interfaces.IngestionManager.
+      expiration_manager: The operation's _interfaces.ExpirationManager.
+    """
+    self._termination_manager = termination_manager
+    self._transmission_manager = transmission_manager
+    self._ingestion_manager = ingestion_manager
+    self._expiration_manager = expiration_manager
+
+    self._last_packet_seen = False
+
+  def _abortive(self, packet):
+    """Determines whether or not (and if so, how) a packet is abortive.
+
+    Args:
+      packet: A just-arrived packet.
+
+    Returns:
+      One of packets.Kind.EXPIRATION, packets.Kind.SERVICER_FAILURE, or
+        packets.Kind.RECEPTION_FAILURE, indicating that the packet is abortive
+        and how, or None, indicating that the packet is not abortive.
+    """
+    if packet.kind is packets.Kind.EXPIRATION:
+      return packets.Kind.EXPIRATION
+    elif packet.kind is packets.Kind.SERVICER_FAILURE:
+      return packets.Kind.SERVICER_FAILURE
+    elif packet.kind is packets.Kind.RECEPTION_FAILURE:
+      return packets.Kind.SERVICER_FAILURE
+    elif self._last_packet_seen:
+      return packets.Kind.RECEPTION_FAILURE
+    else:
+      return None
+
+  def abort_if_abortive(self, packet):
+    """See _Receiver.abort_if_abortive for specification."""
+    return _abort_if_abortive(
+        packet, self._abortive, self._termination_manager,
+        self._transmission_manager, self._ingestion_manager,
+        self._expiration_manager)
+
+  def receive(self, packet):
+    """See _Receiver.receive for specification."""
+    if packet.kind is packets.Kind.CONTINUATION:
+      self._ingestion_manager.consume(packet.payload)
+    elif packet.kind is packets.Kind.COMPLETION:
+      self._last_packet_seen = True
+      if packet.payload is None:
+        self._ingestion_manager.terminate()
+      else:
+        self._ingestion_manager.consume_and_terminate(packet.payload)
+
+  def reception_failure(self):
+    """See _Receiver.reception_failure for specification."""
+    _reception_failure(
+        self._termination_manager, self._transmission_manager,
+        self._ingestion_manager, self._expiration_manager)
+
+
+class _ReceptionManager(_interfaces.ReceptionManager):
+  """A ReceptionManager based around a _Receiver passed to it."""
+
+  def __init__(self, lock, receiver):
+    """Constructor.
+
+    Args:
+      lock: The operation-servicing-wide lock object.
+      receiver: A _Receiver responsible for handling received packets.
+    """
+    self._lock = lock
+    self._receiver = receiver
+
+    self._lowest_unseen_sequence_number = 0
+    self._out_of_sequence_packets = {}
+    self._completed_sequence_number = None
+    self._aborted = False
+
+  def _sequence_failure(self, packet):
+    """Determines a just-arrived packet's sequential legitimacy.
+
+    Args:
+      packet: A just-arrived packet.
+
+    Returns:
+      True if the packet is sequentially legitimate; False otherwise.
+    """
+    if packet.sequence_number < self._lowest_unseen_sequence_number:
+      return True
+    elif packet.sequence_number in self._out_of_sequence_packets:
+      return True
+    elif (self._completed_sequence_number is not None and
+          self._completed_sequence_number <= packet.sequence_number):
+      return True
+    else:
+      return False
+
+  def _process(self, packet):
+    """Process those packets ready to be processed.
+
+    Args:
+      packet: A just-arrived packet the sequence number of which matches this
+        _ReceptionManager's _lowest_unseen_sequence_number field.
+    """
+    while True:
+      completed = self._receiver.receive(packet)
+      if completed:
+        self._out_of_sequence_packets.clear()
+        self._completed_sequence_number = packet.sequence_number
+        self._lowest_unseen_sequence_number = packet.sequence_number + 1
+        return
+      else:
+        next_packet = self._out_of_sequence_packets.pop(
+            packet.sequence_number + 1, None)
+        if next_packet is None:
+          self._lowest_unseen_sequence_number = packet.sequence_number + 1
+          return
+        else:
+          packet = next_packet
+
+  def receive_packet(self, packet):
+    """See _interfaces.ReceptionManager.receive_packet for specification."""
+    with self._lock:
+      if self._aborted:
+        return
+      elif self._sequence_failure(packet):
+        self._receiver.reception_failure()
+        self._aborted = True
+      elif self._receiver.abort_if_abortive(packet):
+        self._aborted = True
+      elif packet.sequence_number == self._lowest_unseen_sequence_number:
+        self._process(packet)
+      else:
+        self._out_of_sequence_packets[packet.sequence_number] = packet
+
+
+def front_reception_manager(
+    lock, termination_manager, transmission_manager, ingestion_manager,
+    expiration_manager):
+  """Creates a _interfaces.ReceptionManager for front-side use.
+
+  Args:
+    lock: The operation-servicing-wide lock object.
+    termination_manager: The operation's _interfaces.TerminationManager.
+    transmission_manager: The operation's _interfaces.TransmissionManager.
+    ingestion_manager: The operation's _interfaces.IngestionManager.
+    expiration_manager: The operation's _interfaces.ExpirationManager.
+
+  Returns:
+    A _interfaces.ReceptionManager appropriate for front-side use.
+  """
+  return _ReceptionManager(
+      lock, _FrontReceiver(
+          termination_manager, transmission_manager, ingestion_manager,
+          expiration_manager))
+
+
+def back_reception_manager(
+    lock, termination_manager, transmission_manager, ingestion_manager,
+    expiration_manager):
+  """Creates a _interfaces.ReceptionManager for back-side use.
+
+  Args:
+    lock: The operation-servicing-wide lock object.
+    termination_manager: The operation's _interfaces.TerminationManager.
+    transmission_manager: The operation's _interfaces.TransmissionManager.
+    ingestion_manager: The operation's _interfaces.IngestionManager.
+    expiration_manager: The operation's _interfaces.ExpirationManager.
+
+  Returns:
+    A _interfaces.ReceptionManager appropriate for back-side use.
+  """
+  return _ReceptionManager(
+      lock, _BackReceiver(
+          termination_manager, transmission_manager, ingestion_manager,
+          expiration_manager))
diff --git a/src/python/_framework/base/packets/_termination.py b/src/python/_framework/base/packets/_termination.py
new file mode 100644
index 0000000000..d586c2167b
--- /dev/null
+++ b/src/python/_framework/base/packets/_termination.py
@@ -0,0 +1,201 @@
+# Copyright 2015, Google Inc.
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+"""State and behavior for operation termination."""
+
+from _framework.base import interfaces
+from _framework.base.packets import _constants
+from _framework.base.packets import _interfaces
+from _framework.base.packets import packets
+from _framework.foundation import callable_util
+
+_CALLBACK_EXCEPTION_LOG_MESSAGE = 'Exception calling termination callback!'
+
+# TODO(nathaniel): enum module.
+_EMISSION = 'emission'
+_TRANSMISSION = 'transmission'
+_INGESTION = 'ingestion'
+
+_FRONT_NOT_LISTENING_REQUIREMENTS = (_TRANSMISSION,)
+_BACK_NOT_LISTENING_REQUIREMENTS = (_EMISSION, _INGESTION,)
+_LISTENING_REQUIREMENTS = (_TRANSMISSION, _INGESTION,)
+
+_KINDS_TO_OUTCOMES = {
+    packets.Kind.COMPLETION: interfaces.COMPLETED,
+    packets.Kind.CANCELLATION: interfaces.CANCELLED,
+    packets.Kind.EXPIRATION: interfaces.EXPIRED,
+    packets.Kind.RECEPTION_FAILURE: interfaces.RECEPTION_FAILURE,
+    packets.Kind.TRANSMISSION_FAILURE: interfaces.TRANSMISSION_FAILURE,
+    packets.Kind.SERVICER_FAILURE: interfaces.SERVICER_FAILURE,
+    packets.Kind.SERVICED_FAILURE: interfaces.SERVICED_FAILURE,
+    }
+
+
+class _TerminationManager(_interfaces.TerminationManager):
+  """An implementation of _interfaces.TerminationManager."""
+
+  def __init__(
+      self, work_pool, utility_pool, action, requirements, local_failure):
+    """Constructor.
+
+    Args:
+      work_pool: A thread pool in which customer work will be done.
+      utility_pool: A thread pool in which work utility work will be done.
+      action: An action to call on operation termination.
+      requirements: A combination of _EMISSION, _TRANSMISSION, and _INGESTION
+        identifying what must finish for the operation to be considered
+        completed.
+      local_failure: A packets.Kind specifying what constitutes local failure of
+        customer work.
+    """
+    self._work_pool = work_pool
+    self._utility_pool = utility_pool
+    self._action = action
+    self._local_failure = local_failure
+    self._has_locally_failed = False
+
+    self._outstanding_requirements = set(requirements)
+    self._kind = None
+    self._callbacks = []
+
+  def _terminate(self, kind):
+    """Terminates the operation.
+
+    Args:
+      kind: One of packets.Kind.COMPLETION, packets.Kind.CANCELLATION,
+        packets.Kind.EXPIRATION, packets.Kind.RECEPTION_FAILURE,
+        packets.Kind.TRANSMISSION_FAILURE, packets.Kind.SERVICER_FAILURE, or
+        packets.Kind.SERVICED_FAILURE.
+    """
+    self._outstanding_requirements = None
+    callbacks = list(self._callbacks)
+    self._callbacks = None
+    self._kind = kind
+    outcome = _KINDS_TO_OUTCOMES[kind]
+
+    act = callable_util.with_exceptions_logged(
+        self._action, _constants.INTERNAL_ERROR_LOG_MESSAGE)
+
+    if self._has_locally_failed:
+      self._utility_pool.submit(act, outcome)
+    else:
+      def call_callbacks_and_act(callbacks, outcome):
+        for callback in callbacks:
+          callback_outcome = callable_util.call_logging_exceptions(
+              callback, _CALLBACK_EXCEPTION_LOG_MESSAGE, outcome)
+          if callback_outcome.exception is not None:
+            outcome = _KINDS_TO_OUTCOMES[self._local_failure]
+            break
+        self._utility_pool.submit(act, outcome)
+
+      self._work_pool.submit(callable_util.with_exceptions_logged(
+          call_callbacks_and_act,
+          _constants.INTERNAL_ERROR_LOG_MESSAGE),
+                             callbacks, outcome)
+
+  def is_active(self):
+    """See _interfaces.TerminationManager.is_active for specification."""
+    return self._outstanding_requirements is not None
+
+  def add_callback(self, callback):
+    """See _interfaces.TerminationManager.add_callback for specification."""
+    if not self._has_locally_failed:
+      if self._outstanding_requirements is None:
+        self._work_pool.submit(
+            callable_util.with_exceptions_logged(
+                callback, _CALLBACK_EXCEPTION_LOG_MESSAGE),
+            _KINDS_TO_OUTCOMES[self._kind])
+      else:
+        self._callbacks.append(callback)
+
+  def emission_complete(self):
+    """See superclass method for specification."""
+    if self._outstanding_requirements is not None:
+      self._outstanding_requirements.discard(_EMISSION)
+      if not self._outstanding_requirements:
+        self._terminate(packets.Kind.COMPLETION)
+
+  def transmission_complete(self):
+    """See superclass method for specification."""
+    if self._outstanding_requirements is not None:
+      self._outstanding_requirements.discard(_TRANSMISSION)
+      if not self._outstanding_requirements:
+        self._terminate(packets.Kind.COMPLETION)
+
+  def ingestion_complete(self):
+    """See superclass method for specification."""
+    if self._outstanding_requirements is not None:
+      self._outstanding_requirements.discard(_INGESTION)
+      if not self._outstanding_requirements:
+        self._terminate(packets.Kind.COMPLETION)
+
+  def abort(self, kind):
+    """See _interfaces.TerminationManager.abort for specification."""
+    if kind == self._local_failure:
+      self._has_failed_locally = True
+    if self._outstanding_requirements is not None:
+      self._terminate(kind)
+
+
+def front_termination_manager(work_pool, utility_pool, action, subscription):
+  """Creates a TerminationManager appropriate for front-side use.
+
+  Args:
+    work_pool: A thread pool in which customer work will be done.
+    utility_pool: A thread pool in which work utility work will be done.
+    action: An action to call on operation termination.
+    subscription: One of interfaces.FULL, interfaces.termination_only, or
+      interfaces.NONE.
+
+  Returns:
+    A TerminationManager appropriate for front-side use.
+  """
+  return _TerminationManager(
+      work_pool, utility_pool, action,
+      _FRONT_NOT_LISTENING_REQUIREMENTS if subscription == interfaces.NONE else
+      _LISTENING_REQUIREMENTS, packets.Kind.SERVICED_FAILURE)
+
+
+def back_termination_manager(work_pool, utility_pool, action, subscription):
+  """Creates a TerminationManager appropriate for back-side use.
+
+  Args:
+    work_pool: A thread pool in which customer work will be done.
+    utility_pool: A thread pool in which work utility work will be done.
+    action: An action to call on operation termination.
+    subscription: One of interfaces.FULL, interfaces.termination_only, or
+      interfaces.NONE.
+
+  Returns:
+    A TerminationManager appropriate for back-side use.
+  """
+  return _TerminationManager(
+      work_pool, utility_pool, action,
+      _BACK_NOT_LISTENING_REQUIREMENTS if subscription == interfaces.NONE else
+      _LISTENING_REQUIREMENTS, packets.Kind.SERVICER_FAILURE)
diff --git a/src/python/_framework/base/packets/_transmission.py b/src/python/_framework/base/packets/_transmission.py
new file mode 100644
index 0000000000..006128774d
--- /dev/null
+++ b/src/python/_framework/base/packets/_transmission.py
@@ -0,0 +1,393 @@
+# Copyright 2015, Google Inc.
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+"""State and behavior for packet transmission during an operation."""
+
+import abc
+
+from _framework.base import interfaces
+from _framework.base.packets import _constants
+from _framework.base.packets import _interfaces
+from _framework.base.packets import packets
+from _framework.foundation import callable_util
+
+_TRANSMISSION_EXCEPTION_LOG_MESSAGE = 'Exception during transmission!'
+
+_FRONT_TO_BACK_NO_TRANSMISSION_KINDS = (
+    packets.Kind.SERVICER_FAILURE,
+    )
+_BACK_TO_FRONT_NO_TRANSMISSION_KINDS = (
+    packets.Kind.CANCELLATION,
+    packets.Kind.SERVICED_FAILURE,
+    )
+
+
+class _Packetizer(object):
+  """Common specification of different packet-creating behavior."""
+  __metaclass__ = abc.ABCMeta
+
+  @abc.abstractmethod
+  def packetize(self, operation_id, sequence_number, payload, complete):
+    """Creates a packet indicating ordinary operation progress.
+
+    Args:
+      operation_id: The operation ID for the current operation.
+      sequence_number: A sequence number for the packet.
+      payload: A customer payload object. May be None if sequence_number is
+        zero or complete is true.
+      complete: A boolean indicating whether or not the packet should describe
+        itself as (but for a later indication of operation abortion) the last
+        packet to be sent.
+
+    Returns:
+      An object of an appropriate type suitable for transmission to the other
+        side of the operation.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def packetize_abortion(self, operation_id, sequence_number, kind):
+    """Creates a packet indicating that the operation is aborted.
+
+    Args:
+      operation_id: The operation ID for the current operation.
+      sequence_number: A sequence number for the packet.
+      kind: One of the values of packets.Kind indicating operational abortion.
+
+    Returns:
+      An object of an appropriate type suitable for transmission to the other
+        side of the operation, or None if transmission is not appropriate for
+        the given kind.
+    """
+    raise NotImplementedError()
+
+
+class _FrontPacketizer(_Packetizer):
+  """Front-side packet-creating behavior."""
+
+  def __init__(self, name, subscription, trace_id, timeout):
+    """Constructor.
+
+    Args:
+      name: The name of the operation.
+      subscription: One of interfaces.FULL, interfaces.TERMINATION_ONLY, or
+        interfaces.NONE describing the interest the front has in packets sent
+        from the back.
+      trace_id: A uuid.UUID identifying a set of related operations to which
+        this operation belongs.
+      timeout: A length of time in seconds to allow for the entire operation.
+    """
+    self._name = name
+    self._subscription = subscription
+    self._trace_id = trace_id
+    self._timeout = timeout
+
+  def packetize(self, operation_id, sequence_number, payload, complete):
+    """See _Packetizer.packetize for specification."""
+    if sequence_number:
+      return packets.FrontToBackPacket(
+          operation_id, sequence_number,
+          packets.Kind.COMPLETION if complete else packets.Kind.CONTINUATION,
+          self._name, self._subscription, self._trace_id, payload,
+          self._timeout)
+    else:
+      return packets.FrontToBackPacket(
+          operation_id, 0,
+          packets.Kind.ENTIRE if complete else packets.Kind.COMMENCEMENT,
+          self._name, self._subscription, self._trace_id, payload,
+          self._timeout)
+
+  def packetize_abortion(self, operation_id, sequence_number, kind):
+    """See _Packetizer.packetize_abortion for specification."""
+    if kind in _FRONT_TO_BACK_NO_TRANSMISSION_KINDS:
+      return None
+    else:
+      return packets.FrontToBackPacket(
+          operation_id, sequence_number, kind, None, None, None, None, None)
+
+
+class _BackPacketizer(_Packetizer):
+  """Back-side packet-creating behavior."""
+
+  def packetize(self, operation_id, sequence_number, payload, complete):
+    """See _Packetizer.packetize for specification."""
+    return packets.BackToFrontPacket(
+        operation_id, sequence_number,
+        packets.Kind.COMPLETION if complete else packets.Kind.CONTINUATION,
+        payload)
+
+  def packetize_abortion(self, operation_id, sequence_number, kind):
+    """See _Packetizer.packetize_abortion for specification."""
+    if kind in _BACK_TO_FRONT_NO_TRANSMISSION_KINDS:
+      return None
+    else:
+      return packets.BackToFrontPacket(
+          operation_id, sequence_number, kind, None)
+
+
+class TransmissionManager(_interfaces.TransmissionManager):
+  """A _interfaces.TransmissionManager on which other managers may be set."""
+  __metaclass__ = abc.ABCMeta
+
+  @abc.abstractmethod
+  def set_ingestion_and_expiration_managers(
+      self, ingestion_manager, expiration_manager):
+    """Sets two of the other managers with which this manager may interact.
+
+    Args:
+      ingestion_manager: The _interfaces.IngestionManager associated with the
+        current operation.
+      expiration_manager: The _interfaces.ExpirationManager associated with the
+        current operation.
+    """
+    raise NotImplementedError()
+
+
+class _EmptyTransmissionManager(TransmissionManager):
+  """A completely no-operative _interfaces.TransmissionManager."""
+
+  def set_ingestion_and_expiration_managers(
+      self, ingestion_manager, expiration_manager):
+    """See overriden method for specification."""
+
+  def inmit(self, emission, complete):
+    """See _interfaces.TransmissionManager.inmit for specification."""
+
+  def abort(self, category):
+    """See _interfaces.TransmissionManager.abort for specification."""
+
+
+class _TransmittingTransmissionManager(TransmissionManager):
+  """A TransmissionManager implementation that sends packets."""
+
+  def __init__(
+      self, lock, pool, callback, operation_id, packetizer,
+      termination_manager):
+    """Constructor.
+
+    Args:
+      lock: The operation-servicing-wide lock object.
+      pool: A thread pool in which the work of transmitting packets will be
+        performed.
+      callback: A callable that accepts packets and sends them to the other side
+        of the operation.
+      operation_id: The operation's ID.
+      packetizer: A _Packetizer for packet creation.
+      termination_manager: The _interfaces.TerminationManager associated with
+        this operation.
+    """
+    self._lock = lock
+    self._pool = pool
+    self._callback = callback
+    self._operation_id = operation_id
+    self._packetizer = packetizer
+    self._termination_manager = termination_manager
+    self._ingestion_manager = None
+    self._expiration_manager = None
+
+    self._emissions = []
+    self._emission_complete = False
+    self._kind = None
+    self._lowest_unused_sequence_number = 0
+    self._transmitting = False
+
+  def set_ingestion_and_expiration_managers(
+      self, ingestion_manager, expiration_manager):
+    """See overridden method for specification."""
+    self._ingestion_manager = ingestion_manager
+    self._expiration_manager = expiration_manager
+
+  def _lead_packet(self, emission, complete):
+    """Creates a packet suitable for leading off the transmission loop.
+
+    Args:
+      emission: A customer payload object to be sent to the other side of the
+        operation.
+      complete: Whether or not the sequence of customer payloads ends with
+        the passed object.
+
+    Returns:
+      A packet with which to lead off the transmission loop.
+    """
+    sequence_number = self._lowest_unused_sequence_number
+    self._lowest_unused_sequence_number += 1
+    return self._packetizer.packetize(
+        self._operation_id, sequence_number, emission, complete)
+
+  def _abortive_response_packet(self, kind):
+    """Creates a packet indicating operation abortion.
+
+    Args:
+      kind: One of the values of packets.Kind indicating operational abortion.
+
+    Returns:
+      A packet indicating operation abortion.
+    """
+    packet = self._packetizer.packetize_abortion(
+        self._operation_id, self._lowest_unused_sequence_number, kind)
+    if packet is None:
+      return None
+    else:
+      self._lowest_unused_sequence_number += 1
+      return packet
+
+  def _next_packet(self):
+    """Creates the next packet to be sent to the other side of the operation.
+
+    Returns:
+      A (completed, packet) tuple comprised of a boolean indicating whether or
+        not the sequence of packets has completed normally and a packet to send
+        to the other side if the sequence of packets hasn't completed. The tuple
+        will never have both a True first element and a non-None second element.
+    """
+    if self._emissions is None:
+      return False, None
+    elif self._kind is None:
+      if self._emissions:
+        payload = self._emissions.pop(0)
+        complete = self._emission_complete and not self._emissions
+        sequence_number = self._lowest_unused_sequence_number
+        self._lowest_unused_sequence_number += 1
+        return complete, self._packetizer.packetize(
+            self._operation_id, sequence_number, payload, complete)
+      else:
+        return self._emission_complete, None
+    else:
+      packet = self._abortive_response_packet(self._kind)
+      self._emissions = None
+      return False, None if packet is None else packet
+
+  def _transmit(self, packet):
+    """Commences the transmission loop sending packets.
+
+    Args:
+      packet: A packet to be sent to the other side of the operation.
+    """
+    def transmit(packet):
+      while True:
+        transmission_outcome = callable_util.call_logging_exceptions(
+            self._callback, _TRANSMISSION_EXCEPTION_LOG_MESSAGE, packet)
+        if transmission_outcome.exception is None:
+          with self._lock:
+            complete, packet = self._next_packet()
+            if packet is None:
+              if complete:
+                self._termination_manager.transmission_complete()
+              self._transmitting = False
+              return
+        else:
+          with self._lock:
+            self._emissions = None
+            self._termination_manager.abort(packets.Kind.TRANSMISSION_FAILURE)
+            self._ingestion_manager.abort()
+            self._expiration_manager.abort()
+            self._transmitting = False
+            return
+
+    self._pool.submit(callable_util.with_exceptions_logged(
+        transmit, _constants.INTERNAL_ERROR_LOG_MESSAGE), packet)
+    self._transmitting = True
+
+  def inmit(self, emission, complete):
+    """See _interfaces.TransmissionManager.inmit for specification."""
+    if self._emissions is not None and self._kind is None:
+      self._emission_complete = complete
+      if self._transmitting:
+        self._emissions.append(emission)
+      else:
+        self._transmit(self._lead_packet(emission, complete))
+
+  def abort(self, kind):
+    """See _interfaces.TransmissionManager.abort for specification."""
+    if self._emissions is not None and self._kind is None:
+      self._kind = kind
+      if not self._transmitting:
+        packet = self._abortive_response_packet(kind)
+        self._emissions = None
+        if packet is not None:
+          self._transmit(packet)
+
+
+def front_transmission_manager(
+    lock, pool, callback, operation_id, name, subscription, trace_id, timeout,
+    termination_manager):
+  """Creates a TransmissionManager appropriate for front-side use.
+
+  Args:
+    lock: The operation-servicing-wide lock object.
+    pool: A thread pool in which the work of transmitting packets will be
+      performed.
+    callback: A callable that accepts packets and sends them to the other side
+      of the operation.
+    operation_id: The operation's ID.
+    name: The name of the operation.
+    subscription: One of interfaces.FULL, interfaces.TERMINATION_ONLY, or
+      interfaces.NONE describing the interest the front has in packets sent
+      from the back.
+    trace_id: A uuid.UUID identifying a set of related operations to which
+      this operation belongs.
+    timeout: A length of time in seconds to allow for the entire operation.
+    termination_manager: The _interfaces.TerminationManager associated with
+      this operation.
+
+  Returns:
+    A TransmissionManager appropriate for front-side use.
+  """
+  return _TransmittingTransmissionManager(
+      lock, pool, callback, operation_id, _FrontPacketizer(
+          name, subscription, trace_id, timeout),
+      termination_manager)
+
+
+def back_transmission_manager(
+    lock, pool, callback, operation_id, termination_manager, subscription):
+  """Creates a TransmissionManager appropriate for back-side use.
+
+  Args:
+    lock: The operation-servicing-wide lock object.
+    pool: A thread pool in which the work of transmitting packets will be
+      performed.
+    callback: A callable that accepts packets and sends them to the other side
+      of the operation.
+    operation_id: The operation's ID.
+    termination_manager: The _interfaces.TerminationManager associated with
+      this operation.
+    subscription: One of interfaces.FULL, interfaces.TERMINATION_ONLY, or
+      interfaces.NONE describing the interest the front has in packets sent from
+      the back.
+
+  Returns:
+    A TransmissionManager appropriate for back-side use.
+  """
+  if subscription == interfaces.NONE:
+    return _EmptyTransmissionManager()
+  else:
+    return _TransmittingTransmissionManager(
+        lock, pool, callback, operation_id, _BackPacketizer(),
+        termination_manager)
diff --git a/src/python/_framework/base/packets/implementations.py b/src/python/_framework/base/packets/implementations.py
new file mode 100644
index 0000000000..2f07054d4d
--- /dev/null
+++ b/src/python/_framework/base/packets/implementations.py
@@ -0,0 +1,77 @@
+# Copyright 2015, Google Inc.
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+"""Entry points into the packet-exchange-based implementation the base layer."""
+
+# interfaces is referenced from specification in this module.
+from _framework.base.packets import _ends
+from _framework.base.packets import interfaces  # pylint: disable=unused-import
+
+
+def front(work_pool, transmission_pool, utility_pool):
+  """Factory function for creating interfaces.Fronts.
+
+  Args:
+    work_pool: A thread pool to be used for doing work within the created Front
+      object.
+    transmission_pool: A thread pool to be used within the created Front object
+      for transmitting values to some Back object.
+    utility_pool: A thread pool to be used within the created Front object for
+      utility tasks.
+
+  Returns:
+    An interfaces.Front.
+  """
+  return _ends.Front(work_pool, transmission_pool, utility_pool)
+
+
+def back(
+    servicer, work_pool, transmission_pool, utility_pool, default_timeout,
+    maximum_timeout):
+  """Factory function for creating interfaces.Backs.
+
+  Args:
+    servicer: An interfaces.Servicer for servicing operations.
+    work_pool: A thread pool to be used for doing work within the created Back
+      object.
+    transmission_pool: A thread pool to be used within the created Back object
+      for transmitting values to some Front object.
+    utility_pool: A thread pool to be used within the created Back object for
+      utility tasks.
+    default_timeout: A length of time in seconds to be used as the default
+      time alloted for a single operation.
+    maximum_timeout: A length of time in seconds to be used as the maximum
+      time alloted for a single operation.
+
+  Returns:
+    An interfaces.Back.
+  """
+  return _ends.Back(
+      servicer, work_pool, transmission_pool, utility_pool, default_timeout,
+      maximum_timeout)
diff --git a/src/python/_framework/base/packets/implementations_test.py b/src/python/_framework/base/packets/implementations_test.py
new file mode 100644
index 0000000000..8bb5353176
--- /dev/null
+++ b/src/python/_framework/base/packets/implementations_test.py
@@ -0,0 +1,80 @@
+# Copyright 2015, Google Inc.
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+"""Tests for _framework.base.packets.implementations."""
+
+import unittest
+
+from _framework.base import interfaces_test
+from _framework.base import util
+from _framework.base.packets import implementations
+from _framework.foundation import logging_pool
+
+POOL_MAX_WORKERS = 100
+DEFAULT_TIMEOUT = 30
+MAXIMUM_TIMEOUT = 60
+
+
+class ImplementationsTest(
+    interfaces_test.FrontAndBackTest, unittest.TestCase):
+
+  def setUp(self):
+    self.memory_transmission_pool = logging_pool.pool(POOL_MAX_WORKERS)
+    self.front_work_pool = logging_pool.pool(POOL_MAX_WORKERS)
+    self.front_transmission_pool = logging_pool.pool(POOL_MAX_WORKERS)
+    self.front_utility_pool = logging_pool.pool(POOL_MAX_WORKERS)
+    self.back_work_pool = logging_pool.pool(POOL_MAX_WORKERS)
+    self.back_transmission_pool = logging_pool.pool(POOL_MAX_WORKERS)
+    self.back_utility_pool = logging_pool.pool(POOL_MAX_WORKERS)
+    self.test_pool = logging_pool.pool(POOL_MAX_WORKERS)
+    self.test_servicer = interfaces_test.TestServicer(self.test_pool)
+    self.front = implementations.front(
+        self.front_work_pool, self.front_transmission_pool,
+        self.front_utility_pool)
+    self.back = implementations.back(
+        self.test_servicer, self.back_work_pool, self.back_transmission_pool,
+        self.back_utility_pool, DEFAULT_TIMEOUT, MAXIMUM_TIMEOUT)
+    self.front.join_rear_link(self.back)
+    self.back.join_fore_link(self.front)
+
+  def tearDown(self):
+    util.wait_for_idle(self.back)
+    util.wait_for_idle(self.front)
+    self.memory_transmission_pool.shutdown(wait=True)
+    self.front_work_pool.shutdown(wait=True)
+    self.front_transmission_pool.shutdown(wait=True)
+    self.front_utility_pool.shutdown(wait=True)
+    self.back_work_pool.shutdown(wait=True)
+    self.back_transmission_pool.shutdown(wait=True)
+    self.back_utility_pool.shutdown(wait=True)
+    self.test_pool.shutdown(wait=True)
+
+
+if __name__ == '__main__':
+  unittest.main()
diff --git a/src/python/_framework/base/packets/in_memory.py b/src/python/_framework/base/packets/in_memory.py
new file mode 100644
index 0000000000..17daf3acf7
--- /dev/null
+++ b/src/python/_framework/base/packets/in_memory.py
@@ -0,0 +1,108 @@
+# Copyright 2015, Google Inc.
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+"""Entry points into the packet-exchange-based implementation the base layer."""
+
+import threading
+
+from _framework.base.packets import _constants
+from _framework.base.packets import interfaces
+from _framework.foundation import callable_util
+
+
+class _Serializer(object):
+  """A utility for serializing values that may arrive concurrently."""
+
+  def __init__(self, pool):
+    self._lock = threading.Lock()
+    self._pool = pool
+    self._sink = None
+    self._spinning = False
+    self._values = []
+
+  def _spin(self, sink, value):
+    while True:
+      sink(value)
+      with self._lock:
+        if self._sink is None or not self._values:
+          self._spinning = False
+          return
+        else:
+          sink, value = self._sink, self._values.pop(0)
+
+  def set_sink(self, sink):
+    with self._lock:
+      self._sink = sink
+      if sink is not None and self._values and not self._spinning:
+        self._spinning = True
+        self._pool.submit(
+            callable_util.with_exceptions_logged(
+                self._spin, _constants.INTERNAL_ERROR_LOG_MESSAGE),
+            sink, self._values.pop(0))
+
+  def add_value(self, value):
+    with self._lock:
+      if self._sink and not self._spinning:
+        self._spinning = True
+        self._pool.submit(
+            callable_util.with_exceptions_logged(
+                self._spin, _constants.INTERNAL_ERROR_LOG_MESSAGE),
+            self._sink, value)
+      else:
+        self._values.append(value)
+
+
+class Link(interfaces.ForeLink, interfaces.RearLink):
+  """A trivial implementation of interfaces.ForeLink and interfaces.RearLink."""
+
+  def __init__(self, pool):
+    """Constructor.
+
+    Args:
+      pool: A thread pool to be used for serializing ticket exchange in each
+        direction.
+    """
+    self._front_to_back = _Serializer(pool)
+    self._back_to_front = _Serializer(pool)
+
+  def join_fore_link(self, fore_link):
+    """See interfaces.RearLink.join_fore_link for specification."""
+    self._back_to_front.set_sink(fore_link.accept_back_to_front_ticket)
+
+  def join_rear_link(self, rear_link):
+    """See interfaces.ForeLink.join_rear_link for specification."""
+    self._front_to_back.set_sink(rear_link.accept_front_to_back_ticket)
+
+  def accept_front_to_back_ticket(self, ticket):
+    """See interfaces.ForeLink.accept_front_to_back_ticket for specification."""
+    self._front_to_back.add_value(ticket)
+
+  def accept_back_to_front_ticket(self, ticket):
+    """See interfaces.RearLink.accept_back_to_front_ticket for specification."""
+    self._back_to_front.add_value(ticket)
diff --git a/src/python/_framework/base/packets/interfaces.py b/src/python/_framework/base/packets/interfaces.py
new file mode 100644
index 0000000000..99f9e87772
--- /dev/null
+++ b/src/python/_framework/base/packets/interfaces.py
@@ -0,0 +1,84 @@
+# Copyright 2015, Google Inc.
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+"""Interfaces defined and used by the base layer of RPC Framework."""
+
+import abc
+
+# packets is referenced from specifications in this module.
+from _framework.base import interfaces
+from _framework.base.packets import packets  # pylint: disable=unused-import
+
+
+class ForeLink(object):
+  """Accepts back-to-front tickets and emits front-to-back tickets."""
+  __metaclass__ = abc.ABCMeta
+
+  @abc.abstractmethod
+  def accept_back_to_front_ticket(self, ticket):
+    """Accept a packets.BackToFrontPacket.
+
+    Args:
+      ticket: Any packets.BackToFrontPacket.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def join_rear_link(self, rear_link):
+    """Mates this object with a peer with which it will exchange tickets."""
+    raise NotImplementedError()
+
+
+class RearLink(object):
+  """Accepts front-to-back tickets and emits back-to-front tickets."""
+  __metaclass__ = abc.ABCMeta
+
+  @abc.abstractmethod
+  def accept_front_to_back_ticket(self, ticket):
+    """Accepts a packets.FrontToBackPacket.
+
+    Args:
+      ticket: Any packets.FrontToBackPacket.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def join_fore_link(self, fore_link):
+    """Mates this object with a peer with which it will exchange tickets."""
+    raise NotImplementedError()
+
+
+class Front(ForeLink, interfaces.Front):
+  """Clientish objects that operate by sending and receiving tickets."""
+  __metaclass__ = abc.ABCMeta
+
+
+class Back(RearLink, interfaces.Back):
+  """Serverish objects that operate by sending and receiving tickets."""
+  __metaclass__ = abc.ABCMeta
diff --git a/src/python/_framework/base/packets/null.py b/src/python/_framework/base/packets/null.py
new file mode 100644
index 0000000000..9b40a00505
--- /dev/null
+++ b/src/python/_framework/base/packets/null.py
@@ -0,0 +1,56 @@
+# Copyright 2015, Google Inc.
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+"""Null links that ignore tickets passed to them."""
+
+from _framework.base.packets import interfaces
+
+
+class _NullForeLink(interfaces.ForeLink):
+  """A do-nothing ForeLink."""
+
+  def accept_back_to_front_ticket(self, ticket):
+    pass
+
+  def join_rear_link(self, rear_link):
+    raise NotImplementedError()
+
+
+class _NullRearLink(interfaces.RearLink):
+  """A do-nothing RearLink."""
+
+  def accept_front_to_back_ticket(self, ticket):
+    pass
+
+  def join_fore_link(self, fore_link):
+    raise NotImplementedError()
+
+
+NULL_FORE_LINK = _NullForeLink()
+NULL_REAR_LINK = _NullRearLink()
diff --git a/src/python/_framework/base/packets/packets.py b/src/python/_framework/base/packets/packets.py
new file mode 100644
index 0000000000..1315ca650e
--- /dev/null
+++ b/src/python/_framework/base/packets/packets.py
@@ -0,0 +1,112 @@
+# Copyright 2015, Google Inc.
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+"""Packets used between fronts and backs."""
+
+import collections
+import enum
+
+# interfaces is referenced from specifications in this module.
+from _framework.base import interfaces  # pylint: disable=unused-import
+
+
+@enum.unique
+class Kind(enum.Enum):
+  """Identifies the overall kind of a ticket."""
+
+  COMMENCEMENT = 'commencement'
+  CONTINUATION = 'continuation'
+  COMPLETION = 'completion'
+  ENTIRE = 'entire'
+  CANCELLATION = 'cancellation'
+  EXPIRATION = 'expiration'
+  SERVICER_FAILURE = 'servicer failure'
+  SERVICED_FAILURE = 'serviced failure'
+  RECEPTION_FAILURE = 'reception failure'
+  TRANSMISSION_FAILURE = 'transmission failure'
+
+
+class FrontToBackPacket(
+    collections.namedtuple(
+        'FrontToBackPacket',
+        ['operation_id', 'sequence_number', 'kind', 'name', 'subscription',
+         'trace_id', 'payload', 'timeout'])):
+  """A sum type for all values sent from a front to a back.
+
+  Attributes:
+    operation_id: A unique-with-respect-to-equality hashable object identifying
+      a particular operation.
+    sequence_number: A zero-indexed integer sequence number identifying the
+      packet's place among all the packets sent from front to back for this
+      particular operation. Must be zero if kind is Kind.COMMENCEMENT or
+      Kind.ENTIRE. Must be positive for any other kind.
+    kind: One of Kind.COMMENCEMENT, Kind.CONTINUATION, Kind.COMPLETION,
+      Kind.ENTIRE, Kind.CANCELLATION, Kind.EXPIRATION, Kind.SERVICED_FAILURE,
+      Kind.RECEPTION_FAILURE, or Kind.TRANSMISSION_FAILURE.
+    name: The name of an operation. Must be present if kind is Kind.COMMENCEMENT
+      or Kind.ENTIRE. Must be None for any other kind.
+    subscription: One of interfaces.FULL, interfaces.TERMINATION_ONLY, or
+      interfaces.NONE describing the interest the front has in packets sent from
+      the back. Must be present if kind is Kind.COMMENCEMENT or Kind.ENTIRE.
+      Must be None for any other kind.
+    trace_id: A uuid.UUID identifying a set of related operations to which this
+      operation belongs. May be None.
+    payload: A customer payload object. Must be present if kind is
+      Kind.CONTINUATION. Must be None if kind is Kind.CANCELLATION. May be None
+      for any other kind.
+    timeout: An optional length of time (measured from the beginning of the
+      operation) to allow for the entire operation. If None, a default value on
+      the back will be used. If present and excessively large, the back may
+      limit the operation to a smaller duration of its choice. May be present
+      for any ticket kind; setting a value on a later ticket allows fronts
+      to request time extensions (or even time reductions!) on in-progress
+      operations.
+  """
+
+
+class BackToFrontPacket(
+    collections.namedtuple(
+        'BackToFrontPacket',
+        ['operation_id', 'sequence_number', 'kind', 'payload'])):
+  """A sum type for all values sent from a back to a front.
+
+  Attributes:
+    operation_id: A unique-with-respect-to-equality hashable object identifying
+      a particular operation.
+    sequence_number: A zero-indexed integer sequence number identifying the
+      packet's place among all the packets sent from back to front for this
+      particular operation.
+    kind: One of Kind.CONTINUATION, Kind.COMPLETION, Kind.EXPIRATION,
+      Kind.SERVICER_FAILURE, Kind.RECEPTION_FAILURE, or
+      Kind.TRANSMISSION_FAILURE.
+    payload: A customer payload object. Must be present if kind is
+      Kind.CONTINUATION. May be None if kind is Kind.COMPLETION. Must be None if
+      kind is Kind.EXPIRATION, Kind.SERVICER_FAILURE, Kind.RECEPTION_FAILURE, or
+      Kind.TRANSMISSION_FAILURE.
+  """
diff --git a/src/python/_framework/base/util.py b/src/python/_framework/base/util.py
new file mode 100644
index 0000000000..6bbd18a59a
--- /dev/null
+++ b/src/python/_framework/base/util.py
@@ -0,0 +1,91 @@
+# Copyright 2015, Google Inc.
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+"""Utilities helpful for working with the base layer of RPC Framework."""
+
+import collections
+import threading
+
+from _framework.base import interfaces
+
+
+class _ServicedSubscription(
+    collections.namedtuple('_ServicedSubscription', ['category', 'ingestor']),
+    interfaces.ServicedSubscription):
+  """See interfaces.ServicedSubscription for specification."""
+
+_NONE_SUBSCRIPTION = _ServicedSubscription(interfaces.NONE, None)
+_TERMINATION_ONLY_SUBSCRIPTION = _ServicedSubscription(
+    interfaces.TERMINATION_ONLY, None)
+
+
+def none_serviced_subscription():
+  """Creates a "none" interfaces.ServicedSubscription object.
+
+  Returns:
+    An interfaces.ServicedSubscription indicating no subscription to an
+      operation's results (such as would be the case for a fire-and-forget
+      operation invocation).
+  """
+  return _NONE_SUBSCRIPTION
+
+
+def termination_only_serviced_subscription():
+  """Creates a "termination only" interfaces.ServicedSubscription object.
+
+  Returns:
+    An interfaces.ServicedSubscription indicating that the front-side customer
+      is interested only in the overall termination outcome of the operation
+      (such as completion or expiration) and would ignore the actual results of
+      the operation.
+  """
+  return _TERMINATION_ONLY_SUBSCRIPTION
+
+
+def full_serviced_subscription(ingestor):
+  """Creates a "full" interfaces.ServicedSubscription object.
+
+  Args:
+    ingestor: A ServicedIngestor.
+
+  Returns:
+    A ServicedSubscription object indicating a full subscription.
+  """
+  return _ServicedSubscription(interfaces.FULL, ingestor)
+
+
+def wait_for_idle(end):
+  """Waits for an interfaces.End to complete all operations.
+
+  Args:
+    end: Any interfaces.End.
+  """
+  event = threading.Event()
+  end.add_idle_action(event.set)
+  event.wait()
diff --git a/src/python/_framework/common/__init__.py b/src/python/_framework/common/__init__.py
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/src/python/_framework/common/__init__.py
diff --git a/src/python/_framework/common/cardinality.py b/src/python/_framework/common/cardinality.py
new file mode 100644
index 0000000000..610425e803
--- /dev/null
+++ b/src/python/_framework/common/cardinality.py
@@ -0,0 +1,42 @@
+# Copyright 2015, Google Inc.
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+"""Defines an enum for classifying RPC methods by streaming semantics."""
+
+import enum
+
+
+@enum.unique
+class Cardinality(enum.Enum):
+  """Describes the streaming semantics of an RPC method."""
+
+  UNARY_UNARY = 'request-unary/response-unary'
+  UNARY_STREAM = 'request-unary/response-streaming'
+  STREAM_UNARY = 'request-streaming/response-unary'
+  STREAM_STREAM = 'request-streaming/response-streaming'
diff --git a/src/python/_framework/face/__init__.py b/src/python/_framework/face/__init__.py
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/src/python/_framework/face/__init__.py
diff --git a/src/python/_framework/face/_calls.py b/src/python/_framework/face/_calls.py
new file mode 100644
index 0000000000..ab58e6378b
--- /dev/null
+++ b/src/python/_framework/face/_calls.py
@@ -0,0 +1,310 @@
+# Copyright 2015, Google Inc.
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+"""Utility functions for invoking RPCs."""
+
+import threading
+
+from _framework.base import interfaces as base_interfaces
+from _framework.base import util as base_util
+from _framework.face import _control
+from _framework.face import interfaces
+from _framework.foundation import callable_util
+from _framework.foundation import future
+
+_ITERATOR_EXCEPTION_LOG_MESSAGE = 'Exception iterating over requests!'
+_DONE_CALLBACK_LOG_MESSAGE = 'Exception calling Future "done" callback!'
+
+
+class _RendezvousServicedIngestor(base_interfaces.ServicedIngestor):
+
+  def __init__(self, rendezvous):
+    self._rendezvous = rendezvous
+
+  def consumer(self, operation_context):
+    return self._rendezvous
+
+
+class _EventServicedIngestor(base_interfaces.ServicedIngestor):
+
+  def __init__(self, result_consumer, abortion_callback):
+    self._result_consumer = result_consumer
+    self._abortion_callback = abortion_callback
+
+  def consumer(self, operation_context):
+    operation_context.add_termination_callback(
+        _control.as_operation_termination_callback(self._abortion_callback))
+    return self._result_consumer
+
+
+def _rendezvous_subscription(rendezvous):
+  return base_util.full_serviced_subscription(
+      _RendezvousServicedIngestor(rendezvous))
+
+
+def _unary_event_subscription(completion_callback, abortion_callback):
+  return base_util.full_serviced_subscription(
+      _EventServicedIngestor(
+          _control.UnaryConsumer(completion_callback), abortion_callback))
+
+
+def _stream_event_subscription(result_consumer, abortion_callback):
+  return base_util.full_serviced_subscription(
+      _EventServicedIngestor(result_consumer, abortion_callback))
+
+
+class _OperationCancellableIterator(interfaces.CancellableIterator):
+  """An interfaces.CancellableIterator for response-streaming operations."""
+
+  def __init__(self, rendezvous, operation):
+    self._rendezvous = rendezvous
+    self._operation = operation
+
+  def __iter__(self):
+    return self
+
+  def next(self):
+    return next(self._rendezvous)
+
+  def cancel(self):
+    self._operation.cancel()
+    self._rendezvous.set_outcome(base_interfaces.CANCELLED)
+
+
+class _OperationFuture(future.Future):
+  """A future.Future interface to an operation."""
+
+  def __init__(self, rendezvous, operation):
+    self._condition = threading.Condition()
+    self._rendezvous = rendezvous
+    self._operation = operation
+
+    self._outcome = None
+    self._callbacks = []
+
+  def cancel(self):
+    """See future.Future.cancel for specification."""
+    with self._condition:
+      if self._outcome is None:
+        self._operation.cancel()
+        self._outcome = future.aborted()
+        self._condition.notify_all()
+    return False
+
+  def cancelled(self):
+    """See future.Future.cancelled for specification."""
+    return False
+
+  def done(self):
+    """See future.Future.done for specification."""
+    with self._condition:
+      return (self._outcome is not None and
+              self._outcome.category is not future.ABORTED)
+
+  def outcome(self):
+    """See future.Future.outcome for specification."""
+    with self._condition:
+      while self._outcome is None:
+        self._condition.wait()
+      return self._outcome
+
+  def add_done_callback(self, callback):
+    """See future.Future.add_done_callback for specification."""
+    with self._condition:
+      if self._callbacks is not None:
+        self._callbacks.add(callback)
+        return
+
+      outcome = self._outcome
+
+    callable_util.call_logging_exceptions(
+        callback, _DONE_CALLBACK_LOG_MESSAGE, outcome)
+
+  def on_operation_termination(self, operation_outcome):
+    """Indicates to this object that the operation has terminated.
+
+    Args:
+      operation_outcome: One of base_interfaces.COMPLETED,
+        base_interfaces.CANCELLED, base_interfaces.EXPIRED,
+        base_interfaces.RECEPTION_FAILURE, base_interfaces.TRANSMISSION_FAILURE,
+        base_interfaces.SERVICED_FAILURE, or base_interfaces.SERVICER_FAILURE
+        indicating the categorical outcome of the operation.
+    """
+    with self._condition:
+      if (self._outcome is None and
+          operation_outcome != base_interfaces.COMPLETED):
+        self._outcome = future.raised(
+            _control.abortion_outcome_to_exception(operation_outcome))
+        self._condition.notify_all()
+
+      outcome = self._outcome
+      rendezvous = self._rendezvous
+      callbacks = list(self._callbacks)
+      self._callbacks = None
+
+    if outcome is None:
+      try:
+        return_value = next(rendezvous)
+      except Exception as e:  # pylint: disable=broad-except
+        outcome = future.raised(e)
+      else:
+        outcome = future.returned(return_value)
+      with self._condition:
+        if self._outcome is None:
+          self._outcome = outcome
+          self._condition.notify_all()
+        else:
+          outcome = self._outcome
+
+    for callback in callbacks:
+      callable_util.call_logging_exceptions(
+          callback, _DONE_CALLBACK_LOG_MESSAGE, outcome)
+
+
+class _Call(interfaces.Call):
+
+  def __init__(self, operation):
+    self._operation = operation
+    self.context = _control.RpcContext(operation.context)
+
+  def cancel(self):
+    self._operation.cancel()
+
+
+def blocking_value_in_value_out(front, name, payload, timeout, trace_id):
+  """Services in a blocking fashion a value-in value-out servicer method."""
+  rendezvous = _control.Rendezvous()
+  subscription = _rendezvous_subscription(rendezvous)
+  operation = front.operate(
+      name, payload, True, timeout, subscription, trace_id)
+  operation.context.add_termination_callback(rendezvous.set_outcome)
+  return next(rendezvous)
+
+
+def future_value_in_value_out(front, name, payload, timeout, trace_id):
+  """Services a value-in value-out servicer method by returning a Future."""
+  rendezvous = _control.Rendezvous()
+  subscription = _rendezvous_subscription(rendezvous)
+  operation = front.operate(
+      name, payload, True, timeout, subscription, trace_id)
+  operation.context.add_termination_callback(rendezvous.set_outcome)
+  operation_future = _OperationFuture(rendezvous, operation)
+  operation.context.add_termination_callback(
+      operation_future.on_operation_termination)
+  return operation_future
+
+
+def inline_value_in_stream_out(front, name, payload, timeout, trace_id):
+  """Services a value-in stream-out servicer method."""
+  rendezvous = _control.Rendezvous()
+  subscription = _rendezvous_subscription(rendezvous)
+  operation = front.operate(
+      name, payload, True, timeout, subscription, trace_id)
+  operation.context.add_termination_callback(rendezvous.set_outcome)
+  return _OperationCancellableIterator(rendezvous, operation)
+
+
+def blocking_stream_in_value_out(
+    front, name, payload_iterator, timeout, trace_id):
+  """Services in a blocking fashion a stream-in value-out servicer method."""
+  rendezvous = _control.Rendezvous()
+  subscription = _rendezvous_subscription(rendezvous)
+  operation = front.operate(name, None, False, timeout, subscription, trace_id)
+  operation.context.add_termination_callback(rendezvous.set_outcome)
+  for payload in payload_iterator:
+    operation.consumer.consume(payload)
+  operation.consumer.terminate()
+  return next(rendezvous)
+
+
+def future_stream_in_value_out(
+    front, name, payload_iterator, timeout, trace_id, pool):
+  """Services a stream-in value-out servicer method by returning a Future."""
+  rendezvous = _control.Rendezvous()
+  subscription = _rendezvous_subscription(rendezvous)
+  operation = front.operate(name, None, False, timeout, subscription, trace_id)
+  operation.context.add_termination_callback(rendezvous.set_outcome)
+  pool.submit(
+      callable_util.with_exceptions_logged(
+          _control.pipe_iterator_to_consumer, _ITERATOR_EXCEPTION_LOG_MESSAGE),
+      payload_iterator, operation.consumer, lambda: True, True)
+  operation_future = _OperationFuture(rendezvous, operation)
+  operation.context.add_termination_callback(
+      operation_future.on_operation_termination)
+  return operation_future
+
+
+def inline_stream_in_stream_out(
+    front, name, payload_iterator, timeout, trace_id, pool):
+  """Services a stream-in stream-out servicer method."""
+  rendezvous = _control.Rendezvous()
+  subscription = _rendezvous_subscription(rendezvous)
+  operation = front.operate(name, None, False, timeout, subscription, trace_id)
+  operation.context.add_termination_callback(rendezvous.set_outcome)
+  pool.submit(
+      callable_util.with_exceptions_logged(
+          _control.pipe_iterator_to_consumer, _ITERATOR_EXCEPTION_LOG_MESSAGE),
+      payload_iterator, operation.consumer, lambda: True, True)
+  return _OperationCancellableIterator(rendezvous, operation)
+
+
+def event_value_in_value_out(
+    front, name, payload, completion_callback, abortion_callback, timeout,
+    trace_id):
+  subscription = _unary_event_subscription(
+      completion_callback, abortion_callback)
+  operation = front.operate(
+      name, payload, True, timeout, subscription, trace_id)
+  return _Call(operation)
+
+
+def event_value_in_stream_out(
+    front, name, payload, result_payload_consumer, abortion_callback, timeout,
+    trace_id):
+  subscription = _stream_event_subscription(
+      result_payload_consumer, abortion_callback)
+  operation = front.operate(
+      name, payload, True, timeout, subscription, trace_id)
+  return _Call(operation)
+
+
+def event_stream_in_value_out(
+    front, name, completion_callback, abortion_callback, timeout, trace_id):
+  subscription = _unary_event_subscription(
+      completion_callback, abortion_callback)
+  operation = front.operate(name, None, False, timeout, subscription, trace_id)
+  return _Call(operation), operation.consumer
+
+
+def event_stream_in_stream_out(
+    front, name, result_payload_consumer, abortion_callback, timeout, trace_id):
+  subscription = _stream_event_subscription(
+      result_payload_consumer, abortion_callback)
+  operation = front.operate(name, None, False, timeout, subscription, trace_id)
+  return _Call(operation), operation.consumer
diff --git a/src/python/_framework/face/_control.py b/src/python/_framework/face/_control.py
new file mode 100644
index 0000000000..2c221321d6
--- /dev/null
+++ b/src/python/_framework/face/_control.py
@@ -0,0 +1,194 @@
+# Copyright 2015, Google Inc.
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+"""State and behavior for translating between sync and async control flow."""
+
+import threading
+
+from _framework.base import interfaces as base_interfaces
+from _framework.face import exceptions
+from _framework.face import interfaces
+from _framework.foundation import abandonment
+from _framework.foundation import stream
+
+INTERNAL_ERROR_LOG_MESSAGE = ':-( RPC Framework (Face) Internal Error! :-('
+
+_OPERATION_OUTCOME_TO_RPC_ABORTION = {
+    base_interfaces.CANCELLED: interfaces.CANCELLED,
+    base_interfaces.EXPIRED: interfaces.EXPIRED,
+    base_interfaces.RECEPTION_FAILURE: interfaces.NETWORK_FAILURE,
+    base_interfaces.TRANSMISSION_FAILURE: interfaces.NETWORK_FAILURE,
+    base_interfaces.SERVICED_FAILURE: interfaces.SERVICED_FAILURE,
+    base_interfaces.SERVICER_FAILURE: interfaces.SERVICER_FAILURE,
+    }
+
+
+def _as_operation_termination_callback(rpc_abortion_callback):
+  def operation_termination_callback(operation_outcome):
+    rpc_abortion = _OPERATION_OUTCOME_TO_RPC_ABORTION.get(
+        operation_outcome, None)
+    if rpc_abortion is not None:
+      rpc_abortion_callback(rpc_abortion)
+  return operation_termination_callback
+
+
+def _abortion_outcome_to_exception(abortion_outcome):
+  if abortion_outcome == base_interfaces.CANCELLED:
+    return exceptions.CancellationError()
+  elif abortion_outcome == base_interfaces.EXPIRED:
+    return exceptions.ExpirationError()
+  elif abortion_outcome == base_interfaces.SERVICER_FAILURE:
+    return exceptions.ServicerError()
+  elif abortion_outcome == base_interfaces.SERVICED_FAILURE:
+    return exceptions.ServicedError()
+  else:
+    return exceptions.NetworkError()
+
+
+class UnaryConsumer(stream.Consumer):
+  """A stream.Consumer that should only ever be passed one value."""
+
+  def __init__(self, on_termination):
+    self._on_termination = on_termination
+    self._value = None
+
+  def consume(self, value):
+    self._value = value
+
+  def terminate(self):
+    self._on_termination(self._value)
+
+  def consume_and_terminate(self, value):
+    self._on_termination(value)
+
+
+class Rendezvous(stream.Consumer):
+  """A rendez-vous with stream.Consumer and iterator interfaces."""
+
+  def __init__(self):
+    self._condition = threading.Condition()
+    self._values = []
+    self._values_completed = False
+    self._abortion = None
+
+  def consume(self, value):
+    with self._condition:
+      self._values.append(value)
+      self._condition.notify()
+
+  def terminate(self):
+    with self._condition:
+      self._values_completed = True
+      self._condition.notify()
+
+  def consume_and_terminate(self, value):
+    with self._condition:
+      self._values.append(value)
+      self._values_completed = True
+      self._condition.notify()
+
+  def __iter__(self):
+    return self
+
+  def next(self):
+    with self._condition:
+      while ((self._abortion is None) and
+             (not self._values) and
+             (not self._values_completed)):
+        self._condition.wait()
+      if self._abortion is not None:
+        raise _abortion_outcome_to_exception(self._abortion)
+      elif self._values:
+        return self._values.pop(0)
+      elif self._values_completed:
+        raise StopIteration()
+      else:
+        raise AssertionError('Unreachable code reached!')
+
+  def set_outcome(self, outcome):
+    with self._condition:
+      if outcome != base_interfaces.COMPLETED:
+        self._abortion = outcome
+        self._condition.notify()
+
+
+class RpcContext(interfaces.RpcContext):
+  """A wrapped base_interfaces.OperationContext."""
+
+  def __init__(self, operation_context):
+    self._operation_context = operation_context
+
+  def is_active(self):
+    return self._operation_context.is_active()
+
+  def time_remaining(self):
+    return self._operation_context.time_remaining()
+
+  def add_abortion_callback(self, abortion_callback):
+    self._operation_context.add_termination_callback(
+        _as_operation_termination_callback(abortion_callback))
+
+
+def pipe_iterator_to_consumer(iterator, consumer, active, terminate):
+  """Pipes values emitted from an iterator to a stream.Consumer.
+
+  Args:
+    iterator: An iterator from which values will be emitted.
+    consumer: A stream.Consumer to which values will be passed.
+    active: A no-argument callable that returns True if the work being done by
+      this function is still valid and should not be abandoned and False if the
+      work being done by this function should be abandoned.
+    terminate: A boolean indicating whether or not this function should
+      terminate the given consumer after passing to it all values emitted by the
+      given iterator.
+
+  Raises:
+    abandonment.Abandoned: If this function quits early after seeing False
+      returned by the active function passed to it.
+    Exception: This function raises whatever exceptions are raised by iterating
+      over the given iterator.
+  """
+  for element in iterator:
+    if not active():
+      raise abandonment.Abandoned()
+
+    consumer.consume(element)
+
+    if not active():
+      raise abandonment.Abandoned()
+  if terminate:
+    consumer.terminate()
+
+
+def abortion_outcome_to_exception(abortion_outcome):
+  return _abortion_outcome_to_exception(abortion_outcome)
+
+
+def as_operation_termination_callback(rpc_abortion_callback):
+  return _as_operation_termination_callback(rpc_abortion_callback)
diff --git a/src/python/_framework/face/_service.py b/src/python/_framework/face/_service.py
new file mode 100644
index 0000000000..d758c2f148
--- /dev/null
+++ b/src/python/_framework/face/_service.py
@@ -0,0 +1,189 @@
+# Copyright 2015, Google Inc.
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+"""Behaviors for servicing RPCs."""
+
+# base_interfaces and interfaces are referenced from specification in this
+# module.
+from _framework.base import interfaces as base_interfaces  # pylint: disable=unused-import
+from _framework.face import _control
+from _framework.face import exceptions
+from _framework.face import interfaces  # pylint: disable=unused-import
+from _framework.foundation import abandonment
+from _framework.foundation import callable_util
+from _framework.foundation import stream
+from _framework.foundation import stream_util
+
+
+class _ValueInStreamOutConsumer(stream.Consumer):
+  """A stream.Consumer that maps inputs one-to-many onto outputs."""
+
+  def __init__(self, behavior, context, downstream):
+    """Constructor.
+
+    Args:
+      behavior: A callable that takes a single value and an
+        interfaces.RpcContext and returns a generator of arbitrarily many
+        values.
+      context: An interfaces.RpcContext.
+      downstream: A stream.Consumer to which to pass the values generated by the
+        given behavior.
+    """
+    self._behavior = behavior
+    self._context = context
+    self._downstream = downstream
+
+  def consume(self, value):
+    _control.pipe_iterator_to_consumer(
+        self._behavior(value, self._context), self._downstream,
+        self._context.is_active, False)
+
+  def terminate(self):
+    self._downstream.terminate()
+
+  def consume_and_terminate(self, value):
+    _control.pipe_iterator_to_consumer(
+        self._behavior(value, self._context), self._downstream,
+        self._context.is_active, True)
+
+
+def _pool_wrap(behavior, operation_context):
+  """Wraps an operation-related behavior so that it may be called in a pool.
+
+  Args:
+    behavior: A callable related to carrying out an operation.
+    operation_context: A base_interfaces.OperationContext for the operation.
+
+  Returns:
+    A callable that when called carries out the behavior of the given callable
+      and handles whatever exceptions it raises appropriately.
+  """
+  def translation(*args):
+    try:
+      behavior(*args)
+    except (
+        abandonment.Abandoned,
+        exceptions.ExpirationError,
+        exceptions.CancellationError,
+        exceptions.ServicedError,
+        exceptions.NetworkError) as e:
+      if operation_context.is_active():
+        operation_context.fail(e)
+    except Exception as e:
+      operation_context.fail(e)
+  return callable_util.with_exceptions_logged(
+      translation, _control.INTERNAL_ERROR_LOG_MESSAGE)
+
+
+def adapt_inline_value_in_value_out(method):
+  def adaptation(response_consumer, operation_context):
+    rpc_context = _control.RpcContext(operation_context)
+    return stream_util.TransformingConsumer(
+        lambda request: method.service(request, rpc_context), response_consumer)
+  return adaptation
+
+
+def adapt_inline_value_in_stream_out(method):
+  def adaptation(response_consumer, operation_context):
+    rpc_context = _control.RpcContext(operation_context)
+    return _ValueInStreamOutConsumer(
+        method.service, rpc_context, response_consumer)
+  return adaptation
+
+
+def adapt_inline_stream_in_value_out(method, pool):
+  def adaptation(response_consumer, operation_context):
+    rendezvous = _control.Rendezvous()
+    operation_context.add_termination_callback(rendezvous.set_outcome)
+    def in_pool_thread():
+      response_consumer.consume_and_terminate(
+          method.service(rendezvous, _control.RpcContext(operation_context)))
+    pool.submit(_pool_wrap(in_pool_thread, operation_context))
+    return rendezvous
+  return adaptation
+
+
+def adapt_inline_stream_in_stream_out(method, pool):
+  """Adapts an interfaces.InlineStreamInStreamOutMethod for use with Consumers.
+
+   RPCs may be serviced by calling the return value of this function, passing
+   request values to the stream.Consumer returned from that call, and receiving
+   response values from the stream.Consumer passed to that call.
+
+  Args:
+    method: An interfaces.InlineStreamInStreamOutMethod.
+    pool: A thread pool.
+
+  Returns:
+    A callable that takes a stream.Consumer and a
+      base_interfaces.OperationContext and returns a stream.Consumer.
+  """
+  def adaptation(response_consumer, operation_context):
+    rendezvous = _control.Rendezvous()
+    operation_context.add_termination_callback(rendezvous.set_outcome)
+    def in_pool_thread():
+      _control.pipe_iterator_to_consumer(
+          method.service(rendezvous, _control.RpcContext(operation_context)),
+          response_consumer, operation_context.is_active, True)
+    pool.submit(_pool_wrap(in_pool_thread, operation_context))
+    return rendezvous
+  return adaptation
+
+
+def adapt_event_value_in_value_out(method):
+  def adaptation(response_consumer, operation_context):
+    def on_payload(payload):
+      method.service(
+          payload, response_consumer.consume_and_terminate,
+          _control.RpcContext(operation_context))
+    return _control.UnaryConsumer(on_payload)
+  return adaptation
+
+
+def adapt_event_value_in_stream_out(method):
+  def adaptation(response_consumer, operation_context):
+    def on_payload(payload):
+      method.service(
+          payload, response_consumer, _control.RpcContext(operation_context))
+    return _control.UnaryConsumer(on_payload)
+  return adaptation
+
+
+def adapt_event_stream_in_value_out(method):
+  def adaptation(response_consumer, operation_context):
+    rpc_context = _control.RpcContext(operation_context)
+    return method.service(response_consumer.consume_and_terminate, rpc_context)
+  return adaptation
+
+
+def adapt_event_stream_in_stream_out(method):
+  def adaptation(response_consumer, operation_context):
+    return method.service(
+        response_consumer, _control.RpcContext(operation_context))
+  return adaptation
diff --git a/src/python/_framework/face/_test_case.py b/src/python/_framework/face/_test_case.py
new file mode 100644
index 0000000000..50b55c389f
--- /dev/null
+++ b/src/python/_framework/face/_test_case.py
@@ -0,0 +1,81 @@
+# Copyright 2015, Google Inc.
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+"""Common lifecycle code for in-memory-ticket-exchange Face-layer tests."""
+
+from _framework.face import implementations
+from _framework.face.testing import base_util
+from _framework.face.testing import test_case
+from _framework.foundation import logging_pool
+
+_TIMEOUT = 3
+_MAXIMUM_POOL_SIZE = 100
+
+
+class FaceTestCase(test_case.FaceTestCase):
+  """Provides abstract Face-layer tests an in-memory implementation."""
+
+  def set_up_implementation(
+      self,
+      name,
+      methods,
+      inline_value_in_value_out_methods,
+      inline_value_in_stream_out_methods,
+      inline_stream_in_value_out_methods,
+      inline_stream_in_stream_out_methods,
+      event_value_in_value_out_methods,
+      event_value_in_stream_out_methods,
+      event_stream_in_value_out_methods,
+      event_stream_in_stream_out_methods,
+      multi_method):
+    servicer_pool = logging_pool.pool(_MAXIMUM_POOL_SIZE)
+    stub_pool = logging_pool.pool(_MAXIMUM_POOL_SIZE)
+
+    servicer = implementations.servicer(
+        servicer_pool,
+        inline_value_in_value_out_methods=inline_value_in_value_out_methods,
+        inline_value_in_stream_out_methods=inline_value_in_stream_out_methods,
+        inline_stream_in_value_out_methods=inline_stream_in_value_out_methods,
+        inline_stream_in_stream_out_methods=inline_stream_in_stream_out_methods,
+        event_value_in_value_out_methods=event_value_in_value_out_methods,
+        event_value_in_stream_out_methods=event_value_in_stream_out_methods,
+        event_stream_in_value_out_methods=event_stream_in_value_out_methods,
+        event_stream_in_stream_out_methods=event_stream_in_stream_out_methods,
+        multi_method=multi_method)
+
+    linked_pair = base_util.linked_pair(servicer, _TIMEOUT)
+    server = implementations.server()
+    stub = implementations.stub(linked_pair.front, stub_pool)
+    return server, stub, (servicer_pool, stub_pool, linked_pair)
+
+  def tear_down_implementation(self, memo):
+    servicer_pool, stub_pool, linked_pair = memo
+    linked_pair.shut_down()
+    stub_pool.shutdown(wait=True)
+    servicer_pool.shutdown(wait=True)
diff --git a/src/python/_framework/face/blocking_invocation_inline_service_test.py b/src/python/_framework/face/blocking_invocation_inline_service_test.py
new file mode 100644
index 0000000000..96563c94ee
--- /dev/null
+++ b/src/python/_framework/face/blocking_invocation_inline_service_test.py
@@ -0,0 +1,46 @@
+# Copyright 2015, Google Inc.
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+"""One of the tests of the Face layer of RPC Framework."""
+
+import unittest
+
+from _framework.face import _test_case
+from _framework.face.testing import blocking_invocation_inline_service_test_case as test_case
+
+
+class BlockingInvocationInlineServiceTest(
+    _test_case.FaceTestCase,
+    test_case.BlockingInvocationInlineServiceTestCase,
+    unittest.TestCase):
+  pass
+
+
+if __name__ == '__main__':
+  unittest.main()
diff --git a/src/python/_framework/face/demonstration.py b/src/python/_framework/face/demonstration.py
new file mode 100644
index 0000000000..501ec6b3f8
--- /dev/null
+++ b/src/python/_framework/face/demonstration.py
@@ -0,0 +1,118 @@
+# Copyright 2015, Google Inc.
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+"""Demonstration-suitable implementation of the face layer of RPC Framework."""
+
+from _framework.base import util as _base_util
+from _framework.base.packets import implementations as _tickets_implementations
+from _framework.face import implementations
+from _framework.foundation import logging_pool
+
+_POOL_SIZE_LIMIT = 20
+
+_MAXIMUM_TIMEOUT = 90
+
+
+class LinkedPair(object):
+  """A Server and Stub that are linked to one another.
+
+  Attributes:
+    server: A Server.
+    stub: A Stub.
+  """
+
+  def shut_down(self):
+    """Shuts down this object and releases its resources."""
+    raise NotImplementedError()
+
+
+class _LinkedPair(LinkedPair):
+
+  def __init__(self, server, stub, front, back, pools):
+    self.server = server
+    self.stub = stub
+    self._front = front
+    self._back = back
+    self._pools = pools
+
+  def shut_down(self):
+    _base_util.wait_for_idle(self._front)
+    _base_util.wait_for_idle(self._back)
+
+    for pool in self._pools:
+      pool.shutdown(wait=True)
+
+
+def server_and_stub(
+    default_timeout,
+    inline_value_in_value_out_methods=None,
+    inline_value_in_stream_out_methods=None,
+    inline_stream_in_value_out_methods=None,
+    inline_stream_in_stream_out_methods=None,
+    event_value_in_value_out_methods=None,
+    event_value_in_stream_out_methods=None,
+    event_stream_in_value_out_methods=None,
+    event_stream_in_stream_out_methods=None,
+    multi_method=None):
+  """Creates a Server and Stub linked together for use."""
+  front_work_pool = logging_pool.pool(_POOL_SIZE_LIMIT)
+  front_transmission_pool = logging_pool.pool(_POOL_SIZE_LIMIT)
+  front_utility_pool = logging_pool.pool(_POOL_SIZE_LIMIT)
+  back_work_pool = logging_pool.pool(_POOL_SIZE_LIMIT)
+  back_transmission_pool = logging_pool.pool(_POOL_SIZE_LIMIT)
+  back_utility_pool = logging_pool.pool(_POOL_SIZE_LIMIT)
+  stub_pool = logging_pool.pool(_POOL_SIZE_LIMIT)
+  pools = (
+      front_work_pool, front_transmission_pool, front_utility_pool,
+      back_work_pool, back_transmission_pool, back_utility_pool,
+      stub_pool)
+
+  servicer = implementations.servicer(
+      back_work_pool,
+      inline_value_in_value_out_methods=inline_value_in_value_out_methods,
+      inline_value_in_stream_out_methods=inline_value_in_stream_out_methods,
+      inline_stream_in_value_out_methods=inline_stream_in_value_out_methods,
+      inline_stream_in_stream_out_methods=inline_stream_in_stream_out_methods,
+      event_value_in_value_out_methods=event_value_in_value_out_methods,
+      event_value_in_stream_out_methods=event_value_in_stream_out_methods,
+      event_stream_in_value_out_methods=event_stream_in_value_out_methods,
+      event_stream_in_stream_out_methods=event_stream_in_stream_out_methods,
+      multi_method=multi_method)
+
+  front = _tickets_implementations.front(
+      front_work_pool, front_transmission_pool, front_utility_pool)
+  back = _tickets_implementations.back(
+      servicer, back_work_pool, back_transmission_pool, back_utility_pool,
+      default_timeout, _MAXIMUM_TIMEOUT)
+  front.join_rear_link(back)
+  back.join_fore_link(front)
+
+  stub = implementations.stub(front, stub_pool)
+
+  return _LinkedPair(implementations.server(), stub, front, back, pools)
diff --git a/src/python/_framework/face/event_invocation_synchronous_event_service_test.py b/src/python/_framework/face/event_invocation_synchronous_event_service_test.py
new file mode 100644
index 0000000000..48e05b2478
--- /dev/null
+++ b/src/python/_framework/face/event_invocation_synchronous_event_service_test.py
@@ -0,0 +1,46 @@
+# Copyright 2015, Google Inc.
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+"""One of the tests of the Face layer of RPC Framework."""
+
+import unittest
+
+from _framework.face import _test_case
+from _framework.face.testing import event_invocation_synchronous_event_service_test_case as test_case
+
+
+class EventInvocationSynchronousEventServiceTest(
+    _test_case.FaceTestCase,
+    test_case.EventInvocationSynchronousEventServiceTestCase,
+    unittest.TestCase):
+  pass
+
+
+if __name__ == '__main__':
+  unittest.main()
diff --git a/src/python/_framework/face/exceptions.py b/src/python/_framework/face/exceptions.py
new file mode 100644
index 0000000000..f112df70bc
--- /dev/null
+++ b/src/python/_framework/face/exceptions.py
@@ -0,0 +1,77 @@
+# Copyright 2015, Google Inc.
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+"""Exceptions used in the Face layer of RPC Framework."""
+
+import abc
+
+
+class NoSuchMethodError(Exception):
+  """Raised by customer code to indicate an unrecognized RPC method name.
+
+  Attributes:
+    name: The unrecognized name.
+  """
+
+  def __init__(self, name):
+    """Constructor.
+
+    Args:
+      name: The unrecognized RPC method name.
+    """
+    super(NoSuchMethodError, self).__init__()
+    self.name = name
+
+
+class RpcError(Exception):
+  """Common super type for all exceptions raised by the Face layer.
+
+  Only RPC Framework should instantiate and raise these exceptions.
+  """
+  __metaclass__ = abc.ABCMeta
+
+
+class CancellationError(RpcError):
+  """Indicates that an RPC has been cancelled."""
+
+
+class ExpirationError(RpcError):
+  """Indicates that an RPC has expired ("timed out")."""
+
+
+class NetworkError(RpcError):
+  """Indicates that some error occurred on the network."""
+
+
+class ServicedError(RpcError):
+  """Indicates that the Serviced failed in the course of an RPC."""
+
+
+class ServicerError(RpcError):
+  """Indicates that the Servicer failed in the course of servicing an RPC."""
diff --git a/src/python/_framework/face/future_invocation_asynchronous_event_service_test.py b/src/python/_framework/face/future_invocation_asynchronous_event_service_test.py
new file mode 100644
index 0000000000..96f5fe85d3
--- /dev/null
+++ b/src/python/_framework/face/future_invocation_asynchronous_event_service_test.py
@@ -0,0 +1,46 @@
+# Copyright 2015, Google Inc.
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+"""One of the tests of the Face layer of RPC Framework."""
+
+import unittest
+
+from _framework.face import _test_case
+from _framework.face.testing import future_invocation_asynchronous_event_service_test_case as test_case
+
+
+class FutureInvocationAsynchronousEventServiceTest(
+    _test_case.FaceTestCase,
+    test_case.FutureInvocationAsynchronousEventServiceTestCase,
+    unittest.TestCase):
+  pass
+
+
+if __name__ == '__main__':
+  unittest.main()
diff --git a/src/python/_framework/face/implementations.py b/src/python/_framework/face/implementations.py
new file mode 100644
index 0000000000..94362e2007
--- /dev/null
+++ b/src/python/_framework/face/implementations.py
@@ -0,0 +1,246 @@
+# Copyright 2015, Google Inc.
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+"""Entry points into the Face layer of RPC Framework."""
+
+from _framework.base import exceptions as _base_exceptions
+from _framework.base import interfaces as base_interfaces
+from _framework.face import _calls
+from _framework.face import _service
+from _framework.face import exceptions
+from _framework.face import interfaces
+
+
+class _BaseServicer(base_interfaces.Servicer):
+
+  def __init__(self, methods, multi_method):
+    self._methods = methods
+    self._multi_method = multi_method
+
+  def service(self, name, context, output_consumer):
+    method = self._methods.get(name, None)
+    if method is not None:
+      return method(output_consumer, context)
+    elif self._multi_method is not None:
+      try:
+        return self._multi_method.service(name, output_consumer, context)
+      except exceptions.NoSuchMethodError:
+        raise _base_exceptions.NoSuchMethodError()
+    else:
+      raise _base_exceptions.NoSuchMethodError()
+
+
+class _Server(interfaces.Server):
+  """An interfaces.Server implementation."""
+
+
+class _Stub(interfaces.Stub):
+  """An interfaces.Stub implementation."""
+
+  def __init__(self, front, pool):
+    self._front = front
+    self._pool = pool
+
+  def blocking_value_in_value_out(self, name, request, timeout):
+    return _calls.blocking_value_in_value_out(
+        self._front, name, request, timeout, 'unused trace ID')
+
+  def future_value_in_value_out(self, name, request, timeout):
+    return _calls.future_value_in_value_out(
+        self._front, name, request, timeout, 'unused trace ID')
+
+  def inline_value_in_stream_out(self, name, request, timeout):
+    return _calls.inline_value_in_stream_out(
+        self._front, name, request, timeout, 'unused trace ID')
+
+  def blocking_stream_in_value_out(self, name, request_iterator, timeout):
+    return _calls.blocking_stream_in_value_out(
+        self._front, name, request_iterator, timeout, 'unused trace ID')
+
+  def future_stream_in_value_out(self, name, request_iterator, timeout):
+    return _calls.future_stream_in_value_out(
+        self._front, name, request_iterator, timeout, 'unused trace ID',
+        self._pool)
+
+  def inline_stream_in_stream_out(self, name, request_iterator, timeout):
+    return _calls.inline_stream_in_stream_out(
+        self._front, name, request_iterator, timeout, 'unused trace ID',
+        self._pool)
+
+  def event_value_in_value_out(
+      self, name, request, response_callback, abortion_callback, timeout):
+    return _calls.event_value_in_value_out(
+        self._front, name, request, response_callback, abortion_callback,
+        timeout, 'unused trace ID')
+
+  def event_value_in_stream_out(
+      self, name, request, response_consumer, abortion_callback, timeout):
+    return _calls.event_value_in_stream_out(
+        self._front, name, request, response_consumer, abortion_callback,
+        timeout, 'unused trace ID')
+
+  def event_stream_in_value_out(
+      self, name, response_callback, abortion_callback, timeout):
+    return _calls.event_stream_in_value_out(
+        self._front, name, response_callback, abortion_callback, timeout,
+        'unused trace ID')
+
+  def event_stream_in_stream_out(
+      self, name, response_consumer, abortion_callback, timeout):
+    return _calls.event_stream_in_stream_out(
+        self._front, name, response_consumer, abortion_callback, timeout,
+        'unused trace ID')
+
+
+def _aggregate_methods(
+    pool,
+    inline_value_in_value_out_methods,
+    inline_value_in_stream_out_methods,
+    inline_stream_in_value_out_methods,
+    inline_stream_in_stream_out_methods,
+    event_value_in_value_out_methods,
+    event_value_in_stream_out_methods,
+    event_stream_in_value_out_methods,
+    event_stream_in_stream_out_methods):
+  """Aggregates methods coded in according to different interfaces."""
+  methods = {}
+
+  def adapt_unpooled_methods(adapted_methods, unadapted_methods, adaptation):
+    if unadapted_methods is not None:
+      for name, unadapted_method in unadapted_methods.iteritems():
+        adapted_methods[name] = adaptation(unadapted_method)
+
+  def adapt_pooled_methods(adapted_methods, unadapted_methods, adaptation):
+    if unadapted_methods is not None:
+      for name, unadapted_method in unadapted_methods.iteritems():
+        adapted_methods[name] = adaptation(unadapted_method, pool)
+
+  adapt_unpooled_methods(
+      methods, inline_value_in_value_out_methods,
+      _service.adapt_inline_value_in_value_out)
+  adapt_unpooled_methods(
+      methods, inline_value_in_stream_out_methods,
+      _service.adapt_inline_value_in_stream_out)
+  adapt_pooled_methods(
+      methods, inline_stream_in_value_out_methods,
+      _service.adapt_inline_stream_in_value_out)
+  adapt_pooled_methods(
+      methods, inline_stream_in_stream_out_methods,
+      _service.adapt_inline_stream_in_stream_out)
+  adapt_unpooled_methods(
+      methods, event_value_in_value_out_methods,
+      _service.adapt_event_value_in_value_out)
+  adapt_unpooled_methods(
+      methods, event_value_in_stream_out_methods,
+      _service.adapt_event_value_in_stream_out)
+  adapt_unpooled_methods(
+      methods, event_stream_in_value_out_methods,
+      _service.adapt_event_stream_in_value_out)
+  adapt_unpooled_methods(
+      methods, event_stream_in_stream_out_methods,
+      _service.adapt_event_stream_in_stream_out)
+
+  return methods
+
+
+def servicer(
+    pool,
+    inline_value_in_value_out_methods=None,
+    inline_value_in_stream_out_methods=None,
+    inline_stream_in_value_out_methods=None,
+    inline_stream_in_stream_out_methods=None,
+    event_value_in_value_out_methods=None,
+    event_value_in_stream_out_methods=None,
+    event_stream_in_value_out_methods=None,
+    event_stream_in_stream_out_methods=None,
+    multi_method=None):
+  """Creates a base_interfaces.Servicer.
+
+  The key sets of the passed dictionaries must be disjoint. It is guaranteed
+  that any passed MultiMethod implementation will only be called to service an
+  RPC if the RPC method name is not present in the key sets of the passed
+  dictionaries.
+
+  Args:
+    pool: A thread pool.
+    inline_value_in_value_out_methods: A dictionary mapping method names to
+      interfaces.InlineValueInValueOutMethod implementations.
+    inline_value_in_stream_out_methods: A dictionary mapping method names to
+      interfaces.InlineValueInStreamOutMethod implementations.
+    inline_stream_in_value_out_methods: A dictionary mapping method names to
+      interfaces.InlineStreamInValueOutMethod implementations.
+    inline_stream_in_stream_out_methods: A dictionary mapping method names to
+      interfaces.InlineStreamInStreamOutMethod implementations.
+    event_value_in_value_out_methods: A dictionary mapping method names to
+      interfaces.EventValueInValueOutMethod implementations.
+    event_value_in_stream_out_methods: A dictionary mapping method names to
+      interfaces.EventValueInStreamOutMethod implementations.
+    event_stream_in_value_out_methods: A dictionary mapping method names to
+      interfaces.EventStreamInValueOutMethod implementations.
+    event_stream_in_stream_out_methods: A dictionary mapping method names to
+      interfaces.EventStreamInStreamOutMethod implementations.
+    multi_method: An implementation of interfaces.MultiMethod.
+
+  Returns:
+    A base_interfaces.Servicer that services RPCs via the given implementations.
+  """
+  methods = _aggregate_methods(
+      pool,
+      inline_value_in_value_out_methods,
+      inline_value_in_stream_out_methods,
+      inline_stream_in_value_out_methods,
+      inline_stream_in_stream_out_methods,
+      event_value_in_value_out_methods,
+      event_value_in_stream_out_methods,
+      event_stream_in_value_out_methods,
+      event_stream_in_stream_out_methods)
+
+  return _BaseServicer(methods, multi_method)
+
+
+def server():
+  """Creates an interfaces.Server.
+
+  Returns:
+    An interfaces.Server.
+  """
+  return _Server()
+
+
+def stub(front, pool):
+  """Creates an interfaces.Stub.
+
+  Args:
+    front: A base_interfaces.Front.
+    pool: A futures.ThreadPoolExecutor.
+
+  Returns:
+    An interfaces.Stub that performs RPCs via the given base_interfaces.Front.
+  """
+  return _Stub(front, pool)
diff --git a/src/python/_framework/face/interfaces.py b/src/python/_framework/face/interfaces.py
new file mode 100644
index 0000000000..0cc7c70df3
--- /dev/null
+++ b/src/python/_framework/face/interfaces.py
@@ -0,0 +1,545 @@
+# Copyright 2015, Google Inc.
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+"""Interfaces for the face layer of RPC Framework."""
+
+import abc
+
+# exceptions, abandonment, and future are referenced from specification in this
+# module.
+from _framework.face import exceptions  # pylint: disable=unused-import
+from _framework.foundation import abandonment  # pylint: disable=unused-import
+from _framework.foundation import future  # pylint: disable=unused-import
+
+
+class CancellableIterator(object):
+  """Implements the Iterator protocol and affords a cancel method."""
+  __metaclass__ = abc.ABCMeta
+
+  @abc.abstractmethod
+  def __iter__(self):
+    """Returns the self object in accordance with the Iterator protocol."""
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def next(self):
+    """Returns a value or raises StopIteration per the Iterator protocol."""
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def cancel(self):
+    """Requests cancellation of whatever computation underlies this iterator."""
+    raise NotImplementedError()
+
+
+# Constants that categorize RPC abortion.
+# TODO(nathaniel): Learn and use Python's enum library for this de facto
+# enumerated type
+CANCELLED = 'abortion: cancelled'
+EXPIRED = 'abortion: expired'
+NETWORK_FAILURE = 'abortion: network failure'
+SERVICED_FAILURE = 'abortion: serviced failure'
+SERVICER_FAILURE = 'abortion: servicer failure'
+
+
+class RpcContext(object):
+  """Provides RPC-related information and action."""
+  __metaclass__ = abc.ABCMeta
+
+  @abc.abstractmethod
+  def is_active(self):
+    """Describes whether the RPC is active or has terminated."""
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def time_remaining(self):
+    """Describes the length of allowed time remaining for the RPC.
+
+    Returns:
+      A nonnegative float indicating the length of allowed time in seconds
+      remaining for the RPC to complete before it is considered to have timed
+      out.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def add_abortion_callback(self, abortion_callback):
+    """Registers a callback to be called if the RPC is aborted.
+
+    Args:
+      abortion_callback: A callable to be called and passed one of CANCELLED,
+        EXPIRED, NETWORK_FAILURE, SERVICED_FAILURE, or SERVICER_FAILURE in the
+        event of RPC abortion.
+    """
+    raise NotImplementedError()
+
+
+class InlineValueInValueOutMethod(object):
+  """A type for inline unary-request-unary-response RPC methods."""
+  __metaclass__ = abc.ABCMeta
+
+  @abc.abstractmethod
+  def service(self, request, context):
+    """Services an RPC that accepts one value and produces one value.
+
+    Args:
+      request: The single request value for the RPC.
+      context: An RpcContext object.
+
+    Returns:
+      The single response value for the RPC.
+
+    Raises:
+      abandonment.Abandoned: If no response is necessary because the RPC has
+        been aborted.
+    """
+    raise NotImplementedError()
+
+
+class InlineValueInStreamOutMethod(object):
+  """A type for inline unary-request-stream-response RPC methods."""
+  __metaclass__ = abc.ABCMeta
+
+  @abc.abstractmethod
+  def service(self, request, context):
+    """Services an RPC that accepts one value and produces a stream of values.
+
+    Args:
+      request: The single request value for the RPC.
+      context: An RpcContext object.
+
+    Yields:
+      The values that comprise the response stream of the RPC.
+
+    Raises:
+      abandonment.Abandoned: If completing the response stream is not necessary
+        because the RPC has been aborted.
+    """
+    raise NotImplementedError()
+
+
+class InlineStreamInValueOutMethod(object):
+  """A type for inline stream-request-unary-response RPC methods."""
+  __metaclass__ = abc.ABCMeta
+
+  @abc.abstractmethod
+  def service(self, request_iterator, context):
+    """Services an RPC that accepts a stream of values and produces one value.
+
+    Args:
+      request_iterator: An iterator that yields the request values of the RPC.
+        Drawing values from this iterator may also raise exceptions.RpcError to
+        indicate abortion of the RPC.
+      context: An RpcContext object.
+
+    Yields:
+      The values that comprise the response stream of the RPC.
+
+    Raises:
+      abandonment.Abandoned: If no response is necessary because the RPC has
+        been aborted.
+      exceptions.RpcError: Implementations of this method must not deliberately
+        raise exceptions.RpcError but may allow such errors raised by the
+        request_iterator passed to them to propagate through their bodies
+        uncaught.
+    """
+    raise NotImplementedError()
+
+
+class InlineStreamInStreamOutMethod(object):
+  """A type for inline stream-request-stream-response RPC methods."""
+  __metaclass__ = abc.ABCMeta
+
+  @abc.abstractmethod
+  def service(self, request_iterator, context):
+    """Services an RPC that accepts and produces streams of values.
+
+    Args:
+      request_iterator: An iterator that yields the request values of the RPC.
+        Drawing values from this iterator may also raise exceptions.RpcError to
+        indicate abortion of the RPC.
+      context: An RpcContext object.
+
+    Yields:
+      The values that comprise the response stream of the RPC.
+
+    Raises:
+      abandonment.Abandoned: If completing the response stream is not necessary
+        because the RPC has been aborted.
+      exceptions.RpcError: Implementations of this method must not deliberately
+        raise exceptions.RpcError but may allow such errors raised by the
+        request_iterator passed to them to propagate through their bodies
+        uncaught.
+    """
+    raise NotImplementedError()
+
+
+class EventValueInValueOutMethod(object):
+  """A type for event-driven unary-request-unary-response RPC methods."""
+  __metaclass__ = abc.ABCMeta
+
+  @abc.abstractmethod
+  def service(self, request, response_callback, context):
+    """Services an RPC that accepts one value and produces one value.
+
+    Args:
+      request: The single request value for the RPC.
+      response_callback: A callback to be called to accept the response value of
+        the RPC.
+      context: An RpcContext object.
+
+    Raises:
+      abandonment.Abandoned: May or may not be raised when the RPC has been
+        aborted.
+    """
+    raise NotImplementedError()
+
+
+class EventValueInStreamOutMethod(object):
+  """A type for event-driven unary-request-stream-response RPC methods."""
+  __metaclass__ = abc.ABCMeta
+
+  @abc.abstractmethod
+  def service(self, request, response_consumer, context):
+    """Services an RPC that accepts one value and produces a stream of values.
+
+    Args:
+      request: The single request value for the RPC.
+      response_consumer: A stream.Consumer to be called to accept the response
+        values of the RPC.
+      context: An RpcContext object.
+
+    Raises:
+      abandonment.Abandoned: May or may not be raised when the RPC has been
+        aborted.
+    """
+    raise NotImplementedError()
+
+
+class EventStreamInValueOutMethod(object):
+  """A type for event-driven stream-request-unary-response RPC methods."""
+  __metaclass__ = abc.ABCMeta
+
+  @abc.abstractmethod
+  def service(self, response_callback, context):
+    """Services an RPC that accepts a stream of values and produces one value.
+
+    Args:
+      response_callback: A callback to be called to accept the response value of
+        the RPC.
+      context: An RpcContext object.
+
+    Returns:
+      A stream.Consumer with which to accept the request values of the RPC. The
+        consumer returned from this method may or may not be invoked to
+        completion: in the case of RPC abortion, RPC Framework will simply stop
+        passing values to this object. Implementations must not assume that this
+        object will be called to completion of the request stream or even called
+        at all.
+
+    Raises:
+      abandonment.Abandoned: May or may not be raised when the RPC has been
+        aborted.
+    """
+    raise NotImplementedError()
+
+
+class EventStreamInStreamOutMethod(object):
+  """A type for event-driven stream-request-stream-response RPC methods."""
+  __metaclass__ = abc.ABCMeta
+
+  @abc.abstractmethod
+  def service(self, response_consumer, context):
+    """Services an RPC that accepts and produces streams of values.
+
+    Args:
+      response_consumer: A stream.Consumer to be called to accept the response
+        values of the RPC.
+      context: An RpcContext object.
+
+    Returns:
+      A stream.Consumer with which to accept the request values of the RPC. The
+        consumer returned from this method may or may not be invoked to
+        completion: in the case of RPC abortion, RPC Framework will simply stop
+        passing values to this object. Implementations must not assume that this
+        object will be called to completion of the request stream or even called
+        at all.
+
+    Raises:
+      abandonment.Abandoned: May or may not be raised when the RPC has been
+        aborted.
+    """
+    raise NotImplementedError()
+
+
+class MultiMethod(object):
+  """A general type able to service many RPC methods."""
+  __metaclass__ = abc.ABCMeta
+
+  @abc.abstractmethod
+  def service(self, name, response_consumer, context):
+    """Services an RPC.
+
+    Args:
+      name: The RPC method name.
+      response_consumer: A stream.Consumer to be called to accept the response
+        values of the RPC.
+      context: An RpcContext object.
+
+    Returns:
+      A stream.Consumer with which to accept the request values of the RPC. The
+        consumer returned from this method may or may not be invoked to
+        completion: in the case of RPC abortion, RPC Framework will simply stop
+        passing values to this object. Implementations must not assume that this
+        object will be called to completion of the request stream or even called
+        at all.
+
+    Raises:
+      abandonment.Abandoned: May or may not be raised when the RPC has been
+        aborted.
+      exceptions.NoSuchMethodError: If this MultiMethod does not recognize the
+        given RPC method name and is not able to service the RPC.
+    """
+    raise NotImplementedError()
+
+
+class Server(object):
+  """Specification of a running server that services RPCs."""
+  __metaclass__ = abc.ABCMeta
+
+
+class Call(object):
+  """Invocation-side representation of an RPC.
+
+  Attributes:
+    context: An RpcContext affording information about the RPC.
+  """
+  __metaclass__ = abc.ABCMeta
+
+  @abc.abstractmethod
+  def cancel(self):
+    """Requests cancellation of the RPC."""
+    raise NotImplementedError()
+
+
+class Stub(object):
+  """Affords RPC methods to callers."""
+  __metaclass__ = abc.ABCMeta
+
+  @abc.abstractmethod
+  def blocking_value_in_value_out(self, name, request, timeout):
+    """Invokes a unary-request-unary-response RPC method.
+
+    This method blocks until either returning the response value of the RPC
+    (in the event of RPC completion) or raising an exception (in the event of
+    RPC abortion).
+
+    Args:
+      name: The RPC method name.
+      request: The request value for the RPC.
+      timeout: A duration of time in seconds to allow for the RPC.
+
+    Returns:
+      The response value for the RPC.
+
+    Raises:
+      exceptions.RpcError: Indicating that the RPC was aborted.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def future_value_in_value_out(self, name, request, timeout):
+    """Invokes a unary-request-unary-response RPC method.
+
+    Args:
+      name: The RPC method name.
+      request: The request value for the RPC.
+      timeout: A duration of time in seconds to allow for the RPC.
+
+    Returns:
+      A future.Future representing the RPC. In the event of RPC completion, the
+        returned Future will return an outcome indicating that the RPC returned
+        the response value of the RPC. In the event of RPC abortion, the
+        returned Future will return an outcome indicating that the RPC raised
+        an exceptions.RpcError.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def inline_value_in_stream_out(self, name, request, timeout):
+    """Invokes a unary-request-stream-response RPC method.
+
+    Args:
+      name: The RPC method name.
+      request: The request value for the RPC.
+      timeout: A duration of time in seconds to allow for the RPC.
+
+    Returns:
+      A CancellableIterator that yields the response values of the RPC and
+        affords RPC cancellation. Drawing response values from the returned
+        CancellableIterator may raise exceptions.RpcError indicating abortion of
+        the RPC.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def blocking_stream_in_value_out(self, name, request_iterator, timeout):
+    """Invokes a stream-request-unary-response RPC method.
+
+    This method blocks until either returning the response value of the RPC
+    (in the event of RPC completion) or raising an exception (in the event of
+    RPC abortion).
+
+    Args:
+      name: The RPC method name.
+      request_iterator: An iterator that yields the request values of the RPC.
+      timeout: A duration of time in seconds to allow for the RPC.
+
+    Returns:
+      The response value for the RPC.
+
+    Raises:
+      exceptions.RpcError: Indicating that the RPC was aborted.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def future_stream_in_value_out(self, name, request_iterator, timeout):
+    """Invokes a stream-request-unary-response RPC method.
+
+    Args:
+      name: The RPC method name.
+      request_iterator: An iterator that yields the request values of the RPC.
+      timeout: A duration of time in seconds to allow for the RPC.
+
+    Returns:
+      A future.Future representing the RPC. In the event of RPC completion, the
+        returned Future will return an outcome indicating that the RPC returned
+        the response value of the RPC. In the event of RPC abortion, the
+        returned Future will return an outcome indicating that the RPC raised
+        an exceptions.RpcError.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def inline_stream_in_stream_out(self, name, request_iterator, timeout):
+    """Invokes a stream-request-stream-response RPC method.
+
+    Args:
+      name: The RPC method name.
+      request_iterator: An iterator that yields the request values of the RPC.
+      timeout: A duration of time in seconds to allow for the RPC.
+
+    Returns:
+      A CancellableIterator that yields the response values of the RPC and
+        affords RPC cancellation. Drawing response values from the returned
+        CancellableIterator may raise exceptions.RpcError indicating abortion of
+        the RPC.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def event_value_in_value_out(
+      self, name, request, response_callback, abortion_callback, timeout):
+    """Event-driven invocation of a unary-request-unary-response RPC method.
+
+    Args:
+      name: The RPC method name.
+      request: The request value for the RPC.
+      response_callback: A callback to be called to accept the response value
+        of the RPC.
+      abortion_callback: A callback to be called to accept one of CANCELLED,
+        EXPIRED, NETWORK_FAILURE, or SERVICER_FAILURE in the event of RPC
+        abortion.
+      timeout: A duration of time in seconds to allow for the RPC.
+
+    Returns:
+      A Call object for the RPC.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def event_value_in_stream_out(
+      self, name, request, response_consumer, abortion_callback, timeout):
+    """Event-driven invocation of a unary-request-stream-response RPC method.
+
+    Args:
+      name: The RPC method name.
+      request: The request value for the RPC.
+      response_consumer: A stream.Consumer to be called to accept the response
+        values of the RPC.
+      abortion_callback: A callback to be called to accept one of CANCELLED,
+        EXPIRED, NETWORK_FAILURE, or SERVICER_FAILURE in the event of RPC
+        abortion.
+      timeout: A duration of time in seconds to allow for the RPC.
+
+    Returns:
+      A Call object for the RPC.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def event_stream_in_value_out(
+      self, name, response_callback, abortion_callback, timeout):
+    """Event-driven invocation of a unary-request-unary-response RPC method.
+
+    Args:
+      name: The RPC method name.
+      response_callback: A callback to be called to accept the response value
+        of the RPC.
+      abortion_callback: A callback to be called to accept one of CANCELLED,
+        EXPIRED, NETWORK_FAILURE, or SERVICER_FAILURE in the event of RPC
+        abortion.
+      timeout: A duration of time in seconds to allow for the RPC.
+
+    Returns:
+      A pair of a Call object for the RPC and a stream.Consumer to which the
+        request values of the RPC should be passed.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def event_stream_in_stream_out(
+      self, name, response_consumer, abortion_callback, timeout):
+    """Event-driven invocation of a unary-request-stream-response RPC method.
+
+    Args:
+      name: The RPC method name.
+      response_consumer: A stream.Consumer to be called to accept the response
+        values of the RPC.
+      abortion_callback: A callback to be called to accept one of CANCELLED,
+        EXPIRED, NETWORK_FAILURE, or SERVICER_FAILURE in the event of RPC
+        abortion.
+      timeout: A duration of time in seconds to allow for the RPC.
+
+    Returns:
+      A pair of a Call object for the RPC and a stream.Consumer to which the
+        request values of the RPC should be passed.
+    """
+    raise NotImplementedError()
diff --git a/src/python/_framework/face/testing/__init__.py b/src/python/_framework/face/testing/__init__.py
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/src/python/_framework/face/testing/__init__.py
diff --git a/src/python/_framework/face/testing/base_util.py b/src/python/_framework/face/testing/base_util.py
new file mode 100644
index 0000000000..d9ccb3af8f
--- /dev/null
+++ b/src/python/_framework/face/testing/base_util.py
@@ -0,0 +1,102 @@
+# Copyright 2015, Google Inc.
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+"""Utilities for creating Base-layer objects for use in Face-layer tests."""
+
+import abc
+
+# interfaces is referenced from specification in this module.
+from _framework.base import util as _base_util
+from _framework.base.packets import implementations
+from _framework.base.packets import in_memory
+from _framework.base.packets import interfaces  # pylint: disable=unused-import
+from _framework.foundation import logging_pool
+
+_POOL_SIZE_LIMIT = 20
+
+_MAXIMUM_TIMEOUT = 90
+
+
+class LinkedPair(object):
+  """A Front and Back that are linked to one another.
+
+  Attributes:
+    front: An interfaces.Front.
+    back: An interfaces.Back.
+  """
+
+  __metaclass__ = abc.ABCMeta
+
+  @abc.abstractmethod
+  def shut_down(self):
+    """Shuts down this object and releases its resources."""
+    raise NotImplementedError()
+
+
+class _LinkedPair(LinkedPair):
+
+  def __init__(self, front, back, pools):
+    self.front = front
+    self.back = back
+    self._pools = pools
+
+  def shut_down(self):
+    _base_util.wait_for_idle(self.front)
+    _base_util.wait_for_idle(self.back)
+
+    for pool in self._pools:
+      pool.shutdown(wait=True)
+
+
+def linked_pair(servicer, default_timeout):
+  """Creates a Server and Stub linked together for use."""
+  link_pool = logging_pool.pool(_POOL_SIZE_LIMIT)
+  front_work_pool = logging_pool.pool(_POOL_SIZE_LIMIT)
+  front_transmission_pool = logging_pool.pool(_POOL_SIZE_LIMIT)
+  front_utility_pool = logging_pool.pool(_POOL_SIZE_LIMIT)
+  back_work_pool = logging_pool.pool(_POOL_SIZE_LIMIT)
+  back_transmission_pool = logging_pool.pool(_POOL_SIZE_LIMIT)
+  back_utility_pool = logging_pool.pool(_POOL_SIZE_LIMIT)
+  pools = (
+      link_pool,
+      front_work_pool, front_transmission_pool, front_utility_pool,
+      back_work_pool, back_transmission_pool, back_utility_pool)
+
+  link = in_memory.Link(link_pool)
+  front = implementations.front(
+      front_work_pool, front_transmission_pool, front_utility_pool)
+  back = implementations.back(
+      servicer, back_work_pool, back_transmission_pool, back_utility_pool,
+      default_timeout, _MAXIMUM_TIMEOUT)
+  front.join_rear_link(link)
+  link.join_fore_link(front)
+  back.join_fore_link(link)
+  link.join_rear_link(back)
+
+  return _LinkedPair(front, back, pools)
diff --git a/src/python/_framework/face/testing/blocking_invocation_inline_service_test_case.py b/src/python/_framework/face/testing/blocking_invocation_inline_service_test_case.py
new file mode 100644
index 0000000000..0b1a2f0bd2
--- /dev/null
+++ b/src/python/_framework/face/testing/blocking_invocation_inline_service_test_case.py
@@ -0,0 +1,223 @@
+# Copyright 2015, Google Inc.
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+"""A test to verify an implementation of the Face layer of RPC Framework."""
+
+# unittest is referenced from specification in this module.
+import abc
+import unittest  # pylint: disable=unused-import
+
+from _framework.face import exceptions
+from _framework.face.testing import control
+from _framework.face.testing import coverage
+from _framework.face.testing import digest
+from _framework.face.testing import stock_service
+from _framework.face.testing import test_case
+
+_TIMEOUT = 3
+
+
+class BlockingInvocationInlineServiceTestCase(
+    test_case.FaceTestCase, coverage.BlockingCoverage):
+  """A test of the Face layer of RPC Framework.
+
+  Concrete subclasses must also extend unittest.TestCase.
+  """
+  __metaclass__ = abc.ABCMeta
+
+  def setUp(self):
+    """See unittest.TestCase.setUp for full specification.
+
+    Overriding implementations must call this implementation.
+    """
+    self.control = control.PauseFailControl()
+    self.digest = digest.digest(
+        stock_service.STOCK_TEST_SERVICE, self.control, None)
+
+    self.server, self.stub, self.memo = self.set_up_implementation(
+        self.digest.name, self.digest.methods,
+        self.digest.inline_unary_unary_methods,
+        self.digest.inline_unary_stream_methods,
+        self.digest.inline_stream_unary_methods,
+        self.digest.inline_stream_stream_methods,
+        {}, {}, {}, {}, None)
+
+  def tearDown(self):
+    """See unittest.TestCase.tearDown for full specification.
+
+    Overriding implementations must call this implementation.
+    """
+    self.tear_down_implementation(self.memo)
+
+  def testSuccessfulUnaryRequestUnaryResponse(self):
+    for name, test_messages_sequence in (
+        self.digest.unary_unary_messages_sequences.iteritems()):
+      for test_messages in test_messages_sequence:
+        request = test_messages.request()
+
+        response = self.stub.blocking_value_in_value_out(
+            name, request, _TIMEOUT)
+
+        test_messages.verify(request, response, self)
+
+  def testSuccessfulUnaryRequestStreamResponse(self):
+    for name, test_messages_sequence in (
+        self.digest.unary_stream_messages_sequences.iteritems()):
+      for test_messages in test_messages_sequence:
+        request = test_messages.request()
+
+        response_iterator = self.stub.inline_value_in_stream_out(
+            name, request, _TIMEOUT)
+        responses = list(response_iterator)
+
+        test_messages.verify(request, responses, self)
+
+  def testSuccessfulStreamRequestUnaryResponse(self):
+    for name, test_messages_sequence in (
+        self.digest.stream_unary_messages_sequences.iteritems()):
+      for test_messages in test_messages_sequence:
+        requests = test_messages.requests()
+
+        response = self.stub.blocking_stream_in_value_out(
+            name, iter(requests), _TIMEOUT)
+
+        test_messages.verify(requests, response, self)
+
+  def testSuccessfulStreamRequestStreamResponse(self):
+    for name, test_messages_sequence in (
+        self.digest.stream_stream_messages_sequences.iteritems()):
+      for test_messages in test_messages_sequence:
+        requests = test_messages.requests()
+
+        response_iterator = self.stub.inline_stream_in_stream_out(
+            name, iter(requests), _TIMEOUT)
+        responses = list(response_iterator)
+
+        test_messages.verify(requests, responses, self)
+
+  def testSequentialInvocations(self):
+    for name, test_messages_sequence in (
+        self.digest.unary_unary_messages_sequences.iteritems()):
+      for test_messages in test_messages_sequence:
+        first_request = test_messages.request()
+        second_request = test_messages.request()
+
+        first_response = self.stub.blocking_value_in_value_out(
+            name, first_request, _TIMEOUT)
+
+        test_messages.verify(first_request, first_response, self)
+
+        second_response = self.stub.blocking_value_in_value_out(
+            name, second_request, _TIMEOUT)
+
+        test_messages.verify(second_request, second_response, self)
+
+  def testExpiredUnaryRequestUnaryResponse(self):
+    for name, test_messages_sequence in (
+        self.digest.unary_unary_messages_sequences.iteritems()):
+      for test_messages in test_messages_sequence:
+        request = test_messages.request()
+
+        with self.control.pause(), self.assertRaises(
+            exceptions.ExpirationError):
+          self.stub.blocking_value_in_value_out(name, request, _TIMEOUT)
+
+  def testExpiredUnaryRequestStreamResponse(self):
+    for name, test_messages_sequence in (
+        self.digest.unary_stream_messages_sequences.iteritems()):
+      for test_messages in test_messages_sequence:
+        request = test_messages.request()
+
+        with self.control.pause(), self.assertRaises(
+            exceptions.ExpirationError):
+          response_iterator = self.stub.inline_value_in_stream_out(
+              name, request, _TIMEOUT)
+          list(response_iterator)
+
+  def testExpiredStreamRequestUnaryResponse(self):
+    for name, test_messages_sequence in (
+        self.digest.stream_unary_messages_sequences.iteritems()):
+      for test_messages in test_messages_sequence:
+        requests = test_messages.requests()
+
+        with self.control.pause(), self.assertRaises(
+            exceptions.ExpirationError):
+          self.stub.blocking_stream_in_value_out(name, iter(requests), _TIMEOUT)
+
+  def testExpiredStreamRequestStreamResponse(self):
+    for name, test_messages_sequence in (
+        self.digest.stream_stream_messages_sequences.iteritems()):
+      for test_messages in test_messages_sequence:
+        requests = test_messages.requests()
+
+        with self.control.pause(), self.assertRaises(
+            exceptions.ExpirationError):
+          response_iterator = self.stub.inline_stream_in_stream_out(
+              name, iter(requests), _TIMEOUT)
+          list(response_iterator)
+
+  def testFailedUnaryRequestUnaryResponse(self):
+    for name, test_messages_sequence in (
+        self.digest.unary_unary_messages_sequences.iteritems()):
+      for test_messages in test_messages_sequence:
+        request = test_messages.request()
+
+        with self.control.fail(), self.assertRaises(exceptions.ServicerError):
+          self.stub.blocking_value_in_value_out(name, request, _TIMEOUT)
+
+  def testFailedUnaryRequestStreamResponse(self):
+    for name, test_messages_sequence in (
+        self.digest.unary_stream_messages_sequences.iteritems()):
+      for test_messages in test_messages_sequence:
+        request = test_messages.request()
+
+        with self.control.fail(), self.assertRaises(exceptions.ServicerError):
+          response_iterator = self.stub.inline_value_in_stream_out(
+              name, request, _TIMEOUT)
+          list(response_iterator)
+
+  def testFailedStreamRequestUnaryResponse(self):
+    for name, test_messages_sequence in (
+        self.digest.stream_unary_messages_sequences.iteritems()):
+      for test_messages in test_messages_sequence:
+        requests = test_messages.requests()
+
+        with self.control.fail(), self.assertRaises(exceptions.ServicerError):
+          self.stub.blocking_stream_in_value_out(name, iter(requests), _TIMEOUT)
+
+  def testFailedStreamRequestStreamResponse(self):
+    for name, test_messages_sequence in (
+        self.digest.stream_stream_messages_sequences.iteritems()):
+      for test_messages in test_messages_sequence:
+        requests = test_messages.requests()
+
+        with self.control.fail(), self.assertRaises(exceptions.ServicerError):
+          response_iterator = self.stub.inline_stream_in_stream_out(
+              name, iter(requests), _TIMEOUT)
+          list(response_iterator)
diff --git a/src/python/_framework/face/testing/callback.py b/src/python/_framework/face/testing/callback.py
new file mode 100644
index 0000000000..7a20869abe
--- /dev/null
+++ b/src/python/_framework/face/testing/callback.py
@@ -0,0 +1,94 @@
+# Copyright 2015, Google Inc.
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+"""A utility useful in tests of asynchronous, event-driven interfaces."""
+
+import threading
+
+from _framework.foundation import stream
+
+
+class Callback(stream.Consumer):
+  """A utility object useful in tests of asynchronous code."""
+
+  def __init__(self):
+    self._condition = threading.Condition()
+    self._unary_response = None
+    self._streamed_responses = []
+    self._completed = False
+    self._abortion = None
+
+  def abort(self, abortion):
+    with self._condition:
+      self._abortion = abortion
+      self._condition.notify_all()
+
+  def complete(self, unary_response):
+    with self._condition:
+      self._unary_response = unary_response
+      self._completed = True
+      self._condition.notify_all()
+
+  def consume(self, streamed_response):
+    with self._condition:
+      self._streamed_responses.append(streamed_response)
+
+  def terminate(self):
+    with self._condition:
+      self._completed = True
+      self._condition.notify_all()
+
+  def consume_and_terminate(self, streamed_response):
+    with self._condition:
+      self._streamed_responses.append(streamed_response)
+      self._completed = True
+      self._condition.notify_all()
+
+  def block_until_terminated(self):
+    with self._condition:
+      while self._abortion is None and not self._completed:
+        self._condition.wait()
+
+  def response(self):
+    with self._condition:
+      if self._abortion is None:
+        return self._unary_response
+      else:
+        raise AssertionError('Aborted with abortion "%s"!' % self._abortion)
+
+  def responses(self):
+    with self._condition:
+      if self._abortion is None:
+        return list(self._streamed_responses)
+      else:
+        raise AssertionError('Aborted with abortion "%s"!' % self._abortion)
+
+  def abortion(self):
+    with self._condition:
+      return self._abortion
diff --git a/src/python/_framework/face/testing/control.py b/src/python/_framework/face/testing/control.py
new file mode 100644
index 0000000000..3960c4e649
--- /dev/null
+++ b/src/python/_framework/face/testing/control.py
@@ -0,0 +1,87 @@
+# Copyright 2015, Google Inc.
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+"""Code for instructing systems under test to block or fail."""
+
+import abc
+import contextlib
+import threading
+
+
+class Control(object):
+  """An object that accepts program control from a system under test.
+
+  Systems under test passed a Control should call its control() method
+  frequently during execution. The control() method may block, raise an
+  exception, or do nothing, all according to the enclosing test's desire for
+  the system under test to simulate hanging, failing, or functioning.
+  """
+
+  __metaclass__ = abc.ABCMeta
+
+  @abc.abstractmethod
+  def control(self):
+    """Potentially does anything."""
+    raise NotImplementedError()
+
+
+class PauseFailControl(Control):
+  """A Control that can be used to pause or fail code under control."""
+
+  def __init__(self):
+    self._condition = threading.Condition()
+    self._paused = False
+    self._fail = False
+
+  def control(self):
+    with self._condition:
+      if self._fail:
+        raise ValueError()
+
+      while self._paused:
+        self._condition.wait()
+
+  @contextlib.contextmanager
+  def pause(self):
+    """Pauses code under control while controlling code is in context."""
+    with self._condition:
+      self._paused = True
+    yield
+    with self._condition:
+      self._paused = False
+      self._condition.notify_all()
+
+  @contextlib.contextmanager
+  def fail(self):
+    """Fails code under control while controlling code is in context."""
+    with self._condition:
+      self._fail = True
+    yield
+    with self._condition:
+      self._fail = False
diff --git a/src/python/_framework/face/testing/coverage.py b/src/python/_framework/face/testing/coverage.py
new file mode 100644
index 0000000000..f3aca113fe
--- /dev/null
+++ b/src/python/_framework/face/testing/coverage.py
@@ -0,0 +1,123 @@
+# Copyright 2015, Google Inc.
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+"""Governs coverage for the tests of the Face layer of RPC Framework."""
+
+import abc
+
+# These classes are only valid when inherited by unittest.TestCases.
+# pylint: disable=invalid-name
+
+
+class BlockingCoverage(object):
+  """Specification of test coverage for blocking behaviors."""
+
+  __metaclass__ = abc.ABCMeta
+
+  @abc.abstractmethod
+  def testSuccessfulUnaryRequestUnaryResponse(self):
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def testSuccessfulUnaryRequestStreamResponse(self):
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def testSuccessfulStreamRequestUnaryResponse(self):
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def testSuccessfulStreamRequestStreamResponse(self):
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def testSequentialInvocations(self):
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def testExpiredUnaryRequestUnaryResponse(self):
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def testExpiredUnaryRequestStreamResponse(self):
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def testExpiredStreamRequestUnaryResponse(self):
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def testExpiredStreamRequestStreamResponse(self):
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def testFailedUnaryRequestUnaryResponse(self):
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def testFailedUnaryRequestStreamResponse(self):
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def testFailedStreamRequestUnaryResponse(self):
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def testFailedStreamRequestStreamResponse(self):
+    raise NotImplementedError()
+
+
+class FullCoverage(BlockingCoverage):
+  """Specification of test coverage for non-blocking behaviors."""
+
+  __metaclass__ = abc.ABCMeta
+
+  @abc.abstractmethod
+  def testParallelInvocations(self):
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def testWaitingForSomeButNotAllParallelInvocations(self):
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def testCancelledUnaryRequestUnaryResponse(self):
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def testCancelledUnaryRequestStreamResponse(self):
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def testCancelledStreamRequestUnaryResponse(self):
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def testCancelledStreamRequestStreamResponse(self):
+    raise NotImplementedError()
diff --git a/src/python/_framework/face/testing/digest.py b/src/python/_framework/face/testing/digest.py
new file mode 100644
index 0000000000..8d1291c975
--- /dev/null
+++ b/src/python/_framework/face/testing/digest.py
@@ -0,0 +1,446 @@
+# Copyright 2015, Google Inc.
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+"""Code for making a service.TestService more amenable to use in tests."""
+
+import collections
+import threading
+
+# testing_control, interfaces, and testing_service are referenced from
+# specification in this module.
+from _framework.face import exceptions
+from _framework.face import interfaces as face_interfaces
+from _framework.face.testing import control as testing_control  # pylint: disable=unused-import
+from _framework.face.testing import interfaces  # pylint: disable=unused-import
+from _framework.face.testing import service as testing_service  # pylint: disable=unused-import
+from _framework.foundation import stream
+from _framework.foundation import stream_util
+
+_IDENTITY = lambda x: x
+
+
+class TestServiceDigest(
+    collections.namedtuple(
+        'TestServiceDigest',
+        ['name',
+         'methods',
+         'inline_unary_unary_methods',
+         'inline_unary_stream_methods',
+         'inline_stream_unary_methods',
+         'inline_stream_stream_methods',
+         'event_unary_unary_methods',
+         'event_unary_stream_methods',
+         'event_stream_unary_methods',
+         'event_stream_stream_methods',
+         'multi_method',
+         'unary_unary_messages_sequences',
+         'unary_stream_messages_sequences',
+         'stream_unary_messages_sequences',
+         'stream_stream_messages_sequences'])):
+  """A transformation of a service.TestService.
+
+  Attributes:
+    name: The RPC service name to be used in the test.
+    methods: A sequence of interfaces.Method objects describing the RPC
+      methods that will be called during the test.
+    inline_unary_unary_methods: A dict from method name to
+      face_interfaces.InlineValueInValueOutMethod object to be used in tests of
+      in-line calls to behaviors under test.
+    inline_unary_stream_methods: A dict from method name to
+      face_interfaces.InlineValueInStreamOutMethod object to be used in tests of
+      in-line calls to behaviors under test.
+    inline_stream_unary_methods: A dict from method name to
+      face_interfaces.InlineStreamInValueOutMethod object to be used in tests of
+      in-line calls to behaviors under test.
+    inline_stream_stream_methods: A dict from method name to
+      face_interfaces.InlineStreamInStreamOutMethod object to be used in tests
+      of in-line calls to behaviors under test.
+    event_unary_unary_methods: A dict from method name to
+      face_interfaces.EventValueInValueOutMethod object to be used in tests of
+      event-driven calls to behaviors under test.
+    event_unary_stream_methods: A dict from method name to
+      face_interfaces.EventValueInStreamOutMethod object to be used in tests of
+      event-driven calls to behaviors under test.
+    event_stream_unary_methods: A dict from method name to
+      face_interfaces.EventStreamInValueOutMethod object to be used in tests of
+      event-driven calls to behaviors under test.
+    event_stream_stream_methods: A dict from method name to
+      face_interfaces.EventStreamInStreamOutMethod object to be used in tests of
+      event-driven calls to behaviors under test.
+    multi_method: A face_interfaces.MultiMethod to be used in tests of generic
+      calls to behaviors under test.
+    unary_unary_messages_sequences: A dict from method name to sequence of
+      service.UnaryUnaryTestMessages objects to be used to test the method
+      with the given name.
+    unary_stream_messages_sequences: A dict from method name to sequence of
+      service.UnaryStreamTestMessages objects to be used to test the method
+      with the given name.
+    stream_unary_messages_sequences: A dict from method name to sequence of
+      service.StreamUnaryTestMessages objects to be used to test the method
+      with the given name.
+    stream_stream_messages_sequences: A dict from method name to sequence of
+      service.StreamStreamTestMessages objects to be used to test the
+      method with the given name.
+    serialization: A serial.Serialization object describing serialization
+      behaviors for all the RPC methods.
+  """
+
+
+class _BufferingConsumer(stream.Consumer):
+  """A trivial Consumer that dumps what it consumes in a user-mutable buffer."""
+
+  def __init__(self):
+    self.consumed = []
+    self.terminated = False
+
+  def consume(self, value):
+    self.consumed.append(value)
+
+  def terminate(self):
+    self.terminated = True
+
+  def consume_and_terminate(self, value):
+    self.consumed.append(value)
+    self.terminated = True
+
+
+class _InlineUnaryUnaryMethod(face_interfaces.InlineValueInValueOutMethod):
+
+  def __init__(self, unary_unary_test_method, control):
+    self._test_method = unary_unary_test_method
+    self._control = control
+
+  def service(self, request, context):
+    response_list = []
+    self._test_method.service(
+        request, response_list.append, context, self._control)
+    return response_list.pop(0)
+
+
+class _EventUnaryUnaryMethod(face_interfaces.EventValueInValueOutMethod):
+
+  def __init__(self, unary_unary_test_method, control, pool):
+    self._test_method = unary_unary_test_method
+    self._control = control
+    self._pool = pool
+
+  def service(self, request, response_callback, context):
+    if self._pool is None:
+      self._test_method.service(
+          request, response_callback, context, self._control)
+    else:
+      self._pool.submit(
+          self._test_method.service, request, response_callback, context,
+          self._control)
+
+
+class _InlineUnaryStreamMethod(face_interfaces.InlineValueInStreamOutMethod):
+
+  def __init__(self, unary_stream_test_method, control):
+    self._test_method = unary_stream_test_method
+    self._control = control
+
+  def service(self, request, context):
+    response_consumer = _BufferingConsumer()
+    self._test_method.service(
+        request, response_consumer, context, self._control)
+    for response in response_consumer.consumed:
+      yield response
+
+
+class _EventUnaryStreamMethod(face_interfaces.EventValueInStreamOutMethod):
+
+  def __init__(self, unary_stream_test_method, control, pool):
+    self._test_method = unary_stream_test_method
+    self._control = control
+    self._pool = pool
+
+  def service(self, request, response_consumer, context):
+    if self._pool is None:
+      self._test_method.service(
+          request, response_consumer, context, self._control)
+    else:
+      self._pool.submit(
+          self._test_method.service, request, response_consumer, context,
+          self._control)
+
+
+class _InlineStreamUnaryMethod(face_interfaces.InlineStreamInValueOutMethod):
+
+  def __init__(self, stream_unary_test_method, control):
+    self._test_method = stream_unary_test_method
+    self._control = control
+
+  def service(self, request_iterator, context):
+    response_list = []
+    request_consumer = self._test_method.service(
+        response_list.append, context, self._control)
+    for request in request_iterator:
+      request_consumer.consume(request)
+    request_consumer.terminate()
+    return response_list.pop(0)
+
+
+class _EventStreamUnaryMethod(face_interfaces.EventStreamInValueOutMethod):
+
+  def __init__(self, stream_unary_test_method, control, pool):
+    self._test_method = stream_unary_test_method
+    self._control = control
+    self._pool = pool
+
+  def service(self, response_callback, context):
+    request_consumer = self._test_method.service(
+        response_callback, context, self._control)
+    if self._pool is None:
+      return request_consumer
+    else:
+      return stream_util.ThreadSwitchingConsumer(request_consumer, self._pool)
+
+
+class _InlineStreamStreamMethod(face_interfaces.InlineStreamInStreamOutMethod):
+
+  def __init__(self, stream_stream_test_method, control):
+    self._test_method = stream_stream_test_method
+    self._control = control
+
+  def service(self, request_iterator, context):
+    response_consumer = _BufferingConsumer()
+    request_consumer = self._test_method.service(
+        response_consumer, context, self._control)
+
+    for request in request_iterator:
+      request_consumer.consume(request)
+      while response_consumer.consumed:
+        yield response_consumer.consumed.pop(0)
+    response_consumer.terminate()
+
+
+class _EventStreamStreamMethod(face_interfaces.EventStreamInStreamOutMethod):
+
+  def __init__(self, stream_stream_test_method, control, pool):
+    self._test_method = stream_stream_test_method
+    self._control = control
+    self._pool = pool
+
+  def service(self, response_consumer, context):
+    request_consumer = self._test_method.service(
+        response_consumer, context, self._control)
+    if self._pool is None:
+      return request_consumer
+    else:
+      return stream_util.ThreadSwitchingConsumer(request_consumer, self._pool)
+
+
+class _UnaryConsumer(stream.Consumer):
+  """A Consumer that only allows consumption of exactly one value."""
+
+  def __init__(self, action):
+    self._lock = threading.Lock()
+    self._action = action
+    self._consumed = False
+    self._terminated = False
+
+  def consume(self, value):
+    with self._lock:
+      if self._consumed:
+        raise ValueError('Unary consumer already consumed!')
+      elif self._terminated:
+        raise ValueError('Unary consumer already terminated!')
+      else:
+        self._consumed = True
+
+    self._action(value)
+
+  def terminate(self):
+    with self._lock:
+      if not self._consumed:
+        raise ValueError('Unary consumer hasn\'t yet consumed!')
+      elif self._terminated:
+        raise ValueError('Unary consumer already terminated!')
+      else:
+        self._terminated = True
+
+  def consume_and_terminate(self, value):
+    with self._lock:
+      if self._consumed:
+        raise ValueError('Unary consumer already consumed!')
+      elif self._terminated:
+        raise ValueError('Unary consumer already terminated!')
+      else:
+        self._consumed = True
+        self._terminated = True
+
+    self._action(value)
+
+
+class _UnaryUnaryAdaptation(object):
+
+  def __init__(self, unary_unary_test_method):
+    self._method = unary_unary_test_method
+
+  def service(self, response_consumer, context, control):
+    def action(request):
+      self._method.service(
+          request, response_consumer.consume_and_terminate, context, control)
+    return _UnaryConsumer(action)
+
+
+class _UnaryStreamAdaptation(object):
+
+  def __init__(self, unary_stream_test_method):
+    self._method = unary_stream_test_method
+
+  def service(self, response_consumer, context, control):
+    def action(request):
+      self._method.service(request, response_consumer, context, control)
+    return _UnaryConsumer(action)
+
+
+class _StreamUnaryAdaptation(object):
+
+  def __init__(self, stream_unary_test_method):
+    self._method = stream_unary_test_method
+
+  def service(self, response_consumer, context, control):
+    return self._method.service(
+        response_consumer.consume_and_terminate, context, control)
+
+
+class _MultiMethod(face_interfaces.MultiMethod):
+
+  def __init__(self, methods, control, pool):
+    self._methods = methods
+    self._control = control
+    self._pool = pool
+
+  def service(self, name, response_consumer, context):
+    method = self._methods.get(name, None)
+    if method is None:
+      raise exceptions.NoSuchMethodError(name)
+    elif self._pool is None:
+      return method(response_consumer, context, self._control)
+    else:
+      request_consumer = method(response_consumer, context, self._control)
+      return stream_util.ThreadSwitchingConsumer(request_consumer, self._pool)
+
+
+class _Assembly(
+    collections.namedtuple(
+        '_Assembly',
+        ['methods', 'inlines', 'events', 'adaptations', 'messages'])):
+  """An intermediate structure created when creating a TestServiceDigest."""
+
+
+def _assemble(
+    scenarios, names, inline_method_constructor, event_method_constructor,
+    adapter, control, pool):
+  """Creates an _Assembly from the given scenarios."""
+  methods = []
+  inlines = {}
+  events = {}
+  adaptations = {}
+  messages = {}
+  for name, scenario in scenarios.iteritems():
+    if name in names:
+      raise ValueError('Repeated name "%s"!' % name)
+
+    test_method = scenario[0]
+    inline_method = inline_method_constructor(test_method, control)
+    event_method = event_method_constructor(test_method, control, pool)
+    adaptation = adapter(test_method)
+
+    methods.append(test_method)
+    inlines[name] = inline_method
+    events[name] = event_method
+    adaptations[name] = adaptation
+    messages[name] = scenario[1]
+
+  return _Assembly(methods, inlines, events, adaptations, messages)
+
+
+def digest(service, control, pool):
+  """Creates a TestServiceDigest from a TestService.
+
+  Args:
+    service: A testing_service.TestService.
+    control: A testing_control.Control.
+    pool: If RPC methods should be serviced in a separate thread, a thread pool.
+      None if RPC methods should be serviced in the thread belonging to the
+      run-time that calls for their service.
+
+  Returns:
+    A TestServiceDigest synthesized from the given service.TestService.
+  """
+  names = set()
+
+  unary_unary = _assemble(
+      service.unary_unary_scenarios(), names, _InlineUnaryUnaryMethod,
+      _EventUnaryUnaryMethod, _UnaryUnaryAdaptation, control, pool)
+  names.update(set(unary_unary.inlines))
+
+  unary_stream = _assemble(
+      service.unary_stream_scenarios(), names, _InlineUnaryStreamMethod,
+      _EventUnaryStreamMethod, _UnaryStreamAdaptation, control, pool)
+  names.update(set(unary_stream.inlines))
+
+  stream_unary = _assemble(
+      service.stream_unary_scenarios(), names, _InlineStreamUnaryMethod,
+      _EventStreamUnaryMethod, _StreamUnaryAdaptation, control, pool)
+  names.update(set(stream_unary.inlines))
+
+  stream_stream = _assemble(
+      service.stream_stream_scenarios(), names, _InlineStreamStreamMethod,
+      _EventStreamStreamMethod, _IDENTITY, control, pool)
+  names.update(set(stream_stream.inlines))
+
+  methods = list(unary_unary.methods)
+  methods.extend(unary_stream.methods)
+  methods.extend(stream_unary.methods)
+  methods.extend(stream_stream.methods)
+  adaptations = dict(unary_unary.adaptations)
+  adaptations.update(unary_stream.adaptations)
+  adaptations.update(stream_unary.adaptations)
+  adaptations.update(stream_stream.adaptations)
+
+  return TestServiceDigest(
+      service.name(),
+      methods,
+      unary_unary.inlines,
+      unary_stream.inlines,
+      stream_unary.inlines,
+      stream_stream.inlines,
+      unary_unary.events,
+      unary_stream.events,
+      stream_unary.events,
+      stream_stream.events,
+      _MultiMethod(adaptations, control, pool),
+      unary_unary.messages,
+      unary_stream.messages,
+      stream_unary.messages,
+      stream_stream.messages)
diff --git a/src/python/_framework/face/testing/event_invocation_synchronous_event_service_test_case.py b/src/python/_framework/face/testing/event_invocation_synchronous_event_service_test_case.py
new file mode 100644
index 0000000000..dba73a9368
--- /dev/null
+++ b/src/python/_framework/face/testing/event_invocation_synchronous_event_service_test_case.py
@@ -0,0 +1,367 @@
+# Copyright 2015, Google Inc.
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+"""A test to verify an implementation of the Face layer of RPC Framework."""
+
+import abc
+import unittest
+
+from _framework.face import interfaces
+from _framework.face.testing import callback as testing_callback
+from _framework.face.testing import control
+from _framework.face.testing import coverage
+from _framework.face.testing import digest
+from _framework.face.testing import stock_service
+from _framework.face.testing import test_case
+
+_TIMEOUT = 3
+
+
+class EventInvocationSynchronousEventServiceTestCase(
+    test_case.FaceTestCase, coverage.FullCoverage):
+  """A test of the Face layer of RPC Framework.
+
+  Concrete subclasses must also extend unittest.TestCase.
+  """
+  __metaclass__ = abc.ABCMeta
+
+  def setUp(self):
+    """See unittest.TestCase.setUp for full specification.
+
+    Overriding implementations must call this implementation.
+    """
+    self.control = control.PauseFailControl()
+    self.digest = digest.digest(
+        stock_service.STOCK_TEST_SERVICE, self.control, None)
+
+    self.server, self.stub, self.memo = self.set_up_implementation(
+        self.digest.name, self.digest.methods,
+        {}, {}, {}, {},
+        self.digest.event_unary_unary_methods,
+        self.digest.event_unary_stream_methods,
+        self.digest.event_stream_unary_methods,
+        self.digest.event_stream_stream_methods,
+        None)
+
+  def tearDown(self):
+    """See unittest.TestCase.tearDown for full specification.
+
+    Overriding implementations must call this implementation.
+    """
+    self.tear_down_implementation(self.memo)
+
+  def testSuccessfulUnaryRequestUnaryResponse(self):
+    for name, test_messages_sequence in (
+        self.digest.unary_unary_messages_sequences.iteritems()):
+      for test_messages in test_messages_sequence:
+        request = test_messages.request()
+        callback = testing_callback.Callback()
+
+        self.stub.event_value_in_value_out(
+            name, request, callback.complete, callback.abort, _TIMEOUT)
+        callback.block_until_terminated()
+        response = callback.response()
+
+        test_messages.verify(request, response, self)
+
+  def testSuccessfulUnaryRequestStreamResponse(self):
+    for name, test_messages_sequence in (
+        self.digest.unary_stream_messages_sequences.iteritems()):
+      for test_messages in test_messages_sequence:
+        request = test_messages.request()
+        callback = testing_callback.Callback()
+
+        self.stub.event_value_in_stream_out(
+            name, request, callback, callback.abort, _TIMEOUT)
+        callback.block_until_terminated()
+        responses = callback.responses()
+
+        test_messages.verify(request, responses, self)
+
+  def testSuccessfulStreamRequestUnaryResponse(self):
+    for name, test_messages_sequence in (
+        self.digest.stream_unary_messages_sequences.iteritems()):
+      for test_messages in test_messages_sequence:
+        requests = test_messages.requests()
+        callback = testing_callback.Callback()
+
+        unused_call, request_consumer = self.stub.event_stream_in_value_out(
+            name, callback.complete, callback.abort, _TIMEOUT)
+        for request in requests:
+          request_consumer.consume(request)
+        request_consumer.terminate()
+        callback.block_until_terminated()
+        response = callback.response()
+
+        test_messages.verify(requests, response, self)
+
+  def testSuccessfulStreamRequestStreamResponse(self):
+    for name, test_messages_sequence in (
+        self.digest.stream_stream_messages_sequences.iteritems()):
+      for test_messages in test_messages_sequence:
+        requests = test_messages.requests()
+        callback = testing_callback.Callback()
+
+        unused_call, request_consumer = self.stub.event_stream_in_stream_out(
+            name, callback, callback.abort, _TIMEOUT)
+        for request in requests:
+          request_consumer.consume(request)
+        request_consumer.terminate()
+        callback.block_until_terminated()
+        responses = callback.responses()
+
+        test_messages.verify(requests, responses, self)
+
+  def testSequentialInvocations(self):
+    # pylint: disable=cell-var-from-loop
+    for name, test_messages_sequence in (
+        self.digest.unary_unary_messages_sequences.iteritems()):
+      for test_messages in test_messages_sequence:
+        first_request = test_messages.request()
+        second_request = test_messages.request()
+        first_callback = testing_callback.Callback()
+        second_callback = testing_callback.Callback()
+
+        def make_second_invocation(first_response):
+          first_callback.complete(first_response)
+          self.stub.event_value_in_value_out(
+              name, second_request, second_callback.complete,
+              second_callback.abort, _TIMEOUT)
+
+        self.stub.event_value_in_value_out(
+            name, first_request, make_second_invocation, first_callback.abort,
+            _TIMEOUT)
+        second_callback.block_until_terminated()
+
+        first_response = first_callback.response()
+        second_response = second_callback.response()
+        test_messages.verify(first_request, first_response, self)
+        test_messages.verify(second_request, second_response, self)
+
+  def testExpiredUnaryRequestUnaryResponse(self):
+    for name, test_messages_sequence in (
+        self.digest.unary_unary_messages_sequences.iteritems()):
+      for test_messages in test_messages_sequence:
+        request = test_messages.request()
+        callback = testing_callback.Callback()
+
+        with self.control.pause():
+          self.stub.event_value_in_value_out(
+              name, request, callback.complete, callback.abort, _TIMEOUT)
+          callback.block_until_terminated()
+
+        self.assertEqual(interfaces.EXPIRED, callback.abortion())
+
+  def testExpiredUnaryRequestStreamResponse(self):
+    for name, test_messages_sequence in (
+        self.digest.unary_stream_messages_sequences.iteritems()):
+      for test_messages in test_messages_sequence:
+        request = test_messages.request()
+        callback = testing_callback.Callback()
+
+        with self.control.pause():
+          self.stub.event_value_in_stream_out(
+              name, request, callback, callback.abort, _TIMEOUT)
+          callback.block_until_terminated()
+
+        self.assertEqual(interfaces.EXPIRED, callback.abortion())
+
+  def testExpiredStreamRequestUnaryResponse(self):
+    for name, test_messages_sequence in (
+        self.digest.stream_unary_messages_sequences.iteritems()):
+      for unused_test_messages in test_messages_sequence:
+        callback = testing_callback.Callback()
+
+        self.stub.event_stream_in_value_out(
+            name, callback.complete, callback.abort, _TIMEOUT)
+        callback.block_until_terminated()
+
+        self.assertEqual(interfaces.EXPIRED, callback.abortion())
+
+  def testExpiredStreamRequestStreamResponse(self):
+    for name, test_messages_sequence in (
+        self.digest.stream_stream_messages_sequences.iteritems()):
+      for test_messages in test_messages_sequence:
+        requests = test_messages.requests()
+        callback = testing_callback.Callback()
+
+        unused_call, request_consumer = self.stub.event_stream_in_stream_out(
+            name, callback, callback.abort, _TIMEOUT)
+        for request in requests:
+          request_consumer.consume(request)
+        callback.block_until_terminated()
+
+        self.assertEqual(interfaces.EXPIRED, callback.abortion())
+
+  def testFailedUnaryRequestUnaryResponse(self):
+    for name, test_messages_sequence in (
+        self.digest.unary_unary_messages_sequences.iteritems()):
+      for test_messages in test_messages_sequence:
+        request = test_messages.request()
+        callback = testing_callback.Callback()
+
+        with self.control.fail():
+          self.stub.event_value_in_value_out(
+              name, request, callback.complete, callback.abort, _TIMEOUT)
+          callback.block_until_terminated()
+
+        self.assertEqual(interfaces.SERVICER_FAILURE, callback.abortion())
+
+  def testFailedUnaryRequestStreamResponse(self):
+    for name, test_messages_sequence in (
+        self.digest.unary_stream_messages_sequences.iteritems()):
+      for test_messages in test_messages_sequence:
+        request = test_messages.request()
+        callback = testing_callback.Callback()
+
+        with self.control.fail():
+          self.stub.event_value_in_stream_out(
+              name, request, callback, callback.abort, _TIMEOUT)
+          callback.block_until_terminated()
+
+        self.assertEqual(interfaces.SERVICER_FAILURE, callback.abortion())
+
+  def testFailedStreamRequestUnaryResponse(self):
+    for name, test_messages_sequence in (
+        self.digest.stream_unary_messages_sequences.iteritems()):
+      for test_messages in test_messages_sequence:
+        requests = test_messages.requests()
+        callback = testing_callback.Callback()
+
+        with self.control.fail():
+          unused_call, request_consumer = self.stub.event_stream_in_value_out(
+              name, callback.complete, callback.abort, _TIMEOUT)
+          for request in requests:
+            request_consumer.consume(request)
+          request_consumer.terminate()
+          callback.block_until_terminated()
+
+        self.assertEqual(interfaces.SERVICER_FAILURE, callback.abortion())
+
+  def testFailedStreamRequestStreamResponse(self):
+    for name, test_messages_sequence in (
+        self.digest.stream_stream_messages_sequences.iteritems()):
+      for test_messages in test_messages_sequence:
+        requests = test_messages.requests()
+        callback = testing_callback.Callback()
+
+        with self.control.fail():
+          unused_call, request_consumer = self.stub.event_stream_in_stream_out(
+              name, callback, callback.abort, _TIMEOUT)
+          for request in requests:
+            request_consumer.consume(request)
+          request_consumer.terminate()
+          callback.block_until_terminated()
+
+        self.assertEqual(interfaces.SERVICER_FAILURE, callback.abortion())
+
+  def testParallelInvocations(self):
+    for name, test_messages_sequence in (
+        self.digest.unary_unary_messages_sequences.iteritems()):
+      for test_messages in test_messages_sequence:
+        first_request = test_messages.request()
+        first_callback = testing_callback.Callback()
+        second_request = test_messages.request()
+        second_callback = testing_callback.Callback()
+
+        self.stub.event_value_in_value_out(
+            name, first_request, first_callback.complete, first_callback.abort,
+            _TIMEOUT)
+        self.stub.event_value_in_value_out(
+            name, second_request, second_callback.complete,
+            second_callback.abort, _TIMEOUT)
+        first_callback.block_until_terminated()
+        second_callback.block_until_terminated()
+
+        first_response = first_callback.response()
+        second_response = second_callback.response()
+        test_messages.verify(first_request, first_response, self)
+        test_messages.verify(second_request, second_response, self)
+
+  @unittest.skip('TODO(nathaniel): implement.')
+  def testWaitingForSomeButNotAllParallelInvocations(self):
+    raise NotImplementedError()
+
+  def testCancelledUnaryRequestUnaryResponse(self):
+    for name, test_messages_sequence in (
+        self.digest.unary_unary_messages_sequences.iteritems()):
+      for test_messages in test_messages_sequence:
+        request = test_messages.request()
+        callback = testing_callback.Callback()
+
+        with self.control.pause():
+          call = self.stub.event_value_in_value_out(
+              name, request, callback.complete, callback.abort, _TIMEOUT)
+          call.cancel()
+          callback.block_until_terminated()
+
+        self.assertEqual(interfaces.CANCELLED, callback.abortion())
+
+  def testCancelledUnaryRequestStreamResponse(self):
+    for name, test_messages_sequence in (
+        self.digest.unary_stream_messages_sequences.iteritems()):
+      for test_messages in test_messages_sequence:
+        request = test_messages.request()
+        callback = testing_callback.Callback()
+
+        call = self.stub.event_value_in_stream_out(
+            name, request, callback, callback.abort, _TIMEOUT)
+        call.cancel()
+        callback.block_until_terminated()
+
+        self.assertEqual(interfaces.CANCELLED, callback.abortion())
+
+  def testCancelledStreamRequestUnaryResponse(self):
+    for name, test_messages_sequence in (
+        self.digest.stream_unary_messages_sequences.iteritems()):
+      for test_messages in test_messages_sequence:
+        requests = test_messages.requests()
+        callback = testing_callback.Callback()
+
+        call, request_consumer = self.stub.event_stream_in_value_out(
+            name, callback.complete, callback.abort, _TIMEOUT)
+        for request in requests:
+          request_consumer.consume(request)
+        call.cancel()
+        callback.block_until_terminated()
+
+        self.assertEqual(interfaces.CANCELLED, callback.abortion())
+
+  def testCancelledStreamRequestStreamResponse(self):
+    for name, test_messages_sequence in (
+        self.digest.stream_stream_messages_sequences.iteritems()):
+      for unused_test_messages in test_messages_sequence:
+        callback = testing_callback.Callback()
+
+        call, unused_request_consumer = self.stub.event_stream_in_stream_out(
+            name, callback, callback.abort, _TIMEOUT)
+        call.cancel()
+        callback.block_until_terminated()
+
+        self.assertEqual(interfaces.CANCELLED, callback.abortion())
diff --git a/src/python/_framework/face/testing/future_invocation_asynchronous_event_service_test_case.py b/src/python/_framework/face/testing/future_invocation_asynchronous_event_service_test_case.py
new file mode 100644
index 0000000000..cf8b2eeb95
--- /dev/null
+++ b/src/python/_framework/face/testing/future_invocation_asynchronous_event_service_test_case.py
@@ -0,0 +1,377 @@
+# Copyright 2015, Google Inc.
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+"""A test to verify an implementation of the Face layer of RPC Framework."""
+
+import abc
+import contextlib
+import threading
+import unittest
+
+from _framework.face import exceptions
+from _framework.face.testing import control
+from _framework.face.testing import coverage
+from _framework.face.testing import digest
+from _framework.face.testing import stock_service
+from _framework.face.testing import test_case
+from _framework.foundation import future
+from _framework.foundation import logging_pool
+
+_TIMEOUT = 3
+_MAXIMUM_POOL_SIZE = 100
+
+
+class _PauseableIterator(object):
+
+  def __init__(self, upstream):
+    self._upstream = upstream
+    self._condition = threading.Condition()
+    self._paused = False
+
+  @contextlib.contextmanager
+  def pause(self):
+    with self._condition:
+      self._paused = True
+    yield
+    with self._condition:
+      self._paused = False
+      self._condition.notify_all()
+
+  def __iter__(self):
+    return self
+
+  def next(self):
+    with self._condition:
+      while self._paused:
+        self._condition.wait()
+    return next(self._upstream)
+
+
+class FutureInvocationAsynchronousEventServiceTestCase(
+    test_case.FaceTestCase, coverage.FullCoverage):
+  """A test of the Face layer of RPC Framework.
+
+  Concrete subclasses must also extend unittest.TestCase.
+  """
+  __metaclass__ = abc.ABCMeta
+
+  def setUp(self):
+    """See unittest.TestCase.setUp for full specification.
+
+    Overriding implementations must call this implementation.
+    """
+    self.control = control.PauseFailControl()
+    self.digest_pool = logging_pool.pool(_MAXIMUM_POOL_SIZE)
+    self.digest = digest.digest(
+        stock_service.STOCK_TEST_SERVICE, self.control, self.digest_pool)
+
+    self.server, self.stub, self.memo = self.set_up_implementation(
+        self.digest.name, self.digest.methods,
+        {}, {}, {}, {},
+        self.digest.event_unary_unary_methods,
+        self.digest.event_unary_stream_methods,
+        self.digest.event_stream_unary_methods,
+        self.digest.event_stream_stream_methods,
+        None)
+
+  def tearDown(self):
+    """See unittest.TestCase.tearDown for full specification.
+
+    Overriding implementations must call this implementation.
+    """
+    self.tear_down_implementation(self.memo)
+    self.digest_pool.shutdown(wait=True)
+
+  def testSuccessfulUnaryRequestUnaryResponse(self):
+    for name, test_messages_sequence in (
+        self.digest.unary_unary_messages_sequences.iteritems()):
+      for test_messages in test_messages_sequence:
+        request = test_messages.request()
+
+        response_future = self.stub.future_value_in_value_out(
+            name, request, _TIMEOUT)
+        response = response_future.outcome().return_value
+
+        test_messages.verify(request, response, self)
+
+  def testSuccessfulUnaryRequestStreamResponse(self):
+    for name, test_messages_sequence in (
+        self.digest.unary_stream_messages_sequences.iteritems()):
+      for test_messages in test_messages_sequence:
+        request = test_messages.request()
+
+        response_iterator = self.stub.inline_value_in_stream_out(
+            name, request, _TIMEOUT)
+        responses = list(response_iterator)
+
+        test_messages.verify(request, responses, self)
+
+  def testSuccessfulStreamRequestUnaryResponse(self):
+    for name, test_messages_sequence in (
+        self.digest.stream_unary_messages_sequences.iteritems()):
+      for test_messages in test_messages_sequence:
+        requests = test_messages.requests()
+        request_iterator = _PauseableIterator(iter(requests))
+
+        # Use of a paused iterator of requests allows us to test that control is
+        # returned to calling code before the iterator yields any requests.
+        with request_iterator.pause():
+          response_future = self.stub.future_stream_in_value_out(
+              name, request_iterator, _TIMEOUT)
+        response = response_future.outcome().return_value
+
+        test_messages.verify(requests, response, self)
+
+  def testSuccessfulStreamRequestStreamResponse(self):
+    for name, test_messages_sequence in (
+        self.digest.stream_stream_messages_sequences.iteritems()):
+      for test_messages in test_messages_sequence:
+        requests = test_messages.requests()
+        request_iterator = _PauseableIterator(iter(requests))
+
+        # Use of a paused iterator of requests allows us to test that control is
+        # returned to calling code before the iterator yields any requests.
+        with request_iterator.pause():
+          response_iterator = self.stub.inline_stream_in_stream_out(
+              name, request_iterator, _TIMEOUT)
+        responses = list(response_iterator)
+
+        test_messages.verify(requests, responses, self)
+
+  def testSequentialInvocations(self):
+    for name, test_messages_sequence in (
+        self.digest.unary_unary_messages_sequences.iteritems()):
+      for test_messages in test_messages_sequence:
+        first_request = test_messages.request()
+        second_request = test_messages.request()
+
+        first_response_future = self.stub.future_value_in_value_out(
+            name, first_request, _TIMEOUT)
+        first_response = first_response_future.outcome().return_value
+
+        test_messages.verify(first_request, first_response, self)
+
+        second_response_future = self.stub.future_value_in_value_out(
+            name, second_request, _TIMEOUT)
+        second_response = second_response_future.outcome().return_value
+
+        test_messages.verify(second_request, second_response, self)
+
+  def testExpiredUnaryRequestUnaryResponse(self):
+    for name, test_messages_sequence in (
+        self.digest.unary_unary_messages_sequences.iteritems()):
+      for test_messages in test_messages_sequence:
+        request = test_messages.request()
+
+        with self.control.pause():
+          response_future = self.stub.future_value_in_value_out(
+              name, request, _TIMEOUT)
+          outcome = response_future.outcome()
+
+        self.assertIsInstance(
+            outcome.exception, exceptions.ExpirationError)
+
+  def testExpiredUnaryRequestStreamResponse(self):
+    for name, test_messages_sequence in (
+        self.digest.unary_stream_messages_sequences.iteritems()):
+      for test_messages in test_messages_sequence:
+        request = test_messages.request()
+
+        with self.control.pause(), self.assertRaises(
+            exceptions.ExpirationError):
+          response_iterator = self.stub.inline_value_in_stream_out(
+              name, request, _TIMEOUT)
+          list(response_iterator)
+
+  def testExpiredStreamRequestUnaryResponse(self):
+    for name, test_messages_sequence in (
+        self.digest.stream_unary_messages_sequences.iteritems()):
+      for test_messages in test_messages_sequence:
+        requests = test_messages.requests()
+
+        with self.control.pause():
+          response_future = self.stub.future_stream_in_value_out(
+              name, iter(requests), _TIMEOUT)
+          outcome = response_future.outcome()
+
+        self.assertIsInstance(
+            outcome.exception, exceptions.ExpirationError)
+
+  def testExpiredStreamRequestStreamResponse(self):
+    for name, test_messages_sequence in (
+        self.digest.stream_stream_messages_sequences.iteritems()):
+      for test_messages in test_messages_sequence:
+        requests = test_messages.requests()
+
+        with self.control.pause(), self.assertRaises(
+            exceptions.ExpirationError):
+          response_iterator = self.stub.inline_stream_in_stream_out(
+              name, iter(requests), _TIMEOUT)
+          list(response_iterator)
+
+  def testFailedUnaryRequestUnaryResponse(self):
+    for name, test_messages_sequence in (
+        self.digest.unary_unary_messages_sequences.iteritems()):
+      for test_messages in test_messages_sequence:
+        request = test_messages.request()
+
+        with self.control.fail():
+          response_future = self.stub.future_value_in_value_out(
+              name, request, _TIMEOUT)
+          outcome = response_future.outcome()
+
+        # Because the servicer fails outside of the thread from which the
+        # servicer-side runtime called into it its failure is indistinguishable
+        # from simply not having called its response_callback before the
+        # expiration of the RPC.
+        self.assertIsInstance(outcome.exception, exceptions.ExpirationError)
+
+  def testFailedUnaryRequestStreamResponse(self):
+    for name, test_messages_sequence in (
+        self.digest.unary_stream_messages_sequences.iteritems()):
+      for test_messages in test_messages_sequence:
+        request = test_messages.request()
+
+        # Because the servicer fails outside of the thread from which the
+        # servicer-side runtime called into it its failure is indistinguishable
+        # from simply not having called its response_consumer before the
+        # expiration of the RPC.
+        with self.control.fail(), self.assertRaises(exceptions.ExpirationError):
+          response_iterator = self.stub.inline_value_in_stream_out(
+              name, request, _TIMEOUT)
+          list(response_iterator)
+
+  def testFailedStreamRequestUnaryResponse(self):
+    for name, test_messages_sequence in (
+        self.digest.stream_unary_messages_sequences.iteritems()):
+      for test_messages in test_messages_sequence:
+        requests = test_messages.requests()
+
+        with self.control.fail():
+          response_future = self.stub.future_stream_in_value_out(
+              name, iter(requests), _TIMEOUT)
+          outcome = response_future.outcome()
+
+        # Because the servicer fails outside of the thread from which the
+        # servicer-side runtime called into it its failure is indistinguishable
+        # from simply not having called its response_callback before the
+        # expiration of the RPC.
+        self.assertIsInstance(outcome.exception, exceptions.ExpirationError)
+
+  def testFailedStreamRequestStreamResponse(self):
+    for name, test_messages_sequence in (
+        self.digest.stream_stream_messages_sequences.iteritems()):
+      for test_messages in test_messages_sequence:
+        requests = test_messages.requests()
+
+        # Because the servicer fails outside of the thread from which the
+        # servicer-side runtime called into it its failure is indistinguishable
+        # from simply not having called its response_consumer before the
+        # expiration of the RPC.
+        with self.control.fail(), self.assertRaises(exceptions.ExpirationError):
+          response_iterator = self.stub.inline_stream_in_stream_out(
+              name, iter(requests), _TIMEOUT)
+          list(response_iterator)
+
+  def testParallelInvocations(self):
+    for name, test_messages_sequence in (
+        self.digest.unary_unary_messages_sequences.iteritems()):
+      for test_messages in test_messages_sequence:
+        first_request = test_messages.request()
+        second_request = test_messages.request()
+
+        first_response_future = self.stub.future_value_in_value_out(
+            name, first_request, _TIMEOUT)
+        second_response_future = self.stub.future_value_in_value_out(
+            name, second_request, _TIMEOUT)
+        first_response = first_response_future.outcome().return_value
+        second_response = second_response_future.outcome().return_value
+
+        test_messages.verify(first_request, first_response, self)
+        test_messages.verify(second_request, second_response, self)
+
+  @unittest.skip('TODO(nathaniel): implement.')
+  def testWaitingForSomeButNotAllParallelInvocations(self):
+    raise NotImplementedError()
+
+  def testCancelledUnaryRequestUnaryResponse(self):
+    for name, test_messages_sequence in (
+        self.digest.unary_unary_messages_sequences.iteritems()):
+      for test_messages in test_messages_sequence:
+        request = test_messages.request()
+
+        with self.control.pause():
+          response_future = self.stub.future_value_in_value_out(
+              name, request, _TIMEOUT)
+          cancelled = response_future.cancel()
+
+        self.assertFalse(cancelled)
+        self.assertEqual(future.ABORTED, response_future.outcome().category)
+
+  def testCancelledUnaryRequestStreamResponse(self):
+    for name, test_messages_sequence in (
+        self.digest.unary_stream_messages_sequences.iteritems()):
+      for test_messages in test_messages_sequence:
+        request = test_messages.request()
+
+        with self.control.pause():
+          response_iterator = self.stub.inline_value_in_stream_out(
+              name, request, _TIMEOUT)
+          response_iterator.cancel()
+
+        with self.assertRaises(exceptions.CancellationError):
+          next(response_iterator)
+
+  def testCancelledStreamRequestUnaryResponse(self):
+    for name, test_messages_sequence in (
+        self.digest.stream_unary_messages_sequences.iteritems()):
+      for test_messages in test_messages_sequence:
+        requests = test_messages.requests()
+
+        with self.control.pause():
+          response_future = self.stub.future_stream_in_value_out(
+              name, iter(requests), _TIMEOUT)
+          cancelled = response_future.cancel()
+
+        self.assertFalse(cancelled)
+        self.assertEqual(future.ABORTED, response_future.outcome().category)
+
+  def testCancelledStreamRequestStreamResponse(self):
+    for name, test_messages_sequence in (
+        self.digest.stream_stream_messages_sequences.iteritems()):
+      for test_messages in test_messages_sequence:
+        requests = test_messages.requests()
+
+        with self.control.pause():
+          response_iterator = self.stub.inline_stream_in_stream_out(
+              name, iter(requests), _TIMEOUT)
+          response_iterator.cancel()
+
+        with self.assertRaises(exceptions.CancellationError):
+          next(response_iterator)
diff --git a/src/python/_framework/face/testing/interfaces.py b/src/python/_framework/face/testing/interfaces.py
new file mode 100644
index 0000000000..253f6f118d
--- /dev/null
+++ b/src/python/_framework/face/testing/interfaces.py
@@ -0,0 +1,117 @@
+# Copyright 2015, Google Inc.
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+"""Interfaces implemented by data sets used in Face-layer tests."""
+
+import abc
+
+# cardinality is referenced from specification in this module.
+from _framework.common import cardinality  # pylint: disable=unused-import
+
+
+class Method(object):
+  """An RPC method to be used in tests of RPC implementations."""
+  __metaclass__ = abc.ABCMeta
+
+  @abc.abstractmethod
+  def name(self):
+    """Identify the name of the method.
+
+    Returns:
+      The name of the method.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def cardinality(self):
+    """Identify the cardinality of the method.
+
+    Returns:
+      A cardinality.Cardinality value describing the streaming semantics of the
+        method.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def request_class(self):
+    """Identify the class used for the method's request objects.
+
+    Returns:
+      The class object of the class to which the method's request objects
+        belong.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def response_class(self):
+    """Identify the class used for the method's response objects.
+
+    Returns:
+      The class object of the class to which the method's response objects
+        belong.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def serialize_request(self, request):
+    """Serialize the given request object.
+
+    Args:
+      request: A request object appropriate for this method.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def deserialize_request(self, serialized_request):
+    """Synthesize a request object from a given bytestring.
+
+    Args:
+      serialized_request: A bytestring deserializable into a request object
+        appropriate for this method.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def serialize_response(self, response):
+    """Serialize the given response object.
+
+    Args:
+      response: A response object appropriate for this method.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def deserialize_response(self, serialized_response):
+    """Synthesize a response object from a given bytestring.
+
+    Args:
+      serialized_response: A bytestring deserializable into a response object
+        appropriate for this method.
+    """
+    raise NotImplementedError()
diff --git a/src/python/_framework/face/testing/serial.py b/src/python/_framework/face/testing/serial.py
new file mode 100644
index 0000000000..47fc5822de
--- /dev/null
+++ b/src/python/_framework/face/testing/serial.py
@@ -0,0 +1,70 @@
+# Copyright 2015, Google Inc.
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+"""Utility for serialization in the context of test RPC services."""
+
+import collections
+
+
+class Serialization(
+    collections.namedtuple(
+        '_Serialization',
+        ['request_serializers',
+         'request_deserializers',
+         'response_serializers',
+         'response_deserializers'])):
+  """An aggregation of serialization behaviors for an RPC service.
+
+  Attributes:
+    request_serializers: A dict from method name to request object serializer
+      behavior.
+    request_deserializers: A dict from method name to request object
+      deserializer behavior.
+    response_serializers: A dict from method name to response object serializer
+      behavior.
+    response_deserializers: A dict from method name to response object
+      deserializer behavior.
+  """
+
+
+def serialization(methods):
+  """Creates a Serialization from a sequences of interfaces.Method objects."""
+  request_serializers = {}
+  request_deserializers = {}
+  response_serializers = {}
+  response_deserializers = {}
+  for method in methods:
+    name = method.name()
+    request_serializers[name] = method.serialize_request
+    request_deserializers[name] = method.deserialize_request
+    response_serializers[name] = method.serialize_response
+    response_deserializers[name] = method.deserialize_response
+  return Serialization(
+      request_serializers, request_deserializers, response_serializers,
+      response_deserializers)
diff --git a/src/python/_framework/face/testing/service.py b/src/python/_framework/face/testing/service.py
new file mode 100644
index 0000000000..771346ec2e
--- /dev/null
+++ b/src/python/_framework/face/testing/service.py
@@ -0,0 +1,337 @@
+# Copyright 2015, Google Inc.
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+"""Private interfaces implemented by data sets used in Face-layer tests."""
+
+import abc
+
+# interfaces is referenced from specification in this module.
+from _framework.face import interfaces as face_interfaces  # pylint: disable=unused-import
+from _framework.face.testing import interfaces
+
+
+class UnaryUnaryTestMethod(interfaces.Method):
+  """Like face_interfaces.EventValueInValueOutMethod but with a control."""
+
+  __metaclass__ = abc.ABCMeta
+
+  @abc.abstractmethod
+  def service(self, request, response_callback, context, control):
+    """Services an RPC that accepts one message and produces one message.
+
+    Args:
+      request: The single request message for the RPC.
+      response_callback: A callback to be called to accept the response message
+        of the RPC.
+      context: An face_interfaces.RpcContext object.
+      control: A test_control.Control to control execution of this method.
+
+    Raises:
+      abandonment.Abandoned: May or may not be raised when the RPC has been
+        aborted.
+    """
+    raise NotImplementedError()
+
+
+class UnaryUnaryTestMessages(object):
+  """A type for unary-request-unary-response message pairings."""
+
+  __metaclass__ = abc.ABCMeta
+
+  @abc.abstractmethod
+  def request(self):
+    """Affords a request message.
+
+    Implementations of this method should return a different message with each
+    call so that multiple test executions of the test method may be made with
+    different inputs.
+
+    Returns:
+      A request message.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def verify(self, request, response, test_case):
+    """Verifies that the computed response matches the given request.
+
+    Args:
+      request: A request message.
+      response: A response message.
+      test_case: A unittest.TestCase object affording useful assertion methods.
+
+    Raises:
+      AssertionError: If the request and response do not match, indicating that
+        there was some problem executing the RPC under test.
+    """
+    raise NotImplementedError()
+
+
+class UnaryStreamTestMethod(interfaces.Method):
+  """Like face_interfaces.EventValueInStreamOutMethod but with a control."""
+
+  __metaclass__ = abc.ABCMeta
+
+  @abc.abstractmethod
+  def service(self, request, response_consumer, context, control):
+    """Services an RPC that takes one message and produces a stream of messages.
+
+    Args:
+      request: The single request message for the RPC.
+      response_consumer: A stream.Consumer to be called to accept the response
+        messages of the RPC.
+      context: An RpcContext object.
+      control: A test_control.Control to control execution of this method.
+
+    Raises:
+      abandonment.Abandoned: May or may not be raised when the RPC has been
+        aborted.
+    """
+    raise NotImplementedError()
+
+
+class UnaryStreamTestMessages(object):
+  """A type for unary-request-stream-response message pairings."""
+
+  __metaclass__ = abc.ABCMeta
+
+  @abc.abstractmethod
+  def request(self):
+    """Affords a request message.
+
+    Implementations of this method should return a different message with each
+    call so that multiple test executions of the test method may be made with
+    different inputs.
+
+    Returns:
+      A request message.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def verify(self, request, responses, test_case):
+    """Verifies that the computed responses match the given request.
+
+    Args:
+      request: A request message.
+      responses: A sequence of response messages.
+      test_case: A unittest.TestCase object affording useful assertion methods.
+
+    Raises:
+      AssertionError: If the request and responses do not match, indicating that
+        there was some problem executing the RPC under test.
+    """
+    raise NotImplementedError()
+
+
+class StreamUnaryTestMethod(interfaces.Method):
+  """Like face_interfaces.EventStreamInValueOutMethod but with a control."""
+
+  __metaclass__ = abc.ABCMeta
+
+  @abc.abstractmethod
+  def service(self, response_callback, context, control):
+    """Services an RPC that takes a stream of messages and produces one message.
+
+    Args:
+      response_callback: A callback to be called to accept the response message
+        of the RPC.
+      context: An RpcContext object.
+      control: A test_control.Control to control execution of this method.
+
+    Returns:
+      A stream.Consumer with which to accept the request messages of the RPC.
+        The consumer returned from this method may or may not be invoked to
+        completion: in the case of RPC abortion, RPC Framework will simply stop
+        passing messages to this object. Implementations must not assume that
+        this object will be called to completion of the request stream or even
+        called at all.
+
+    Raises:
+      abandonment.Abandoned: May or may not be raised when the RPC has been
+        aborted.
+    """
+    raise NotImplementedError()
+
+
+class StreamUnaryTestMessages(object):
+  """A type for stream-request-unary-response message pairings."""
+
+  __metaclass__ = abc.ABCMeta
+
+  @abc.abstractmethod
+  def requests(self):
+    """Affords a sequence of request messages.
+
+    Implementations of this method should return a different sequences with each
+    call so that multiple test executions of the test method may be made with
+    different inputs.
+
+    Returns:
+      A sequence of request messages.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def verify(self, requests, response, test_case):
+    """Verifies that the computed response matches the given requests.
+
+    Args:
+      requests: A sequence of request messages.
+      response: A response message.
+      test_case: A unittest.TestCase object affording useful assertion methods.
+
+    Raises:
+      AssertionError: If the requests and response do not match, indicating that
+        there was some problem executing the RPC under test.
+    """
+    raise NotImplementedError()
+
+
+class StreamStreamTestMethod(interfaces.Method):
+  """Like face_interfaces.EventStreamInStreamOutMethod but with a control."""
+
+  __metaclass__ = abc.ABCMeta
+
+  @abc.abstractmethod
+  def service(self, response_consumer, context, control):
+    """Services an RPC that accepts and produces streams of messages.
+
+    Args:
+      response_consumer: A stream.Consumer to be called to accept the response
+        messages of the RPC.
+      context: An RpcContext object.
+      control: A test_control.Control to control execution of this method.
+
+    Returns:
+      A stream.Consumer with which to accept the request messages of the RPC.
+        The consumer returned from this method may or may not be invoked to
+        completion: in the case of RPC abortion, RPC Framework will simply stop
+        passing messages to this object. Implementations must not assume that
+        this object will be called to completion of the request stream or even
+        called at all.
+
+    Raises:
+      abandonment.Abandoned: May or may not be raised when the RPC has been
+        aborted.
+    """
+    raise NotImplementedError()
+
+
+class StreamStreamTestMessages(object):
+  """A type for stream-request-stream-response message pairings."""
+
+  __metaclass__ = abc.ABCMeta
+
+  @abc.abstractmethod
+  def requests(self):
+    """Affords a sequence of request messages.
+
+    Implementations of this method should return a different sequences with each
+    call so that multiple test executions of the test method may be made with
+    different inputs.
+
+    Returns:
+      A sequence of request messages.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def verify(self, requests, responses, test_case):
+    """Verifies that the computed response matches the given requests.
+
+    Args:
+      requests: A sequence of request messages.
+      responses: A sequence of response messages.
+      test_case: A unittest.TestCase object affording useful assertion methods.
+
+    Raises:
+      AssertionError: If the requests and responses do not match, indicating
+        that there was some problem executing the RPC under test.
+    """
+    raise NotImplementedError()
+
+
+class TestService(object):
+  """A specification of implemented RPC methods to use in tests."""
+
+  __metaclass__ = abc.ABCMeta
+
+  @abc.abstractmethod
+  def name(self):
+    """Identifies the RPC service name used during the test.
+
+    Returns:
+      The RPC service name to be used for the test.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def unary_unary_scenarios(self):
+    """Affords unary-request-unary-response test methods and their messages.
+
+    Returns:
+      A dict from method name to pair. The first element of the pair
+        is a UnaryUnaryTestMethod object and the second element is a sequence
+        of UnaryUnaryTestMethodMessages objects.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def unary_stream_scenarios(self):
+    """Affords unary-request-stream-response test methods and their messages.
+
+    Returns:
+      A dict from method name to pair. The first element of the pair is a
+        UnaryStreamTestMethod object and the second element is a sequence of
+        UnaryStreamTestMethodMessages objects.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def stream_unary_scenarios(self):
+    """Affords stream-request-unary-response test methods and their messages.
+
+    Returns:
+      A dict from method name to pair. The first element of the pair is a
+        StreamUnaryTestMethod object and the second element is a sequence of
+        StreamUnaryTestMethodMessages objects.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def stream_stream_scenarios(self):
+    """Affords stream-request-stream-response test methods and their messages.
+
+    Returns:
+      A dict from method name to pair. The first element of the pair is a
+        StreamStreamTestMethod object and the second element is a sequence of
+        StreamStreamTestMethodMessages objects.
+    """
+    raise NotImplementedError()
diff --git a/src/python/_framework/face/testing/stock_service.py b/src/python/_framework/face/testing/stock_service.py
new file mode 100644
index 0000000000..bd82877e83
--- /dev/null
+++ b/src/python/_framework/face/testing/stock_service.py
@@ -0,0 +1,374 @@
+# Copyright 2015, Google Inc.
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+"""Examples of Python implementations of the stock.proto Stock service."""
+
+from _framework.common import cardinality
+from _framework.face.testing import service
+from _framework.foundation import abandonment
+from _framework.foundation import stream
+from _framework.foundation import stream_util
+from _junkdrawer import stock_pb2
+
+SYMBOL_FORMAT = 'test symbol:%03d'
+STREAM_LENGTH = 400
+
+# A test-appropriate security-pricing function. :-P
+_price = lambda symbol_name: float(hash(symbol_name) % 4096)
+
+
+def _get_last_trade_price(stock_request, stock_reply_callback, control, active):
+  """A unary-request, unary-response test method."""
+  control.control()
+  if active():
+    stock_reply_callback(
+        stock_pb2.StockReply(
+            symbol=stock_request.symbol, price=_price(stock_request.symbol)))
+  else:
+    raise abandonment.Abandoned()
+
+
+def _get_last_trade_price_multiple(stock_reply_consumer, control, active):
+  """A stream-request, stream-response test method."""
+  def stock_reply_for_stock_request(stock_request):
+    control.control()
+    if active():
+      return stock_pb2.StockReply(
+          symbol=stock_request.symbol, price=_price(stock_request.symbol))
+    else:
+      raise abandonment.Abandoned()
+  return stream_util.TransformingConsumer(
+      stock_reply_for_stock_request, stock_reply_consumer)
+
+
+def _watch_future_trades(stock_request, stock_reply_consumer, control, active):
+  """A unary-request, stream-response test method."""
+  base_price = _price(stock_request.symbol)
+  for index in range(stock_request.num_trades_to_watch):
+    control.control()
+    if active():
+      stock_reply_consumer.consume(
+          stock_pb2.StockReply(
+              symbol=stock_request.symbol, price=base_price + index))
+    else:
+      raise abandonment.Abandoned()
+  stock_reply_consumer.terminate()
+
+
+def _get_highest_trade_price(stock_reply_callback, control, active):
+  """A stream-request, unary-response test method."""
+
+  class StockRequestConsumer(stream.Consumer):
+    """Keeps an ongoing record of the most valuable symbol yet consumed."""
+
+    def __init__(self):
+      self._symbol = None
+      self._price = None
+
+    def consume(self, stock_request):
+      control.control()
+      if active():
+        if self._price is None:
+          self._symbol = stock_request.symbol
+          self._price = _price(stock_request.symbol)
+        else:
+          candidate_price = _price(stock_request.symbol)
+          if self._price < candidate_price:
+            self._symbol = stock_request.symbol
+            self._price = candidate_price
+
+    def terminate(self):
+      control.control()
+      if active():
+        if self._symbol is None:
+          raise ValueError()
+        else:
+          stock_reply_callback(
+              stock_pb2.StockReply(symbol=self._symbol, price=self._price))
+          self._symbol = None
+          self._price = None
+
+    def consume_and_terminate(self, stock_request):
+      control.control()
+      if active():
+        if self._price is None:
+          stock_reply_callback(
+              stock_pb2.StockReply(
+                  symbol=stock_request.symbol,
+                  price=_price(stock_request.symbol)))
+        else:
+          candidate_price = _price(stock_request.symbol)
+          if self._price < candidate_price:
+            stock_reply_callback(
+                stock_pb2.StockReply(
+                    symbol=stock_request.symbol, price=candidate_price))
+          else:
+            stock_reply_callback(
+                stock_pb2.StockReply(
+                    symbol=self._symbol, price=self._price))
+
+        self._symbol = None
+        self._price = None
+
+  return StockRequestConsumer()
+
+
+class GetLastTradePrice(service.UnaryUnaryTestMethod):
+  """GetLastTradePrice for use in tests."""
+
+  def name(self):
+    return 'GetLastTradePrice'
+
+  def cardinality(self):
+    return cardinality.Cardinality.UNARY_UNARY
+
+  def request_class(self):
+    return stock_pb2.StockRequest
+
+  def response_class(self):
+    return stock_pb2.StockReply
+
+  def serialize_request(self, request):
+    return request.SerializeToString()
+
+  def deserialize_request(self, serialized_request):
+    return stock_pb2.StockRequest.FromString(serialized_request)
+
+  def serialize_response(self, response):
+    return response.SerializeToString()
+
+  def deserialize_response(self, serialized_response):
+    return stock_pb2.StockReply.FromString(serialized_response)
+
+  def service(self, request, response_callback, context, control):
+    _get_last_trade_price(
+        request, response_callback, control, context.is_active)
+
+
+class GetLastTradePriceMessages(service.UnaryUnaryTestMessages):
+
+  def __init__(self):
+    self._index = 0
+
+  def request(self):
+    symbol = SYMBOL_FORMAT % self._index
+    self._index += 1
+    return stock_pb2.StockRequest(symbol=symbol)
+
+  def verify(self, request, response, test_case):
+    test_case.assertEqual(request.symbol, response.symbol)
+    test_case.assertEqual(_price(request.symbol), response.price)
+
+
+class GetLastTradePriceMultiple(service.StreamStreamTestMethod):
+  """GetLastTradePriceMultiple for use in tests."""
+
+  def name(self):
+    return 'GetLastTradePriceMultiple'
+
+  def cardinality(self):
+    return cardinality.Cardinality.STREAM_STREAM
+
+  def request_class(self):
+    return stock_pb2.StockRequest
+
+  def response_class(self):
+    return stock_pb2.StockReply
+
+  def serialize_request(self, request):
+    return request.SerializeToString()
+
+  def deserialize_request(self, serialized_request):
+    return stock_pb2.StockRequest.FromString(serialized_request)
+
+  def serialize_response(self, response):
+    return response.SerializeToString()
+
+  def deserialize_response(self, serialized_response):
+    return stock_pb2.StockReply.FromString(serialized_response)
+
+  def service(self, response_consumer, context, control):
+    return _get_last_trade_price_multiple(
+        response_consumer, control, context.is_active)
+
+
+class GetLastTradePriceMultipleMessages(service.StreamStreamTestMessages):
+  """Pairs of message streams for use with GetLastTradePriceMultiple."""
+
+  def __init__(self):
+    self._index = 0
+
+  def requests(self):
+    base_index = self._index
+    self._index += 1
+    return [
+        stock_pb2.StockRequest(symbol=SYMBOL_FORMAT % (base_index + index))
+        for index in range(STREAM_LENGTH)]
+
+  def verify(self, requests, responses, test_case):
+    test_case.assertEqual(len(requests), len(responses))
+    for stock_request, stock_reply in zip(requests, responses):
+      test_case.assertEqual(stock_request.symbol, stock_reply.symbol)
+      test_case.assertEqual(_price(stock_request.symbol), stock_reply.price)
+
+
+class WatchFutureTrades(service.UnaryStreamTestMethod):
+  """WatchFutureTrades for use in tests."""
+
+  def name(self):
+    return 'WatchFutureTrades'
+
+  def cardinality(self):
+    return cardinality.Cardinality.UNARY_STREAM
+
+  def request_class(self):
+    return stock_pb2.StockRequest
+
+  def response_class(self):
+    return stock_pb2.StockReply
+
+  def serialize_request(self, request):
+    return request.SerializeToString()
+
+  def deserialize_request(self, serialized_request):
+    return stock_pb2.StockRequest.FromString(serialized_request)
+
+  def serialize_response(self, response):
+    return response.SerializeToString()
+
+  def deserialize_response(self, serialized_response):
+    return stock_pb2.StockReply.FromString(serialized_response)
+
+  def service(self, request, response_consumer, context, control):
+    _watch_future_trades(request, response_consumer, control, context.is_active)
+
+
+class WatchFutureTradesMessages(service.UnaryStreamTestMessages):
+  """Pairs of a single request message and a sequence of response messages."""
+
+  def __init__(self):
+    self._index = 0
+
+  def request(self):
+    symbol = SYMBOL_FORMAT % self._index
+    self._index += 1
+    return stock_pb2.StockRequest(
+        symbol=symbol, num_trades_to_watch=STREAM_LENGTH)
+
+  def verify(self, request, responses, test_case):
+    test_case.assertEqual(STREAM_LENGTH, len(responses))
+    base_price = _price(request.symbol)
+    for index, response in enumerate(responses):
+      test_case.assertEqual(base_price + index, response.price)
+
+
+class GetHighestTradePrice(service.StreamUnaryTestMethod):
+  """GetHighestTradePrice for use in tests."""
+
+  def name(self):
+    return 'GetHighestTradePrice'
+
+  def cardinality(self):
+    return cardinality.Cardinality.STREAM_UNARY
+
+  def request_class(self):
+    return stock_pb2.StockRequest
+
+  def response_class(self):
+    return stock_pb2.StockReply
+
+  def serialize_request(self, request):
+    return request.SerializeToString()
+
+  def deserialize_request(self, serialized_request):
+    return stock_pb2.StockRequest.FromString(serialized_request)
+
+  def serialize_response(self, response):
+    return response.SerializeToString()
+
+  def deserialize_response(self, serialized_response):
+    return stock_pb2.StockReply.FromString(serialized_response)
+
+  def service(self, response_callback, context, control):
+    return _get_highest_trade_price(
+        response_callback, control, context.is_active)
+
+
+class GetHighestTradePriceMessages(service.StreamUnaryTestMessages):
+
+  def requests(self):
+    return [
+        stock_pb2.StockRequest(symbol=SYMBOL_FORMAT % index)
+        for index in range(STREAM_LENGTH)]
+
+  def verify(self, requests, response, test_case):
+    price = None
+    symbol = None
+    for stock_request in requests:
+      current_symbol = stock_request.symbol
+      current_price = _price(current_symbol)
+      if price is None or price < current_price:
+        price = current_price
+        symbol = current_symbol
+    test_case.assertEqual(price, response.price)
+    test_case.assertEqual(symbol, response.symbol)
+
+
+class StockTestService(service.TestService):
+  """A corpus of test data with one method of each RPC cardinality."""
+
+  def name(self):
+    return 'Stock'
+
+  def unary_unary_scenarios(self):
+    return {
+        'GetLastTradePrice': (
+            GetLastTradePrice(), [GetLastTradePriceMessages()]),
+    }
+
+  def unary_stream_scenarios(self):
+    return {
+        'WatchFutureTrades': (
+            WatchFutureTrades(), [WatchFutureTradesMessages()]),
+    }
+
+  def stream_unary_scenarios(self):
+    return {
+        'GetHighestTradePrice': (
+            GetHighestTradePrice(), [GetHighestTradePriceMessages()])
+    }
+
+  def stream_stream_scenarios(self):
+    return {
+        'GetLastTradePriceMultiple': (
+            GetLastTradePriceMultiple(), [GetLastTradePriceMultipleMessages()]),
+    }
+
+
+STOCK_TEST_SERVICE = StockTestService()
diff --git a/src/python/_framework/face/testing/test_case.py b/src/python/_framework/face/testing/test_case.py
new file mode 100644
index 0000000000..09b5a67f5a
--- /dev/null
+++ b/src/python/_framework/face/testing/test_case.py
@@ -0,0 +1,111 @@
+# Copyright 2015, Google Inc.
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+"""Tools for creating tests of implementations of the Face layer."""
+
+import abc
+
+# face_interfaces and interfaces are referenced in specification in this module.
+from _framework.face import interfaces as face_interfaces  # pylint: disable=unused-import
+from _framework.face.testing import interfaces  # pylint: disable=unused-import
+
+
+class FaceTestCase(object):
+  """Describes a test of the Face Layer of RPC Framework.
+
+  Concrete subclasses must also inherit from unittest.TestCase and from at least
+  one class that defines test methods.
+  """
+  __metaclass__ = abc.ABCMeta
+
+  @abc.abstractmethod
+  def set_up_implementation(
+      self,
+      name,
+      methods,
+      inline_value_in_value_out_methods,
+      inline_value_in_stream_out_methods,
+      inline_stream_in_value_out_methods,
+      inline_stream_in_stream_out_methods,
+      event_value_in_value_out_methods,
+      event_value_in_stream_out_methods,
+      event_stream_in_value_out_methods,
+      event_stream_in_stream_out_methods,
+      multi_method):
+    """Instantiates the Face Layer implementation under test.
+
+    Args:
+      name: The service name to be used in the test.
+      methods: A sequence of interfaces.Method objects describing the RPC
+        methods that will be called during the test.
+      inline_value_in_value_out_methods: A dictionary from string method names
+        to face_interfaces.InlineValueInValueOutMethod implementations of those
+        methods.
+      inline_value_in_stream_out_methods: A dictionary from string method names
+        to face_interfaces.InlineValueInStreamOutMethod implementations of those
+        methods.
+      inline_stream_in_value_out_methods: A dictionary from string method names
+        to face_interfaces.InlineStreamInValueOutMethod implementations of those
+        methods.
+      inline_stream_in_stream_out_methods: A dictionary from string method names
+        to face_interfaces.InlineStreamInStreamOutMethod implementations of
+        those methods.
+      event_value_in_value_out_methods: A dictionary from string method names
+        to face_interfaces.EventValueInValueOutMethod implementations of those
+        methods.
+      event_value_in_stream_out_methods: A dictionary from string method names
+        to face_interfaces.EventValueInStreamOutMethod implementations of those
+        methods.
+      event_stream_in_value_out_methods: A dictionary from string method names
+        to face_interfaces.EventStreamInValueOutMethod implementations of those
+        methods.
+      event_stream_in_stream_out_methods: A dictionary from string method names
+        to face_interfaces.EventStreamInStreamOutMethod implementations of those
+        methods.
+      multi_method: An face_interfaces.MultiMethod, or None.
+
+    Returns:
+      A sequence of length three the first element of which is a
+        face_interfaces.Server, the second element of which is a
+        face_interfaces.Stub, (both of which are backed by the given method
+        implementations), and the third element of which is an arbitrary memo
+        object to be kept and passed to tearDownImplementation at the conclusion
+        of the test.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def tear_down_implementation(self, memo):
+    """Destroys the Face layer implementation under test.
+
+    Args:
+      memo: The object from the third position of the return value of
+        set_up_implementation.
+    """
+    raise NotImplementedError()
diff --git a/src/python/_framework/foundation/_later_test.py b/src/python/_framework/foundation/_later_test.py
new file mode 100644
index 0000000000..fbd17a4ad9
--- /dev/null
+++ b/src/python/_framework/foundation/_later_test.py
@@ -0,0 +1,145 @@
+# Copyright 2015, Google Inc.
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+"""Tests of the later module."""
+
+import threading
+import time
+import unittest
+
+from _framework.foundation import future
+from _framework.foundation import later
+
+TICK = 0.1
+
+
+class LaterTest(unittest.TestCase):
+
+  def test_simple_delay(self):
+    lock = threading.Lock()
+    cell = [0]
+    def increment_cell():
+      with lock:
+        cell[0] += 1
+    computation_future = later.later(TICK * 2, increment_cell)
+    self.assertFalse(computation_future.done())
+    self.assertFalse(computation_future.cancelled())
+    time.sleep(TICK)
+    self.assertFalse(computation_future.done())
+    self.assertFalse(computation_future.cancelled())
+    with lock:
+      self.assertEqual(0, cell[0])
+    time.sleep(TICK * 2)
+    self.assertTrue(computation_future.done())
+    self.assertFalse(computation_future.cancelled())
+    with lock:
+      self.assertEqual(1, cell[0])
+    outcome = computation_future.outcome()
+    self.assertEqual(future.RETURNED, outcome.category)
+
+  def test_callback(self):
+    lock = threading.Lock()
+    cell = [0]
+    callback_called = [False]
+    outcome_passed_to_callback = [None]
+    def increment_cell():
+      with lock:
+        cell[0] += 1
+    computation_future = later.later(TICK * 2, increment_cell)
+    def callback(outcome):
+      with lock:
+        callback_called[0] = True
+        outcome_passed_to_callback[0] = outcome
+    computation_future.add_done_callback(callback)
+    time.sleep(TICK)
+    with lock:
+      self.assertFalse(callback_called[0])
+    time.sleep(TICK * 2)
+    with lock:
+      self.assertTrue(callback_called[0])
+      self.assertEqual(future.RETURNED, outcome_passed_to_callback[0].category)
+
+      callback_called[0] = False
+      outcome_passed_to_callback[0] = None
+
+    computation_future.add_done_callback(callback)
+    with lock:
+      self.assertTrue(callback_called[0])
+      self.assertEqual(future.RETURNED, outcome_passed_to_callback[0].category)
+
+  def test_cancel(self):
+    lock = threading.Lock()
+    cell = [0]
+    callback_called = [False]
+    outcome_passed_to_callback = [None]
+    def increment_cell():
+      with lock:
+        cell[0] += 1
+    computation_future = later.later(TICK * 2, increment_cell)
+    def callback(outcome):
+      with lock:
+        callback_called[0] = True
+        outcome_passed_to_callback[0] = outcome
+    computation_future.add_done_callback(callback)
+    time.sleep(TICK)
+    with lock:
+      self.assertFalse(callback_called[0])
+    computation_future.cancel()
+    self.assertTrue(computation_future.cancelled())
+    self.assertFalse(computation_future.done())
+    self.assertEqual(future.ABORTED, computation_future.outcome().category)
+    with lock:
+      self.assertTrue(callback_called[0])
+      self.assertEqual(future.ABORTED, outcome_passed_to_callback[0].category)
+
+  def test_outcome(self):
+    lock = threading.Lock()
+    cell = [0]
+    callback_called = [False]
+    outcome_passed_to_callback = [None]
+    def increment_cell():
+      with lock:
+        cell[0] += 1
+    computation_future = later.later(TICK * 2, increment_cell)
+    def callback(outcome):
+      with lock:
+        callback_called[0] = True
+        outcome_passed_to_callback[0] = outcome
+    computation_future.add_done_callback(callback)
+    returned_outcome = computation_future.outcome()
+    self.assertEqual(future.RETURNED, returned_outcome.category)
+
+    # The callback may not yet have been called! Sleep a tick.
+    time.sleep(TICK)
+    with lock:
+      self.assertTrue(callback_called[0])
+      self.assertEqual(future.RETURNED, outcome_passed_to_callback[0].category)
+
+if __name__ == '__main__':
+  unittest.main()
diff --git a/src/python/_framework/foundation/_timer_future.py b/src/python/_framework/foundation/_timer_future.py
new file mode 100644
index 0000000000..86bc073d56
--- /dev/null
+++ b/src/python/_framework/foundation/_timer_future.py
@@ -0,0 +1,156 @@
+# Copyright 2015, Google Inc.
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+"""Affords a Future implementation based on Python's threading.Timer."""
+
+import threading
+import time
+
+from _framework.foundation import future
+
+
+class TimerFuture(future.Future):
+  """A Future implementation based around Timer objects."""
+
+  def __init__(self, compute_time, computation):
+    """Constructor.
+
+    Args:
+      compute_time: The time after which to begin this future's computation.
+      computation: The computation to be performed within this Future.
+    """
+    self._lock = threading.Lock()
+    self._compute_time = compute_time
+    self._computation = computation
+    self._timer = None
+    self._computing = False
+    self._computed = False
+    self._cancelled = False
+    self._outcome = None
+    self._waiting = []
+
+  def _compute(self):
+    """Performs the computation embedded in this Future.
+
+    Or doesn't, if the time to perform it has not yet arrived.
+    """
+    with self._lock:
+      time_remaining = self._compute_time - time.time()
+      if 0 < time_remaining:
+        self._timer = threading.Timer(time_remaining, self._compute)
+        self._timer.start()
+        return
+      else:
+        self._computing = True
+
+    try:
+      returned_value = self._computation()
+      outcome = future.returned(returned_value)
+    except Exception as e:  # pylint: disable=broad-except
+      outcome = future.raised(e)
+
+    with self._lock:
+      self._computing = False
+      self._computed = True
+      self._outcome = outcome
+      waiting = self._waiting
+
+    for callback in waiting:
+      callback(outcome)
+
+  def start(self):
+    """Starts this Future.
+
+    This must be called exactly once, immediately after construction.
+    """
+    with self._lock:
+      self._timer = threading.Timer(
+          self._compute_time - time.time(), self._compute)
+      self._timer.start()
+
+  def cancel(self):
+    """See future.Future.cancel for specification."""
+    with self._lock:
+      if self._computing or self._computed:
+        return False
+      elif self._cancelled:
+        return True
+      else:
+        self._timer.cancel()
+        self._cancelled = True
+        self._outcome = future.aborted()
+        outcome = self._outcome
+        waiting = self._waiting
+
+    for callback in waiting:
+      try:
+        callback(outcome)
+      except Exception:  # pylint: disable=broad-except
+        pass
+
+    return True
+
+  def cancelled(self):
+    """See future.Future.cancelled for specification."""
+    with self._lock:
+      return self._cancelled
+
+  def done(self):
+    """See future.Future.done for specification."""
+    with self._lock:
+      return self._computed
+
+  def outcome(self):
+    """See future.Future.outcome for specification."""
+    with self._lock:
+      if self._computed or self._cancelled:
+        return self._outcome
+
+      condition = threading.Condition()
+      def notify_condition(unused_outcome):
+        with condition:
+          condition.notify()
+      self._waiting.append(notify_condition)
+
+    with condition:
+      condition.wait()
+
+    with self._lock:
+      return self._outcome
+
+  def add_done_callback(self, callback):
+    """See future.Future.add_done_callback for specification."""
+    with self._lock:
+      if not self._computed and not self._cancelled:
+        self._waiting.append(callback)
+        return
+      else:
+        outcome = self._outcome
+
+    callback(outcome)
diff --git a/src/python/_framework/foundation/abandonment.py b/src/python/_framework/foundation/abandonment.py
new file mode 100644
index 0000000000..960b4d06b4
--- /dev/null
+++ b/src/python/_framework/foundation/abandonment.py
@@ -0,0 +1,38 @@
+# Copyright 2015, Google Inc.
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+"""Utilities for indicating abandonment of computation."""
+
+
+class Abandoned(Exception):
+  """Indicates that some computation is being abandoned.
+
+  Abandoning a computation is different than returning a value or raising
+  an exception indicating some operational or programming defect.
+  """
diff --git a/src/python/_framework/foundation/callable_util.py b/src/python/_framework/foundation/callable_util.py
new file mode 100644
index 0000000000..1f7546cb76
--- /dev/null
+++ b/src/python/_framework/foundation/callable_util.py
@@ -0,0 +1,78 @@
+# Copyright 2015, Google Inc.
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+"""Utilities for working with callables."""
+
+import functools
+import logging
+
+from _framework.foundation import future
+
+
+def _call_logging_exceptions(behavior, message, *args, **kwargs):
+  try:
+    return future.returned(behavior(*args, **kwargs))
+  except Exception as e:  # pylint: disable=broad-except
+    logging.exception(message)
+    return future.raised(e)
+
+
+def with_exceptions_logged(behavior, message):
+  """Wraps a callable in a try-except that logs any exceptions it raises.
+
+  Args:
+    behavior: Any callable.
+    message: A string to log if the behavior raises an exception.
+
+  Returns:
+    A callable that when executed invokes the given behavior. The returned
+      callable takes the same arguments as the given behavior but returns a
+      future.Outcome describing whether the given behavior returned a value or
+      raised an exception.
+  """
+  @functools.wraps(behavior)
+  def wrapped_behavior(*args, **kwargs):
+    return _call_logging_exceptions(behavior, message, *args, **kwargs)
+  return wrapped_behavior
+
+
+def call_logging_exceptions(behavior, message, *args, **kwargs):
+  """Calls a behavior in a try-except that logs any exceptions it raises.
+
+  Args:
+    behavior: Any callable.
+    message: A string to log if the behavior raises an exception.
+    *args: Positional arguments to pass to the given behavior.
+    **kwargs: Keyword arguments to pass to the given behavior.
+
+  Returns:
+    A future.Outcome describing whether the given behavior returned a value or
+      raised an exception.
+  """
+  return _call_logging_exceptions(behavior, message, *args, **kwargs)
diff --git a/src/python/_framework/foundation/future.py b/src/python/_framework/foundation/future.py
new file mode 100644
index 0000000000..f00c503257
--- /dev/null
+++ b/src/python/_framework/foundation/future.py
@@ -0,0 +1,172 @@
+# Copyright 2015, Google Inc.
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+"""The Future interface missing from Python's standard library.
+
+Python's concurrent.futures library defines a Future class very much like the
+Future defined here, but since that class is concrete and without construction
+semantics it is only available within the concurrent.futures library itself.
+The Future class defined here is an entirely abstract interface that anyone may
+implement and use.
+"""
+
+import abc
+import collections
+
+RETURNED = object()
+RAISED = object()
+ABORTED = object()
+
+
+class Outcome(object):
+  """A sum type describing the outcome of some computation.
+
+  Attributes:
+    category: One of RETURNED, RAISED, or ABORTED, respectively indicating
+      that the computation returned a value, raised an exception, or was
+      aborted.
+    return_value: The value returned by the computation. Must be present if
+      category is RETURNED.
+    exception: The exception raised by the computation. Must be present if
+      category is RAISED.
+  """
+  __metaclass__ = abc.ABCMeta
+
+
+class _EasyOutcome(
+    collections.namedtuple('_EasyOutcome',
+                           ['category', 'return_value', 'exception']),
+    Outcome):
+  """A trivial implementation of Outcome."""
+
+# All Outcomes describing abortion are indistinguishable so there might as well
+# be only one.
+_ABORTED_OUTCOME = _EasyOutcome(ABORTED, None, None)
+
+
+def aborted():
+  """Returns an Outcome indicating that a computation was aborted.
+
+  Returns:
+    An Outcome indicating that a computation was aborted.
+  """
+  return _ABORTED_OUTCOME
+
+
+def raised(exception):
+  """Returns an Outcome indicating that a computation raised an exception.
+
+  Args:
+    exception: The exception raised by the computation.
+
+  Returns:
+    An Outcome indicating that a computation raised the given exception.
+  """
+  return _EasyOutcome(RAISED, None, exception)
+
+
+def returned(value):
+  """Returns an Outcome indicating that a computation returned a value.
+
+  Args:
+    value: The value returned by the computation.
+
+  Returns:
+    An Outcome indicating that a computation returned the given value.
+  """
+  return _EasyOutcome(RETURNED, value, None)
+
+
+class Future(object):
+  """A representation of a computation happening in another control flow.
+
+  Computations represented by a Future may have already completed, may be
+  ongoing, or may be yet to be begun.
+
+  Computations represented by a Future are considered uninterruptable; once
+  started they will be allowed to terminate either by returning or raising
+  an exception.
+  """
+  __metaclass__ = abc.ABCMeta
+
+  @abc.abstractmethod
+  def cancel(self):
+    """Attempts to cancel the computation.
+
+    Returns:
+      True if the computation will not be allowed to take place or False if
+        the computation has already taken place or is currently taking place.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def cancelled(self):
+    """Describes whether the computation was cancelled.
+
+    Returns:
+      True if the computation was cancelled and did not take place or False
+        if the computation took place, is taking place, or is scheduled to
+        take place in the future.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def done(self):
+    """Describes whether the computation has taken place.
+
+    Returns:
+      True if the computation took place; False otherwise.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def outcome(self):
+    """Accesses the outcome of the computation.
+
+    If the computation has not yet completed, this method blocks until it has.
+
+    Returns:
+      An Outcome describing the outcome of the computation.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def add_done_callback(self, callback):
+    """Adds a function to be called at completion of the computation.
+
+    The callback will be passed an Outcome object describing the outcome of
+    the computation.
+
+    If the computation has already completed, the callback will be called
+    immediately.
+
+    Args:
+      callback: A callable taking an Outcome as its single parameter.
+    """
+    raise NotImplementedError()
diff --git a/src/python/_framework/foundation/later.py b/src/python/_framework/foundation/later.py
new file mode 100644
index 0000000000..fc2cf578d0
--- /dev/null
+++ b/src/python/_framework/foundation/later.py
@@ -0,0 +1,51 @@
+# Copyright 2015, Google Inc.
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+"""Enables scheduling execution at a later time."""
+
+import time
+
+from _framework.foundation import _timer_future
+
+
+def later(delay, computation):
+  """Schedules later execution of a callable.
+
+  Args:
+    delay: Any numeric value. Represents the minimum length of time in seconds
+      to allow to pass before beginning the computation. No guarantees are made
+      about the maximum length of time that will pass.
+    computation: A callable that accepts no arguments.
+
+  Returns:
+    A Future representing the scheduled computation.
+  """
+  timer_future = _timer_future.TimerFuture(time.time() + delay, computation)
+  timer_future.start()
+  return timer_future
diff --git a/src/python/_framework/foundation/stream.py b/src/python/_framework/foundation/stream.py
new file mode 100644
index 0000000000..75c0cf145b
--- /dev/null
+++ b/src/python/_framework/foundation/stream.py
@@ -0,0 +1,60 @@
+# Copyright 2015, Google Inc.
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+"""Interfaces related to streams of values or objects."""
+
+import abc
+
+
+class Consumer(object):
+  """Interface for consumers of finite streams of values or objects."""
+  __metaclass__ = abc.ABCMeta
+
+  @abc.abstractmethod
+  def consume(self, value):
+    """Accepts a value.
+
+    Args:
+      value: Any value accepted by this Consumer.
+    """
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def terminate(self):
+    """Indicates to this Consumer that no more values will be supplied."""
+    raise NotImplementedError()
+
+  @abc.abstractmethod
+  def consume_and_terminate(self, value):
+    """Supplies a value and signals that no more values will be supplied.
+
+    Args:
+      value: Any value accepted by this Consumer.
+    """
+    raise NotImplementedError()
diff --git a/src/python/_framework/foundation/stream_testing.py b/src/python/_framework/foundation/stream_testing.py
new file mode 100644
index 0000000000..c1acedc5c6
--- /dev/null
+++ b/src/python/_framework/foundation/stream_testing.py
@@ -0,0 +1,73 @@
+# Copyright 2015, Google Inc.
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+"""Utilities for testing stream-related code."""
+
+from _framework.foundation import stream
+
+
+class TestConsumer(stream.Consumer):
+  """A stream.Consumer instrumented for testing.
+
+  Attributes:
+    calls: A sequence of value-termination pairs describing the history of calls
+      made on this object.
+  """
+
+  def __init__(self):
+    self.calls = []
+
+  def consume(self, value):
+    """See stream.Consumer.consume for specification."""
+    self.calls.append((value, False))
+
+  def terminate(self):
+    """See stream.Consumer.terminate for specification."""
+    self.calls.append((None, True))
+
+  def consume_and_terminate(self, value):
+    """See stream.Consumer.consume_and_terminate for specification."""
+    self.calls.append((value, True))
+
+  def is_legal(self):
+    """Reports whether or not a legal sequence of calls has been made."""
+    terminated = False
+    for value, terminal in self.calls:
+      if terminated:
+        return False
+      elif terminal:
+        terminated = True
+      elif value is None:
+        return False
+    else:  # pylint: disable=useless-else-on-loop
+      return True
+
+  def values(self):
+    """Returns the sequence of values that have been passed to this Consumer."""
+    return [value for value, _ in self.calls if value]
diff --git a/src/python/_framework/foundation/stream_util.py b/src/python/_framework/foundation/stream_util.py
new file mode 100644
index 0000000000..3a9c043316
--- /dev/null
+++ b/src/python/_framework/foundation/stream_util.py
@@ -0,0 +1,160 @@
+# Copyright 2015, Google Inc.
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+"""Helpful utilities related to the stream module."""
+
+import logging
+import threading
+
+from _framework.foundation import stream
+
+_NO_VALUE = object()
+
+
+class TransformingConsumer(stream.Consumer):
+  """A stream.Consumer that passes a transformation of its input to another."""
+
+  def __init__(self, transformation, downstream):
+    self._transformation = transformation
+    self._downstream = downstream
+
+  def consume(self, value):
+    self._downstream.consume(self._transformation(value))
+
+  def terminate(self):
+    self._downstream.terminate()
+
+  def consume_and_terminate(self, value):
+    self._downstream.consume_and_terminate(self._transformation(value))
+
+
+class IterableConsumer(stream.Consumer):
+  """A Consumer that when iterated over emits the values it has consumed."""
+
+  def __init__(self):
+    self._condition = threading.Condition()
+    self._values = []
+    self._active = True
+
+  def consume(self, stock_reply):
+    with self._condition:
+      if self._active:
+        self._values.append(stock_reply)
+        self._condition.notify()
+
+  def terminate(self):
+    with self._condition:
+      self._active = False
+      self._condition.notify()
+
+  def consume_and_terminate(self, stock_reply):
+    with self._condition:
+      if self._active:
+        self._values.append(stock_reply)
+        self._active = False
+        self._condition.notify()
+
+  def __iter__(self):
+    return self
+
+  def next(self):
+    with self._condition:
+      while self._active and not self._values:
+        self._condition.wait()
+      if self._values:
+        return self._values.pop(0)
+      else:
+        raise StopIteration()
+
+
+class ThreadSwitchingConsumer(stream.Consumer):
+  """A Consumer decorator that affords serialization and asynchrony."""
+
+  def __init__(self, sink, pool):
+    self._lock = threading.Lock()
+    self._sink = sink
+    self._pool = pool
+    # True if self._spin has been submitted to the pool to be called once and
+    # that call has not yet returned, False otherwise.
+    self._spinning = False
+    self._values = []
+    self._active = True
+
+  def _spin(self, sink, value, terminate):
+    while True:
+      try:
+        if value is _NO_VALUE:
+          sink.terminate()
+        elif terminate:
+          sink.consume_and_terminate(value)
+        else:
+          sink.consume(value)
+      except Exception as e:  # pylint:disable=broad-except
+        logging.exception(e)
+
+      with self._lock:
+        if terminate:
+          self._spinning = False
+          return
+        elif self._values:
+          value = self._values.pop(0)
+          terminate = not self._values and not self._active
+        elif not self._active:
+          value = _NO_VALUE
+          terminate = True
+        else:
+          self._spinning = False
+          return
+
+  def consume(self, value):
+    with self._lock:
+      if self._active:
+        if self._spinning:
+          self._values.append(value)
+        else:
+          self._pool.submit(self._spin, self._sink, value, False)
+          self._spinning = True
+
+  def terminate(self):
+    with self._lock:
+      if self._active:
+        self._active = False
+        if not self._spinning:
+          self._pool.submit(self._spin, self._sink, _NO_VALUE, True)
+          self._spinning = True
+
+  def consume_and_terminate(self, value):
+    with self._lock:
+      if self._active:
+        self._active = False
+        if self._spinning:
+          self._values.append(value)
+        else:
+          self._pool.submit(self._spin, self._sink, value, True)
+          self._spinning = True
diff --git a/src/python/_junkdrawer/__init__.py b/src/python/_junkdrawer/__init__.py
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/src/python/_junkdrawer/__init__.py
diff --git a/src/python/_junkdrawer/stock_pb2.py b/src/python/_junkdrawer/stock_pb2.py
new file mode 100644
index 0000000000..eef18f82d6
--- /dev/null
+++ b/src/python/_junkdrawer/stock_pb2.py
@@ -0,0 +1,152 @@
+# Copyright 2015, Google Inc.
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+# TODO(nathaniel): Remove this from source control after having made
+# generation from the stock.proto source part of GRPC's build-and-test
+# process.
+
+# Generated by the protocol buffer compiler.  DO NOT EDIT!
+# source: stock.proto
+
+import sys
+_b=sys.version_info[0]<3 and (lambda x:x) or (lambda x:x.encode('latin1'))
+from google.protobuf import descriptor as _descriptor
+from google.protobuf import message as _message
+from google.protobuf import reflection as _reflection
+from google.protobuf import symbol_database as _symbol_database
+from google.protobuf import descriptor_pb2
+# @@protoc_insertion_point(imports)
+
+_sym_db = _symbol_database.Default()
+
+
+
+
+DESCRIPTOR = _descriptor.FileDescriptor(
+  name='stock.proto',
+  package='stock',
+  serialized_pb=_b('\n\x0bstock.proto\x12\x05stock\">\n\x0cStockRequest\x12\x0e\n\x06symbol\x18\x01 \x01(\t\x12\x1e\n\x13num_trades_to_watch\x18\x02 \x01(\x05:\x01\x30\"+\n\nStockReply\x12\r\n\x05price\x18\x01 \x01(\x02\x12\x0e\n\x06symbol\x18\x02 \x01(\t2\x96\x02\n\x05Stock\x12=\n\x11GetLastTradePrice\x12\x13.stock.StockRequest\x1a\x11.stock.StockReply\"\x00\x12I\n\x19GetLastTradePriceMultiple\x12\x13.stock.StockRequest\x1a\x11.stock.StockReply\"\x00(\x01\x30\x01\x12?\n\x11WatchFutureTrades\x12\x13.stock.StockRequest\x1a\x11.stock.StockReply\"\x00\x30\x01\x12\x42\n\x14GetHighestTradePrice\x12\x13.stock.StockRequest\x1a\x11.stock.StockReply\"\x00(\x01')
+)
+_sym_db.RegisterFileDescriptor(DESCRIPTOR)
+
+
+
+
+_STOCKREQUEST = _descriptor.Descriptor(
+  name='StockRequest',
+  full_name='stock.StockRequest',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='symbol', full_name='stock.StockRequest.symbol', index=0,
+      number=1, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=_b("").decode('utf-8'),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None),
+    _descriptor.FieldDescriptor(
+      name='num_trades_to_watch', full_name='stock.StockRequest.num_trades_to_watch', index=1,
+      number=2, type=5, cpp_type=1, label=1,
+      has_default_value=True, default_value=0,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None),
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+  ],
+  options=None,
+  is_extendable=False,
+  extension_ranges=[],
+  oneofs=[
+  ],
+  serialized_start=22,
+  serialized_end=84,
+)
+
+
+_STOCKREPLY = _descriptor.Descriptor(
+  name='StockReply',
+  full_name='stock.StockReply',
+  filename=None,
+  file=DESCRIPTOR,
+  containing_type=None,
+  fields=[
+    _descriptor.FieldDescriptor(
+      name='price', full_name='stock.StockReply.price', index=0,
+      number=1, type=2, cpp_type=6, label=1,
+      has_default_value=False, default_value=0,
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None),
+    _descriptor.FieldDescriptor(
+      name='symbol', full_name='stock.StockReply.symbol', index=1,
+      number=2, type=9, cpp_type=9, label=1,
+      has_default_value=False, default_value=_b("").decode('utf-8'),
+      message_type=None, enum_type=None, containing_type=None,
+      is_extension=False, extension_scope=None,
+      options=None),
+  ],
+  extensions=[
+  ],
+  nested_types=[],
+  enum_types=[
+  ],
+  options=None,
+  is_extendable=False,
+  extension_ranges=[],
+  oneofs=[
+  ],
+  serialized_start=86,
+  serialized_end=129,
+)
+
+DESCRIPTOR.message_types_by_name['StockRequest'] = _STOCKREQUEST
+DESCRIPTOR.message_types_by_name['StockReply'] = _STOCKREPLY
+
+StockRequest = _reflection.GeneratedProtocolMessageType('StockRequest', (_message.Message,), dict(
+  DESCRIPTOR = _STOCKREQUEST,
+  __module__ = 'stock_pb2'
+  # @@protoc_insertion_point(class_scope:stock.StockRequest)
+  ))
+_sym_db.RegisterMessage(StockRequest)
+
+StockReply = _reflection.GeneratedProtocolMessageType('StockReply', (_message.Message,), dict(
+  DESCRIPTOR = _STOCKREPLY,
+  __module__ = 'stock_pb2'
+  # @@protoc_insertion_point(class_scope:stock.StockReply)
+  ))
+_sym_db.RegisterMessage(StockReply)
+
+
+# @@protoc_insertion_point(module_scope)
diff --git a/tools/run_tests/run_python.sh b/tools/run_tests/run_python.sh
index 0d5ed0238d..ef40602eb3 100755
--- a/tools/run_tests/run_python.sh
+++ b/tools/run_tests/run_python.sh
@@ -6,5 +6,6 @@ set -ex
 cd $(dirname $0)/../..
 
 root=`pwd`
-python2.7_virtual_environment/bin/python2.7 -B -m unittest discover -s src/python -p '*.py'
-python3.4 -B -m unittest discover -s src/python -p '*.py'
+PYTHONPATH=third_party/protobuf/python python2.7_virtual_environment/bin/python2.7 -B -m unittest discover -s src/python -p '*.py'
+# TODO(nathaniel): Get this working again (requires 3.X-friendly protobuf)
+# python3.4 -B -m unittest discover -s src/python -p '*.py'