Changed default string type to be str

This impacts the following APIs:
  Metadata: Key is always a str, Value is bytes for binary metadata,
    str otherwise
  Call Details: str type
  gRPC method: str type
  hostname/target: str type

21 files changed, 225 insertions, 229 deletions

diff --git a/src/python/grpcio/grpc/_channel.py b/src/python/grpcio/grpc/_channel.py
index cf6175d031..a89b501303 100644
--- a/src/python/grpcio/grpc/_channel.py
+++ b/src/python/grpcio/grpc/_channel.py
@@ -364,13 +364,13 @@ class _Rendezvous(grpc.RpcError, grpc.Future, grpc.Call):
     with self._state.condition:
       while self._state.initial_metadata is None:
         self._state.condition.wait()
-      return self._state.initial_metadata
+      return _common.application_metadata(self._state.initial_metadata)
 
   def trailing_metadata(self):
     with self._state.condition:
       while self._state.trailing_metadata is None:
         self._state.condition.wait()
-      return self._state.trailing_metadata
+      return _common.application_metadata(self._state.trailing_metadata)
 
   def code(self):
     with self._state.condition:
@@ -382,7 +382,7 @@ class _Rendezvous(grpc.RpcError, grpc.Future, grpc.Call):
     with self._state.condition:
       while self._state.details is None:
         self._state.condition.wait()
-      return self._state.details
+      return _common.decode(self._state.details)
 
   def _repr(self):
     with self._state.condition:
@@ -390,7 +390,7 @@ class _Rendezvous(grpc.RpcError, grpc.Future, grpc.Call):
         return '<_Rendezvous object of in-flight RPC>'
       else:
         return '<_Rendezvous of RPC that terminated with ({}, {})>'.format(
-            self._state.code, self._state.details)
+            self._state.code, _common.decode(self._state.details))
 
   def __repr__(self):
     return self._repr()
@@ -451,7 +451,7 @@ class _UnaryUnaryMultiCallable(grpc.UnaryUnaryMultiCallable):
       state = _RPCState(_UNARY_UNARY_INITIAL_DUE, None, None, None, None)
       operations = (
           cygrpc.operation_send_initial_metadata(
-              _common.metadata(metadata), _EMPTY_FLAGS),
+              _common.cygrpc_metadata(metadata), _EMPTY_FLAGS),
           cygrpc.operation_send_message(serialized_request, _EMPTY_FLAGS),
           cygrpc.operation_send_close_from_client(_EMPTY_FLAGS),
           cygrpc.operation_receive_initial_metadata(_EMPTY_FLAGS),
@@ -529,7 +529,7 @@ class _UnaryStreamMultiCallable(grpc.UnaryStreamMultiCallable):
             event_handler)
         operations = (
             cygrpc.operation_send_initial_metadata(
-                _common.metadata(metadata), _EMPTY_FLAGS),
+                _common.cygrpc_metadata(metadata), _EMPTY_FLAGS),
             cygrpc.operation_send_message(serialized_request, _EMPTY_FLAGS),
             cygrpc.operation_send_close_from_client(_EMPTY_FLAGS),
             cygrpc.operation_receive_status_on_client(_EMPTY_FLAGS),
@@ -564,7 +564,7 @@ class _StreamUnaryMultiCallable(grpc.StreamUnaryMultiCallable):
           None)
       operations = (
           cygrpc.operation_send_initial_metadata(
-              _common.metadata(metadata), _EMPTY_FLAGS),
+              _common.cygrpc_metadata(metadata), _EMPTY_FLAGS),
           cygrpc.operation_receive_message(_EMPTY_FLAGS),
           cygrpc.operation_receive_status_on_client(_EMPTY_FLAGS),
       )
@@ -608,7 +608,7 @@ class _StreamUnaryMultiCallable(grpc.StreamUnaryMultiCallable):
           event_handler)
       operations = (
           cygrpc.operation_send_initial_metadata(
-              _common.metadata(metadata), _EMPTY_FLAGS),
+              _common.cygrpc_metadata(metadata), _EMPTY_FLAGS),
           cygrpc.operation_receive_message(_EMPTY_FLAGS),
           cygrpc.operation_receive_status_on_client(_EMPTY_FLAGS),
       )
@@ -645,7 +645,7 @@ class _StreamStreamMultiCallable(grpc.StreamStreamMultiCallable):
           event_handler)
       operations = (
           cygrpc.operation_send_initial_metadata(
-              _common.metadata(metadata), _EMPTY_FLAGS),
+              _common.cygrpc_metadata(metadata), _EMPTY_FLAGS),
           cygrpc.operation_receive_status_on_client(_EMPTY_FLAGS),
       )
       call.start_batch(cygrpc.Operations(operations), event_handler)
@@ -846,8 +846,13 @@ def _options(options):
   else:
     pairs = list(options) + [
         (cygrpc.ChannelArgKey.primary_user_agent_string, _USER_AGENT)]
-  return cygrpc.ChannelArgs(
-      cygrpc.ChannelArg(arg_name, arg_value) for arg_name, arg_value in pairs)
+  encoded_pairs = [
+      (_common.encode(arg_name), arg_value) if isinstance(arg_value, int)
+      else (_common.encode(arg_name), _common.encode(arg_value))
+      for arg_name, arg_value in pairs]
+  return cygrpc.ChannelArgs([
+      cygrpc.ChannelArg(arg_name, arg_value)
+      for arg_name, arg_value in encoded_pairs])
 
 
 class Channel(grpc.Channel):
@@ -860,7 +865,8 @@ class Channel(grpc.Channel):
       options: Configuration options for the channel.
       credentials: A cygrpc.ChannelCredentials or None.
     """
-    self._channel = cygrpc.Channel(target, _options(options), credentials)
+    self._channel = cygrpc.Channel(
+        _common.encode(target), _options(options), credentials)
     self._call_state = _ChannelCallState(self._channel)
     self._connectivity_state = _ChannelConnectivityState(self._channel)
 
@@ -873,26 +879,26 @@ class Channel(grpc.Channel):
   def unary_unary(
       self, method, request_serializer=None, response_deserializer=None):
     return _UnaryUnaryMultiCallable(
-        self._channel, _create_channel_managed_call(self._call_state), method,
-        request_serializer, response_deserializer)
+        self._channel, _create_channel_managed_call(self._call_state),
+        _common.encode(method), request_serializer, response_deserializer)
 
   def unary_stream(
       self, method, request_serializer=None, response_deserializer=None):
     return _UnaryStreamMultiCallable(
-        self._channel, _create_channel_managed_call(self._call_state), method,
-        request_serializer, response_deserializer)
+        self._channel, _create_channel_managed_call(self._call_state),
+        _common.encode(method), request_serializer, response_deserializer)
 
   def stream_unary(
       self, method, request_serializer=None, response_deserializer=None):
     return _StreamUnaryMultiCallable(
-        self._channel, _create_channel_managed_call(self._call_state), method,
-        request_serializer, response_deserializer)
+        self._channel, _create_channel_managed_call(self._call_state),
+        _common.encode(method), request_serializer, response_deserializer)
 
   def stream_stream(
       self, method, request_serializer=None, response_deserializer=None):
     return _StreamStreamMultiCallable(
-        self._channel, _create_channel_managed_call(self._call_state), method,
-        request_serializer, response_deserializer)
+        self._channel, _create_channel_managed_call(self._call_state),
+        _common.encode(method), request_serializer, response_deserializer)
 
   def __del__(self):
     _moot(self._connectivity_state)
diff --git a/src/python/grpcio/grpc/_common.py b/src/python/grpcio/grpc/_common.py
index f351bea9e3..4d7d521419 100644
--- a/src/python/grpcio/grpc/_common.py
+++ b/src/python/grpcio/grpc/_common.py
@@ -76,9 +76,37 @@ STATUS_CODE_TO_CYGRPC_STATUS_CODE = {
 }
 
 
-def metadata(application_metadata):
+def encode(s):
+  if isinstance(s, bytes):
+    return s
+  else:
+    return s.encode('ascii')
+
+
+def decode(b):
+  if isinstance(b, str):
+    return b
+  else:
+    try:
+      return b.decode('utf8')
+    except UnicodeDecodeError:
+      logging.exception('Invalid encoding on {}'.format(b))
+      return b.decode('latin1')
+
+
+def cygrpc_metadata(application_metadata):
   return _EMPTY_METADATA if application_metadata is None else cygrpc.Metadata(
-      cygrpc.Metadatum(key, value) for key, value in application_metadata)
+      cygrpc.Metadatum(encode(key), encode(value))
+      for key, value in application_metadata)
+
+
+def application_metadata(cygrpc_metadata):
+  if cygrpc_metadata is None:
+    return ()
+  else:
+    return tuple(
+        (decode(key), value if key[-4:] == b'-bin' else decode(value))
+        for key, value in cygrpc_metadata)
 
 
 def _transform(message, transformer, exception_message):
@@ -101,17 +129,8 @@ def deserialize(serialized_message, deserializer):
                     'Exception deserializing message!')
 
 
-def _encode(s):
-  if isinstance(s, bytes):
-    return s
-  else:
-    return s.encode('ascii')
-
-
 def fully_qualified_method(group, method):
-  group = _encode(group)
-  method = _encode(method)
-  return b'/' + group + b'/' + method
+  return '/{}/{}'.format(group, method)
 
 
 class CleanupThread(threading.Thread):
diff --git a/src/python/grpcio/grpc/_cython/_cygrpc/channel.pyx.pxi b/src/python/grpcio/grpc/_cython/_cygrpc/channel.pyx.pxi
index 866cff0d01..1406696510 100644
--- a/src/python/grpcio/grpc/_cython/_cygrpc/channel.pyx.pxi
+++ b/src/python/grpcio/grpc/_cython/_cygrpc/channel.pyx.pxi
@@ -32,9 +32,8 @@ cimport cpython
 
 cdef class Channel:
 
-  def __cinit__(self, target, ChannelArgs arguments=None,
+  def __cinit__(self, bytes target, ChannelArgs arguments=None,
                 ChannelCredentials channel_credentials=None):
-    target = str_to_bytes(target)
     cdef grpc_channel_args *c_arguments = NULL
     cdef char *c_target = NULL
     self.c_channel = NULL
@@ -57,8 +56,6 @@ cdef class Channel:
   def create_call(self, Call parent, int flags,
                   CompletionQueue queue not None,
                   method, host, Timespec deadline not None):
-    method = str_to_bytes(method)
-    host = str_to_bytes(host)
     if queue.is_shutting_down:
       raise ValueError("queue must not be shutting down or shutdown")
     cdef char *method_c_string = method
diff --git a/src/python/grpcio/grpc/_cython/_cygrpc/credentials.pyx.pxi b/src/python/grpcio/grpc/_cython/_cygrpc/credentials.pyx.pxi
index 470382d609..b24e69243e 100644
--- a/src/python/grpcio/grpc/_cython/_cygrpc/credentials.pyx.pxi
+++ b/src/python/grpcio/grpc/_cython/_cygrpc/credentials.pyx.pxi
@@ -82,7 +82,7 @@ cdef class ServerCredentials:
 
 cdef class CredentialsMetadataPlugin:
 
-  def __cinit__(self, object plugin_callback, name):
+  def __cinit__(self, object plugin_callback, bytes name):
     """
     Args:
       plugin_callback (callable): Callback accepting a service URL (str/bytes)
@@ -91,9 +91,8 @@ cdef class CredentialsMetadataPlugin:
         when called should be non-blocking and eventually call the callback
         object with the appropriate status code/details and metadata (if
         successful).
-      name (str): Plugin name.
+      name (bytes): Plugin name.
     """
-    name = str_to_bytes(name)
     if not callable(plugin_callback):
       raise ValueError('expected callable plugin_callback')
     self.plugin_callback = plugin_callback
@@ -130,8 +129,7 @@ cdef void plugin_get_metadata(
     grpc_credentials_plugin_metadata_cb cb, void *user_data) with gil:
   def python_callback(
       Metadata metadata, grpc_status_code status,
-      error_details):
-    error_details = str_to_bytes(error_details)
+      bytes error_details):
     cb(user_data, metadata.c_metadata_array.metadata,
        metadata.c_metadata_array.count, status, error_details)
   cdef CredentialsMetadataPlugin self = <CredentialsMetadataPlugin>state
diff --git a/src/python/grpcio/grpc/_cython/_cygrpc/records.pyx.pxi b/src/python/grpcio/grpc/_cython/_cygrpc/records.pyx.pxi
index 0055d0d3a2..8e651e880f 100644
--- a/src/python/grpcio/grpc/_cython/_cygrpc/records.pyx.pxi
+++ b/src/python/grpcio/grpc/_cython/_cygrpc/records.pyx.pxi
@@ -231,17 +231,10 @@ cdef class Event:
 
 cdef class ByteBuffer:
 
-  def __cinit__(self, data):
+  def __cinit__(self, bytes data):
     if data is None:
       self.c_byte_buffer = NULL
       return
-    if isinstance(data, ByteBuffer):
-      data = (<ByteBuffer>data).bytes()
-      if data is None:
-        self.c_byte_buffer = NULL
-        return
-    else:
-      data = str_to_bytes(data)
 
     cdef char *c_data = data
     cdef gpr_slice data_slice
@@ -296,26 +289,28 @@ cdef class ByteBuffer:
 
 cdef class SslPemKeyCertPair:
 
-  def __cinit__(self, private_key, certificate_chain):
-    self.private_key = str_to_bytes(private_key)
-    self.certificate_chain = str_to_bytes(certificate_chain)
+  def __cinit__(self, bytes private_key, bytes certificate_chain):
+    self.private_key = private_key
+    self.certificate_chain = certificate_chain
     self.c_pair.private_key = self.private_key
     self.c_pair.certificate_chain = self.certificate_chain
 
 
 cdef class ChannelArg:
 
-  def __cinit__(self, key, value):
-    self.key = str_to_bytes(key)
+  def __cinit__(self, bytes key, value):
+    self.key = key
     self.c_arg.key = self.key
     if isinstance(value, int):
-      self.value = int(value)
+      self.value = value
       self.c_arg.type = GRPC_ARG_INTEGER
       self.c_arg.value.integer = self.value
-    else:
-      self.value = str_to_bytes(value)
+    elif isinstance(value, bytes):
+      self.value = value
       self.c_arg.type = GRPC_ARG_STRING
       self.c_arg.value.string = self.value
+    else:
+      raise TypeError('Expected int or bytes, got {}'.format(type(value)))
 
 
 cdef class ChannelArgs:
@@ -347,9 +342,9 @@ cdef class ChannelArgs:
 
 cdef class Metadatum:
 
-  def __cinit__(self, key, value):
-    self._key = str_to_bytes(key)
-    self._value = str_to_bytes(value)
+  def __cinit__(self, bytes key, bytes value):
+    self._key = key
+    self._value = value
     self.c_metadata.key = self._key
     self.c_metadata.value = self._value
     self.c_metadata.value_length = len(self._value)
@@ -563,8 +558,7 @@ def operation_send_close_from_client(int flags):
   return op
 
 def operation_send_status_from_server(
-    Metadata metadata, grpc_status_code code, details, int flags):
-  details = str_to_bytes(details)
+    Metadata metadata, grpc_status_code code, bytes details, int flags):
   cdef Operation op = Operation()
   op.c_op.type = GRPC_OP_SEND_STATUS_FROM_SERVER
   op.c_op.flags = flags
diff --git a/src/python/grpcio/grpc/_cython/_cygrpc/server.pyx.pxi b/src/python/grpcio/grpc/_cython/_cygrpc/server.pyx.pxi
index 42afeb8498..3e03b6efe1 100644
--- a/src/python/grpcio/grpc/_cython/_cygrpc/server.pyx.pxi
+++ b/src/python/grpcio/grpc/_cython/_cygrpc/server.pyx.pxi
@@ -101,7 +101,7 @@ cdef class Server:
     # Ensure the core has gotten a chance to do the start-up work
     self.backup_shutdown_queue.poll(Timespec(None))
 
-  def add_http2_port(self, address,
+  def add_http2_port(self, bytes address,
                      ServerCredentials server_credentials=None):
     address = str_to_bytes(address)
     self.references.append(address)
diff --git a/src/python/grpcio/grpc/_plugin_wrapping.py b/src/python/grpcio/grpc/_plugin_wrapping.py
index 4e9cfe710c..7cb5218c22 100644
--- a/src/python/grpcio/grpc/_plugin_wrapping.py
+++ b/src/python/grpcio/grpc/_plugin_wrapping.py
@@ -31,6 +31,7 @@ import collections
 import threading
 
 import grpc
+from grpc import _common
 from grpc._cython import cygrpc
 
 
@@ -62,17 +63,16 @@ class _WrappedCygrpcCallback(object):
     # TODO(atash) translate different Exception superclasses into different
     # status codes.
     self.cygrpc_callback(
-        cygrpc.Metadata([]), cygrpc.StatusCode.internal, error.message)
+        _common.EMPTY_METADATA, cygrpc.StatusCode.internal,
+        _common.encode(str(error)))
 
   def _invoke_success(self, metadata):
     try:
-      cygrpc_metadata = cygrpc.Metadata(
-          cygrpc.Metadatum(key, value)
-          for key, value in metadata)
+      cygrpc_metadata = _common.cygrpc_metadata(metadata)
     except Exception as error:
       self._invoke_failure(error)
       return
-    self.cygrpc_callback(cygrpc_metadata, cygrpc.StatusCode.ok, '')
+    self.cygrpc_callback(cygrpc_metadata, cygrpc.StatusCode.ok, b'')
 
   def __call__(self, metadata, error):
     with self.is_called_lock:
@@ -101,7 +101,7 @@ class _WrappedPlugin(object):
   def __call__(self, context, cygrpc_callback):
     wrapped_cygrpc_callback = _WrappedCygrpcCallback(cygrpc_callback)
     wrapped_context = AuthMetadataContext(
-        context.service_url, context.method_name)
+        _common.decode(context.service_url), _common.decode(context.method_name))
     try:
       self.plugin(
           wrapped_context, AuthMetadataPluginCallback(wrapped_cygrpc_callback))
@@ -120,4 +120,4 @@ def call_credentials_metadata_plugin(plugin, name):
       plugin's invocation must be non-blocking.
   """
   return cygrpc.call_credentials_metadata_plugin(
-      cygrpc.CredentialsMetadataPlugin(_WrappedPlugin(plugin), name))
+      cygrpc.CredentialsMetadataPlugin(_WrappedPlugin(plugin), _common.encode(name)))
diff --git a/src/python/grpcio/grpc/_server.py b/src/python/grpcio/grpc/_server.py
index bf20f15f72..f4c114056f 100644
--- a/src/python/grpcio/grpc/_server.py
+++ b/src/python/grpcio/grpc/_server.py
@@ -87,7 +87,7 @@ def _abortion_code(state, code):
 
 
 def _details(state):
-  return '' if state.details is None else state.details
+  return b'' if state.details is None else state.details
 
 
 class _HandlerCallDetails(
@@ -146,14 +146,14 @@ def _abort(state, call, code, details):
           cygrpc.operation_send_initial_metadata(
               _EMPTY_METADATA, _EMPTY_FLAGS),
           cygrpc.operation_send_status_from_server(
-              _common.metadata(state.trailing_metadata), effective_code,
+              _common.cygrpc_metadata(state.trailing_metadata), effective_code,
               effective_details, _EMPTY_FLAGS),
       )
       token = _SEND_INITIAL_METADATA_AND_SEND_STATUS_FROM_SERVER_TOKEN
     else:
       operations = (
           cygrpc.operation_send_status_from_server(
-              _common.metadata(state.trailing_metadata), effective_code,
+              _common.cygrpc_metadata(state.trailing_metadata), effective_code,
               effective_details, _EMPTY_FLAGS),
       )
       token = _SEND_STATUS_FROM_SERVER_TOKEN
@@ -191,7 +191,7 @@ def _receive_message(state, call, request_deserializer):
         if request is None:
           _abort(
               state, call, cygrpc.StatusCode.internal,
-              'Exception deserializing request!')
+              b'Exception deserializing request!')
         else:
           state.request = request
         state.condition.notify_all()
@@ -244,10 +244,10 @@ class _Context(grpc.ServicerContext):
       self._state.disable_next_compression = True
 
   def invocation_metadata(self):
-    return self._rpc_event.request_metadata
+    return _common.application_metadata(self._rpc_event.request_metadata)
 
   def peer(self):
-    return self._rpc_event.operation_call.peer()
+    return _common.decode(self._rpc_event.operation_call.peer())
 
   def send_initial_metadata(self, initial_metadata):
     with self._state.condition:
@@ -256,7 +256,7 @@ class _Context(grpc.ServicerContext):
       else:
         if self._state.initial_metadata_allowed:
           operation = cygrpc.operation_send_initial_metadata(
-              _common.metadata(initial_metadata), _EMPTY_FLAGS)
+              _common.cygrpc_metadata(initial_metadata), _EMPTY_FLAGS)
           self._rpc_event.operation_call.start_batch(
               cygrpc.Operations((operation,)),
               _send_initial_metadata(self._state))
@@ -267,7 +267,8 @@ class _Context(grpc.ServicerContext):
 
   def set_trailing_metadata(self, trailing_metadata):
     with self._state.condition:
-      self._state.trailing_metadata = trailing_metadata
+      self._state.trailing_metadata = _common.cygrpc_metadata(
+          trailing_metadata)
 
   def set_code(self, code):
     with self._state.condition:
@@ -275,7 +276,7 @@ class _Context(grpc.ServicerContext):
 
   def set_details(self, details):
     with self._state.condition:
-      self._state.details = details
+      self._state.details = _common.encode(details)
 
 
 class _RequestIterator(object):
@@ -346,7 +347,7 @@ def _unary_request(rpc_event, state, request_deserializer):
                   rpc_event.request_call_details.method)
               _abort(
                   state, rpc_event.operation_call,
-                  cygrpc.StatusCode.unimplemented, details)
+                  cygrpc.StatusCode.unimplemented, _common.encode(details))
               return None
             elif state.client is _CANCELLED:
               return None
@@ -366,8 +367,8 @@ def _call_behavior(rpc_event, state, behavior, argument, request_deserializer):
       if e not in state.rpc_errors:
         details = 'Exception calling application: {}'.format(e)
         logging.exception(details)
-        _abort(
-            state, rpc_event.operation_call, cygrpc.StatusCode.unknown, details)
+        _abort(state, rpc_event.operation_call,
+               cygrpc.StatusCode.unknown, _common.encode(details))
     return None, False
 
 
@@ -381,8 +382,8 @@ def _take_response_from_response_iterator(rpc_event, state, response_iterator):
       if e not in state.rpc_errors:
         details = 'Exception iterating responses: {}'.format(e)
         logging.exception(details)
-        _abort(
-            state, rpc_event.operation_call, cygrpc.StatusCode.unknown, details)
+        _abort(state, rpc_event.operation_call,
+               cygrpc.StatusCode.unknown, _common.encode(details))
     return None, False
 
 
@@ -392,7 +393,7 @@ def _serialize_response(rpc_event, state, response, response_serializer):
     with state.condition:
       _abort(
           state, rpc_event.operation_call, cygrpc.StatusCode.internal,
-          'Failed to serialize response!')
+          b'Failed to serialize response!')
     return None
   else:
     return serialized_response
@@ -428,7 +429,7 @@ def _send_response(rpc_event, state, serialized_response):
 def _status(rpc_event, state, serialized_response):
   with state.condition:
     if state.client is not _CANCELLED:
-      trailing_metadata = _common.metadata(state.trailing_metadata)
+      trailing_metadata = _common.cygrpc_metadata(state.trailing_metadata)
       code = _completion_code(state)
       details = _details(state)
       operations = [
@@ -532,7 +533,8 @@ def _find_method_handler(rpc_event, generic_handlers):
   for generic_handler in generic_handlers:
     method_handler = generic_handler.service(
         _HandlerCallDetails(
-            rpc_event.request_call_details.method, rpc_event.request_metadata))
+            _common.decode(rpc_event.request_call_details.method),
+            rpc_event.request_metadata))
     if method_handler is not None:
       return method_handler
   else:
@@ -545,7 +547,7 @@ def _handle_unrecognized_method(rpc_event):
       cygrpc.operation_receive_close_on_server(_EMPTY_FLAGS),
       cygrpc.operation_send_status_from_server(
           _EMPTY_METADATA, cygrpc.StatusCode.unimplemented,
-          'Method not found!', _EMPTY_FLAGS),
+          b'Method not found!', _EMPTY_FLAGS),
   )
   rpc_state = _RPCState()
   rpc_event.operation_call.start_batch(
@@ -740,10 +742,10 @@ class Server(grpc.Server):
     _add_generic_handlers(self._state, generic_rpc_handlers)
 
   def add_insecure_port(self, address):
-    return _add_insecure_port(self._state, address)
+    return _add_insecure_port(self._state, _common.encode(address))
 
   def add_secure_port(self, address, server_credentials):
-    return _add_secure_port(self._state, address, server_credentials)
+    return _add_secure_port(self._state, _common.encode(address), server_credentials)
 
   def start(self):
     _start(self._state)
diff --git a/src/python/grpcio/grpc/beta/_server_adaptations.py b/src/python/grpcio/grpc/beta/_server_adaptations.py
index c695434dac..1e1f80156a 100644
--- a/src/python/grpcio/grpc/beta/_server_adaptations.py
+++ b/src/python/grpcio/grpc/beta/_server_adaptations.py
@@ -79,7 +79,8 @@ class _FaceServicerContext(face.ServicerContext):
     return _ServerProtocolContext(self._servicer_context)
 
   def invocation_metadata(self):
-    return self._servicer_context.invocation_metadata()
+    return _common.cygrpc_metadata(
+        self._servicer_context.invocation_metadata())
 
   def initial_metadata(self, initial_metadata):
     self._servicer_context.send_initial_metadata(initial_metadata)
diff --git a/src/python/grpcio/tests/unit/_compression_test.py b/src/python/grpcio/tests/unit/_compression_test.py
index 6eddb6f83f..9e8b8578c1 100644
--- a/src/python/grpcio/tests/unit/_compression_test.py
+++ b/src/python/grpcio/tests/unit/_compression_test.py
@@ -37,8 +37,8 @@ from grpc.framework.foundation import logging_pool
 from tests.unit import test_common
 from tests.unit.framework.common import test_constants
 
-_UNARY_UNARY = b'/test/UnaryUnary'
-_STREAM_STREAM = b'/test/StreamStream'
+_UNARY_UNARY = '/test/UnaryUnary'
+_STREAM_STREAM = '/test/StreamStream'
 
 
 def handle_unary(request, servicer_context):
diff --git a/src/python/grpcio/tests/unit/_cython/_cancel_many_calls_test.py b/src/python/grpcio/tests/unit/_cython/_cancel_many_calls_test.py
index c1de779014..cac0c8b3b9 100644
--- a/src/python/grpcio/tests/unit/_cython/_cancel_many_calls_test.py
+++ b/src/python/grpcio/tests/unit/_cython/_cancel_many_calls_test.py
@@ -159,9 +159,9 @@ class CancelManyCallsTest(unittest.TestCase):
     server_completion_queue = cygrpc.CompletionQueue()
     server = cygrpc.Server()
     server.register_completion_queue(server_completion_queue)
-    port = server.add_http2_port('[::]:0')
+    port = server.add_http2_port(b'[::]:0')
     server.start()
-    channel = cygrpc.Channel('localhost:{}'.format(port))
+    channel = cygrpc.Channel('localhost:{}'.format(port).encode())
 
     state = _State()
 
diff --git a/src/python/grpcio/tests/unit/_cython/_channel_test.py b/src/python/grpcio/tests/unit/_cython/_channel_test.py
index 3dc7a246ae..f9c8a3ac62 100644
--- a/src/python/grpcio/tests/unit/_cython/_channel_test.py
+++ b/src/python/grpcio/tests/unit/_cython/_channel_test.py
@@ -37,7 +37,7 @@ from tests.unit.framework.common import test_constants
 
 
 def _channel_and_completion_queue():
-  channel = cygrpc.Channel('localhost:54321', cygrpc.ChannelArgs(()))
+  channel = cygrpc.Channel(b'localhost:54321', cygrpc.ChannelArgs(()))
   completion_queue = cygrpc.CompletionQueue()
   return channel, completion_queue
 
diff --git a/src/python/grpcio/tests/unit/_cython/_read_some_but_not_all_responses_test.py b/src/python/grpcio/tests/unit/_cython/_read_some_but_not_all_responses_test.py
index 6ae7a90fbe..27fcee0d6f 100644
--- a/src/python/grpcio/tests/unit/_cython/_read_some_but_not_all_responses_test.py
+++ b/src/python/grpcio/tests/unit/_cython/_read_some_but_not_all_responses_test.py
@@ -126,9 +126,9 @@ class ReadSomeButNotAllResponsesTest(unittest.TestCase):
     server_completion_queue = cygrpc.CompletionQueue()
     server = cygrpc.Server()
     server.register_completion_queue(server_completion_queue)
-    port = server.add_http2_port('[::]:0')
+    port = server.add_http2_port(b'[::]:0')
     server.start()
-    channel = cygrpc.Channel('localhost:{}'.format(port))
+    channel = cygrpc.Channel('localhost:{}'.format(port).encode())
 
     server_shutdown_tag = 'server_shutdown_tag'
     server_driver = _ServerDriver(server_completion_queue, server_shutdown_tag)
diff --git a/src/python/grpcio/tests/unit/_cython/cygrpc_test.py b/src/python/grpcio/tests/unit/_cython/cygrpc_test.py
index a006a20ce3..b740695e35 100644
--- a/src/python/grpcio/tests/unit/_cython/cygrpc_test.py
+++ b/src/python/grpcio/tests/unit/_cython/cygrpc_test.py
@@ -46,38 +46,38 @@ def _metadata_plugin_callback(context, callback):
   callback(cygrpc.Metadata(
       [cygrpc.Metadatum(_CALL_CREDENTIALS_METADATA_KEY,
                         _CALL_CREDENTIALS_METADATA_VALUE)]),
-      cygrpc.StatusCode.ok, '')
+      cygrpc.StatusCode.ok, b'')
 
 
 class TypeSmokeTest(unittest.TestCase):
 
   def testStringsInUtilitiesUpDown(self):
     self.assertEqual(0, cygrpc.StatusCode.ok)
-    metadatum = cygrpc.Metadatum('a', 'b')
-    self.assertEqual('a'.encode(), metadatum.key)
-    self.assertEqual('b'.encode(), metadatum.value)
+    metadatum = cygrpc.Metadatum(b'a', b'b')
+    self.assertEqual(b'a', metadatum.key)
+    self.assertEqual(b'b', metadatum.value)
     metadata = cygrpc.Metadata([metadatum])
     self.assertEqual(1, len(metadata))
     self.assertEqual(metadatum.key, metadata[0].key)
 
   def testMetadataIteration(self):
     metadata = cygrpc.Metadata([
-        cygrpc.Metadatum('a', 'b'), cygrpc.Metadatum('c', 'd')])
+        cygrpc.Metadatum(b'a', b'b'), cygrpc.Metadatum(b'c', b'd')])
     iterator = iter(metadata)
     metadatum = next(iterator)
     self.assertIsInstance(metadatum, cygrpc.Metadatum)
-    self.assertEqual(metadatum.key, 'a'.encode())
-    self.assertEqual(metadatum.value, 'b'.encode())
+    self.assertEqual(metadatum.key, b'a')
+    self.assertEqual(metadatum.value, b'b')
     metadatum = next(iterator)
     self.assertIsInstance(metadatum, cygrpc.Metadatum)
-    self.assertEqual(metadatum.key, 'c'.encode())
-    self.assertEqual(metadatum.value, 'd'.encode())
+    self.assertEqual(metadatum.key, b'c')
+    self.assertEqual(metadatum.value, b'd')
     with self.assertRaises(StopIteration):
       next(iterator)
 
   def testOperationsIteration(self):
     operations = cygrpc.Operations([
-        cygrpc.operation_send_message('asdf', _EMPTY_FLAGS)])
+        cygrpc.operation_send_message(b'asdf', _EMPTY_FLAGS)])
     iterator = iter(operations)
     operation = next(iterator)
     self.assertIsInstance(operation, cygrpc.Operation)
@@ -87,7 +87,7 @@ class TypeSmokeTest(unittest.TestCase):
       next(iterator)
 
   def testOperationFlags(self):
-    operation = cygrpc.operation_send_message('asdf',
+    operation = cygrpc.operation_send_message(b'asdf',
                                               cygrpc.WriteFlag.no_compress)
     self.assertEqual(cygrpc.WriteFlag.no_compress, operation.flags)
 
@@ -105,16 +105,16 @@ class TypeSmokeTest(unittest.TestCase):
     del server
 
   def testChannelUpDown(self):
-    channel = cygrpc.Channel('[::]:0', cygrpc.ChannelArgs([]))
+    channel = cygrpc.Channel(b'[::]:0', cygrpc.ChannelArgs([]))
     del channel
 
   def testCredentialsMetadataPluginUpDown(self):
     plugin = cygrpc.CredentialsMetadataPlugin(
-        lambda ignored_a, ignored_b: None, '')
+        lambda ignored_a, ignored_b: None, b'')
     del plugin
 
   def testCallCredentialsFromPluginUpDown(self):
-    plugin = cygrpc.CredentialsMetadataPlugin(_metadata_plugin_callback, '')
+    plugin = cygrpc.CredentialsMetadataPlugin(_metadata_plugin_callback, b'')
     call_credentials = cygrpc.call_credentials_metadata_plugin(plugin)
     del plugin
     del call_credentials
@@ -123,7 +123,7 @@ class TypeSmokeTest(unittest.TestCase):
     server = cygrpc.Server()
     completion_queue = cygrpc.CompletionQueue()
     server.register_completion_queue(completion_queue)
-    port = server.add_http2_port('[::]:0')
+    port = server.add_http2_port(b'[::]:0')
     self.assertIsInstance(port, int)
     server.start()
     del server
@@ -131,7 +131,7 @@ class TypeSmokeTest(unittest.TestCase):
   def testServerStartShutdown(self):
     completion_queue = cygrpc.CompletionQueue()
     server = cygrpc.Server()
-    server.add_http2_port('[::]:0')
+    server.add_http2_port(b'[::]:0')
     server.register_completion_queue(completion_queue)
     server.start()
     shutdown_tag = object()
@@ -150,9 +150,9 @@ class ServerClientMixin(object):
     self.server = cygrpc.Server()
     self.server.register_completion_queue(self.server_completion_queue)
     if server_credentials:
-      self.port = self.server.add_http2_port('[::]:0', server_credentials)
+      self.port = self.server.add_http2_port(b'[::]:0', server_credentials)
     else:
-      self.port = self.server.add_http2_port('[::]:0')
+      self.port = self.server.add_http2_port(b'[::]:0')
     self.server.start()
     self.client_completion_queue = cygrpc.CompletionQueue()
     if client_credentials:
@@ -160,10 +160,10 @@ class ServerClientMixin(object):
           cygrpc.ChannelArg(cygrpc.ChannelArgKey.ssl_target_name_override,
                             host_override)])
       self.client_channel = cygrpc.Channel(
-          'localhost:{}'.format(self.port), client_channel_arguments,
+          'localhost:{}'.format(self.port).encode(), client_channel_arguments,
           client_credentials)
     else:
-      self.client_channel = cygrpc.Channel('localhost:{}'.format(self.port))
+      self.client_channel = cygrpc.Channel('localhost:{}'.format(self.port).encode())
     if host_override:
       self.host_argument = None  # default host
       self.expected_host = host_override
diff --git a/src/python/grpcio/tests/unit/_empty_message_test.py b/src/python/grpcio/tests/unit/_empty_message_test.py
index f324f6216b..8c7d697728 100644
--- a/src/python/grpcio/tests/unit/_empty_message_test.py
+++ b/src/python/grpcio/tests/unit/_empty_message_test.py
@@ -37,10 +37,10 @@ from tests.unit.framework.common import test_constants
 _REQUEST = b''
 _RESPONSE = b''
 
-_UNARY_UNARY = b'/test/UnaryUnary'
-_UNARY_STREAM = b'/test/UnaryStream'
-_STREAM_UNARY = b'/test/StreamUnary'
-_STREAM_STREAM = b'/test/StreamStream'
+_UNARY_UNARY = '/test/UnaryUnary'
+_UNARY_STREAM = '/test/UnaryStream'
+_STREAM_UNARY = '/test/StreamUnary'
+_STREAM_STREAM = '/test/StreamStream'
 
 
 def handle_unary_unary(request, servicer_context):
diff --git a/src/python/grpcio/tests/unit/_metadata_code_details_test.py b/src/python/grpcio/tests/unit/_metadata_code_details_test.py
index dd74268cbf..0fd02d2a22 100644
--- a/src/python/grpcio/tests/unit/_metadata_code_details_test.py
+++ b/src/python/grpcio/tests/unit/_metadata_code_details_test.py
@@ -47,29 +47,29 @@ _REQUEST_DESERIALIZER = lambda unused_serialized_request: object()
 _RESPONSE_SERIALIZER = lambda unused_response: _SERIALIZED_RESPONSE
 _RESPONSE_DESERIALIZER = lambda unused_serialized_resopnse: object()
 
-_SERVICE = b'test.TestService'
-_UNARY_UNARY = b'UnaryUnary'
-_UNARY_STREAM = b'UnaryStream'
-_STREAM_UNARY = b'StreamUnary'
-_STREAM_STREAM = b'StreamStream'
+_SERVICE = 'test.TestService'
+_UNARY_UNARY = 'UnaryUnary'
+_UNARY_STREAM = 'UnaryStream'
+_STREAM_UNARY = 'StreamUnary'
+_STREAM_STREAM = 'StreamStream'
 
 _CLIENT_METADATA = (
-    (b'client-md-key', b'client-md-key'),
-    (b'client-md-key-bin', b'\x00\x01')
+    ('client-md-key', 'client-md-key'),
+    ('client-md-key-bin', b'\x00\x01')
 )
 
 _SERVER_INITIAL_METADATA = (
-    (b'server-initial-md-key', b'server-initial-md-value'),
-    (b'server-initial-md-key-bin', b'\x00\x02')
+    ('server-initial-md-key', 'server-initial-md-value'),
+    ('server-initial-md-key-bin', b'\x00\x02')
 )
 
 _SERVER_TRAILING_METADATA = (
-    (b'server-trailing-md-key', b'server-trailing-md-value'),
-    (b'server-trailing-md-key-bin', b'\x00\x03')
+    ('server-trailing-md-key', 'server-trailing-md-value'),
+    ('server-trailing-md-key-bin', b'\x00\x03')
 )
 
 _NON_OK_CODE = grpc.StatusCode.NOT_FOUND
-_DETAILS = b'Test details!'
+_DETAILS = 'Test details!'
 
 
 class _Servicer(object):
@@ -195,15 +195,15 @@ class MetadataCodeDetailsTest(unittest.TestCase):
 
     channel = grpc.insecure_channel('localhost:{}'.format(port))
     self._unary_unary = channel.unary_unary(
-        b'/'.join((b'', _SERVICE, _UNARY_UNARY,)),
+        '/'.join(('', _SERVICE, _UNARY_UNARY,)),
         request_serializer=_REQUEST_SERIALIZER,
         response_deserializer=_RESPONSE_DESERIALIZER,)
     self._unary_stream = channel.unary_stream(
-        b'/'.join((b'', _SERVICE, _UNARY_STREAM,)),)
+        '/'.join(('', _SERVICE, _UNARY_STREAM,)),)
     self._stream_unary = channel.stream_unary(
-        b'/'.join((b'', _SERVICE, _STREAM_UNARY,)),)
+        '/'.join(('', _SERVICE, _STREAM_UNARY,)),)
     self._stream_stream = channel.stream_stream(
-        b'/'.join((b'', _SERVICE, _STREAM_STREAM,)),
+        '/'.join(('', _SERVICE, _STREAM_STREAM,)),
         request_serializer=_REQUEST_SERIALIZER,
         response_deserializer=_RESPONSE_DESERIALIZER,)
 
diff --git a/src/python/grpcio/tests/unit/_metadata_test.py b/src/python/grpcio/tests/unit/_metadata_test.py
index 2cb13f236b..c637a28039 100644
--- a/src/python/grpcio/tests/unit/_metadata_test.py
+++ b/src/python/grpcio/tests/unit/_metadata_test.py
@@ -44,33 +44,33 @@ _CHANNEL_ARGS = (('grpc.primary_user_agent', 'primary-agent'),
 _REQUEST = b'\x00\x00\x00'
 _RESPONSE = b'\x00\x00\x00'
 
-_UNARY_UNARY = b'/test/UnaryUnary'
-_UNARY_STREAM = b'/test/UnaryStream'
-_STREAM_UNARY = b'/test/StreamUnary'
-_STREAM_STREAM = b'/test/StreamStream'
+_UNARY_UNARY = '/test/UnaryUnary'
+_UNARY_STREAM = '/test/UnaryStream'
+_STREAM_UNARY = '/test/StreamUnary'
+_STREAM_STREAM = '/test/StreamStream'
 
 _USER_AGENT = 'Python-gRPC-{}'.format(_grpcio_metadata.__version__)
 
 _CLIENT_METADATA = (
-    (b'client-md-key', b'client-md-key'),
-    (b'client-md-key-bin', b'\x00\x01')
+    ('client-md-key', 'client-md-key'),
+    ('client-md-key-bin', b'\x00\x01')
 )
 
 _SERVER_INITIAL_METADATA = (
-    (b'server-initial-md-key', b'server-initial-md-value'),
-    (b'server-initial-md-key-bin', b'\x00\x02')
+    ('server-initial-md-key', 'server-initial-md-value'),
+    ('server-initial-md-key-bin', b'\x00\x02')
 )
 
 _SERVER_TRAILING_METADATA = (
-    (b'server-trailing-md-key', b'server-trailing-md-value'),
-    (b'server-trailing-md-key-bin', b'\x00\x03')
+    ('server-trailing-md-key', 'server-trailing-md-value'),
+    ('server-trailing-md-key-bin', b'\x00\x03')
 )
 
 
 def user_agent(metadata):
   for key, val in metadata:
-    if key == b'user-agent':
-      return val.decode('ascii')
+    if key == 'user-agent':
+      return val
   raise KeyError('No user agent!')
 
 
diff --git a/src/python/grpcio/tests/unit/_rpc_test.py b/src/python/grpcio/tests/unit/_rpc_test.py
index 9814504edf..c70d65a6df 100644
--- a/src/python/grpcio/tests/unit/_rpc_test.py
+++ b/src/python/grpcio/tests/unit/_rpc_test.py
@@ -45,10 +45,10 @@ _DESERIALIZE_REQUEST = lambda bytestring: bytestring[len(bytestring) // 2:]
 _SERIALIZE_RESPONSE = lambda bytestring: bytestring * 3
 _DESERIALIZE_RESPONSE = lambda bytestring: bytestring[:len(bytestring) // 3]
 
-_UNARY_UNARY = b'/test/UnaryUnary'
-_UNARY_STREAM = b'/test/UnaryStream'
-_STREAM_UNARY = b'/test/StreamUnary'
-_STREAM_STREAM = b'/test/StreamStream'
+_UNARY_UNARY = '/test/UnaryUnary'
+_UNARY_STREAM = '/test/UnaryStream'
+_STREAM_UNARY = '/test/StreamUnary'
+_STREAM_STREAM = '/test/StreamStream'
 
 
 class _Callback(object):
@@ -79,7 +79,7 @@ class _Handler(object):
   def handle_unary_unary(self, request, servicer_context):
     self._control.control()
     if servicer_context is not None:
-      servicer_context.set_trailing_metadata(((b'testkey', b'testvalue',),))
+      servicer_context.set_trailing_metadata((('testkey', 'testvalue',),))
     return request
 
   def handle_unary_stream(self, request, servicer_context):
@@ -88,7 +88,7 @@ class _Handler(object):
       yield request
     self._control.control()
     if servicer_context is not None:
-      servicer_context.set_trailing_metadata(((b'testkey', b'testvalue',),))
+      servicer_context.set_trailing_metadata((('testkey', 'testvalue',),))
 
   def handle_stream_unary(self, request_iterator, servicer_context):
     if servicer_context is not None:
@@ -100,13 +100,13 @@ class _Handler(object):
       response_elements.append(request)
     self._control.control()
     if servicer_context is not None:
-      servicer_context.set_trailing_metadata(((b'testkey', b'testvalue',),))
+      servicer_context.set_trailing_metadata((('testkey', 'testvalue',),))
     return b''.join(response_elements)
 
   def handle_stream_stream(self, request_iterator, servicer_context):
     self._control.control()
     if servicer_context is not None:
-      servicer_context.set_trailing_metadata(((b'testkey', b'testvalue',),))
+      servicer_context.set_trailing_metadata((('testkey', 'testvalue',),))
     for request in request_iterator:
       self._control.control()
       yield request
@@ -185,7 +185,7 @@ class RPCTest(unittest.TestCase):
     self._server_pool = logging_pool.pool(test_constants.THREAD_CONCURRENCY)
 
     self._server = grpc.server((), self._server_pool)
-    port = self._server.add_insecure_port(b'[::]:0')
+    port = self._server.add_insecure_port('[::]:0')
     self._server.add_generic_rpc_handlers((_GenericHandler(self._handler),))
     self._server.start()
 
@@ -195,7 +195,7 @@ class RPCTest(unittest.TestCase):
     request = b'abc'
 
     with self.assertRaises(grpc.RpcError) as exception_context:
-      self._channel.unary_unary(b'NoSuchMethod')(request)
+      self._channel.unary_unary('NoSuchMethod')(request)
 
     self.assertEqual(
         grpc.StatusCode.UNIMPLEMENTED, exception_context.exception.code())
@@ -207,7 +207,7 @@ class RPCTest(unittest.TestCase):
     multi_callable = _unary_unary_multi_callable(self._channel)
     response = multi_callable(
         request, metadata=(
-            (b'test', b'SuccessfulUnaryRequestBlockingUnaryResponse'),))
+            ('test', 'SuccessfulUnaryRequestBlockingUnaryResponse'),))
 
     self.assertEqual(expected_response, response)
 
@@ -218,7 +218,7 @@ class RPCTest(unittest.TestCase):
     multi_callable = _unary_unary_multi_callable(self._channel)
     response, call = multi_callable.with_call(
         request, metadata=(
-            (b'test', b'SuccessfulUnaryRequestBlockingUnaryResponseWithCall'),))
+            ('test', 'SuccessfulUnaryRequestBlockingUnaryResponseWithCall'),))
 
     self.assertEqual(expected_response, response)
     self.assertIs(grpc.StatusCode.OK, call.code())
@@ -230,7 +230,7 @@ class RPCTest(unittest.TestCase):
     multi_callable = _unary_unary_multi_callable(self._channel)
     response_future = multi_callable.future(
         request, metadata=(
-            (b'test', b'SuccessfulUnaryRequestFutureUnaryResponse'),))
+            ('test', 'SuccessfulUnaryRequestFutureUnaryResponse'),))
     response = response_future.result()
 
     self.assertEqual(expected_response, response)
@@ -242,7 +242,7 @@ class RPCTest(unittest.TestCase):
     multi_callable = _unary_stream_multi_callable(self._channel)
     response_iterator = multi_callable(
         request,
-        metadata=((b'test', b'SuccessfulUnaryRequestStreamResponse'),))
+        metadata=(('test', 'SuccessfulUnaryRequestStreamResponse'),))
     responses = tuple(response_iterator)
 
     self.assertSequenceEqual(expected_responses, responses)
@@ -255,7 +255,7 @@ class RPCTest(unittest.TestCase):
     multi_callable = _stream_unary_multi_callable(self._channel)
     response = multi_callable(
         request_iterator,
-        metadata=((b'test', b'SuccessfulStreamRequestBlockingUnaryResponse'),))
+        metadata=(('test', 'SuccessfulStreamRequestBlockingUnaryResponse'),))
 
     self.assertEqual(expected_response, response)
 
@@ -268,7 +268,7 @@ class RPCTest(unittest.TestCase):
     response, call = multi_callable.with_call(
         request_iterator,
         metadata=(
-            (b'test', b'SuccessfulStreamRequestBlockingUnaryResponseWithCall'),
+            ('test', 'SuccessfulStreamRequestBlockingUnaryResponseWithCall'),
         ))
 
     self.assertEqual(expected_response, response)
@@ -283,7 +283,7 @@ class RPCTest(unittest.TestCase):
     response_future = multi_callable.future(
         request_iterator,
         metadata=(
-            (b'test', b'SuccessfulStreamRequestFutureUnaryResponse'),))
+            ('test', 'SuccessfulStreamRequestFutureUnaryResponse'),))
     response = response_future.result()
 
     self.assertEqual(expected_response, response)
@@ -297,7 +297,7 @@ class RPCTest(unittest.TestCase):
     multi_callable = _stream_stream_multi_callable(self._channel)
     response_iterator = multi_callable(
         request_iterator,
-        metadata=((b'test', b'SuccessfulStreamRequestStreamResponse'),))
+        metadata=(('test', 'SuccessfulStreamRequestStreamResponse'),))
     responses = tuple(response_iterator)
 
     self.assertSequenceEqual(expected_responses, responses)
@@ -312,9 +312,9 @@ class RPCTest(unittest.TestCase):
 
     multi_callable = _unary_unary_multi_callable(self._channel)
     first_response = multi_callable(
-        first_request, metadata=((b'test', b'SequentialInvocations'),))
+        first_request, metadata=(('test', 'SequentialInvocations'),))
     second_response = multi_callable(
-        second_request, metadata=((b'test', b'SequentialInvocations'),))
+        second_request, metadata=(('test', 'SequentialInvocations'),))
 
     self.assertEqual(expected_first_response, first_response)
     self.assertEqual(expected_second_response, second_response)
@@ -331,7 +331,7 @@ class RPCTest(unittest.TestCase):
       request_iterator = iter(requests)
       response_future = pool.submit(
           multi_callable, request_iterator,
-          metadata=((b'test', b'ConcurrentBlockingInvocations'),))
+          metadata=(('test', 'ConcurrentBlockingInvocations'),))
       response_futures[index] = response_future
     responses = tuple(
         response_future.result() for response_future in response_futures)
@@ -350,7 +350,7 @@ class RPCTest(unittest.TestCase):
       request_iterator = iter(requests)
       response_future = multi_callable.future(
           request_iterator,
-          metadata=((b'test', b'ConcurrentFutureInvocations'),))
+          metadata=(('test', 'ConcurrentFutureInvocations'),))
       response_futures[index] = response_future
     responses = tuple(
         response_future.result() for response_future in response_futures)
@@ -380,8 +380,8 @@ class RPCTest(unittest.TestCase):
       inner_response_future = multi_callable.future(
           request,
           metadata=(
-              (b'test',
-               b'WaitingForSomeButNotAllConcurrentFutureInvocations'),))
+              ('test',
+               'WaitingForSomeButNotAllConcurrentFutureInvocations'),))
       outer_response_future = pool.submit(wrap_future(inner_response_future))
       response_futures[index] = outer_response_future
 
@@ -400,7 +400,7 @@ class RPCTest(unittest.TestCase):
     response_iterator = multi_callable(
         request,
         metadata=(
-            (b'test', b'ConsumingOneStreamResponseUnaryRequest'),))
+            ('test', 'ConsumingOneStreamResponseUnaryRequest'),))
     next(response_iterator)
 
   def testConsumingSomeButNotAllStreamResponsesUnaryRequest(self):
@@ -410,7 +410,7 @@ class RPCTest(unittest.TestCase):
     response_iterator = multi_callable(
         request,
         metadata=(
-            (b'test', b'ConsumingSomeButNotAllStreamResponsesUnaryRequest'),))
+            ('test', 'ConsumingSomeButNotAllStreamResponsesUnaryRequest'),))
     for _ in range(test_constants.STREAM_LENGTH // 2):
       next(response_iterator)
 
@@ -422,7 +422,7 @@ class RPCTest(unittest.TestCase):
     response_iterator = multi_callable(
         request_iterator,
         metadata=(
-            (b'test', b'ConsumingSomeButNotAllStreamResponsesStreamRequest'),))
+            ('test', 'ConsumingSomeButNotAllStreamResponsesStreamRequest'),))
     for _ in range(test_constants.STREAM_LENGTH // 2):
       next(response_iterator)
 
@@ -434,7 +434,7 @@ class RPCTest(unittest.TestCase):
     response_iterator = multi_callable(
         request_iterator,
         metadata=(
-            (b'test', b'ConsumingTooManyStreamResponsesStreamRequest'),))
+            ('test', 'ConsumingTooManyStreamResponsesStreamRequest'),))
     for _ in range(test_constants.STREAM_LENGTH):
       next(response_iterator)
     for _ in range(test_constants.STREAM_LENGTH):
@@ -453,7 +453,7 @@ class RPCTest(unittest.TestCase):
     with self._control.pause():
       response_future = multi_callable.future(
           request,
-          metadata=((b'test', b'CancelledUnaryRequestUnaryResponse'),))
+          metadata=(('test', 'CancelledUnaryRequestUnaryResponse'),))
       response_future.cancel()
 
     self.assertTrue(response_future.cancelled())
@@ -468,7 +468,7 @@ class RPCTest(unittest.TestCase):
     with self._control.pause():
       response_iterator = multi_callable(
           request,
-          metadata=((b'test', b'CancelledUnaryRequestStreamResponse'),))
+          metadata=(('test', 'CancelledUnaryRequestStreamResponse'),))
       self._control.block_until_paused()
       response_iterator.cancel()
 
@@ -488,7 +488,7 @@ class RPCTest(unittest.TestCase):
     with self._control.pause():
       response_future = multi_callable.future(
           request_iterator,
-          metadata=((b'test', b'CancelledStreamRequestUnaryResponse'),))
+          metadata=(('test', 'CancelledStreamRequestUnaryResponse'),))
       self._control.block_until_paused()
       response_future.cancel()
 
@@ -508,7 +508,7 @@ class RPCTest(unittest.TestCase):
     with self._control.pause():
       response_iterator = multi_callable(
           request_iterator,
-          metadata=((b'test', b'CancelledStreamRequestStreamResponse'),))
+          metadata=(('test', 'CancelledStreamRequestStreamResponse'),))
       response_iterator.cancel()
 
     with self.assertRaises(grpc.RpcError):
@@ -526,7 +526,7 @@ class RPCTest(unittest.TestCase):
       with self.assertRaises(grpc.RpcError) as exception_context:
         multi_callable.with_call(
             request, timeout=test_constants.SHORT_TIMEOUT,
-            metadata=((b'test', b'ExpiredUnaryRequestBlockingUnaryResponse'),))
+            metadata=(('test', 'ExpiredUnaryRequestBlockingUnaryResponse'),))
 
     self.assertIsNotNone(exception_context.exception.initial_metadata())
     self.assertIs(
@@ -542,7 +542,7 @@ class RPCTest(unittest.TestCase):
     with self._control.pause():
       response_future = multi_callable.future(
           request, timeout=test_constants.SHORT_TIMEOUT,
-          metadata=((b'test', b'ExpiredUnaryRequestFutureUnaryResponse'),))
+          metadata=(('test', 'ExpiredUnaryRequestFutureUnaryResponse'),))
       response_future.add_done_callback(callback)
       value_passed_to_callback = callback.value()
 
@@ -567,7 +567,7 @@ class RPCTest(unittest.TestCase):
       with self.assertRaises(grpc.RpcError) as exception_context:
         response_iterator = multi_callable(
             request, timeout=test_constants.SHORT_TIMEOUT,
-            metadata=((b'test', b'ExpiredUnaryRequestStreamResponse'),))
+            metadata=(('test', 'ExpiredUnaryRequestStreamResponse'),))
         next(response_iterator)
 
     self.assertIs(
@@ -583,7 +583,7 @@ class RPCTest(unittest.TestCase):
       with self.assertRaises(grpc.RpcError) as exception_context:
         multi_callable(
             request_iterator, timeout=test_constants.SHORT_TIMEOUT,
-            metadata=((b'test', b'ExpiredStreamRequestBlockingUnaryResponse'),))
+            metadata=(('test', 'ExpiredStreamRequestBlockingUnaryResponse'),))
 
     self.assertIsNotNone(exception_context.exception.initial_metadata())
     self.assertIs(
@@ -600,7 +600,7 @@ class RPCTest(unittest.TestCase):
     with self._control.pause():
       response_future = multi_callable.future(
           request_iterator, timeout=test_constants.SHORT_TIMEOUT,
-          metadata=((b'test', b'ExpiredStreamRequestFutureUnaryResponse'),))
+          metadata=(('test', 'ExpiredStreamRequestFutureUnaryResponse'),))
       response_future.add_done_callback(callback)
       value_passed_to_callback = callback.value()
 
@@ -625,7 +625,7 @@ class RPCTest(unittest.TestCase):
       with self.assertRaises(grpc.RpcError) as exception_context:
         response_iterator = multi_callable(
             request_iterator, timeout=test_constants.SHORT_TIMEOUT,
-            metadata=((b'test', b'ExpiredStreamRequestStreamResponse'),))
+            metadata=(('test', 'ExpiredStreamRequestStreamResponse'),))
         next(response_iterator)
 
     self.assertIs(
@@ -640,7 +640,7 @@ class RPCTest(unittest.TestCase):
       with self.assertRaises(grpc.RpcError) as exception_context:
         multi_callable.with_call(
             request,
-            metadata=((b'test', b'FailedUnaryRequestBlockingUnaryResponse'),))
+            metadata=(('test', 'FailedUnaryRequestBlockingUnaryResponse'),))
 
     self.assertIs(grpc.StatusCode.UNKNOWN, exception_context.exception.code())
 
@@ -652,7 +652,7 @@ class RPCTest(unittest.TestCase):
     with self._control.fail():
       response_future = multi_callable.future(
           request,
-          metadata=((b'test', b'FailedUnaryRequestFutureUnaryResponse'),))
+          metadata=(('test', 'FailedUnaryRequestFutureUnaryResponse'),))
       response_future.add_done_callback(callback)
       value_passed_to_callback = callback.value()
 
@@ -672,7 +672,7 @@ class RPCTest(unittest.TestCase):
       with self._control.fail():
         response_iterator = multi_callable(
             request,
-            metadata=((b'test', b'FailedUnaryRequestStreamResponse'),))
+            metadata=(('test', 'FailedUnaryRequestStreamResponse'),))
         next(response_iterator)
 
     self.assertIs(grpc.StatusCode.UNKNOWN, exception_context.exception.code())
@@ -686,7 +686,7 @@ class RPCTest(unittest.TestCase):
       with self.assertRaises(grpc.RpcError) as exception_context:
         multi_callable(
             request_iterator,
-            metadata=((b'test', b'FailedStreamRequestBlockingUnaryResponse'),))
+            metadata=(('test', 'FailedStreamRequestBlockingUnaryResponse'),))
 
     self.assertIs(grpc.StatusCode.UNKNOWN, exception_context.exception.code())
 
@@ -699,7 +699,7 @@ class RPCTest(unittest.TestCase):
     with self._control.fail():
       response_future = multi_callable.future(
           request_iterator,
-          metadata=((b'test', b'FailedStreamRequestFutureUnaryResponse'),))
+          metadata=(('test', 'FailedStreamRequestFutureUnaryResponse'),))
       response_future.add_done_callback(callback)
       value_passed_to_callback = callback.value()
 
@@ -720,7 +720,7 @@ class RPCTest(unittest.TestCase):
       with self.assertRaises(grpc.RpcError) as exception_context:
         response_iterator = multi_callable(
             request_iterator,
-            metadata=((b'test', b'FailedStreamRequestStreamResponse'),))
+            metadata=(('test', 'FailedStreamRequestStreamResponse'),))
         tuple(response_iterator)
 
     self.assertIs(grpc.StatusCode.UNKNOWN, exception_context.exception.code())
@@ -732,7 +732,7 @@ class RPCTest(unittest.TestCase):
     multi_callable = _unary_unary_multi_callable(self._channel)
     multi_callable.future(
         request,
-        metadata=((b'test', b'IgnoredUnaryRequestFutureUnaryResponse'),))
+        metadata=(('test', 'IgnoredUnaryRequestFutureUnaryResponse'),))
 
   def testIgnoredUnaryRequestStreamResponse(self):
     request = b'\x37\x17'
@@ -740,7 +740,7 @@ class RPCTest(unittest.TestCase):
     multi_callable = _unary_stream_multi_callable(self._channel)
     multi_callable(
         request,
-        metadata=((b'test', b'IgnoredUnaryRequestStreamResponse'),))
+        metadata=(('test', 'IgnoredUnaryRequestStreamResponse'),))
 
   def testIgnoredStreamRequestFutureUnaryResponse(self):
     requests = tuple(b'\x07\x18' for _ in range(test_constants.STREAM_LENGTH))
@@ -749,7 +749,7 @@ class RPCTest(unittest.TestCase):
     multi_callable = _stream_unary_multi_callable(self._channel)
     multi_callable.future(
         request_iterator,
-        metadata=((b'test', b'IgnoredStreamRequestFutureUnaryResponse'),))
+        metadata=(('test', 'IgnoredStreamRequestFutureUnaryResponse'),))
 
   def testIgnoredStreamRequestStreamResponse(self):
     requests = tuple(b'\x67\x88' for _ in range(test_constants.STREAM_LENGTH))
@@ -758,7 +758,7 @@ class RPCTest(unittest.TestCase):
     multi_callable = _stream_stream_multi_callable(self._channel)
     multi_callable(
         request_iterator,
-        metadata=((b'test', b'IgnoredStreamRequestStreamResponse'),))
+        metadata=(('test', 'IgnoredStreamRequestStreamResponse'),))
 
 
 if __name__ == '__main__':
diff --git a/src/python/grpcio/tests/unit/beta/_utilities_test.py b/src/python/grpcio/tests/unit/beta/_utilities_test.py
index 08ce98e751..90fe10c77c 100644
--- a/src/python/grpcio/tests/unit/beta/_utilities_test.py
+++ b/src/python/grpcio/tests/unit/beta/_utilities_test.py
@@ -33,21 +33,12 @@ import threading
 import time
 import unittest
 
-from grpc._adapter import _low
-from grpc._adapter import _types
 from grpc.beta import implementations
 from grpc.beta import utilities
 from grpc.framework.foundation import future
 from tests.unit.framework.common import test_constants
 
 
-def _drive_completion_queue(completion_queue):
-  while True:
-    event = completion_queue.next(time.time() + 24 * 60 * 60)
-    if event.type == _types.EventType.QUEUE_SHUTDOWN:
-      break
-
-
 class _Callback(object):
 
   def __init__(self):
@@ -87,13 +78,9 @@ class ChannelConnectivityTest(unittest.TestCase):
     self.assertFalse(ready_future.running())
 
   def test_immediately_connectable_channel_connectivity(self):
-    server_completion_queue = _low.CompletionQueue()
-    server = _low.Server(server_completion_queue, [])
-    port = server.add_http2_port('[::]:0')
+    server = implementations.server({})
+    port = server.add_insecure_port('[::]:0')
     server.start()
-    server_completion_queue_thread = threading.Thread(
-        target=_drive_completion_queue, args=(server_completion_queue,))
-    server_completion_queue_thread.start()
     channel = implementations.insecure_channel('localhost', port)
     callback = _Callback()
 
@@ -114,9 +101,7 @@ class ChannelConnectivityTest(unittest.TestCase):
       self.assertFalse(ready_future.running())
     finally:
       ready_future.cancel()
-      server.shutdown()
-      server_completion_queue.shutdown()
-      server_completion_queue_thread.join()
+      server.stop(0)
 
 
 if __name__ == '__main__':
diff --git a/src/python/grpcio/tests/unit/beta/test_utilities.py b/src/python/grpcio/tests/unit/beta/test_utilities.py
index 8ccad04e05..692da9c97d 100644
--- a/src/python/grpcio/tests/unit/beta/test_utilities.py
+++ b/src/python/grpcio/tests/unit/beta/test_utilities.py
@@ -51,5 +51,5 @@ def not_really_secure_channel(
   target = '%s:%d' % (host, port)
   channel = grpc.secure_channel(
       target, channel_credentials,
-      ((b'grpc.ssl_target_name_override', server_host_override,),))
+      (('grpc.ssl_target_name_override', server_host_override,),))
   return implementations.Channel(channel)
diff --git a/src/python/grpcio/tests/unit/test_common.py b/src/python/grpcio/tests/unit/test_common.py
index b779f65e7e..c8886bf4ca 100644
--- a/src/python/grpcio/tests/unit/test_common.py
+++ b/src/python/grpcio/tests/unit/test_common.py
@@ -33,10 +33,10 @@ import collections
 
 import six
 
-INVOCATION_INITIAL_METADATA = ((b'0', b'abc'), (b'1', b'def'), (b'2', b'ghi'),)
-SERVICE_INITIAL_METADATA = ((b'3', b'jkl'), (b'4', b'mno'), (b'5', b'pqr'),)
-SERVICE_TERMINAL_METADATA = ((b'6', b'stu'), (b'7', b'vwx'), (b'8', b'yza'),)
-DETAILS = b'test details'
+INVOCATION_INITIAL_METADATA = (('0', 'abc'), ('1', 'def'), ('2', 'ghi'),)
+SERVICE_INITIAL_METADATA = (('3', 'jkl'), ('4', 'mno'), ('5', 'pqr'),)
+SERVICE_TERMINAL_METADATA = (('6', 'stu'), ('7', 'vwx'), ('8', 'yza'),)
+DETAILS = 'test details'
 
 
 def metadata_transmitted(original_metadata, transmitted_metadata):
@@ -59,16 +59,10 @@ def metadata_transmitted(original_metadata, transmitted_metadata):
       original_metadata after having been transmitted via gRPC.
   """
   original = collections.defaultdict(list)
-  for key_value_pair in original_metadata:
-    key, value = tuple(key_value_pair)
-    if not isinstance(key, bytes):
-      key = key.encode()
-    if not isinstance(value, bytes):
-      value = value.encode()
+  for key, value in original_metadata:
     original[key].append(value)
   transmitted = collections.defaultdict(list)
-  for key_value_pair in transmitted_metadata:
-    key, value = tuple(key_value_pair)
+  for key, value in transmitted_metadata:
     transmitted[key].append(value)
 
   for key, values in six.iteritems(original):