Merge github.com:grpc/grpc into help-help-im-stuck-and-i-cant-reach-my-tcp-connection

90 files changed, 4481 insertions, 2365 deletions

diff --git a/src/core/channel/census_filter.c b/src/core/channel/census_filter.c
index 7e393a01a6..83b7682848 100644
--- a/src/core/channel/census_filter.c
+++ b/src/core/channel/census_filter.c
@@ -84,7 +84,8 @@ static void extract_and_annotate_method_tag(grpc_stream_op_buffer* sopb,
   }
 }
 
-static void client_mutate_op(grpc_call_element* elem, grpc_transport_op* op) {
+static void client_mutate_op(grpc_call_element* elem,
+                             grpc_transport_stream_op* op) {
   call_data* calld = elem->call_data;
   channel_data* chand = elem->channel_data;
   if (op->send_ops) {
@@ -93,7 +94,7 @@ static void client_mutate_op(grpc_call_element* elem, grpc_transport_op* op) {
 }
 
 static void client_start_transport_op(grpc_call_element* elem,
-                                      grpc_transport_op* op) {
+                                      grpc_transport_stream_op* op) {
   call_data* calld = elem->call_data;
   GPR_ASSERT((calld->op_id.upper != 0) || (calld->op_id.lower != 0));
   client_mutate_op(elem, op);
@@ -110,7 +111,8 @@ static void server_on_done_recv(void* ptr, int success) {
   calld->on_done_recv(calld->recv_user_data, success);
 }
 
-static void server_mutate_op(grpc_call_element* elem, grpc_transport_op* op) {
+static void server_mutate_op(grpc_call_element* elem,
+                             grpc_transport_stream_op* op) {
   call_data* calld = elem->call_data;
   if (op->recv_ops) {
     /* substitute our callback for the op callback */
@@ -123,7 +125,7 @@ static void server_mutate_op(grpc_call_element* elem, grpc_transport_op* op) {
 }
 
 static void server_start_transport_op(grpc_call_element* elem,
-                                      grpc_transport_op* op) {
+                                      grpc_transport_stream_op* op) {
   call_data* calld = elem->call_data;
   GPR_ASSERT((calld->op_id.upper != 0) || (calld->op_id.lower != 0));
   server_mutate_op(elem, op);
@@ -145,7 +147,7 @@ static void channel_op(grpc_channel_element* elem,
 
 static void client_init_call_elem(grpc_call_element* elem,
                                   const void* server_transport_data,
-                                  grpc_transport_op* initial_op) {
+                                  grpc_transport_stream_op* initial_op) {
   call_data* d = elem->call_data;
   GPR_ASSERT(d != NULL);
   init_rpc_stats(&d->stats);
@@ -163,7 +165,7 @@ static void client_destroy_call_elem(grpc_call_element* elem) {
 
 static void server_init_call_elem(grpc_call_element* elem,
                                   const void* server_transport_data,
-                                  grpc_transport_op* initial_op) {
+                                  grpc_transport_stream_op* initial_op) {
   call_data* d = elem->call_data;
   GPR_ASSERT(d != NULL);
   init_rpc_stats(&d->stats);
@@ -200,11 +202,23 @@ static void destroy_channel_elem(grpc_channel_element* elem) {
 }
 
 const grpc_channel_filter grpc_client_census_filter = {
-    client_start_transport_op, channel_op, sizeof(call_data),
-    client_init_call_elem, client_destroy_call_elem, sizeof(channel_data),
-    init_channel_elem, destroy_channel_elem, "census-client"};
+    client_start_transport_op,
+    channel_op,
+    sizeof(call_data),
+    client_init_call_elem,
+    client_destroy_call_elem,
+    sizeof(channel_data),
+    init_channel_elem,
+    destroy_channel_elem,
+    "census-client"};
 
 const grpc_channel_filter grpc_server_census_filter = {
-    server_start_transport_op, channel_op, sizeof(call_data),
-    server_init_call_elem, server_destroy_call_elem, sizeof(channel_data),
-    init_channel_elem, destroy_channel_elem, "census-server"};
+    server_start_transport_op,
+    channel_op,
+    sizeof(call_data),
+    server_init_call_elem,
+    server_destroy_call_elem,
+    sizeof(channel_data),
+    init_channel_elem,
+    destroy_channel_elem,
+    "census-server"};
diff --git a/src/core/channel/channel_args.c b/src/core/channel/channel_args.c
index 166d559a45..140f8bd656 100644
--- a/src/core/channel/channel_args.c
+++ b/src/core/channel/channel_args.c
@@ -62,7 +62,8 @@ static grpc_arg copy_arg(const grpc_arg *src) {
 }
 
 grpc_channel_args *grpc_channel_args_copy_and_add(const grpc_channel_args *src,
-                                                  const grpc_arg *to_add) {
+                                                  const grpc_arg *to_add,
+                                                  size_t num_to_add) {
   grpc_channel_args *dst = gpr_malloc(sizeof(grpc_channel_args));
   size_t i;
   size_t src_num_args = (src == NULL) ? 0 : src->num_args;
@@ -71,17 +72,24 @@ grpc_channel_args *grpc_channel_args_copy_and_add(const grpc_channel_args *src,
     dst->args = NULL;
     return dst;
   }
-  dst->num_args = src_num_args + ((to_add == NULL) ? 0 : 1);
+  dst->num_args = src_num_args + num_to_add;
   dst->args = gpr_malloc(sizeof(grpc_arg) * dst->num_args);
   for (i = 0; i < src_num_args; i++) {
     dst->args[i] = copy_arg(&src->args[i]);
   }
-  if (to_add != NULL) dst->args[src_num_args] = copy_arg(to_add);
+  for (i = 0; i < num_to_add; i++) {
+    dst->args[i + src_num_args] = copy_arg(&to_add[i]);
+  }
   return dst;
 }
 
 grpc_channel_args *grpc_channel_args_copy(const grpc_channel_args *src) {
-  return grpc_channel_args_copy_and_add(src, NULL);
+  return grpc_channel_args_copy_and_add(src, NULL, 0);
+}
+
+grpc_channel_args *grpc_channel_args_merge(const grpc_channel_args *a,
+                                           const grpc_channel_args *b) {
+  return grpc_channel_args_copy_and_add(a, b->args, b->num_args);
 }
 
 void grpc_channel_args_destroy(grpc_channel_args *a) {
@@ -131,11 +139,11 @@ grpc_compression_level grpc_channel_args_get_compression_level(
   return GRPC_COMPRESS_LEVEL_NONE;
 }
 
-void grpc_channel_args_set_compression_level(
-    grpc_channel_args **a, grpc_compression_level level) {
+void grpc_channel_args_set_compression_level(grpc_channel_args **a,
+                                             grpc_compression_level level) {
   grpc_arg tmp;
   tmp.type = GRPC_ARG_INTEGER;
   tmp.key = GRPC_COMPRESSION_LEVEL_ARG;
   tmp.value.integer = level;
-  *a = grpc_channel_args_copy_and_add(*a, &tmp);
+  *a = grpc_channel_args_copy_and_add(*a, &tmp, 1);
 }
diff --git a/src/core/channel/channel_args.h b/src/core/channel/channel_args.h
index bf747b26e6..17849b7e59 100644
--- a/src/core/channel/channel_args.h
+++ b/src/core/channel/channel_args.h
@@ -43,7 +43,12 @@ grpc_channel_args *grpc_channel_args_copy(const grpc_channel_args *src);
 /** Copy some arguments and add the to_add parameter in the end.
    If to_add is NULL, it is equivalent to call grpc_channel_args_copy. */
 grpc_channel_args *grpc_channel_args_copy_and_add(const grpc_channel_args *src,
-                                                  const grpc_arg *to_add);
+                                                  const grpc_arg *to_add,
+                                                  size_t num_to_add);
+
+/** Copy args from a then args from b into a new channel args */
+grpc_channel_args *grpc_channel_args_merge(const grpc_channel_args *a,
+                                           const grpc_channel_args *b);
 
 /** Destroy arguments created by grpc_channel_args_copy */
 void grpc_channel_args_destroy(grpc_channel_args *a);
@@ -58,7 +63,7 @@ grpc_compression_level grpc_channel_args_get_compression_level(
 
 /** Sets the compression level in \a a to \a level. Setting it to
  * GRPC_COMPRESS_LEVEL_NONE disables compression for the channel. */
-void grpc_channel_args_set_compression_level(
-    grpc_channel_args **a, grpc_compression_level level);
+void grpc_channel_args_set_compression_level(grpc_channel_args **a,
+                                             grpc_compression_level level);
 
-#endif  /* GRPC_INTERNAL_CORE_CHANNEL_CHANNEL_ARGS_H */
+#endif /* GRPC_INTERNAL_CORE_CHANNEL_CHANNEL_ARGS_H */
diff --git a/src/core/channel/channel_stack.c b/src/core/channel/channel_stack.c
index 9eec8163f5..e38dcb58b7 100644
--- a/src/core/channel/channel_stack.c
+++ b/src/core/channel/channel_stack.c
@@ -102,7 +102,8 @@ grpc_call_element *grpc_call_stack_element(grpc_call_stack *call_stack,
 }
 
 void grpc_channel_stack_init(const grpc_channel_filter **filters,
-                             size_t filter_count, const grpc_channel_args *args,
+                             size_t filter_count, grpc_channel *master,
+                             const grpc_channel_args *args,
                              grpc_mdctx *metadata_context,
                              grpc_channel_stack *stack) {
   size_t call_size =
@@ -122,8 +123,9 @@ void grpc_channel_stack_init(const grpc_channel_filter **filters,
   for (i = 0; i < filter_count; i++) {
     elems[i].filter = filters[i];
     elems[i].channel_data = user_data;
-    elems[i].filter->init_channel_elem(&elems[i], args, metadata_context,
-                                       i == 0, i == (filter_count - 1));
+    elems[i].filter->init_channel_elem(&elems[i], master, args,
+                                       metadata_context, i == 0,
+                                       i == (filter_count - 1));
     user_data += ROUND_UP_TO_ALIGNMENT_SIZE(filters[i]->sizeof_channel_data);
     call_size += ROUND_UP_TO_ALIGNMENT_SIZE(filters[i]->sizeof_call_data);
   }
@@ -148,7 +150,7 @@ void grpc_channel_stack_destroy(grpc_channel_stack *stack) {
 
 void grpc_call_stack_init(grpc_channel_stack *channel_stack,
                           const void *transport_server_data,
-                          grpc_transport_op *initial_op,
+                          grpc_transport_stream_op *initial_op,
                           grpc_call_stack *call_stack) {
   grpc_channel_element *channel_elems = CHANNEL_ELEMS_FROM_STACK(channel_stack);
   size_t count = channel_stack->count;
@@ -184,14 +186,14 @@ void grpc_call_stack_destroy(grpc_call_stack *stack) {
   }
 }
 
-void grpc_call_next_op(grpc_call_element *elem, grpc_transport_op *op) {
+void grpc_call_next_op(grpc_call_element *elem, grpc_transport_stream_op *op) {
   grpc_call_element *next_elem = elem + 1;
-  next_elem->filter->start_transport_op(next_elem, op);
+  next_elem->filter->start_transport_stream_op(next_elem, op);
 }
 
-void grpc_channel_next_op(grpc_channel_element *elem, grpc_channel_op *op) {
-  grpc_channel_element *next_elem = elem + op->dir;
-  next_elem->filter->channel_op(next_elem, elem, op);
+void grpc_channel_next_op(grpc_channel_element *elem, grpc_transport_op *op) {
+  grpc_channel_element *next_elem = elem + 1;
+  next_elem->filter->start_transport_op(next_elem, op);
 }
 
 grpc_channel_stack *grpc_channel_stack_from_top_element(
@@ -206,7 +208,7 @@ grpc_call_stack *grpc_call_stack_from_top_element(grpc_call_element *elem) {
 }
 
 void grpc_call_element_send_cancel(grpc_call_element *cur_elem) {
-  grpc_transport_op op;
+  grpc_transport_stream_op op;
   memset(&op, 0, sizeof(op));
   op.cancel_with_status = GRPC_STATUS_CANCELLED;
   grpc_call_next_op(cur_elem, &op);
diff --git a/src/core/channel/channel_stack.h b/src/core/channel/channel_stack.h
index de0e4e4518..785be8925b 100644
--- a/src/core/channel/channel_stack.h
+++ b/src/core/channel/channel_stack.h
@@ -51,45 +51,6 @@
 typedef struct grpc_channel_element grpc_channel_element;
 typedef struct grpc_call_element grpc_call_element;
 
-/* The direction of the call.
-   The values of the enums (1, -1) matter here - they are used to increment
-   or decrement a pointer to find the next element to call */
-typedef enum { GRPC_CALL_DOWN = 1, GRPC_CALL_UP = -1 } grpc_call_dir;
-
-typedef enum {
-  /* send a goaway message to remote channels indicating that we are going
-     to disconnect in the future */
-  GRPC_CHANNEL_GOAWAY,
-  /* disconnect any underlying transports */
-  GRPC_CHANNEL_DISCONNECT,
-  /* transport received a new call */
-  GRPC_ACCEPT_CALL,
-  /* an underlying transport was closed */
-  GRPC_TRANSPORT_CLOSED,
-  /* an underlying transport is about to be closed */
-  GRPC_TRANSPORT_GOAWAY
-} grpc_channel_op_type;
-
-/* A single filterable operation to be performed on a channel */
-typedef struct {
-  /* The type of operation we're performing */
-  grpc_channel_op_type type;
-  /* The directionality of this call - is it bubbling up the stack, or down? */
-  grpc_call_dir dir;
-
-  /* Argument data, matching up with grpc_channel_op_type names */
-  union {
-    struct {
-      grpc_transport *transport;
-      const void *transport_server_data;
-    } accept_call;
-    struct {
-      grpc_status_code status;
-      gpr_slice message;
-    } goaway;
-  } data;
-} grpc_channel_op;
-
 /* Channel filters specify:
    1. the amount of memory needed in the channel & call (via the sizeof_XXX
       members)
@@ -103,12 +64,12 @@ typedef struct {
 typedef struct {
   /* Called to eg. send/receive data on a call.
      See grpc_call_next_op on how to call the next element in the stack */
-  void (*start_transport_op)(grpc_call_element *elem, grpc_transport_op *op);
+  void (*start_transport_stream_op)(grpc_call_element *elem,
+                                    grpc_transport_stream_op *op);
   /* Called to handle channel level operations - e.g. new calls, or transport
      closure.
      See grpc_channel_next_op on how to call the next element in the stack */
-  void (*channel_op)(grpc_channel_element *elem,
-                     grpc_channel_element *from_elem, grpc_channel_op *op);
+  void (*start_transport_op)(grpc_channel_element *elem, grpc_transport_op *op);
 
   /* sizeof(per call data) */
   size_t sizeof_call_data;
@@ -122,7 +83,7 @@ typedef struct {
      argument.*/
   void (*init_call_elem)(grpc_call_element *elem,
                          const void *server_transport_data,
-                         grpc_transport_op *initial_op);
+                         grpc_transport_stream_op *initial_op);
   /* Destroy per call data.
      The filter does not need to do any chaining */
   void (*destroy_call_elem)(grpc_call_element *elem);
@@ -135,7 +96,7 @@ typedef struct {
      is_first, is_last designate this elements position in the stack, and are
      useful for asserting correct configuration by upper layer code.
      The filter does not need to do any chaining */
-  void (*init_channel_elem)(grpc_channel_element *elem,
+  void (*init_channel_elem)(grpc_channel_element *elem, grpc_channel *master,
                             const grpc_channel_args *args,
                             grpc_mdctx *metadata_context, int is_first,
                             int is_last);
@@ -190,7 +151,8 @@ size_t grpc_channel_stack_size(const grpc_channel_filter **filters,
                                size_t filter_count);
 /* Initialize a channel stack given some filters */
 void grpc_channel_stack_init(const grpc_channel_filter **filters,
-                             size_t filter_count, const grpc_channel_args *args,
+                             size_t filter_count, grpc_channel *master,
+                             const grpc_channel_args *args,
                              grpc_mdctx *metadata_context,
                              grpc_channel_stack *stack);
 /* Destroy a channel stack */
@@ -201,16 +163,16 @@ void grpc_channel_stack_destroy(grpc_channel_stack *stack);
    server. */
 void grpc_call_stack_init(grpc_channel_stack *channel_stack,
                           const void *transport_server_data,
-                          grpc_transport_op *initial_op,
+                          grpc_transport_stream_op *initial_op,
                           grpc_call_stack *call_stack);
 /* Destroy a call stack */
 void grpc_call_stack_destroy(grpc_call_stack *stack);
 
 /* Call the next operation in a call stack */
-void grpc_call_next_op(grpc_call_element *elem, grpc_transport_op *op);
+void grpc_call_next_op(grpc_call_element *elem, grpc_transport_stream_op *op);
 /* Call the next operation (depending on call directionality) in a channel
    stack */
-void grpc_channel_next_op(grpc_channel_element *elem, grpc_channel_op *op);
+void grpc_channel_next_op(grpc_channel_element *elem, grpc_transport_op *op);
 
 /* Given the top element of a channel stack, get the channel stack itself */
 grpc_channel_stack *grpc_channel_stack_from_top_element(
@@ -219,7 +181,7 @@ grpc_channel_stack *grpc_channel_stack_from_top_element(
 grpc_call_stack *grpc_call_stack_from_top_element(grpc_call_element *elem);
 
 void grpc_call_log_op(char *file, int line, gpr_log_severity severity,
-                      grpc_call_element *elem, grpc_transport_op *op);
+                      grpc_call_element *elem, grpc_transport_stream_op *op);
 
 void grpc_call_element_send_cancel(grpc_call_element *cur_elem);
 
diff --git a/src/core/channel/child_channel.c b/src/core/channel/child_channel.c
deleted file mode 100644
index 6690265d75..0000000000
--- a/src/core/channel/child_channel.c
+++ /dev/null
@@ -1,308 +0,0 @@
-/*
- *
- * 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.
- *
- */
-
-#include "src/core/channel/child_channel.h"
-#include "src/core/iomgr/iomgr.h"
-#include <grpc/support/alloc.h>
-
-/* Link back filter: passes up calls to the client channel, pushes down calls
-   down */
-
-static void maybe_destroy_channel(grpc_child_channel *channel);
-
-typedef struct {
-  gpr_mu mu;
-  gpr_cv cv;
-  grpc_channel_element *back;
-  /* # of active calls on the channel */
-  gpr_uint32 active_calls;
-  /* has grpc_child_channel_destroy been called? */
-  gpr_uint8 destroyed;
-  /* has the transport reported itself disconnected? */
-  gpr_uint8 disconnected;
-  /* are we calling 'back' - our parent channel */
-  gpr_uint8 calling_back;
-  /* have we or our parent sent goaway yet? - dup suppression */
-  gpr_uint8 sent_goaway;
-  /* are we currently sending farewell (in this file: goaway + disconnect) */
-  gpr_uint8 sending_farewell;
-  /* have we sent farewell (goaway + disconnect) */
-  gpr_uint8 sent_farewell;
-
-  grpc_iomgr_closure finally_destroy_channel_closure;
-  grpc_iomgr_closure send_farewells_closure;
-} lb_channel_data;
-
-typedef struct { grpc_child_channel *channel; } lb_call_data;
-
-static void lb_start_transport_op(grpc_call_element *elem,
-                                  grpc_transport_op *op) {
-  grpc_call_next_op(elem, op);
-}
-
-/* Currently we assume all channel operations should just be pushed up. */
-static void lb_channel_op(grpc_channel_element *elem,
-                          grpc_channel_element *from_elem,
-                          grpc_channel_op *op) {
-  lb_channel_data *chand = elem->channel_data;
-  grpc_channel_element *back;
-  int calling_back = 0;
-
-  switch (op->dir) {
-    case GRPC_CALL_UP:
-      gpr_mu_lock(&chand->mu);
-      back = chand->back;
-      if (back) {
-        chand->calling_back++;
-        calling_back = 1;
-      }
-      gpr_mu_unlock(&chand->mu);
-      if (back) {
-        back->filter->channel_op(chand->back, elem, op);
-      } else if (op->type == GRPC_TRANSPORT_GOAWAY) {
-        gpr_slice_unref(op->data.goaway.message);
-      }
-      break;
-    case GRPC_CALL_DOWN:
-      grpc_channel_next_op(elem, op);
-      break;
-  }
-
-  gpr_mu_lock(&chand->mu);
-  switch (op->type) {
-    case GRPC_TRANSPORT_CLOSED:
-      chand->disconnected = 1;
-      maybe_destroy_channel(grpc_channel_stack_from_top_element(elem));
-      break;
-    case GRPC_CHANNEL_GOAWAY:
-      chand->sent_goaway = 1;
-      break;
-    case GRPC_CHANNEL_DISCONNECT:
-    case GRPC_TRANSPORT_GOAWAY:
-    case GRPC_ACCEPT_CALL:
-      break;
-  }
-
-  if (calling_back) {
-    chand->calling_back--;
-    gpr_cv_signal(&chand->cv);
-    maybe_destroy_channel(grpc_channel_stack_from_top_element(elem));
-  }
-  gpr_mu_unlock(&chand->mu);
-}
-
-/* Constructor for call_data */
-static void lb_init_call_elem(grpc_call_element *elem,
-                              const void *server_transport_data,
-                              grpc_transport_op *initial_op) {}
-
-/* Destructor for call_data */
-static void lb_destroy_call_elem(grpc_call_element *elem) {}
-
-/* Constructor for channel_data */
-static void lb_init_channel_elem(grpc_channel_element *elem,
-                                 const grpc_channel_args *args,
-                                 grpc_mdctx *metadata_context, int is_first,
-                                 int is_last) {
-  lb_channel_data *chand = elem->channel_data;
-  GPR_ASSERT(is_first);
-  GPR_ASSERT(!is_last);
-  gpr_mu_init(&chand->mu);
-  gpr_cv_init(&chand->cv);
-  chand->back = NULL;
-  chand->destroyed = 0;
-  chand->disconnected = 0;
-  chand->active_calls = 0;
-  chand->sent_goaway = 0;
-  chand->calling_back = 0;
-  chand->sending_farewell = 0;
-  chand->sent_farewell = 0;
-}
-
-/* Destructor for channel_data */
-static void lb_destroy_channel_elem(grpc_channel_element *elem) {
-  lb_channel_data *chand = elem->channel_data;
-  gpr_mu_destroy(&chand->mu);
-  gpr_cv_destroy(&chand->cv);
-}
-
-const grpc_channel_filter grpc_child_channel_top_filter = {
-    lb_start_transport_op,   lb_channel_op,
-    sizeof(lb_call_data),    lb_init_call_elem,    lb_destroy_call_elem,
-    sizeof(lb_channel_data), lb_init_channel_elem, lb_destroy_channel_elem,
-    "child-channel",
-};
-
-/* grpc_child_channel proper */
-
-#define LINK_BACK_ELEM_FROM_CHANNEL(channel) \
-  grpc_channel_stack_element((channel), 0)
-
-#define LINK_BACK_ELEM_FROM_CALL(call) grpc_call_stack_element((call), 0)
-
-static void finally_destroy_channel(void *c, int success) {
-  /* ignore success or not... this is a destruction callback and will only
-     happen once - the only purpose here is to release resources */
-  grpc_child_channel *channel = c;
-  lb_channel_data *chand = LINK_BACK_ELEM_FROM_CHANNEL(channel)->channel_data;
-  /* wait for the initiator to leave the mutex */
-  gpr_mu_lock(&chand->mu);
-  gpr_mu_unlock(&chand->mu);
-  grpc_channel_stack_destroy(channel);
-  gpr_free(channel);
-}
-
-static void send_farewells(void *c, int success) {
-  grpc_child_channel *channel = c;
-  grpc_channel_element *lbelem = LINK_BACK_ELEM_FROM_CHANNEL(channel);
-  lb_channel_data *chand = lbelem->channel_data;
-  int send_goaway;
-  grpc_channel_op op;
-
-  gpr_mu_lock(&chand->mu);
-  send_goaway = !chand->sent_goaway;
-  chand->sent_goaway = 1;
-  gpr_mu_unlock(&chand->mu);
-
-  if (send_goaway) {
-    op.type = GRPC_CHANNEL_GOAWAY;
-    op.dir = GRPC_CALL_DOWN;
-    op.data.goaway.status = GRPC_STATUS_OK;
-    op.data.goaway.message = gpr_slice_from_copied_string("Client disconnect");
-    grpc_channel_next_op(lbelem, &op);
-  }
-
-  op.type = GRPC_CHANNEL_DISCONNECT;
-  op.dir = GRPC_CALL_DOWN;
-  grpc_channel_next_op(lbelem, &op);
-
-  gpr_mu_lock(&chand->mu);
-  chand->sending_farewell = 0;
-  chand->sent_farewell = 1;
-  maybe_destroy_channel(channel);
-  gpr_mu_unlock(&chand->mu);
-}
-
-static void maybe_destroy_channel(grpc_child_channel *channel) {
-  lb_channel_data *chand = LINK_BACK_ELEM_FROM_CHANNEL(channel)->channel_data;
-  if (chand->destroyed && chand->disconnected && chand->active_calls == 0 &&
-      !chand->sending_farewell && !chand->calling_back) {
-    chand->finally_destroy_channel_closure.cb = finally_destroy_channel;
-    chand->finally_destroy_channel_closure.cb_arg = channel;
-    grpc_iomgr_add_callback(&chand->finally_destroy_channel_closure);
-  } else if (chand->destroyed && !chand->disconnected &&
-             chand->active_calls == 0 && !chand->sending_farewell &&
-             !chand->sent_farewell) {
-    chand->sending_farewell = 1;
-    chand->send_farewells_closure.cb = send_farewells;
-    chand->send_farewells_closure.cb_arg = channel;
-    grpc_iomgr_add_callback(&chand->send_farewells_closure);
-  }
-}
-
-grpc_child_channel *grpc_child_channel_create(
-    grpc_channel_element *parent, const grpc_channel_filter **filters,
-    size_t filter_count, const grpc_channel_args *args,
-    grpc_mdctx *metadata_context) {
-  grpc_channel_stack *stk =
-      gpr_malloc(grpc_channel_stack_size(filters, filter_count));
-  lb_channel_data *lb;
-
-  grpc_channel_stack_init(filters, filter_count, args, metadata_context, stk);
-
-  lb = LINK_BACK_ELEM_FROM_CHANNEL(stk)->channel_data;
-  gpr_mu_lock(&lb->mu);
-  lb->back = parent;
-  gpr_mu_unlock(&lb->mu);
-
-  return stk;
-}
-
-void grpc_child_channel_destroy(grpc_child_channel *channel,
-                                int wait_for_callbacks) {
-  grpc_channel_element *lbelem = LINK_BACK_ELEM_FROM_CHANNEL(channel);
-  lb_channel_data *chand = lbelem->channel_data;
-
-  gpr_mu_lock(&chand->mu);
-  while (wait_for_callbacks && chand->calling_back) {
-    gpr_cv_wait(&chand->cv, &chand->mu, gpr_inf_future);
-  }
-
-  chand->back = NULL;
-  chand->destroyed = 1;
-  maybe_destroy_channel(channel);
-  gpr_mu_unlock(&chand->mu);
-}
-
-void grpc_child_channel_handle_op(grpc_child_channel *channel,
-                                  grpc_channel_op *op) {
-  grpc_channel_next_op(LINK_BACK_ELEM_FROM_CHANNEL(channel), op);
-}
-
-grpc_child_call *grpc_child_channel_create_call(grpc_child_channel *channel,
-                                                grpc_call_element *parent,
-                                                grpc_transport_op *initial_op) {
-  grpc_call_stack *stk = gpr_malloc((channel)->call_stack_size);
-  grpc_call_element *lbelem;
-  lb_call_data *lbcalld;
-  lb_channel_data *lbchand;
-
-  grpc_call_stack_init(channel, NULL, initial_op, stk);
-  lbelem = LINK_BACK_ELEM_FROM_CALL(stk);
-  lbchand = lbelem->channel_data;
-  lbcalld = lbelem->call_data;
-  lbcalld->channel = channel;
-
-  gpr_mu_lock(&lbchand->mu);
-  lbchand->active_calls++;
-  gpr_mu_unlock(&lbchand->mu);
-
-  return stk;
-}
-
-void grpc_child_call_destroy(grpc_child_call *call) {
-  grpc_call_element *lbelem = LINK_BACK_ELEM_FROM_CALL(call);
-  lb_call_data *calld = lbelem->call_data;
-  lb_channel_data *chand = lbelem->channel_data;
-  grpc_child_channel *channel = calld->channel;
-  grpc_call_stack_destroy(call);
-  gpr_free(call);
-  gpr_mu_lock(&chand->mu);
-  chand->active_calls--;
-  maybe_destroy_channel(channel);
-  gpr_mu_unlock(&chand->mu);
-}
-
-grpc_call_element *grpc_child_call_get_top_element(grpc_child_call *call) {
-  return LINK_BACK_ELEM_FROM_CALL(call);
-}
diff --git a/src/core/channel/client_channel.c b/src/core/channel/client_channel.c
index 711e105464..871e970eb8 100644
--- a/src/core/channel/client_channel.c
+++ b/src/core/channel/client_channel.c
@@ -34,13 +34,15 @@
 #include "src/core/channel/client_channel.h"
 
 #include <stdio.h>
+#include <string.h>
 
 #include "src/core/channel/channel_args.h"
-#include "src/core/channel/child_channel.h"
 #include "src/core/channel/connected_channel.h"
+#include "src/core/surface/channel.h"
 #include "src/core/iomgr/iomgr.h"
 #include "src/core/iomgr/pollset_set.h"
 #include "src/core/support/string.h"
+#include "src/core/transport/connectivity_state.h"
 #include <grpc/support/alloc.h>
 #include <grpc/support/log.h>
 #include <grpc/support/sync.h>
@@ -51,31 +53,38 @@
 typedef struct call_data call_data;
 
 typedef struct {
-  /* protects children, child_count, child_capacity, active_child,
-     transport_setup_initiated
-     does not protect channel stacks held by children
-     transport_setup is assumed to be set once during construction */
-  gpr_mu mu;
-
-  /* the sending child (may be null) */
-  grpc_child_channel *active_child;
+  /** metadata context for this channel */
   grpc_mdctx *mdctx;
-
-  /* calls waiting for a channel to be ready */
-  call_data **waiting_children;
-  size_t waiting_child_count;
-  size_t waiting_child_capacity;
-
-  /* transport setup for this channel */
-  grpc_transport_setup *transport_setup;
-  int transport_setup_initiated;
-
-  grpc_channel_args *args;
+  /** resolver for this channel */
+  grpc_resolver *resolver;
+  /** master channel - the grpc_channel instance that ultimately owns
+      this channel_data via its channel stack.
+      We occasionally use this to bump the refcount on the master channel
+      to keep ourselves alive through an asynchronous operation. */
+  grpc_channel *master;
+
+  /** mutex protecting client configuration, including all
+      variables below in this data structure */
+  gpr_mu mu_config;
+  /** currently active load balancer - guarded by mu_config */
+  grpc_lb_policy *lb_policy;
+  /** incoming configuration - set by resolver.next
+      guarded by mu_config */
+  grpc_client_config *incoming_configuration;
+  /** a list of closures that are all waiting for config to come in */
+  grpc_iomgr_closure *waiting_for_config_closures;
+  /** resolver callback */
+  grpc_iomgr_closure on_config_changed;
+  /** connectivity state being tracked */
+  grpc_connectivity_state_tracker state_tracker;
 } channel_data;
 
 typedef enum {
   CALL_CREATED,
-  CALL_WAITING,
+  CALL_WAITING_FOR_SEND,
+  CALL_WAITING_FOR_CONFIG,
+  CALL_WAITING_FOR_PICK,
+  CALL_WAITING_FOR_CALL,
   CALL_ACTIVE,
   CALL_CANCELLED
 } call_state;
@@ -84,75 +93,25 @@ struct call_data {
   /* owning element */
   grpc_call_element *elem;
 
+  gpr_mu mu_state;
+
   call_state state;
   gpr_timespec deadline;
-  union {
-    struct {
-      /* our child call stack */
-      grpc_child_call *child_call;
-    } active;
-    grpc_transport_op waiting_op;
-    struct {
-      grpc_linked_mdelem status;
-      grpc_linked_mdelem details;
-    } cancelled;
-  } s;
+  grpc_subchannel *picked_channel;
+  grpc_iomgr_closure async_setup_task;
+  grpc_transport_stream_op waiting_op;
+  /* our child call stack */
+  grpc_subchannel_call *subchannel_call;
+  grpc_linked_mdelem status;
+  grpc_linked_mdelem details;
 };
 
-static int prepare_activate(grpc_call_element *elem,
-                            grpc_child_channel *on_child) {
-  call_data *calld = elem->call_data;
-  channel_data *chand = elem->channel_data;
-  if (calld->state == CALL_CANCELLED) return 0;
-
-  /* no more access to calld->s.waiting allowed */
-  GPR_ASSERT(calld->state == CALL_WAITING);
-
-  if (calld->s.waiting_op.bind_pollset) {
-    grpc_transport_setup_del_interested_party(chand->transport_setup,
-                                              calld->s.waiting_op.bind_pollset);
-  }
-
-  calld->state = CALL_ACTIVE;
-
-  /* create a child call */
-  /* TODO(ctiller): pass the waiting op down here */
-  calld->s.active.child_call =
-      grpc_child_channel_create_call(on_child, elem, NULL);
-
-  return 1;
-}
-
-static void complete_activate(grpc_call_element *elem, grpc_transport_op *op) {
-  call_data *calld = elem->call_data;
-  grpc_call_element *child_elem =
-      grpc_child_call_get_top_element(calld->s.active.child_call);
-
-  GPR_ASSERT(calld->state == CALL_ACTIVE);
-
-  /* continue the start call down the stack, this nees to happen after metadata
-     are flushed*/
-  child_elem->filter->start_transport_op(child_elem, op);
-}
-
-static void remove_waiting_child(channel_data *chand, call_data *calld) {
-  size_t new_count;
-  size_t i;
-  for (i = 0, new_count = 0; i < chand->waiting_child_count; i++) {
-    if (chand->waiting_children[i] == calld) {
-      grpc_transport_setup_del_interested_party(
-          chand->transport_setup, calld->s.waiting_op.bind_pollset);
-      continue;
-    }
-    chand->waiting_children[new_count++] = chand->waiting_children[i];
-  }
-  GPR_ASSERT(new_count == chand->waiting_child_count - 1 ||
-             new_count == chand->waiting_child_count);
-  chand->waiting_child_count = new_count;
-}
+static grpc_iomgr_closure *merge_into_waiting_op(
+    grpc_call_element *elem,
+    grpc_transport_stream_op *new_op) GRPC_MUST_USE_RESULT;
 
 static void handle_op_after_cancellation(grpc_call_element *elem,
-                                         grpc_transport_op *op) {
+                                         grpc_transport_stream_op *op) {
   call_data *calld = elem->call_data;
   channel_data *chand = elem->channel_data;
   if (op->send_ops) {
@@ -163,15 +122,15 @@ static void handle_op_after_cancellation(grpc_call_element *elem,
     char status[GPR_LTOA_MIN_BUFSIZE];
     grpc_metadata_batch mdb;
     gpr_ltoa(GRPC_STATUS_CANCELLED, status);
-    calld->s.cancelled.status.md =
+    calld->status.md =
         grpc_mdelem_from_strings(chand->mdctx, "grpc-status", status);
-    calld->s.cancelled.details.md =
+    calld->details.md =
         grpc_mdelem_from_strings(chand->mdctx, "grpc-message", "Cancelled");
-    calld->s.cancelled.status.prev = calld->s.cancelled.details.next = NULL;
-    calld->s.cancelled.status.next = &calld->s.cancelled.details;
-    calld->s.cancelled.details.prev = &calld->s.cancelled.status;
-    mdb.list.head = &calld->s.cancelled.status;
-    mdb.list.tail = &calld->s.cancelled.details;
+    calld->status.prev = calld->details.next = NULL;
+    calld->status.next = &calld->details;
+    calld->details.prev = &calld->status;
+    mdb.list.head = &calld->status;
+    mdb.list.tail = &calld->details;
     mdb.garbage.head = mdb.garbage.tail = NULL;
     mdb.deadline = gpr_inf_future;
     grpc_sopb_add_metadata(op->recv_ops, mdb);
@@ -183,192 +142,372 @@ static void handle_op_after_cancellation(grpc_call_element *elem,
   }
 }
 
-static void cc_start_transport_op(grpc_call_element *elem,
-                                  grpc_transport_op *op) {
+typedef struct {
+  grpc_iomgr_closure closure;
+  grpc_call_element *elem;
+} waiting_call;
+
+static void perform_transport_stream_op(grpc_call_element *elem,
+                                        grpc_transport_stream_op *op,
+                                        int continuation);
+
+static void continue_with_pick(void *arg, int iomgr_success) {
+  waiting_call *wc = arg;
+  call_data *calld = wc->elem->call_data;
+  perform_transport_stream_op(wc->elem, &calld->waiting_op, 1);
+  gpr_free(wc);
+}
+
+static void add_to_lb_policy_wait_queue_locked_state_config(
+    grpc_call_element *elem) {
+  channel_data *chand = elem->channel_data;
+  waiting_call *wc = gpr_malloc(sizeof(*wc));
+  grpc_iomgr_closure_init(&wc->closure, continue_with_pick, wc);
+  wc->elem = elem;
+  wc->closure.next = chand->waiting_for_config_closures;
+  chand->waiting_for_config_closures = &wc->closure;
+}
+
+static int is_empty(void *p, int len) {
+  char *ptr = p;
+  int i;
+  for (i = 0; i < len; i++) {
+    if (ptr[i] != 0) return 0;
+  }
+  return 1;
+}
+
+static void started_call(void *arg, int iomgr_success) {
+  call_data *calld = arg;
+  grpc_transport_stream_op op;
+  int have_waiting;
+
+  gpr_mu_lock(&calld->mu_state);
+  if (calld->state == CALL_CANCELLED && calld->subchannel_call != NULL) {
+    memset(&op, 0, sizeof(op));
+    op.cancel_with_status = GRPC_STATUS_CANCELLED;
+    gpr_mu_unlock(&calld->mu_state);
+    grpc_subchannel_call_process_op(calld->subchannel_call, &op);
+  } else if (calld->state == CALL_WAITING_FOR_CALL) {
+    have_waiting = !is_empty(&calld->waiting_op, sizeof(calld->waiting_op));
+    if (calld->subchannel_call != NULL) {
+      calld->state = CALL_ACTIVE;
+      gpr_mu_unlock(&calld->mu_state);
+      if (have_waiting) {
+        grpc_subchannel_call_process_op(calld->subchannel_call,
+                                        &calld->waiting_op);
+      }
+    } else {
+      calld->state = CALL_CANCELLED;
+      gpr_mu_unlock(&calld->mu_state);
+      if (have_waiting) {
+        handle_op_after_cancellation(calld->elem, &calld->waiting_op);
+      }
+    }
+  } else {
+    GPR_ASSERT(calld->state == CALL_CANCELLED);
+    gpr_mu_unlock(&calld->mu_state);
+  }
+}
+
+static void picked_target(void *arg, int iomgr_success) {
+  call_data *calld = arg;
+  grpc_pollset *pollset;
+
+  if (calld->picked_channel == NULL) {
+    /* treat this like a cancellation */
+    calld->waiting_op.cancel_with_status = GRPC_STATUS_UNAVAILABLE;
+    perform_transport_stream_op(calld->elem, &calld->waiting_op, 1);
+  } else {
+    gpr_mu_lock(&calld->mu_state);
+    if (calld->state == CALL_CANCELLED) {
+      gpr_mu_unlock(&calld->mu_state);
+      handle_op_after_cancellation(calld->elem, &calld->waiting_op);
+    } else {
+      GPR_ASSERT(calld->state == CALL_WAITING_FOR_PICK);
+      calld->state = CALL_WAITING_FOR_CALL;
+      pollset = calld->waiting_op.bind_pollset;
+      gpr_mu_unlock(&calld->mu_state);
+      grpc_iomgr_closure_init(&calld->async_setup_task, started_call, calld);
+      grpc_subchannel_create_call(calld->picked_channel, pollset,
+                                  &calld->subchannel_call,
+                                  &calld->async_setup_task);
+    }
+  }
+}
+
+static void pick_target(grpc_lb_policy *lb_policy, call_data *calld) {
+  grpc_metadata_batch *initial_metadata;
+  grpc_transport_stream_op *op = &calld->waiting_op;
+
+  GPR_ASSERT(op->bind_pollset);
+  GPR_ASSERT(op->send_ops);
+  GPR_ASSERT(op->send_ops->nops >= 1);
+  GPR_ASSERT(op->send_ops->ops[0].type == GRPC_OP_METADATA);
+  initial_metadata = &op->send_ops->ops[0].data.metadata;
+
+  grpc_iomgr_closure_init(&calld->async_setup_task, picked_target, calld);
+  grpc_lb_policy_pick(lb_policy, op->bind_pollset, initial_metadata,
+                      &calld->picked_channel, &calld->async_setup_task);
+}
+
+static grpc_iomgr_closure *merge_into_waiting_op(
+    grpc_call_element *elem, grpc_transport_stream_op *new_op) {
+  call_data *calld = elem->call_data;
+  grpc_iomgr_closure *consumed_op = NULL;
+  grpc_transport_stream_op *waiting_op = &calld->waiting_op;
+  GPR_ASSERT((waiting_op->send_ops != NULL) + (new_op->send_ops != NULL) <= 1);
+  GPR_ASSERT((waiting_op->recv_ops != NULL) + (new_op->recv_ops != NULL) <= 1);
+  if (new_op->send_ops != NULL) {
+    waiting_op->send_ops = new_op->send_ops;
+    waiting_op->is_last_send = new_op->is_last_send;
+    waiting_op->on_done_send = new_op->on_done_send;
+  }
+  if (new_op->recv_ops != NULL) {
+    waiting_op->recv_ops = new_op->recv_ops;
+    waiting_op->recv_state = new_op->recv_state;
+    waiting_op->on_done_recv = new_op->on_done_recv;
+  }
+  if (new_op->on_consumed != NULL) {
+    if (waiting_op->on_consumed != NULL) {
+      consumed_op = waiting_op->on_consumed;
+    }
+    waiting_op->on_consumed = new_op->on_consumed;
+  }
+  if (new_op->cancel_with_status != GRPC_STATUS_OK) {
+    waiting_op->cancel_with_status = new_op->cancel_with_status;
+  }
+  return consumed_op;
+}
+
+static void perform_transport_stream_op(grpc_call_element *elem,
+                                        grpc_transport_stream_op *op,
+                                        int continuation) {
   call_data *calld = elem->call_data;
   channel_data *chand = elem->channel_data;
-  grpc_call_element *child_elem;
-  grpc_transport_op waiting_op;
+  grpc_subchannel_call *subchannel_call;
+  grpc_lb_policy *lb_policy;
+  grpc_transport_stream_op op2;
+  grpc_iomgr_closure *consumed_op = NULL;
   GPR_ASSERT(elem->filter == &grpc_client_channel_filter);
   GRPC_CALL_LOG_OP(GPR_INFO, elem, op);
 
-  gpr_mu_lock(&chand->mu);
+  gpr_mu_lock(&calld->mu_state);
   switch (calld->state) {
     case CALL_ACTIVE:
-      child_elem = grpc_child_call_get_top_element(calld->s.active.child_call);
-      gpr_mu_unlock(&chand->mu);
-      child_elem->filter->start_transport_op(child_elem, op);
+      GPR_ASSERT(!continuation);
+      subchannel_call = calld->subchannel_call;
+      gpr_mu_unlock(&calld->mu_state);
+      grpc_subchannel_call_process_op(subchannel_call, op);
       break;
-    case CALL_CREATED:
-      if (op->cancel_with_status != GRPC_STATUS_OK) {
-        calld->state = CALL_CANCELLED;
-        gpr_mu_unlock(&chand->mu);
-        handle_op_after_cancellation(elem, op);
-      } else {
-        calld->state = CALL_WAITING;
-        calld->s.waiting_op.bind_pollset = NULL;
-        if (chand->active_child) {
-          /* channel is connected - use the connected stack */
-          if (prepare_activate(elem, chand->active_child)) {
-            gpr_mu_unlock(&chand->mu);
-            /* activate the request (pass it down) outside the lock */
-            complete_activate(elem, op);
-          } else {
-            gpr_mu_unlock(&chand->mu);
+    case CALL_CANCELLED:
+      gpr_mu_unlock(&calld->mu_state);
+      handle_op_after_cancellation(elem, op);
+      break;
+    case CALL_WAITING_FOR_SEND:
+      GPR_ASSERT(!continuation);
+      consumed_op = merge_into_waiting_op(elem, op);
+      if (!calld->waiting_op.send_ops &&
+          calld->waiting_op.cancel_with_status == GRPC_STATUS_OK) {
+        gpr_mu_unlock(&calld->mu_state);
+        break;
+      }
+      *op = calld->waiting_op;
+      memset(&calld->waiting_op, 0, sizeof(calld->waiting_op));
+      continuation = 1;
+    /* fall through */
+    case CALL_WAITING_FOR_CONFIG:
+    case CALL_WAITING_FOR_PICK:
+    case CALL_WAITING_FOR_CALL:
+      if (!continuation) {
+        if (op->cancel_with_status != GRPC_STATUS_OK) {
+          calld->state = CALL_CANCELLED;
+          op2 = calld->waiting_op;
+          memset(&calld->waiting_op, 0, sizeof(calld->waiting_op));
+          if (op->on_consumed) {
+            calld->waiting_op.on_consumed = op->on_consumed;
+            op->on_consumed = NULL;
+          } else if (op2.on_consumed) {
+            calld->waiting_op.on_consumed = op2.on_consumed;
+            op2.on_consumed = NULL;
           }
+          gpr_mu_unlock(&calld->mu_state);
+          handle_op_after_cancellation(elem, op);
+          handle_op_after_cancellation(elem, &op2);
         } else {
-          /* check to see if we should initiate a connection (if we're not
-             already),
-             but don't do so until outside the lock to avoid re-entrancy
-             problems if
-             the callback is immediate */
-          int initiate_transport_setup = 0;
-          if (!chand->transport_setup_initiated) {
-            chand->transport_setup_initiated = 1;
-            initiate_transport_setup = 1;
-          }
-          /* add this call to the waiting set to be resumed once we have a child
-             channel stack, growing the waiting set if needed */
-          if (chand->waiting_child_count == chand->waiting_child_capacity) {
-            chand->waiting_child_capacity =
-                GPR_MAX(chand->waiting_child_capacity * 2, 8);
-            chand->waiting_children = gpr_realloc(
-                chand->waiting_children,
-                chand->waiting_child_capacity * sizeof(call_data *));
-          }
-          calld->s.waiting_op = *op;
-          chand->waiting_children[chand->waiting_child_count++] = calld;
-          grpc_transport_setup_add_interested_party(chand->transport_setup,
-                                                    op->bind_pollset);
-          gpr_mu_unlock(&chand->mu);
-
-          /* finally initiate transport setup if needed */
-          if (initiate_transport_setup) {
-            grpc_transport_setup_initiate(chand->transport_setup);
-          }
+          consumed_op = merge_into_waiting_op(elem, op);
+          gpr_mu_unlock(&calld->mu_state);
         }
+        break;
       }
-      break;
-    case CALL_WAITING:
+    /* fall through */
+    case CALL_CREATED:
       if (op->cancel_with_status != GRPC_STATUS_OK) {
-        waiting_op = calld->s.waiting_op;
-        remove_waiting_child(chand, calld);
         calld->state = CALL_CANCELLED;
-        gpr_mu_unlock(&chand->mu);
-        handle_op_after_cancellation(elem, &waiting_op);
+        gpr_mu_unlock(&calld->mu_state);
         handle_op_after_cancellation(elem, op);
       } else {
-        GPR_ASSERT((calld->s.waiting_op.send_ops == NULL) !=
-                   (op->send_ops == NULL));
-        GPR_ASSERT((calld->s.waiting_op.recv_ops == NULL) !=
-                   (op->recv_ops == NULL));
-        if (op->send_ops) {
-          calld->s.waiting_op.send_ops = op->send_ops;
-          calld->s.waiting_op.is_last_send = op->is_last_send;
-          calld->s.waiting_op.on_done_send = op->on_done_send;
-        }
-        if (op->recv_ops) {
-          calld->s.waiting_op.recv_ops = op->recv_ops;
-          calld->s.waiting_op.recv_state = op->recv_state;
-          calld->s.waiting_op.on_done_recv = op->on_done_recv;
-        }
-        gpr_mu_unlock(&chand->mu);
-        if (op->on_consumed) {
-          op->on_consumed->cb(op->on_consumed->cb_arg, 0);
+        calld->waiting_op = *op;
+
+        if (op->send_ops == NULL) {
+          /* need to have some send ops before we can select the
+             lb target */
+          calld->state = CALL_WAITING_FOR_SEND;
+          gpr_mu_unlock(&calld->mu_state);
+        } else {
+          gpr_mu_lock(&chand->mu_config);
+          lb_policy = chand->lb_policy;
+          if (lb_policy) {
+            GRPC_LB_POLICY_REF(lb_policy, "pick");
+            gpr_mu_unlock(&chand->mu_config);
+            calld->state = CALL_WAITING_FOR_PICK;
+            gpr_mu_unlock(&calld->mu_state);
+
+            pick_target(lb_policy, calld);
+
+            GRPC_LB_POLICY_UNREF(lb_policy, "pick");
+          } else if (chand->resolver != NULL) {
+            calld->state = CALL_WAITING_FOR_CONFIG;
+            add_to_lb_policy_wait_queue_locked_state_config(elem);
+            gpr_mu_unlock(&chand->mu_config);
+            gpr_mu_unlock(&calld->mu_state);
+          } else {
+            calld->state = CALL_CANCELLED;
+            gpr_mu_unlock(&chand->mu_config);
+            gpr_mu_unlock(&calld->mu_state);
+            handle_op_after_cancellation(elem, op);
+          }
         }
       }
       break;
-    case CALL_CANCELLED:
-      gpr_mu_unlock(&chand->mu);
-      handle_op_after_cancellation(elem, op);
-      break;
   }
+
+  if (consumed_op != NULL) {
+    consumed_op->cb(consumed_op->cb_arg, 1);
+  }
+}
+
+static void cc_start_transport_stream_op(grpc_call_element *elem,
+                                         grpc_transport_stream_op *op) {
+  perform_transport_stream_op(elem, op, 0);
+}
+
+static void cc_on_config_changed(void *arg, int iomgr_success) {
+  channel_data *chand = arg;
+  grpc_lb_policy *lb_policy = NULL;
+  grpc_lb_policy *old_lb_policy;
+  grpc_resolver *old_resolver;
+  grpc_iomgr_closure *wakeup_closures = NULL;
+
+  if (chand->incoming_configuration != NULL) {
+    lb_policy = grpc_client_config_get_lb_policy(chand->incoming_configuration);
+    GRPC_LB_POLICY_REF(lb_policy, "channel");
+
+    grpc_client_config_unref(chand->incoming_configuration);
+  }
+
+  chand->incoming_configuration = NULL;
+
+  gpr_mu_lock(&chand->mu_config);
+  old_lb_policy = chand->lb_policy;
+  chand->lb_policy = lb_policy;
+  if (lb_policy != NULL || chand->resolver == NULL /* disconnected */) {
+    wakeup_closures = chand->waiting_for_config_closures;
+    chand->waiting_for_config_closures = NULL;
+  }
+  gpr_mu_unlock(&chand->mu_config);
+
+  if (old_lb_policy) {
+    GRPC_LB_POLICY_UNREF(old_lb_policy, "channel");
+  }
+
+  gpr_mu_lock(&chand->mu_config);
+  if (iomgr_success && chand->resolver) {
+    grpc_resolver *resolver = chand->resolver;
+    GRPC_RESOLVER_REF(resolver, "channel-next");
+    gpr_mu_unlock(&chand->mu_config);
+    GRPC_CHANNEL_INTERNAL_REF(chand->master, "resolver");
+    grpc_resolver_next(chand->resolver, &chand->incoming_configuration,
+                       &chand->on_config_changed);
+    GRPC_RESOLVER_UNREF(resolver, "channel-next");
+  } else {
+    old_resolver = chand->resolver;
+    chand->resolver = NULL;
+    grpc_connectivity_state_set(&chand->state_tracker,
+                                GRPC_CHANNEL_FATAL_FAILURE);
+    gpr_mu_unlock(&chand->mu_config);
+    if (old_resolver != NULL) {
+      grpc_resolver_shutdown(old_resolver);
+      GRPC_RESOLVER_UNREF(old_resolver, "channel");
+    }
+  }
+
+  while (wakeup_closures) {
+    grpc_iomgr_closure *next = wakeup_closures->next;
+    grpc_iomgr_add_callback(wakeup_closures);
+    wakeup_closures = next;
+  }
+
+  GRPC_CHANNEL_INTERNAL_UNREF(chand->master, "resolver");
 }
 
-static void channel_op(grpc_channel_element *elem,
-                       grpc_channel_element *from_elem, grpc_channel_op *op) {
+static void cc_start_transport_op(grpc_channel_element *elem,
+                                  grpc_transport_op *op) {
+  grpc_lb_policy *lb_policy = NULL;
   channel_data *chand = elem->channel_data;
-  grpc_child_channel *child_channel;
-  grpc_channel_op rop;
-  GPR_ASSERT(elem->filter == &grpc_client_channel_filter);
+  grpc_resolver *destroy_resolver = NULL;
+  grpc_iomgr_closure *on_consumed = op->on_consumed;
+  op->on_consumed = NULL;
+
+  GPR_ASSERT(op->set_accept_stream == NULL);
+  GPR_ASSERT(op->bind_pollset == NULL);
+
+  gpr_mu_lock(&chand->mu_config);
+  if (op->on_connectivity_state_change != NULL) {
+    grpc_connectivity_state_notify_on_state_change(
+        &chand->state_tracker, op->connectivity_state,
+        op->on_connectivity_state_change);
+    op->on_connectivity_state_change = NULL;
+    op->connectivity_state = NULL;
+  }
 
-  switch (op->type) {
-    case GRPC_CHANNEL_GOAWAY:
-      /* sending goaway: clear out the active child on the way through */
-      gpr_mu_lock(&chand->mu);
-      child_channel = chand->active_child;
-      chand->active_child = NULL;
-      gpr_mu_unlock(&chand->mu);
-      if (child_channel) {
-        grpc_child_channel_handle_op(child_channel, op);
-        grpc_child_channel_destroy(child_channel, 1);
-      } else {
-        gpr_slice_unref(op->data.goaway.message);
-      }
-      break;
-    case GRPC_CHANNEL_DISCONNECT:
-      /* sending disconnect: clear out the active child on the way through */
-      gpr_mu_lock(&chand->mu);
-      child_channel = chand->active_child;
-      chand->active_child = NULL;
-      gpr_mu_unlock(&chand->mu);
-      if (child_channel) {
-        grpc_child_channel_destroy(child_channel, 1);
-      }
-      /* fake a transport closed to satisfy the refcounting in client */
-      rop.type = GRPC_TRANSPORT_CLOSED;
-      rop.dir = GRPC_CALL_UP;
-      grpc_channel_next_op(elem, &rop);
-      break;
-    case GRPC_TRANSPORT_GOAWAY:
-      /* receiving goaway: if it's from our active child, drop the active child;
-         in all cases consume the event here */
-      gpr_mu_lock(&chand->mu);
-      child_channel = grpc_channel_stack_from_top_element(from_elem);
-      if (child_channel == chand->active_child) {
-        chand->active_child = NULL;
-      } else {
-        child_channel = NULL;
-      }
-      gpr_mu_unlock(&chand->mu);
-      if (child_channel) {
-        grpc_child_channel_destroy(child_channel, 0);
-      }
-      gpr_slice_unref(op->data.goaway.message);
-      break;
-    case GRPC_TRANSPORT_CLOSED:
-      /* receiving disconnect: if it's from our active child, drop the active
-         child; in all cases consume the event here */
-      gpr_mu_lock(&chand->mu);
-      child_channel = grpc_channel_stack_from_top_element(from_elem);
-      if (child_channel == chand->active_child) {
-        chand->active_child = NULL;
-      } else {
-        child_channel = NULL;
-      }
-      gpr_mu_unlock(&chand->mu);
-      if (child_channel) {
-        grpc_child_channel_destroy(child_channel, 0);
-      }
-      break;
-    default:
-      switch (op->dir) {
-        case GRPC_CALL_UP:
-          grpc_channel_next_op(elem, op);
-          break;
-        case GRPC_CALL_DOWN:
-          gpr_log(GPR_ERROR, "unhandled channel op: %d", op->type);
-          abort();
-          break;
-      }
-      break;
+  if (op->disconnect && chand->resolver != NULL) {
+    grpc_connectivity_state_set(&chand->state_tracker,
+                                GRPC_CHANNEL_FATAL_FAILURE);
+    destroy_resolver = chand->resolver;
+    chand->resolver = NULL;
+    if (chand->lb_policy != NULL) {
+      grpc_lb_policy_shutdown(chand->lb_policy);
+    }
+  }
+
+  if (!is_empty(op, sizeof(*op))) {
+    lb_policy = chand->lb_policy;
+    if (lb_policy) {
+      GRPC_LB_POLICY_REF(lb_policy, "broadcast");
+    }
+  }
+  gpr_mu_unlock(&chand->mu_config);
+
+  if (destroy_resolver) {
+    grpc_resolver_shutdown(destroy_resolver);
+    GRPC_RESOLVER_UNREF(destroy_resolver, "channel");
+  }
+
+  if (lb_policy) {
+    grpc_lb_policy_broadcast(lb_policy, op);
+    GRPC_LB_POLICY_UNREF(lb_policy, "broadcast");
+  }
+
+  if (on_consumed) {
+    grpc_iomgr_add_callback(on_consumed);
   }
 }
 
 /* Constructor for call_data */
 static void init_call_elem(grpc_call_element *elem,
                            const void *server_transport_data,
-                           grpc_transport_op *initial_op) {
+                           grpc_transport_stream_op *initial_op) {
   call_data *calld = elem->call_data;
 
   /* TODO(ctiller): is there something useful we can do here? */
@@ -376,6 +515,7 @@ static void init_call_elem(grpc_call_element *elem,
 
   GPR_ASSERT(elem->filter == &grpc_client_channel_filter);
   GPR_ASSERT(server_transport_data == NULL);
+  gpr_mu_init(&calld->mu_state);
   calld->elem = elem;
   calld->state = CALL_CREATED;
   calld->deadline = gpr_inf_future;
@@ -384,161 +524,88 @@ static void init_call_elem(grpc_call_element *elem,
 /* Destructor for call_data */
 static void destroy_call_elem(grpc_call_element *elem) {
   call_data *calld = elem->call_data;
-  channel_data *chand = elem->channel_data;
+  grpc_subchannel_call *subchannel_call;
 
   /* if the call got activated, we need to destroy the child stack also, and
      remove it from the in-flight requests tracked by the child_entry we
      picked */
-  gpr_mu_lock(&chand->mu);
+  gpr_mu_lock(&calld->mu_state);
   switch (calld->state) {
     case CALL_ACTIVE:
-      gpr_mu_unlock(&chand->mu);
-      grpc_child_call_destroy(calld->s.active.child_call);
+      subchannel_call = calld->subchannel_call;
+      gpr_mu_unlock(&calld->mu_state);
+      GRPC_SUBCHANNEL_CALL_UNREF(subchannel_call, "client_channel");
       break;
-    case CALL_WAITING:
-      remove_waiting_child(chand, calld);
-      gpr_mu_unlock(&chand->mu);
+    case CALL_CREATED:
+    case CALL_CANCELLED:
+      gpr_mu_unlock(&calld->mu_state);
       break;
-    default:
-      gpr_mu_unlock(&chand->mu);
+    case CALL_WAITING_FOR_PICK:
+    case CALL_WAITING_FOR_CONFIG:
+    case CALL_WAITING_FOR_CALL:
+    case CALL_WAITING_FOR_SEND:
+      gpr_log(GPR_ERROR, "should never reach here");
+      abort();
       break;
   }
-  GPR_ASSERT(calld->state != CALL_WAITING);
 }
 
 /* Constructor for channel_data */
-static void init_channel_elem(grpc_channel_element *elem,
+static void init_channel_elem(grpc_channel_element *elem, grpc_channel *master,
                               const grpc_channel_args *args,
                               grpc_mdctx *metadata_context, int is_first,
                               int is_last) {
   channel_data *chand = elem->channel_data;
 
-  GPR_ASSERT(!is_first);
+  memset(chand, 0, sizeof(*chand));
+
   GPR_ASSERT(is_last);
   GPR_ASSERT(elem->filter == &grpc_client_channel_filter);
 
-  gpr_mu_init(&chand->mu);
-  chand->active_child = NULL;
-  chand->waiting_children = NULL;
-  chand->waiting_child_count = 0;
-  chand->waiting_child_capacity = 0;
-  chand->transport_setup = NULL;
-  chand->transport_setup_initiated = 0;
-  chand->args = grpc_channel_args_copy(args);
+  gpr_mu_init(&chand->mu_config);
   chand->mdctx = metadata_context;
+  chand->master = master;
+  grpc_iomgr_closure_init(&chand->on_config_changed, cc_on_config_changed,
+                          chand);
+
+  grpc_connectivity_state_init(&chand->state_tracker, GRPC_CHANNEL_IDLE);
 }
 
 /* Destructor for channel_data */
 static void destroy_channel_elem(grpc_channel_element *elem) {
   channel_data *chand = elem->channel_data;
 
-  grpc_transport_setup_cancel(chand->transport_setup);
-
-  if (chand->active_child) {
-    grpc_child_channel_destroy(chand->active_child, 1);
-    chand->active_child = NULL;
+  if (chand->resolver != NULL) {
+    grpc_resolver_shutdown(chand->resolver);
+    GRPC_RESOLVER_UNREF(chand->resolver, "channel");
   }
-
-  grpc_channel_args_destroy(chand->args);
-
-  gpr_mu_destroy(&chand->mu);
-  GPR_ASSERT(chand->waiting_child_count == 0);
-  gpr_free(chand->waiting_children);
+  if (chand->lb_policy != NULL) {
+    GRPC_LB_POLICY_UNREF(chand->lb_policy, "channel");
+  }
+  gpr_mu_destroy(&chand->mu_config);
 }
 
 const grpc_channel_filter grpc_client_channel_filter = {
-    cc_start_transport_op, channel_op,           sizeof(call_data),
-    init_call_elem,        destroy_call_elem,    sizeof(channel_data),
-    init_channel_elem,     destroy_channel_elem, "client-channel",
+    cc_start_transport_stream_op,
+    cc_start_transport_op,
+    sizeof(call_data),
+    init_call_elem,
+    destroy_call_elem,
+    sizeof(channel_data),
+    init_channel_elem,
+    destroy_channel_elem,
+    "client-channel",
 };
 
-grpc_transport_setup_result grpc_client_channel_transport_setup_complete(
-    grpc_channel_stack *channel_stack, grpc_transport *transport,
-    grpc_channel_filter const **channel_filters, size_t num_channel_filters,
-    grpc_mdctx *mdctx) {
-  /* we just got a new transport: lets create a child channel stack for it */
-  grpc_channel_element *elem = grpc_channel_stack_last_element(channel_stack);
-  channel_data *chand = elem->channel_data;
-  size_t num_child_filters = 2 + num_channel_filters;
-  grpc_channel_filter const **child_filters;
-  grpc_transport_setup_result result;
-  grpc_child_channel *old_active = NULL;
-  call_data **waiting_children;
-  size_t waiting_child_count;
-  size_t i;
-  grpc_transport_op *call_ops;
-
-  /* build the child filter stack */
-  child_filters = gpr_malloc(sizeof(grpc_channel_filter *) * num_child_filters);
-  /* we always need a link back filter to get back to the connected channel */
-  child_filters[0] = &grpc_child_channel_top_filter;
-  for (i = 0; i < num_channel_filters; i++) {
-    child_filters[i + 1] = channel_filters[i];
-  }
-  /* and we always need a connected channel to talk to the transport */
-  child_filters[num_child_filters - 1] = &grpc_connected_channel_filter;
-
-  GPR_ASSERT(elem->filter == &grpc_client_channel_filter);
-
-  /* BEGIN LOCKING CHANNEL */
-  gpr_mu_lock(&chand->mu);
-  chand->transport_setup_initiated = 0;
-
-  if (chand->active_child) {
-    old_active = chand->active_child;
-  }
-  chand->active_child = grpc_child_channel_create(
-      elem, child_filters, num_child_filters, chand->args, mdctx);
-  result =
-      grpc_connected_channel_bind_transport(chand->active_child, transport);
-
-  /* capture the waiting children - we'll activate them outside the lock
-     to avoid re-entrancy problems */
-  waiting_children = chand->waiting_children;
-  waiting_child_count = chand->waiting_child_count;
-  /* bumping up inflight_requests here avoids taking a lock per rpc below */
-
-  chand->waiting_children = NULL;
-  chand->waiting_child_count = 0;
-  chand->waiting_child_capacity = 0;
-
-  call_ops = gpr_malloc(sizeof(*call_ops) * waiting_child_count);
-
-  for (i = 0; i < waiting_child_count; i++) {
-    call_ops[i] = waiting_children[i]->s.waiting_op;
-    if (!prepare_activate(waiting_children[i]->elem, chand->active_child)) {
-      waiting_children[i] = NULL;
-      grpc_transport_op_finish_with_failure(&call_ops[i]);
-    }
-  }
-
-  /* END LOCKING CHANNEL */
-  gpr_mu_unlock(&chand->mu);
-
-  /* activate any pending operations - this is safe to do as we guarantee one
-     and only one write operation per request at the surface api - if we lose
-     that guarantee we need to do some curly locking here */
-  for (i = 0; i < waiting_child_count; i++) {
-    if (waiting_children[i]) {
-      complete_activate(waiting_children[i]->elem, &call_ops[i]);
-    }
-  }
-  gpr_free(waiting_children);
-  gpr_free(call_ops);
-  gpr_free(child_filters);
-
-  if (old_active) {
-    grpc_child_channel_destroy(old_active, 1);
-  }
-
-  return result;
-}
-
-void grpc_client_channel_set_transport_setup(grpc_channel_stack *channel_stack,
-                                             grpc_transport_setup *setup) {
+void grpc_client_channel_set_resolver(grpc_channel_stack *channel_stack,
+                                      grpc_resolver *resolver) {
   /* post construction initialization: set the transport setup pointer */
   grpc_channel_element *elem = grpc_channel_stack_last_element(channel_stack);
   channel_data *chand = elem->channel_data;
-  GPR_ASSERT(!chand->transport_setup);
-  chand->transport_setup = setup;
+  GPR_ASSERT(!chand->resolver);
+  chand->resolver = resolver;
+  GRPC_CHANNEL_INTERNAL_REF(chand->master, "resolver");
+  GRPC_RESOLVER_REF(resolver, "channel");
+  grpc_resolver_next(resolver, &chand->incoming_configuration,
+                     &chand->on_config_changed);
 }
diff --git a/src/core/channel/client_channel.h b/src/core/channel/client_channel.h
index 7a67a9f21f..fd2be46145 100644
--- a/src/core/channel/client_channel.h
+++ b/src/core/channel/client_channel.h
@@ -35,6 +35,7 @@
 #define GRPC_INTERNAL_CORE_CHANNEL_CLIENT_CHANNEL_H
 
 #include "src/core/channel/channel_stack.h"
+#include "src/core/client_config/resolver.h"
 
 /* A client channel is a channel that begins disconnected, and can connect
    to some endpoint on demand. If that endpoint disconnects, it will be
@@ -48,15 +49,7 @@ extern const grpc_channel_filter grpc_client_channel_filter;
 /* post-construction initializer to let the client channel know which
    transport setup it should cancel upon destruction, or initiate when it needs
    a connection */
-void grpc_client_channel_set_transport_setup(grpc_channel_stack *channel_stack,
-                                             grpc_transport_setup *setup);
+void grpc_client_channel_set_resolver(grpc_channel_stack *channel_stack,
+                                      grpc_resolver *resolver);
 
-/* grpc_transport_setup_callback for binding new transports into a client
-   channel - user_data should be the channel stack containing the client
-   channel */
-grpc_transport_setup_result grpc_client_channel_transport_setup_complete(
-    grpc_channel_stack *channel_stack, grpc_transport *transport,
-    grpc_channel_filter const **channel_filters, size_t num_channel_filters,
-    grpc_mdctx *mdctx);
-
-#endif  /* GRPC_INTERNAL_CORE_CHANNEL_CLIENT_CHANNEL_H */
+#endif /* GRPC_INTERNAL_CORE_CHANNEL_CLIENT_CHANNEL_H */
diff --git a/src/core/channel/client_setup.c b/src/core/channel/client_setup.c
deleted file mode 100644
index 5be8fa66e9..0000000000
--- a/src/core/channel/client_setup.c
+++ /dev/null
@@ -1,302 +0,0 @@
-/*
- *
- * 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.
- *
- */
-
-#include "src/core/channel/client_setup.h"
-#include "src/core/channel/channel_args.h"
-#include "src/core/channel/channel_stack.h"
-#include "src/core/iomgr/alarm.h"
-#include <grpc/support/alloc.h>
-#include <grpc/support/log.h>
-#include <grpc/support/time.h>
-
-struct grpc_client_setup {
-  grpc_transport_setup base; /* must be first */
-  void (*initiate)(void *user_data, grpc_client_setup_request *request);
-  void (*done)(void *user_data);
-  void *user_data;
-  grpc_channel_args *args;
-  grpc_mdctx *mdctx;
-  grpc_alarm backoff_alarm;
-  gpr_timespec current_backoff_interval;
-  int in_alarm;
-  int in_cb;
-  int cancelled;
-
-  gpr_mu mu;
-  gpr_cv cv;
-  grpc_client_setup_request *active_request;
-  int refs;
-  /** The set of pollsets that are currently interested in this
-      connection being established */
-  grpc_pollset_set interested_parties;
-};
-
-struct grpc_client_setup_request {
-  /* pointer back to the setup object */
-  grpc_client_setup *setup;
-  gpr_timespec deadline;
-};
-
-gpr_timespec grpc_client_setup_request_deadline(grpc_client_setup_request *r) {
-  return r->deadline;
-}
-
-grpc_pollset_set *grpc_client_setup_get_interested_parties(
-    grpc_client_setup_request *r) {
-  return &r->setup->interested_parties;
-}
-
-static void destroy_setup(grpc_client_setup *s) {
-  gpr_mu_destroy(&s->mu);
-  gpr_cv_destroy(&s->cv);
-  s->done(s->user_data);
-  grpc_channel_args_destroy(s->args);
-  grpc_pollset_set_destroy(&s->interested_parties);
-  gpr_free(s);
-}
-
-static void destroy_request(grpc_client_setup_request *r) { gpr_free(r); }
-
-/* initiate handshaking */
-static void setup_initiate(grpc_transport_setup *sp) {
-  grpc_client_setup *s = (grpc_client_setup *)sp;
-  grpc_client_setup_request *r = gpr_malloc(sizeof(grpc_client_setup_request));
-  int in_alarm = 0;
-
-  r->setup = s;
-  r->deadline = gpr_time_add(gpr_now(), gpr_time_from_seconds(60));
-
-  gpr_mu_lock(&s->mu);
-  GPR_ASSERT(s->refs > 0);
-  /* there might be more than one request outstanding if the caller calls
-     initiate in some kind of rapid-fire way: we try to connect each time,
-     and keep track of the latest request (which is the only one that gets
-     to finish) */
-  if (!s->in_alarm) {
-    s->active_request = r;
-    s->refs++;
-  } else {
-    /* TODO(klempner): Maybe do something more clever here */
-    in_alarm = 1;
-  }
-  gpr_mu_unlock(&s->mu);
-
-  if (!in_alarm) {
-    s->initiate(s->user_data, r);
-  } else {
-    destroy_request(r);
-  }
-}
-
-/** implementation of add_interested_party for setup vtable */
-static void setup_add_interested_party(grpc_transport_setup *sp,
-                                       grpc_pollset *pollset) {
-  grpc_client_setup *s = (grpc_client_setup *)sp;
-
-  gpr_mu_lock(&s->mu);
-  grpc_pollset_set_add_pollset(&s->interested_parties, pollset);
-  gpr_mu_unlock(&s->mu);
-}
-
-/** implementation of del_interested_party for setup vtable */
-static void setup_del_interested_party(grpc_transport_setup *sp,
-                                       grpc_pollset *pollset) {
-  grpc_client_setup *s = (grpc_client_setup *)sp;
-
-  gpr_mu_lock(&s->mu);
-  grpc_pollset_set_del_pollset(&s->interested_parties, pollset);
-  gpr_mu_unlock(&s->mu);
-}
-
-/* cancel handshaking: cancel all requests, and shutdown (the caller promises
-   not to initiate again) */
-static void setup_cancel(grpc_transport_setup *sp) {
-  grpc_client_setup *s = (grpc_client_setup *)sp;
-  int cancel_alarm = 0;
-
-  gpr_mu_lock(&s->mu);
-  s->cancelled = 1;
-  while (s->in_cb) {
-    gpr_cv_wait(&s->cv, &s->mu, gpr_inf_future);
-  }
-
-  GPR_ASSERT(s->refs > 0);
-  /* effectively cancels the current request (if any) */
-  s->active_request = NULL;
-  if (s->in_alarm) {
-    cancel_alarm = 1;
-  }
-  if (--s->refs == 0) {
-    gpr_mu_unlock(&s->mu);
-    destroy_setup(s);
-  } else {
-    gpr_mu_unlock(&s->mu);
-  }
-  if (cancel_alarm) {
-    grpc_alarm_cancel(&s->backoff_alarm);
-  }
-}
-
-int grpc_client_setup_cb_begin(grpc_client_setup_request *r,
-                               const char *reason) {
-  gpr_mu_lock(&r->setup->mu);
-  if (r->setup->cancelled) {
-    gpr_mu_unlock(&r->setup->mu);
-    return 0;
-  }
-  r->setup->in_cb++;
-  gpr_mu_unlock(&r->setup->mu);
-  return 1;
-}
-
-void grpc_client_setup_cb_end(grpc_client_setup_request *r,
-                              const char *reason) {
-  gpr_mu_lock(&r->setup->mu);
-  r->setup->in_cb--;
-  if (r->setup->cancelled) gpr_cv_signal(&r->setup->cv);
-  gpr_mu_unlock(&r->setup->mu);
-}
-
-/* vtable for transport setup */
-static const grpc_transport_setup_vtable setup_vtable = {
-    setup_initiate, setup_add_interested_party, setup_del_interested_party,
-    setup_cancel};
-
-void grpc_client_setup_create_and_attach(
-    grpc_channel_stack *newly_minted_channel, const grpc_channel_args *args,
-    grpc_mdctx *mdctx,
-    void (*initiate)(void *user_data, grpc_client_setup_request *request),
-    void (*done)(void *user_data), void *user_data) {
-  grpc_client_setup *s = gpr_malloc(sizeof(grpc_client_setup));
-
-  s->base.vtable = &setup_vtable;
-  gpr_mu_init(&s->mu);
-  gpr_cv_init(&s->cv);
-  s->refs = 1;
-  s->mdctx = mdctx;
-  s->initiate = initiate;
-  s->done = done;
-  s->user_data = user_data;
-  s->active_request = NULL;
-  s->args = grpc_channel_args_copy(args);
-  s->current_backoff_interval = gpr_time_from_micros(1000000);
-  s->in_alarm = 0;
-  s->in_cb = 0;
-  s->cancelled = 0;
-  grpc_pollset_set_init(&s->interested_parties);
-
-  grpc_client_channel_set_transport_setup(newly_minted_channel, &s->base);
-}
-
-int grpc_client_setup_request_should_continue(grpc_client_setup_request *r,
-                                              const char *reason) {
-  int result;
-  if (gpr_time_cmp(gpr_now(), r->deadline) > 0) {
-    result = 0;
-  } else {
-    gpr_mu_lock(&r->setup->mu);
-    result = r->setup->active_request == r;
-    gpr_mu_unlock(&r->setup->mu);
-  }
-  return result;
-}
-
-static void backoff_alarm_done(void *arg /* grpc_client_setup_request */, 
-                               int success) {
-  grpc_client_setup_request *r = arg;
-  grpc_client_setup *s = r->setup;
-  /* Handle status cancelled? */
-  gpr_mu_lock(&s->mu);
-  s->in_alarm = 0;
-  if (s->active_request != NULL || !success) {
-    if (0 == --s->refs) {
-      gpr_mu_unlock(&s->mu);
-      destroy_setup(s);
-      destroy_request(r);
-      return;
-    } else {
-      gpr_mu_unlock(&s->mu);
-      destroy_request(r);
-      return;
-    }
-  }
-  s->active_request = r;
-  gpr_mu_unlock(&s->mu);
-  s->initiate(s->user_data, r);
-}
-
-void grpc_client_setup_request_finish(grpc_client_setup_request *r,
-                                      int was_successful) {
-  int retry = !was_successful;
-  grpc_client_setup *s = r->setup;
-
-  gpr_mu_lock(&s->mu);
-  if (s->active_request == r) {
-    s->active_request = NULL;
-  } else {
-    retry = 0;
-  }
-
-  if (!retry && 0 == --s->refs) {
-    gpr_mu_unlock(&s->mu);
-    destroy_setup(s);
-    destroy_request(r);
-  } else if (retry) {
-    /* TODO(klempner): Replace these values with further consideration. 2x is
-       probably too aggressive of a backoff. */
-    gpr_timespec max_backoff = gpr_time_from_minutes(2);
-    gpr_timespec now = gpr_now();
-    gpr_timespec deadline = gpr_time_add(s->current_backoff_interval, now);
-    GPR_ASSERT(!s->in_alarm);
-    s->in_alarm = 1;
-    grpc_alarm_init(&s->backoff_alarm, deadline, backoff_alarm_done, r, now);
-    s->current_backoff_interval =
-        gpr_time_add(s->current_backoff_interval, s->current_backoff_interval);
-    if (gpr_time_cmp(s->current_backoff_interval, max_backoff) > 0) {
-      s->current_backoff_interval = max_backoff;
-    }
-    gpr_mu_unlock(&s->mu);
-  } else {
-    gpr_mu_unlock(&s->mu);
-    destroy_request(r);
-  }
-}
-
-const grpc_channel_args *grpc_client_setup_get_channel_args(
-    grpc_client_setup_request *r) {
-  return r->setup->args;
-}
-
-grpc_mdctx *grpc_client_setup_get_mdctx(grpc_client_setup_request *r) {
-  return r->setup->mdctx;
-}
diff --git a/src/core/channel/client_setup.h b/src/core/channel/client_setup.h
deleted file mode 100644
index 7d40338840..0000000000
--- a/src/core/channel/client_setup.h
+++ /dev/null
@@ -1,77 +0,0 @@
-/*
- *
- * 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.
- *
- */
-
-#ifndef GRPC_INTERNAL_CORE_CHANNEL_CLIENT_SETUP_H
-#define GRPC_INTERNAL_CORE_CHANNEL_CLIENT_SETUP_H
-
-#include "src/core/channel/client_channel.h"
-#include "src/core/transport/metadata.h"
-#include <grpc/support/time.h>
-
-/* Convenience API's to simplify transport setup */
-
-typedef struct grpc_client_setup grpc_client_setup;
-typedef struct grpc_client_setup_request grpc_client_setup_request;
-
-void grpc_client_setup_create_and_attach(
-    grpc_channel_stack *newly_minted_channel, const grpc_channel_args *args,
-    grpc_mdctx *mdctx,
-    void (*initiate)(void *user_data, grpc_client_setup_request *request),
-    void (*done)(void *user_data), void *user_data);
-
-/* Check that r is the active request: needs to be performed at each callback.
-   If this races, we'll have two connection attempts running at once and the
-   old one will get cleaned up in due course, which is fine. */
-int grpc_client_setup_request_should_continue(grpc_client_setup_request *r,
-                                              const char *reason);
-void grpc_client_setup_request_finish(grpc_client_setup_request *r,
-                                      int was_successful);
-const grpc_channel_args *grpc_client_setup_get_channel_args(
-    grpc_client_setup_request *r);
-
-/* Call before calling back into the setup listener, and call only if
-   this function returns 1. If it returns 1, also promise to call
-   grpc_client_setup_cb_end */
-int grpc_client_setup_cb_begin(grpc_client_setup_request *r,
-                               const char *reason);
-void grpc_client_setup_cb_end(grpc_client_setup_request *r, const char *reason);
-
-/* Get the deadline for a request passed in to initiate. Implementations should
-   make a best effort to honor this deadline. */
-gpr_timespec grpc_client_setup_request_deadline(grpc_client_setup_request *r);
-grpc_pollset_set *grpc_client_setup_get_interested_parties(
-    grpc_client_setup_request *r);
-
-grpc_mdctx *grpc_client_setup_get_mdctx(grpc_client_setup_request *r);
-
-#endif /* GRPC_INTERNAL_CORE_CHANNEL_CLIENT_SETUP_H */
diff --git a/src/core/channel/connected_channel.c b/src/core/channel/connected_channel.c
index 14dda88698..34d07de519 100644
--- a/src/core/channel/connected_channel.c
+++ b/src/core/channel/connected_channel.c
@@ -61,42 +61,27 @@ typedef struct connected_channel_call_data { void *unused; } call_data;
 
 /* Intercept a call operation and either push it directly up or translate it
    into transport stream operations */
-static void con_start_transport_op(grpc_call_element *elem,
-                                   grpc_transport_op *op) {
+static void con_start_transport_stream_op(grpc_call_element *elem,
+                                          grpc_transport_stream_op *op) {
   call_data *calld = elem->call_data;
   channel_data *chand = elem->channel_data;
   GPR_ASSERT(elem->filter == &grpc_connected_channel_filter);
   GRPC_CALL_LOG_OP(GPR_INFO, elem, op);
 
-  grpc_transport_perform_op(chand->transport,
-                            TRANSPORT_STREAM_FROM_CALL_DATA(calld), op);
+  grpc_transport_perform_stream_op(chand->transport,
+                                   TRANSPORT_STREAM_FROM_CALL_DATA(calld), op);
 }
 
-/* Currently we assume all channel operations should just be pushed up. */
-static void channel_op(grpc_channel_element *elem,
-                       grpc_channel_element *from_elem, grpc_channel_op *op) {
+static void con_start_transport_op(grpc_channel_element *elem,
+                                   grpc_transport_op *op) {
   channel_data *chand = elem->channel_data;
-  GPR_ASSERT(elem->filter == &grpc_connected_channel_filter);
-
-  switch (op->type) {
-    case GRPC_CHANNEL_GOAWAY:
-      grpc_transport_goaway(chand->transport, op->data.goaway.status,
-                            op->data.goaway.message);
-      break;
-    case GRPC_CHANNEL_DISCONNECT:
-      grpc_transport_close(chand->transport);
-      break;
-    default:
-      GPR_ASSERT(op->dir == GRPC_CALL_UP);
-      grpc_channel_next_op(elem, op);
-      break;
-  }
+  grpc_transport_perform_op(chand->transport, op);
 }
 
 /* Constructor for call_data */
 static void init_call_elem(grpc_call_element *elem,
                            const void *server_transport_data,
-                           grpc_transport_op *initial_op) {
+                           grpc_transport_stream_op *initial_op) {
   call_data *calld = elem->call_data;
   channel_data *chand = elem->channel_data;
   int r;
@@ -118,11 +103,10 @@ static void destroy_call_elem(grpc_call_element *elem) {
 }
 
 /* Constructor for channel_data */
-static void init_channel_elem(grpc_channel_element *elem,
+static void init_channel_elem(grpc_channel_element *elem, grpc_channel *master,
                               const grpc_channel_args *args, grpc_mdctx *mdctx,
                               int is_first, int is_last) {
   channel_data *cd = (channel_data *)elem->channel_data;
-  GPR_ASSERT(!is_first);
   GPR_ASSERT(is_last);
   GPR_ASSERT(elem->filter == &grpc_connected_channel_filter);
   cd->transport = NULL;
@@ -136,70 +120,23 @@ static void destroy_channel_elem(grpc_channel_element *elem) {
 }
 
 const grpc_channel_filter grpc_connected_channel_filter = {
-    con_start_transport_op, channel_op, sizeof(call_data), init_call_elem,
-    destroy_call_elem, sizeof(channel_data), init_channel_elem,
-    destroy_channel_elem, "connected",
+    con_start_transport_stream_op,
+    con_start_transport_op,
+    sizeof(call_data),
+    init_call_elem,
+    destroy_call_elem,
+    sizeof(channel_data),
+    init_channel_elem,
+    destroy_channel_elem,
+    "connected",
 };
 
-/* Transport callback to accept a new stream... calls up to handle it */
-static void accept_stream(void *user_data, grpc_transport *transport,
-                          const void *transport_server_data) {
-  grpc_channel_element *elem = user_data;
-  channel_data *chand = elem->channel_data;
-  grpc_channel_op op;
-
-  GPR_ASSERT(elem->filter == &grpc_connected_channel_filter);
-  GPR_ASSERT(chand->transport == transport);
-
-  op.type = GRPC_ACCEPT_CALL;
-  op.dir = GRPC_CALL_UP;
-  op.data.accept_call.transport = transport;
-  op.data.accept_call.transport_server_data = transport_server_data;
-  channel_op(elem, NULL, &op);
-}
-
-static void transport_goaway(void *user_data, grpc_transport *transport,
-                             grpc_status_code status, gpr_slice debug) {
-  /* transport got goaway ==> call up and handle it */
-  grpc_channel_element *elem = user_data;
-  channel_data *chand = elem->channel_data;
-  grpc_channel_op op;
-
-  GPR_ASSERT(elem->filter == &grpc_connected_channel_filter);
-  GPR_ASSERT(chand->transport == transport);
-
-  op.type = GRPC_TRANSPORT_GOAWAY;
-  op.dir = GRPC_CALL_UP;
-  op.data.goaway.status = status;
-  op.data.goaway.message = debug;
-  channel_op(elem, NULL, &op);
-}
-
-static void transport_closed(void *user_data, grpc_transport *transport) {
-  /* transport was closed ==> call up and handle it */
-  grpc_channel_element *elem = user_data;
-  channel_data *chand = elem->channel_data;
-  grpc_channel_op op;
-
-  GPR_ASSERT(elem->filter == &grpc_connected_channel_filter);
-  GPR_ASSERT(chand->transport == transport);
-
-  op.type = GRPC_TRANSPORT_CLOSED;
-  op.dir = GRPC_CALL_UP;
-  channel_op(elem, NULL, &op);
-}
-
-const grpc_transport_callbacks connected_channel_transport_callbacks = {
-    accept_stream, transport_goaway, transport_closed,
-};
-
-grpc_transport_setup_result grpc_connected_channel_bind_transport(
-    grpc_channel_stack *channel_stack, grpc_transport *transport) {
+void grpc_connected_channel_bind_transport(grpc_channel_stack *channel_stack,
+                                           grpc_transport *transport) {
   /* Assumes that the connected channel filter is always the last filter
      in a channel stack */
   grpc_channel_element *elem = grpc_channel_stack_last_element(channel_stack);
   channel_data *cd = (channel_data *)elem->channel_data;
-  grpc_transport_setup_result ret;
   GPR_ASSERT(elem->filter == &grpc_connected_channel_filter);
   GPR_ASSERT(cd->transport == NULL);
   cd->transport = transport;
@@ -211,8 +148,4 @@ grpc_transport_setup_result grpc_connected_channel_bind_transport(
      the last call element, and the last call element MUST be the connected
      channel. */
   channel_stack->call_stack_size += grpc_transport_stream_size(transport);
-
-  ret.user_data = elem;
-  ret.callbacks = &connected_channel_transport_callbacks;
-  return ret;
 }
diff --git a/src/core/channel/connected_channel.h b/src/core/channel/connected_channel.h
index 8b35f69b26..b615b0d350 100644
--- a/src/core/channel/connected_channel.h
+++ b/src/core/channel/connected_channel.h
@@ -43,7 +43,7 @@ extern const grpc_channel_filter grpc_connected_channel_filter;
 
 /* Post construction fixup: set the transport in the connected channel.
    Must be called before any call stack using this filter is used. */
-grpc_transport_setup_result grpc_connected_channel_bind_transport(
-    grpc_channel_stack *channel_stack, grpc_transport *transport);
+void grpc_connected_channel_bind_transport(grpc_channel_stack *channel_stack,
+                                           grpc_transport *transport);
 
-#endif  /* GRPC_INTERNAL_CORE_CHANNEL_CONNECTED_CHANNEL_H */
+#endif /* GRPC_INTERNAL_CORE_CHANNEL_CONNECTED_CHANNEL_H */
diff --git a/src/core/channel/http_client_filter.c b/src/core/channel/http_client_filter.c
index 08a2c0df3c..581eb13f58 100644
--- a/src/core/channel/http_client_filter.c
+++ b/src/core/channel/http_client_filter.c
@@ -92,7 +92,8 @@ static void hc_on_recv(void *user_data, int success) {
   calld->on_done_recv->cb(calld->on_done_recv->cb_arg, success);
 }
 
-static void hc_mutate_op(grpc_call_element *elem, grpc_transport_op *op) {
+static void hc_mutate_op(grpc_call_element *elem,
+                         grpc_transport_stream_op *op) {
   /* grab pointers to our data from the call element */
   call_data *calld = elem->call_data;
   channel_data *channeld = elem->channel_data;
@@ -127,33 +128,16 @@ static void hc_mutate_op(grpc_call_element *elem, grpc_transport_op *op) {
 }
 
 static void hc_start_transport_op(grpc_call_element *elem,
-                                  grpc_transport_op *op) {
+                                  grpc_transport_stream_op *op) {
   GRPC_CALL_LOG_OP(GPR_INFO, elem, op);
   hc_mutate_op(elem, op);
   grpc_call_next_op(elem, op);
 }
 
-/* Called on special channel events, such as disconnection or new incoming
-   calls on the server */
-static void channel_op(grpc_channel_element *elem,
-                       grpc_channel_element *from_elem, grpc_channel_op *op) {
-  /* grab pointers to our data from the channel element */
-  channel_data *channeld = elem->channel_data;
-
-  ignore_unused(channeld);
-
-  switch (op->type) {
-    default:
-      /* pass control up or down the stack depending on op->dir */
-      grpc_channel_next_op(elem, op);
-      break;
-  }
-}
-
 /* Constructor for call_data */
 static void init_call_elem(grpc_call_element *elem,
                            const void *server_transport_data,
-                           grpc_transport_op *initial_op) {
+                           grpc_transport_stream_op *initial_op) {
   call_data *calld = elem->call_data;
   calld->sent_initial_metadata = 0;
   calld->got_initial_metadata = 0;
@@ -186,7 +170,7 @@ static const char *scheme_from_args(const grpc_channel_args *args) {
 }
 
 /* Constructor for channel_data */
-static void init_channel_elem(grpc_channel_element *elem,
+static void init_channel_elem(grpc_channel_element *elem, grpc_channel *master,
                               const grpc_channel_args *args, grpc_mdctx *mdctx,
                               int is_first, int is_last) {
   /* grab pointers to our data from the channel element */
@@ -195,7 +179,6 @@ static void init_channel_elem(grpc_channel_element *elem,
   /* The first and the last filters tend to be implemented differently to
      handle the case that there's no 'next' filter to call on the up or down
      path */
-  GPR_ASSERT(!is_first);
   GPR_ASSERT(!is_last);
 
   /* initialize members */
@@ -221,6 +204,6 @@ static void destroy_channel_elem(grpc_channel_element *elem) {
 }
 
 const grpc_channel_filter grpc_http_client_filter = {
-    hc_start_transport_op, channel_op, sizeof(call_data), init_call_elem,
-    destroy_call_elem, sizeof(channel_data), init_channel_elem,
-    destroy_channel_elem, "http-client"};
+    hc_start_transport_op, grpc_channel_next_op, sizeof(call_data),
+    init_call_elem,        destroy_call_elem,    sizeof(channel_data),
+    init_channel_elem,     destroy_channel_elem, "http-client"};
diff --git a/src/core/channel/http_server_filter.c b/src/core/channel/http_server_filter.c
index d3a01fd1a8..db0bf590c6 100644
--- a/src/core/channel/http_server_filter.c
+++ b/src/core/channel/http_server_filter.c
@@ -72,9 +72,6 @@ typedef struct channel_data {
   grpc_mdctx *mdctx;
 } channel_data;
 
-/* used to silence 'variable not used' warnings */
-static void ignore_unused(void *ignored) {}
-
 static grpc_mdelem *server_filter(void *user_data, grpc_mdelem *md) {
   grpc_call_element *elem = user_data;
   channel_data *channeld = elem->channel_data;
@@ -181,7 +178,8 @@ static void hs_on_recv(void *user_data, int success) {
   calld->on_done_recv->cb(calld->on_done_recv->cb_arg, success);
 }
 
-static void hs_mutate_op(grpc_call_element *elem, grpc_transport_op *op) {
+static void hs_mutate_op(grpc_call_element *elem,
+                         grpc_transport_stream_op *op) {
   /* grab pointers to our data from the call element */
   call_data *calld = elem->call_data;
   channel_data *channeld = elem->channel_data;
@@ -209,33 +207,16 @@ static void hs_mutate_op(grpc_call_element *elem, grpc_transport_op *op) {
 }
 
 static void hs_start_transport_op(grpc_call_element *elem,
-                                  grpc_transport_op *op) {
+                                  grpc_transport_stream_op *op) {
   GRPC_CALL_LOG_OP(GPR_INFO, elem, op);
   hs_mutate_op(elem, op);
   grpc_call_next_op(elem, op);
 }
 
-/* Called on special channel events, such as disconnection or new incoming
-   calls on the server */
-static void channel_op(grpc_channel_element *elem,
-                       grpc_channel_element *from_elem, grpc_channel_op *op) {
-  /* grab pointers to our data from the channel element */
-  channel_data *channeld = elem->channel_data;
-
-  ignore_unused(channeld);
-
-  switch (op->type) {
-    default:
-      /* pass control up or down the stack depending on op->dir */
-      grpc_channel_next_op(elem, op);
-      break;
-  }
-}
-
 /* Constructor for call_data */
 static void init_call_elem(grpc_call_element *elem,
                            const void *server_transport_data,
-                           grpc_transport_op *initial_op) {
+                           grpc_transport_stream_op *initial_op) {
   /* grab pointers to our data from the call element */
   call_data *calld = elem->call_data;
   /* initialize members */
@@ -248,7 +229,7 @@ static void init_call_elem(grpc_call_element *elem,
 static void destroy_call_elem(grpc_call_element *elem) {}
 
 /* Constructor for channel_data */
-static void init_channel_elem(grpc_channel_element *elem,
+static void init_channel_elem(grpc_channel_element *elem, grpc_channel *master,
                               const grpc_channel_args *args, grpc_mdctx *mdctx,
                               int is_first, int is_last) {
   /* grab pointers to our data from the channel element */
@@ -297,6 +278,6 @@ static void destroy_channel_elem(grpc_channel_element *elem) {
 }
 
 const grpc_channel_filter grpc_http_server_filter = {
-    hs_start_transport_op, channel_op, sizeof(call_data), init_call_elem,
-    destroy_call_elem, sizeof(channel_data), init_channel_elem,
-    destroy_channel_elem, "http-server"};
+    hs_start_transport_op, grpc_channel_next_op, sizeof(call_data),
+    init_call_elem,        destroy_call_elem,    sizeof(channel_data),
+    init_channel_elem,     destroy_channel_elem, "http-server"};
diff --git a/src/core/channel/noop_filter.c b/src/core/channel/noop_filter.c
index 1d2be716d7..5117723617 100644
--- a/src/core/channel/noop_filter.c
+++ b/src/core/channel/noop_filter.c
@@ -45,7 +45,8 @@ typedef struct channel_data {
 /* used to silence 'variable not used' warnings */
 static void ignore_unused(void *ignored) {}
 
-static void noop_mutate_op(grpc_call_element *elem, grpc_transport_op *op) {
+static void noop_mutate_op(grpc_call_element *elem,
+                           grpc_transport_stream_op *op) {
   /* grab pointers to our data from the call element */
   call_data *calld = elem->call_data;
   channel_data *channeld = elem->channel_data;
@@ -61,35 +62,18 @@ static void noop_mutate_op(grpc_call_element *elem, grpc_transport_op *op) {
      - a network event (or similar) from below, to receive something
    op contains type and call direction information, in addition to the data
    that is being sent or received. */
-static void noop_start_transport_op(grpc_call_element *elem,
-                                    grpc_transport_op *op) {
+static void noop_start_transport_stream_op(grpc_call_element *elem,
+                                           grpc_transport_stream_op *op) {
   noop_mutate_op(elem, op);
 
   /* pass control down the stack */
   grpc_call_next_op(elem, op);
 }
 
-/* Called on special channel events, such as disconnection or new incoming
-   calls on the server */
-static void channel_op(grpc_channel_element *elem,
-                       grpc_channel_element *from_elem, grpc_channel_op *op) {
-  /* grab pointers to our data from the channel element */
-  channel_data *channeld = elem->channel_data;
-
-  ignore_unused(channeld);
-
-  switch (op->type) {
-    default:
-      /* pass control up or down the stack depending on op->dir */
-      grpc_channel_next_op(elem, op);
-      break;
-  }
-}
-
 /* Constructor for call_data */
 static void init_call_elem(grpc_call_element *elem,
                            const void *server_transport_data,
-                           grpc_transport_op *initial_op) {
+                           grpc_transport_stream_op *initial_op) {
   /* grab pointers to our data from the call element */
   call_data *calld = elem->call_data;
   channel_data *channeld = elem->channel_data;
@@ -111,7 +95,7 @@ static void destroy_call_elem(grpc_call_element *elem) {
 }
 
 /* Constructor for channel_data */
-static void init_channel_elem(grpc_channel_element *elem,
+static void init_channel_elem(grpc_channel_element *elem, grpc_channel *master,
                               const grpc_channel_args *args, grpc_mdctx *mdctx,
                               int is_first, int is_last) {
   /* grab pointers to our data from the channel element */
@@ -135,7 +119,12 @@ static void destroy_channel_elem(grpc_channel_element *elem) {
   ignore_unused(channeld);
 }
 
-const grpc_channel_filter grpc_no_op_filter = {
-    noop_start_transport_op, channel_op, sizeof(call_data), init_call_elem,
-    destroy_call_elem, sizeof(channel_data), init_channel_elem,
-    destroy_channel_elem, "no-op"};
+const grpc_channel_filter grpc_no_op_filter = {noop_start_transport_stream_op,
+                                               grpc_channel_next_op,
+                                               sizeof(call_data),
+                                               init_call_elem,
+                                               destroy_call_elem,
+                                               sizeof(channel_data),
+                                               init_channel_elem,
+                                               destroy_channel_elem,
+                                               "no-op"};
diff --git a/src/core/client_config/README.md b/src/core/client_config/README.md
new file mode 100644
index 0000000000..d7aed27223
--- /dev/null
+++ b/src/core/client_config/README.md
@@ -0,0 +1,60 @@
+Client Configuration Support for GRPC
+=====================================
+
+This library provides high level configuration machinery to construct client 
+channels and load balance between them.
+
+Each grpc_channel is created with a grpc_resolver. It is the resolver's duty
+to resolve a name into configuration data for the channel. Such configuration
+data might include:
+
+- a list of (ip, port) addresses to connect to
+- a load balancing policy to decide which server to send a request to
+- a set of filters to mutate outgoing requests (say, by adding metadata)
+
+The resolver provides this data as a stream of grpc_client_config objects to
+the channel. We represent configuration as a stream so that it can be changed
+by the resolver during execution, by reacting to external events (such as a
+new configuration file being pushed to some store).
+
+
+Load Balancing
+--------------
+
+Load balancing configuration is provided by a grpc_lb_policy object, stored as
+part of grpc_client_config. 
+
+A load balancing policies primary job is to pick a target server given only the
+initial metadata for a request. It does this by providing a grpc_subchannel 
+object to the owning channel.
+
+
+Sub-Channels
+------------
+
+A sub-channel provides a connection to a server for a client channel. It has a 
+connectivity state like a regular channel, and so can be connected or 
+disconnected. This connectivity state can be used to inform load balancing 
+decisions (for example, by avoiding disconnected backends).
+
+Configured sub-channels are fully setup to participate in the grpc data plane.
+Their behavior is specified by a set of grpc channel filters defined at their
+construction. To customize this behavior, resolvers build grpc_subchannel_factory 
+objects, which use the decorator pattern to customize construction arguments for 
+concrete grpc_subchannel instances.
+
+
+Naming for GRPC
+===============
+
+Names in GRPC are represented by a URI.
+
+The following schemes are currently supported:
+
+dns:///host:port - dns schemes are currently supported so long as authority is
+                   empty (authority based dns resolution is expected in a future
+                   release)
+
+unix:path        - the unix scheme is used to create and connect to unix domain 
+                   sockets - the authority must be empty, and the path represents
+                   the absolute or relative path to the desired socket
diff --git a/src/core/client_config/client_config.c b/src/core/client_config/client_config.c
new file mode 100644
index 0000000000..4453824148
--- /dev/null
+++ b/src/core/client_config/client_config.c
@@ -0,0 +1,74 @@
+/*
+ *
+ * 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.
+ *
+ */
+
+#include "src/core/client_config/client_config.h"
+
+#include <string.h>
+
+#include <grpc/support/alloc.h>
+
+struct grpc_client_config {
+  gpr_refcount refs;
+  grpc_lb_policy *lb_policy;
+};
+
+grpc_client_config *grpc_client_config_create() {
+  grpc_client_config *c = gpr_malloc(sizeof(*c));
+  memset(c, 0, sizeof(*c));
+  gpr_ref_init(&c->refs, 1);
+  return c;
+}
+
+void grpc_client_config_ref(grpc_client_config *c) { gpr_ref(&c->refs); }
+
+void grpc_client_config_unref(grpc_client_config *c) {
+  if (gpr_unref(&c->refs)) {
+    GRPC_LB_POLICY_UNREF(c->lb_policy, "client_config");
+    gpr_free(c);
+  }
+}
+
+void grpc_client_config_set_lb_policy(grpc_client_config *c,
+                                      grpc_lb_policy *lb_policy) {
+  if (lb_policy) {
+    GRPC_LB_POLICY_REF(lb_policy, "client_config");
+  }
+  if (c->lb_policy) {
+    GRPC_LB_POLICY_UNREF(c->lb_policy, "client_config");
+  }
+  c->lb_policy = lb_policy;
+}
+
+grpc_lb_policy *grpc_client_config_get_lb_policy(grpc_client_config *c) {
+  return c->lb_policy;
+}
diff --git a/src/core/client_config/client_config.h b/src/core/client_config/client_config.h
new file mode 100644
index 0000000000..47612da42c
--- /dev/null
+++ b/src/core/client_config/client_config.h
@@ -0,0 +1,52 @@
+/*
+ *
+ * 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.
+ *
+ */
+
+#ifndef GRPC_INTERNAL_CORE_CLIENT_CONFIG_CLIENT_CONFIG_H
+#define GRPC_INTERNAL_CORE_CLIENT_CONFIG_CLIENT_CONFIG_H
+
+#include "src/core/client_config/lb_policy.h"
+
+/** Total configuration for a client. Provided, and updated, by
+    grpc_resolver */
+typedef struct grpc_client_config grpc_client_config;
+
+grpc_client_config *grpc_client_config_create();
+void grpc_client_config_ref(grpc_client_config *client_config);
+void grpc_client_config_unref(grpc_client_config *client_config);
+
+void grpc_client_config_set_lb_policy(grpc_client_config *client_config,
+                                      grpc_lb_policy *lb_policy);
+grpc_lb_policy *grpc_client_config_get_lb_policy(
+    grpc_client_config *client_config);
+
+#endif /* GRPC_INTERNAL_CORE_CLIENT_CONFIG_CLIENT_CONFIG_H */
diff --git a/src/core/client_config/connector.c b/src/core/client_config/connector.c
new file mode 100644
index 0000000000..a8cd5fc149
--- /dev/null
+++ b/src/core/client_config/connector.c
@@ -0,0 +1,49 @@
+/*
+ *
+ * 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.
+ *
+ */
+
+#include "src/core/client_config/connector.h"
+
+void grpc_connector_ref(grpc_connector *connector) {
+  connector->vtable->ref(connector);
+}
+
+void grpc_connector_unref(grpc_connector *connector) {
+  connector->vtable->unref(connector);
+}
+
+void grpc_connector_connect(grpc_connector *connector,
+                            const grpc_connect_in_args *in_args,
+                            grpc_connect_out_args *out_args,
+                            grpc_iomgr_closure *notify) {
+  connector->vtable->connect(connector, in_args, out_args, notify);
+}
diff --git a/src/core/client_config/connector.h b/src/core/client_config/connector.h
new file mode 100644
index 0000000000..edcb10a36e
--- /dev/null
+++ b/src/core/client_config/connector.h
@@ -0,0 +1,85 @@
+/*
+ *
+ * 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.
+ *
+ */
+
+#ifndef GRPC_INTERNAL_CORE_CLIENT_CONFIG_CONNECTOR_H
+#define GRPC_INTERNAL_CORE_CLIENT_CONFIG_CONNECTOR_H
+
+#include "src/core/channel/channel_stack.h"
+#include "src/core/iomgr/sockaddr.h"
+#include "src/core/transport/transport.h"
+
+typedef struct grpc_connector grpc_connector;
+typedef struct grpc_connector_vtable grpc_connector_vtable;
+
+struct grpc_connector {
+  const grpc_connector_vtable *vtable;
+};
+
+typedef struct {
+  /** set of pollsets interested in this connection */
+  grpc_pollset_set *interested_parties;
+  /** address to connect to */
+  const struct sockaddr *addr;
+  int addr_len;
+  /** deadline for connection */
+  gpr_timespec deadline;
+  /** channel arguments (to be passed to transport) */
+  const grpc_channel_args *channel_args;
+  /** metadata context */
+  grpc_mdctx *metadata_context;
+} grpc_connect_in_args;
+
+typedef struct {
+  /** the connected transport */
+  grpc_transport *transport;
+  /** any additional filters (owned by the caller of connect) */
+  const grpc_channel_filter **filters;
+  size_t num_filters;
+} grpc_connect_out_args;
+
+struct grpc_connector_vtable {
+  void (*ref)(grpc_connector *connector);
+  void (*unref)(grpc_connector *connector);
+  void (*connect)(grpc_connector *connector,
+                  const grpc_connect_in_args *in_args,
+                  grpc_connect_out_args *out_args, grpc_iomgr_closure *notify);
+};
+
+void grpc_connector_ref(grpc_connector *connector);
+void grpc_connector_unref(grpc_connector *connector);
+void grpc_connector_connect(grpc_connector *connector,
+                            const grpc_connect_in_args *in_args,
+                            grpc_connect_out_args *out_args,
+                            grpc_iomgr_closure *notify);
+
+#endif
diff --git a/src/core/client_config/lb_policies/pick_first.c b/src/core/client_config/lb_policies/pick_first.c
new file mode 100644
index 0000000000..73da624aff
--- /dev/null
+++ b/src/core/client_config/lb_policies/pick_first.c
@@ -0,0 +1,268 @@
+/*
+ *
+ * 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.
+ *
+ */
+
+#include "src/core/client_config/lb_policies/pick_first.h"
+
+#include <string.h>
+
+#include <grpc/support/alloc.h>
+#include "src/core/transport/connectivity_state.h"
+
+typedef struct pending_pick {
+  struct pending_pick *next;
+  grpc_pollset *pollset;
+  grpc_subchannel **target;
+  grpc_iomgr_closure *on_complete;
+} pending_pick;
+
+typedef struct {
+  /** base policy: must be first */
+  grpc_lb_policy base;
+  /** all our subchannels */
+  grpc_subchannel **subchannels;
+  size_t num_subchannels;
+
+  grpc_iomgr_closure connectivity_changed;
+
+  /** mutex protecting remaining members */
+  gpr_mu mu;
+  /** the selected channel
+      TODO(ctiller): this should be atomically set so we don't
+                     need to take a mutex in the common case */
+  grpc_subchannel *selected;
+  /** have we started picking? */
+  int started_picking;
+  /** which subchannel are we watching? */
+  size_t checking_subchannel;
+  /** what is the connectivity of that channel? */
+  grpc_connectivity_state checking_connectivity;
+  /** list of picks that are waiting on connectivity */
+  pending_pick *pending_picks;
+
+  /** our connectivity state tracker */
+  grpc_connectivity_state_tracker state_tracker;
+} pick_first_lb_policy;
+
+void pf_destroy(grpc_lb_policy *pol) {
+  pick_first_lb_policy *p = (pick_first_lb_policy *)pol;
+  size_t i;
+  for (i = 0; i < p->num_subchannels; i++) {
+    GRPC_SUBCHANNEL_UNREF(p->subchannels[i], "pick_first");
+  }
+  gpr_free(p->subchannels);
+  gpr_mu_destroy(&p->mu);
+  gpr_free(p);
+}
+
+void pf_shutdown(grpc_lb_policy *pol) {
+  pick_first_lb_policy *p = (pick_first_lb_policy *)pol;
+  pending_pick *pp;
+  gpr_mu_lock(&p->mu);
+  while ((pp = p->pending_picks)) {
+    p->pending_picks = pp->next;
+    *pp->target = NULL;
+    grpc_iomgr_add_delayed_callback(pp->on_complete, 0);
+    gpr_free(pp);
+  }
+  gpr_mu_unlock(&p->mu);
+}
+
+void pf_pick(grpc_lb_policy *pol, grpc_pollset *pollset,
+             grpc_metadata_batch *initial_metadata, grpc_subchannel **target,
+             grpc_iomgr_closure *on_complete) {
+  pick_first_lb_policy *p = (pick_first_lb_policy *)pol;
+  pending_pick *pp;
+  gpr_mu_lock(&p->mu);
+  if (p->selected) {
+    gpr_mu_unlock(&p->mu);
+    *target = p->selected;
+    on_complete->cb(on_complete->cb_arg, 1);
+  } else {
+    if (!p->started_picking) {
+      p->started_picking = 1;
+      p->checking_subchannel = 0;
+      p->checking_connectivity = GRPC_CHANNEL_IDLE;
+      GRPC_LB_POLICY_REF(pol, "pick_first_connectivity");
+      grpc_subchannel_notify_on_state_change(
+          p->subchannels[p->checking_subchannel], &p->checking_connectivity,
+          &p->connectivity_changed);
+    }
+    grpc_subchannel_add_interested_party(p->subchannels[p->checking_subchannel],
+                                         pollset);
+    pp = gpr_malloc(sizeof(*pp));
+    pp->next = p->pending_picks;
+    pp->pollset = pollset;
+    pp->target = target;
+    pp->on_complete = on_complete;
+    p->pending_picks = pp;
+    gpr_mu_unlock(&p->mu);
+  }
+}
+
+static void del_interested_parties_locked(pick_first_lb_policy *p) {
+  pending_pick *pp;
+  for (pp = p->pending_picks; pp; pp = pp->next) {
+    grpc_subchannel_del_interested_party(p->subchannels[p->checking_subchannel],
+                                         pp->pollset);
+  }
+}
+
+static void add_interested_parties_locked(pick_first_lb_policy *p) {
+  pending_pick *pp;
+  for (pp = p->pending_picks; pp; pp = pp->next) {
+    grpc_subchannel_add_interested_party(p->subchannels[p->checking_subchannel],
+                                         pp->pollset);
+  }
+}
+
+static void pf_connectivity_changed(void *arg, int iomgr_success) {
+  pick_first_lb_policy *p = arg;
+  pending_pick *pp;
+  int unref = 0;
+
+  gpr_mu_lock(&p->mu);
+loop:
+  switch (p->checking_connectivity) {
+    case GRPC_CHANNEL_READY:
+      p->selected = p->subchannels[p->checking_subchannel];
+      while ((pp = p->pending_picks)) {
+        p->pending_picks = pp->next;
+        *pp->target = p->selected;
+        grpc_subchannel_del_interested_party(p->selected, pp->pollset);
+        grpc_iomgr_add_delayed_callback(pp->on_complete, 1);
+        gpr_free(pp);
+      }
+      unref = 1;
+      break;
+    case GRPC_CHANNEL_TRANSIENT_FAILURE:
+      del_interested_parties_locked(p);
+      p->checking_subchannel =
+          (p->checking_subchannel + 1) % p->num_subchannels;
+      p->checking_connectivity = grpc_subchannel_check_connectivity(
+          p->subchannels[p->checking_subchannel]);
+      add_interested_parties_locked(p);
+      goto loop;
+    case GRPC_CHANNEL_CONNECTING:
+    case GRPC_CHANNEL_IDLE:
+      grpc_subchannel_notify_on_state_change(
+          p->subchannels[p->checking_subchannel], &p->checking_connectivity,
+          &p->connectivity_changed);
+      break;
+    case GRPC_CHANNEL_FATAL_FAILURE:
+      del_interested_parties_locked(p);
+      GPR_SWAP(grpc_subchannel *, p->subchannels[p->checking_subchannel],
+               p->subchannels[p->num_subchannels - 1]);
+      p->num_subchannels--;
+      GRPC_SUBCHANNEL_UNREF(p->subchannels[p->num_subchannels], "pick_first");
+      if (p->num_subchannels == 0) {
+        while ((pp = p->pending_picks)) {
+          p->pending_picks = pp->next;
+          *pp->target = NULL;
+          grpc_iomgr_add_delayed_callback(pp->on_complete, 1);
+          gpr_free(pp);
+        }
+        unref = 1;
+      } else {
+        p->checking_subchannel %= p->num_subchannels;
+        p->checking_connectivity = grpc_subchannel_check_connectivity(
+            p->subchannels[p->checking_subchannel]);
+        add_interested_parties_locked(p);
+        goto loop;
+      }
+  }
+  gpr_mu_unlock(&p->mu);
+
+  if (unref) {
+    GRPC_LB_POLICY_UNREF(&p->base, "pick_first_connectivity");
+  }
+}
+
+static void pf_broadcast(grpc_lb_policy *pol, grpc_transport_op *op) {
+  pick_first_lb_policy *p = (pick_first_lb_policy *)pol;
+  size_t i;
+  size_t n;
+  grpc_subchannel **subchannels;
+
+  gpr_mu_lock(&p->mu);
+  n = p->num_subchannels;
+  subchannels = gpr_malloc(n * sizeof(*subchannels));
+  for (i = 0; i < n; i++) {
+    subchannels[i] = p->subchannels[i];
+    GRPC_SUBCHANNEL_REF(subchannels[i], "pf_broadcast");
+  }
+  gpr_mu_unlock(&p->mu);
+
+  for (i = 0; i < n; i++) {
+    grpc_subchannel_process_transport_op(subchannels[i], op);
+    GRPC_SUBCHANNEL_UNREF(subchannels[i], "pf_broadcast");
+  }
+  gpr_free(subchannels);
+}
+
+static grpc_connectivity_state pf_check_connectivity(grpc_lb_policy *pol) {
+  pick_first_lb_policy *p = (pick_first_lb_policy *)pol;
+  grpc_connectivity_state st;
+  gpr_mu_lock(&p->mu);
+  st = grpc_connectivity_state_check(&p->state_tracker);
+  gpr_mu_unlock(&p->mu);
+  return st;
+}
+
+static void pf_notify_on_state_change(grpc_lb_policy *pol,
+                                      grpc_connectivity_state *current,
+                                      grpc_iomgr_closure *notify) {
+  pick_first_lb_policy *p = (pick_first_lb_policy *)pol;
+  gpr_mu_lock(&p->mu);
+  grpc_connectivity_state_notify_on_state_change(&p->state_tracker, current,
+                                                 notify);
+  gpr_mu_unlock(&p->mu);
+}
+
+static const grpc_lb_policy_vtable pick_first_lb_policy_vtable = {
+    pf_destroy,   pf_shutdown,           pf_pick,
+    pf_broadcast, pf_check_connectivity, pf_notify_on_state_change};
+
+grpc_lb_policy *grpc_create_pick_first_lb_policy(grpc_subchannel **subchannels,
+                                                 size_t num_subchannels) {
+  pick_first_lb_policy *p = gpr_malloc(sizeof(*p));
+  GPR_ASSERT(num_subchannels);
+  memset(p, 0, sizeof(*p));
+  grpc_lb_policy_init(&p->base, &pick_first_lb_policy_vtable);
+  p->subchannels = gpr_malloc(sizeof(grpc_subchannel *) * num_subchannels);
+  p->num_subchannels = num_subchannels;
+  memcpy(p->subchannels, subchannels,
+         sizeof(grpc_subchannel *) * num_subchannels);
+  grpc_iomgr_closure_init(&p->connectivity_changed, pf_connectivity_changed, p);
+  gpr_mu_init(&p->mu);
+  return &p->base;
+}
diff --git a/src/core/surface/client.h b/src/core/client_config/lb_policies/pick_first.h
index 9db2ccf3d2..94c2a9f0c7 100644
--- a/src/core/surface/client.h
+++ b/src/core/client_config/lb_policies/pick_first.h
@@ -31,11 +31,12 @@
  *
  */
 
-#ifndef GRPC_INTERNAL_CORE_SURFACE_CLIENT_H
-#define GRPC_INTERNAL_CORE_SURFACE_CLIENT_H
+#ifndef GRPC_INTERNAL_CORE_CLIENT_CONFIG_PICK_FIRST_H
+#define GRPC_INTERNAL_CORE_CLIENT_CONFIG_PICK_FIRST_H
 
-#include "src/core/channel/channel_stack.h"
+#include "src/core/client_config/lb_policy.h"
 
-extern const grpc_channel_filter grpc_client_surface_filter;
+grpc_lb_policy *grpc_create_pick_first_lb_policy(grpc_subchannel **subchannels,
+                                                 size_t num_subchannels);
 
-#endif  /* GRPC_INTERNAL_CORE_SURFACE_CLIENT_H */
+#endif
diff --git a/src/core/client_config/lb_policy.c b/src/core/client_config/lb_policy.c
new file mode 100644
index 0000000000..6d1c788742
--- /dev/null
+++ b/src/core/client_config/lb_policy.c
@@ -0,0 +1,79 @@
+/*
+ *
+ * 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.
+ *
+ */
+
+#include "src/core/client_config/lb_policy.h"
+
+void grpc_lb_policy_init(grpc_lb_policy *policy,
+                         const grpc_lb_policy_vtable *vtable) {
+  policy->vtable = vtable;
+  gpr_ref_init(&policy->refs, 1);
+}
+
+#ifdef GRPC_LB_POLICY_REFCOUNT_DEBUG
+void grpc_lb_policy_ref(grpc_lb_policy *policy, const char *file, int line,
+                        const char *reason) {
+  gpr_log(file, line, GPR_LOG_SEVERITY_DEBUG, "LB_POLICY:%p   ref %d -> %d %s",
+          policy, (int)policy->refs.count, (int)policy->refs.count + 1, reason);
+#else
+void grpc_lb_policy_ref(grpc_lb_policy *policy) {
+#endif
+  gpr_ref(&policy->refs);
+}
+
+#ifdef GRPC_LB_POLICY_REFCOUNT_DEBUG
+void grpc_lb_policy_unref(grpc_lb_policy *policy, const char *file, int line,
+                          const char *reason) {
+  gpr_log(file, line, GPR_LOG_SEVERITY_DEBUG, "LB_POLICY:%p unref %d -> %d %s",
+          policy, (int)policy->refs.count, (int)policy->refs.count - 1, reason);
+#else
+void grpc_lb_policy_unref(grpc_lb_policy *policy) {
+#endif
+  if (gpr_unref(&policy->refs)) {
+    policy->vtable->destroy(policy);
+  }
+}
+
+void grpc_lb_policy_shutdown(grpc_lb_policy *policy) {
+  policy->vtable->shutdown(policy);
+}
+
+void grpc_lb_policy_pick(grpc_lb_policy *policy, grpc_pollset *pollset,
+                         grpc_metadata_batch *initial_metadata,
+                         grpc_subchannel **target,
+                         grpc_iomgr_closure *on_complete) {
+  policy->vtable->pick(policy, pollset, initial_metadata, target, on_complete);
+}
+
+void grpc_lb_policy_broadcast(grpc_lb_policy *policy, grpc_transport_op *op) {
+  policy->vtable->broadcast(policy, op);
+}
diff --git a/src/core/client_config/lb_policy.h b/src/core/client_config/lb_policy.h
new file mode 100644
index 0000000000..a468f761cc
--- /dev/null
+++ b/src/core/client_config/lb_policy.h
@@ -0,0 +1,109 @@
+/*
+ *
+ * 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.
+ *
+ */
+
+#ifndef GRPC_INTERNAL_CORE_CLIENT_CONFIG_LB_POLICY_H
+#define GRPC_INTERNAL_CORE_CLIENT_CONFIG_LB_POLICY_H
+
+#include "src/core/client_config/subchannel.h"
+
+/** A load balancing policy: specified by a vtable and a struct (which
+    is expected to be extended to contain some parameters) */
+typedef struct grpc_lb_policy grpc_lb_policy;
+typedef struct grpc_lb_policy_vtable grpc_lb_policy_vtable;
+
+typedef void (*grpc_lb_completion)(void *cb_arg, grpc_subchannel *subchannel,
+                                   grpc_status_code status, const char *errmsg);
+
+struct grpc_lb_policy {
+  const grpc_lb_policy_vtable *vtable;
+  gpr_refcount refs;
+};
+
+struct grpc_lb_policy_vtable {
+  void (*destroy)(grpc_lb_policy *policy);
+
+  void (*shutdown)(grpc_lb_policy *policy);
+
+  /** implement grpc_lb_policy_pick */
+  void (*pick)(grpc_lb_policy *policy, grpc_pollset *pollset,
+               grpc_metadata_batch *initial_metadata, grpc_subchannel **target,
+               grpc_iomgr_closure *on_complete);
+
+  /** broadcast a transport op to all subchannels */
+  void (*broadcast)(grpc_lb_policy *policy, grpc_transport_op *op);
+
+  /** check the current connectivity of the lb_policy */
+  grpc_connectivity_state (*check_connectivity)(grpc_lb_policy *policy);
+
+  /** call notify when the connectivity state of a channel changes from *state.
+      Updates *state with the new state of the policy */
+  void (*notify_on_state_change)(grpc_lb_policy *policy,
+                                 grpc_connectivity_state *state,
+                                 grpc_iomgr_closure *closure);
+};
+
+#ifdef GRPC_LB_POLICY_REFCOUNT_DEBUG
+#define GRPC_LB_POLICY_REF(p, r) \
+  grpc_lb_policy_ref((p), __FILE__, __LINE__, (r))
+#define GRPC_LB_POLICY_UNREF(p, r) \
+  grpc_lb_policy_unref((p), __FILE__, __LINE__, (r))
+void grpc_lb_policy_ref(grpc_lb_policy *policy, const char *file, int line,
+                        const char *reason);
+void grpc_lb_policy_unref(grpc_lb_policy *policy, const char *file, int line,
+                          const char *reason);
+#else
+#define GRPC_LB_POLICY_REF(p, r) grpc_lb_policy_ref((p))
+#define GRPC_LB_POLICY_UNREF(p, r) grpc_lb_policy_unref((p))
+void grpc_lb_policy_ref(grpc_lb_policy *policy);
+void grpc_lb_policy_unref(grpc_lb_policy *policy);
+#endif
+
+/** called by concrete implementations to initialize the base struct */
+void grpc_lb_policy_init(grpc_lb_policy *policy,
+                         const grpc_lb_policy_vtable *vtable);
+
+/** Start shutting down (fail any pending picks) */
+void grpc_lb_policy_shutdown(grpc_lb_policy *policy);
+
+/** Given initial metadata in \a initial_metadata, find an appropriate
+    target for this rpc, and 'return' it by calling \a on_complete after setting
+    \a target.
+    Picking can be asynchronous. Any IO should be done under \a pollset. */
+void grpc_lb_policy_pick(grpc_lb_policy *policy, grpc_pollset *pollset,
+                         grpc_metadata_batch *initial_metadata,
+                         grpc_subchannel **target,
+                         grpc_iomgr_closure *on_complete);
+
+void grpc_lb_policy_broadcast(grpc_lb_policy *policy, grpc_transport_op *op);
+
+#endif /* GRPC_INTERNAL_CORE_CONFIG_LB_POLICY_H */
diff --git a/src/core/client_config/resolver.c b/src/core/client_config/resolver.c
new file mode 100644
index 0000000000..91e42bb684
--- /dev/null
+++ b/src/core/client_config/resolver.c
@@ -0,0 +1,83 @@
+/*
+ *
+ * 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.
+ *
+ */
+
+#include "src/core/client_config/resolver.h"
+
+void grpc_resolver_init(grpc_resolver *resolver,
+                        const grpc_resolver_vtable *vtable) {
+  resolver->vtable = vtable;
+  gpr_ref_init(&resolver->refs, 1);
+}
+
+#ifdef GRPC_RESOLVER_REFCOUNT_DEBUG
+void grpc_resolver_ref(grpc_resolver *resolver, const char *file, int line,
+                       const char *reason) {
+  gpr_log(file, line, GPR_LOG_SEVERITY_DEBUG, "RESOLVER:%p   ref %d -> %d %s",
+          resolver, (int)resolver->refs.count, (int)resolver->refs.count + 1,
+          reason);
+#else
+void grpc_resolver_ref(grpc_resolver *resolver) {
+#endif
+  gpr_ref(&resolver->refs);
+}
+
+#ifdef GRPC_RESOLVER_REFCOUNT_DEBUG
+void grpc_resolver_unref(grpc_resolver *resolver, const char *file, int line,
+                         const char *reason) {
+  gpr_log(file, line, GPR_LOG_SEVERITY_DEBUG, "RESOLVER:%p unref %d -> %d %s",
+          resolver, (int)resolver->refs.count, (int)resolver->refs.count - 1,
+          reason);
+#else
+void grpc_resolver_unref(grpc_resolver *resolver) {
+#endif
+  if (gpr_unref(&resolver->refs)) {
+    resolver->vtable->destroy(resolver);
+  }
+}
+
+void grpc_resolver_shutdown(grpc_resolver *resolver) {
+  resolver->vtable->shutdown(resolver);
+}
+
+void grpc_resolver_channel_saw_error(grpc_resolver *resolver,
+                                     struct sockaddr *failing_address,
+                                     int failing_address_len) {
+  resolver->vtable->channel_saw_error(resolver, failing_address,
+                                      failing_address_len);
+}
+
+void grpc_resolver_next(grpc_resolver *resolver,
+                        grpc_client_config **target_config,
+                        grpc_iomgr_closure *on_complete) {
+  resolver->vtable->next(resolver, target_config, on_complete);
+}
diff --git a/src/core/client_config/resolver.h b/src/core/client_config/resolver.h
new file mode 100644
index 0000000000..8ad87d789b
--- /dev/null
+++ b/src/core/client_config/resolver.h
@@ -0,0 +1,97 @@
+/*
+ *
+ * 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.
+ *
+ */
+
+#ifndef GRPC_INTERNAL_CORE_CLIENT_CONFIG_RESOLVER_H
+#define GRPC_INTERNAL_CORE_CLIENT_CONFIG_RESOLVER_H
+
+#include "src/core/client_config/client_config.h"
+#include "src/core/iomgr/iomgr.h"
+#include "src/core/iomgr/sockaddr.h"
+
+typedef struct grpc_resolver grpc_resolver;
+typedef struct grpc_resolver_vtable grpc_resolver_vtable;
+
+/** grpc_resolver provides grpc_client_config objects to grpc_channel
+    objects */
+struct grpc_resolver {
+  const grpc_resolver_vtable *vtable;
+  gpr_refcount refs;
+};
+
+struct grpc_resolver_vtable {
+  void (*destroy)(grpc_resolver *resolver);
+  void (*shutdown)(grpc_resolver *resolver);
+  void (*channel_saw_error)(grpc_resolver *resolver,
+                            struct sockaddr *failing_address,
+                            int failing_address_len);
+  void (*next)(grpc_resolver *resolver, grpc_client_config **target_config,
+               grpc_iomgr_closure *on_complete);
+};
+
+#ifdef GRPC_RESOLVER_REFCOUNT_DEBUG
+#define GRPC_RESOLVER_REF(p, r) grpc_resolver_ref((p), __FILE__, __LINE__, (r))
+#define GRPC_RESOLVER_UNREF(p, r) \
+  grpc_resolver_unref((p), __FILE__, __LINE__, (r))
+void grpc_resolver_ref(grpc_resolver *policy, const char *file, int line,
+                       const char *reason);
+void grpc_resolver_unref(grpc_resolver *policy, const char *file, int line,
+                         const char *reason);
+#else
+#define GRPC_RESOLVER_REF(p, r) grpc_resolver_ref((p))
+#define GRPC_RESOLVER_UNREF(p, r) grpc_resolver_unref((p))
+void grpc_resolver_ref(grpc_resolver *policy);
+void grpc_resolver_unref(grpc_resolver *policy);
+#endif
+
+void grpc_resolver_init(grpc_resolver *resolver,
+                        const grpc_resolver_vtable *vtable);
+
+void grpc_resolver_shutdown(grpc_resolver *resolver);
+
+/** Notification that the channel has seen an error on some address.
+    Can be used as a hint that re-resolution is desirable soon. */
+void grpc_resolver_channel_saw_error(grpc_resolver *resolver,
+                                     struct sockaddr *failing_address,
+                                     int failing_address_len);
+
+/** Get the next client config. Called by the channel to fetch a new
+    configuration. Expected to set *target_config with a new configuration,
+    and then schedule on_complete for execution.
+
+    If resolution is fatally broken, set *target_config to NULL and
+    schedule on_complete. */
+void grpc_resolver_next(grpc_resolver *resolver,
+                        grpc_client_config **target_config,
+                        grpc_iomgr_closure *on_complete);
+
+#endif /* GRPC_INTERNAL_CORE_CONFIG_RESOLVER_H */
diff --git a/src/core/client_config/resolver_factory.c b/src/core/client_config/resolver_factory.c
new file mode 100644
index 0000000000..6721977e21
--- /dev/null
+++ b/src/core/client_config/resolver_factory.c
@@ -0,0 +1,50 @@
+/*
+ *
+ * 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.
+ *
+ */
+
+#include "src/core/client_config/resolver_factory.h"
+
+void grpc_resolver_factory_ref(grpc_resolver_factory *factory) {
+  factory->vtable->ref(factory);
+}
+
+void grpc_resolver_factory_unref(grpc_resolver_factory *factory) {
+  factory->vtable->unref(factory);
+}
+
+/** Create a resolver instance for a name */
+grpc_resolver *grpc_resolver_factory_create_resolver(
+    grpc_resolver_factory *factory, grpc_uri *uri,
+    grpc_subchannel_factory *subchannel_factory) {
+  if (!factory) return NULL;
+  return factory->vtable->create_resolver(factory, uri, subchannel_factory);
+}
diff --git a/src/core/client_config/resolver_factory.h b/src/core/client_config/resolver_factory.h
new file mode 100644
index 0000000000..c5d85499c6
--- /dev/null
+++ b/src/core/client_config/resolver_factory.h
@@ -0,0 +1,67 @@
+/*
+ *
+ * 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.
+ *
+ */
+
+#ifndef GRPC_INTERNAL_CORE_CLIENT_CONFIG_RESOLVER_FACTORY_H
+#define GRPC_INTERNAL_CORE_CLIENT_CONFIG_RESOLVER_FACTORY_H
+
+#include "src/core/client_config/resolver.h"
+#include "src/core/client_config/subchannel_factory.h"
+#include "src/core/client_config/uri_parser.h"
+
+typedef struct grpc_resolver_factory grpc_resolver_factory;
+typedef struct grpc_resolver_factory_vtable grpc_resolver_factory_vtable;
+
+/** grpc_resolver provides grpc_client_config objects to grpc_channel
+    objects */
+struct grpc_resolver_factory {
+  const grpc_resolver_factory_vtable *vtable;
+};
+
+struct grpc_resolver_factory_vtable {
+  void (*ref)(grpc_resolver_factory *factory);
+  void (*unref)(grpc_resolver_factory *factory);
+
+  grpc_resolver *(*create_resolver)(
+      grpc_resolver_factory *factory, grpc_uri *uri,
+      grpc_subchannel_factory *subchannel_factory);
+};
+
+void grpc_resolver_factory_ref(grpc_resolver_factory *resolver);
+void grpc_resolver_factory_unref(grpc_resolver_factory *resolver);
+
+/** Create a resolver instance for a name */
+grpc_resolver *grpc_resolver_factory_create_resolver(
+    grpc_resolver_factory *factory, grpc_uri *uri,
+    grpc_subchannel_factory *subchannel_factory);
+
+#endif /* GRPC_INTERNAL_CORE_CONFIG_RESOLVER_FACTORY_H */
diff --git a/src/core/client_config/resolver_registry.c b/src/core/client_config/resolver_registry.c
new file mode 100644
index 0000000000..16be2da994
--- /dev/null
+++ b/src/core/client_config/resolver_registry.c
@@ -0,0 +1,124 @@
+/*
+ *
+ * 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.
+ *
+ */
+
+#include "src/core/client_config/resolver_registry.h"
+
+#include <string.h>
+
+#include <grpc/support/alloc.h>
+#include <grpc/support/log.h>
+#include <grpc/support/string_util.h>
+
+#define MAX_RESOLVERS 10
+
+typedef struct {
+  char *scheme;
+  grpc_resolver_factory *factory;
+} registered_resolver;
+
+static registered_resolver g_all_of_the_resolvers[MAX_RESOLVERS];
+static int g_number_of_resolvers = 0;
+
+static char *g_default_resolver_scheme;
+
+void grpc_resolver_registry_init(const char *default_resolver_scheme) {
+  g_number_of_resolvers = 0;
+  g_default_resolver_scheme = gpr_strdup(default_resolver_scheme);
+}
+
+void grpc_resolver_registry_shutdown(void) {
+  int i;
+  for (i = 0; i < g_number_of_resolvers; i++) {
+    gpr_free(g_all_of_the_resolvers[i].scheme);
+    grpc_resolver_factory_unref(g_all_of_the_resolvers[i].factory);
+  }
+  gpr_free(g_default_resolver_scheme);
+}
+
+void grpc_register_resolver_type(const char *scheme,
+                                 grpc_resolver_factory *factory) {
+  int i;
+  for (i = 0; i < g_number_of_resolvers; i++) {
+    GPR_ASSERT(0 != strcmp(scheme, g_all_of_the_resolvers[i].scheme));
+  }
+  GPR_ASSERT(g_number_of_resolvers != MAX_RESOLVERS);
+  g_all_of_the_resolvers[g_number_of_resolvers].scheme = gpr_strdup(scheme);
+  grpc_resolver_factory_ref(factory);
+  g_all_of_the_resolvers[g_number_of_resolvers].factory = factory;
+  g_number_of_resolvers++;
+}
+
+static grpc_resolver_factory *lookup_factory(grpc_uri *uri) {
+  int i;
+
+  /* handling NULL uri's here simplifies grpc_resolver_create */
+  if (!uri) return NULL;
+
+  for (i = 0; i < g_number_of_resolvers; i++) {
+    if (0 == strcmp(uri->scheme, g_all_of_the_resolvers[i].scheme)) {
+      return g_all_of_the_resolvers[i].factory;
+    }
+  }
+
+  return NULL;
+}
+
+grpc_resolver *grpc_resolver_create(
+    const char *name, grpc_subchannel_factory *subchannel_factory) {
+  grpc_uri *uri;
+  char *tmp;
+  grpc_resolver_factory *factory = NULL;
+  grpc_resolver *resolver;
+
+  uri = grpc_uri_parse(name, 1);
+  factory = lookup_factory(uri);
+  if (factory == NULL && g_default_resolver_scheme != NULL) {
+    grpc_uri_destroy(uri);
+    gpr_asprintf(&tmp, "%s%s", g_default_resolver_scheme, name);
+    uri = grpc_uri_parse(tmp, 1);
+    factory = lookup_factory(uri);
+    if (factory == NULL) {
+      grpc_uri_destroy(grpc_uri_parse(name, 0));
+      grpc_uri_destroy(grpc_uri_parse(tmp, 0));
+      gpr_log(GPR_ERROR, "don't know how to resolve '%s' or '%s'", name, tmp);
+    }
+    gpr_free(tmp);
+  } else if (factory == NULL) {
+    grpc_uri_destroy(grpc_uri_parse(name, 0));
+    gpr_log(GPR_ERROR, "don't know how to resolve '%s'", name);
+  }
+  resolver =
+      grpc_resolver_factory_create_resolver(factory, uri, subchannel_factory);
+  grpc_uri_destroy(uri);
+  return resolver;
+}
diff --git a/src/core/client_config/resolver_registry.h b/src/core/client_config/resolver_registry.h
new file mode 100644
index 0000000000..31aa47620a
--- /dev/null
+++ b/src/core/client_config/resolver_registry.h
@@ -0,0 +1,62 @@
+/*
+ *
+ * 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.
+ *
+ */
+
+#ifndef GRPC_INTERNAL_CORE_CLIENT_CONFIG_RESOLVER_REGISTRY_H
+#define GRPC_INTERNAL_CORE_CLIENT_CONFIG_RESOLVER_REGISTRY_H
+
+#include "src/core/client_config/resolver_factory.h"
+
+void grpc_resolver_registry_init(const char *default_prefix);
+void grpc_resolver_registry_shutdown(void);
+
+/** Register a resolver type.
+    URI's of \a scheme will be resolved with the given resolver.
+    If \a priority is greater than zero, then the resolver will be eligible
+    to resolve names that are passed in with no scheme. Higher priority
+    resolvers will be tried before lower priority schemes. */
+void grpc_register_resolver_type(const char *scheme,
+                                 grpc_resolver_factory *factory);
+
+/** Create a resolver given \a name.
+    First tries to parse \a name as a URI. If this succeeds, tries
+    to locate a registered resolver factory based on the URI scheme.
+    If parsing or location fails, prefixes default_prefix from
+    grpc_resolver_registry_init to name, and tries again (if default_prefix
+    was not NULL).
+    If a resolver factory was found, use it to instantiate a resolver and
+    return it.
+    If a resolver factory was not found, return NULL. */
+grpc_resolver *grpc_resolver_create(
+    const char *name, grpc_subchannel_factory *subchannel_factory);
+
+#endif /* GRPC_INTERNAL_CORE_CLIENT_CONFIG_RESOLVER_REGISTRY_H */
diff --git a/src/core/client_config/resolvers/dns_resolver.c b/src/core/client_config/resolvers/dns_resolver.c
new file mode 100644
index 0000000000..ac401bc4d3
--- /dev/null
+++ b/src/core/client_config/resolvers/dns_resolver.c
@@ -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.
+ *
+ */
+
+#include "src/core/client_config/resolvers/dns_resolver.h"
+
+#include <string.h>
+
+#include <grpc/support/alloc.h>
+#include <grpc/support/string_util.h>
+
+#include "src/core/client_config/lb_policies/pick_first.h"
+#include "src/core/iomgr/resolve_address.h"
+#include "src/core/support/string.h"
+
+typedef struct {
+  /** base class: must be first */
+  grpc_resolver base;
+  /** refcount */
+  gpr_refcount refs;
+  /** name to resolve */
+  char *name;
+  /** default port to use */
+  char *default_port;
+  /** subchannel factory */
+  grpc_subchannel_factory *subchannel_factory;
+  /** load balancing policy factory */
+  grpc_lb_policy *(*lb_policy_factory)(grpc_subchannel **subchannels,
+                                       size_t num_subchannels);
+
+  /** mutex guarding the rest of the state */
+  gpr_mu mu;
+  /** are we currently resolving? */
+  int resolving;
+  /** which version of resolved_config have we published? */
+  int published_version;
+  /** which version of resolved_config is current? */
+  int resolved_version;
+  /** pending next completion, or NULL */
+  grpc_iomgr_closure *next_completion;
+  /** target config address for next completion */
+  grpc_client_config **target_config;
+  /** current (fully resolved) config */
+  grpc_client_config *resolved_config;
+} dns_resolver;
+
+static void dns_destroy(grpc_resolver *r);
+
+static void dns_start_resolving_locked(dns_resolver *r);
+static void dns_maybe_finish_next_locked(dns_resolver *r);
+
+static void dns_shutdown(grpc_resolver *r);
+static void dns_channel_saw_error(grpc_resolver *r,
+                                  struct sockaddr *failing_address,
+                                  int failing_address_len);
+static void dns_next(grpc_resolver *r, grpc_client_config **target_config,
+                     grpc_iomgr_closure *on_complete);
+
+static const grpc_resolver_vtable dns_resolver_vtable = {
+    dns_destroy, dns_shutdown, dns_channel_saw_error, dns_next};
+
+static void dns_shutdown(grpc_resolver *resolver) {
+  dns_resolver *r = (dns_resolver *)resolver;
+  gpr_mu_lock(&r->mu);
+  if (r->next_completion != NULL) {
+    *r->target_config = NULL;
+    grpc_iomgr_add_callback(r->next_completion);
+    r->next_completion = NULL;
+  }
+  gpr_mu_unlock(&r->mu);
+}
+
+static void dns_channel_saw_error(grpc_resolver *resolver, struct sockaddr *sa,
+                                  int len) {
+  dns_resolver *r = (dns_resolver *)resolver;
+  gpr_mu_lock(&r->mu);
+  if (!r->resolving) {
+    dns_start_resolving_locked(r);
+  }
+  gpr_mu_unlock(&r->mu);
+}
+
+static void dns_next(grpc_resolver *resolver,
+                     grpc_client_config **target_config,
+                     grpc_iomgr_closure *on_complete) {
+  dns_resolver *r = (dns_resolver *)resolver;
+  gpr_mu_lock(&r->mu);
+  GPR_ASSERT(!r->next_completion);
+  r->next_completion = on_complete;
+  r->target_config = target_config;
+  if (r->resolved_version == 0 && !r->resolving) {
+    dns_start_resolving_locked(r);
+  } else {
+    dns_maybe_finish_next_locked(r);
+  }
+  gpr_mu_unlock(&r->mu);
+}
+
+static void dns_on_resolved(void *arg, grpc_resolved_addresses *addresses) {
+  dns_resolver *r = arg;
+  grpc_client_config *config = NULL;
+  grpc_subchannel **subchannels;
+  grpc_subchannel_args args;
+  grpc_lb_policy *lb_policy;
+  size_t i;
+  if (addresses) {
+    config = grpc_client_config_create();
+    subchannels = gpr_malloc(sizeof(grpc_subchannel *) * addresses->naddrs);
+    for (i = 0; i < addresses->naddrs; i++) {
+      memset(&args, 0, sizeof(args));
+      args.addr = (struct sockaddr *)(addresses->addrs[i].addr);
+      args.addr_len = addresses->addrs[i].len;
+      subchannels[i] = grpc_subchannel_factory_create_subchannel(
+          r->subchannel_factory, &args);
+    }
+    lb_policy = r->lb_policy_factory(subchannels, addresses->naddrs);
+    grpc_client_config_set_lb_policy(config, lb_policy);
+    GRPC_LB_POLICY_UNREF(lb_policy, "construction");
+    grpc_resolved_addresses_destroy(addresses);
+    gpr_free(subchannels);
+  }
+  gpr_mu_lock(&r->mu);
+  GPR_ASSERT(r->resolving);
+  r->resolving = 0;
+  if (r->resolved_config) {
+    grpc_client_config_unref(r->resolved_config);
+  }
+  r->resolved_config = config;
+  r->resolved_version++;
+  dns_maybe_finish_next_locked(r);
+  gpr_mu_unlock(&r->mu);
+
+  GRPC_RESOLVER_UNREF(&r->base, "dns-resolving");
+}
+
+static void dns_start_resolving_locked(dns_resolver *r) {
+  GRPC_RESOLVER_REF(&r->base, "dns-resolving");
+  GPR_ASSERT(!r->resolving);
+  r->resolving = 1;
+  grpc_resolve_address(r->name, r->default_port, dns_on_resolved, r);
+}
+
+static void dns_maybe_finish_next_locked(dns_resolver *r) {
+  if (r->next_completion != NULL &&
+      r->resolved_version != r->published_version) {
+    *r->target_config = r->resolved_config;
+    if (r->resolved_config) {
+      grpc_client_config_ref(r->resolved_config);
+    }
+    grpc_iomgr_add_callback(r->next_completion);
+    r->next_completion = NULL;
+    r->published_version = r->resolved_version;
+  }
+}
+
+static void dns_destroy(grpc_resolver *gr) {
+  dns_resolver *r = (dns_resolver *)gr;
+  gpr_mu_destroy(&r->mu);
+  if (r->resolved_config) {
+    grpc_client_config_unref(r->resolved_config);
+  }
+  grpc_subchannel_factory_unref(r->subchannel_factory);
+  gpr_free(r->name);
+  gpr_free(r->default_port);
+  gpr_free(r);
+}
+
+static grpc_resolver *dns_create(
+    grpc_uri *uri, const char *default_port,
+    grpc_lb_policy *(*lb_policy_factory)(grpc_subchannel **subchannels,
+                                         size_t num_subchannels),
+    grpc_subchannel_factory *subchannel_factory) {
+  dns_resolver *r;
+  const char *path = uri->path;
+
+  if (0 != strcmp(uri->authority, "")) {
+    gpr_log(GPR_ERROR, "authority based uri's not supported");
+    return NULL;
+  }
+
+  if (path[0] == '/') ++path;
+
+  r = gpr_malloc(sizeof(dns_resolver));
+  memset(r, 0, sizeof(*r));
+  gpr_ref_init(&r->refs, 1);
+  gpr_mu_init(&r->mu);
+  grpc_resolver_init(&r->base, &dns_resolver_vtable);
+  r->name = gpr_strdup(path);
+  r->default_port = gpr_strdup(default_port);
+  r->subchannel_factory = subchannel_factory;
+  r->lb_policy_factory = lb_policy_factory;
+  grpc_subchannel_factory_ref(subchannel_factory);
+  return &r->base;
+}
+
+/*
+ * FACTORY
+ */
+
+static void dns_factory_ref(grpc_resolver_factory *factory) {}
+
+static void dns_factory_unref(grpc_resolver_factory *factory) {}
+
+static grpc_resolver *dns_factory_create_resolver(
+    grpc_resolver_factory *factory, grpc_uri *uri,
+    grpc_subchannel_factory *subchannel_factory) {
+  return dns_create(uri, "https", grpc_create_pick_first_lb_policy,
+                    subchannel_factory);
+}
+
+static const grpc_resolver_factory_vtable dns_factory_vtable = {
+    dns_factory_ref, dns_factory_unref, dns_factory_create_resolver};
+static grpc_resolver_factory dns_resolver_factory = {&dns_factory_vtable};
+
+grpc_resolver_factory *grpc_dns_resolver_factory_create() {
+  return &dns_resolver_factory;
+}
diff --git a/src/core/client_config/resolvers/dns_resolver.h b/src/core/client_config/resolvers/dns_resolver.h
new file mode 100644
index 0000000000..a3ef3161a6
--- /dev/null
+++ b/src/core/client_config/resolvers/dns_resolver.h
@@ -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.
+ *
+ */
+
+#ifndef GRPC_INTERNAL_CORE_CLIENT_CONFIG_RESOLVERS_DNS_RESOLVER_H
+#define GRPC_INTERNAL_CORE_CLIENT_CONFIG_RESOLVERS_DNS_RESOLVER_H
+
+#include "src/core/client_config/resolver_factory.h"
+
+/** Create a dns resolver factory */
+grpc_resolver_factory *grpc_dns_resolver_factory_create(void);
+
+#endif /* GRPC_INTERNAL_CORE_CLIENT_CONFIG_RESOLVERS_DNS_RESOLVER_H */
diff --git a/src/core/client_config/resolvers/unix_resolver_posix.c b/src/core/client_config/resolvers/unix_resolver_posix.c
new file mode 100644
index 0000000000..be515d2689
--- /dev/null
+++ b/src/core/client_config/resolvers/unix_resolver_posix.c
@@ -0,0 +1,195 @@
+/*
+ *
+ * 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.
+ *
+ */
+
+#include <grpc/support/port_platform.h>
+#ifdef GPR_POSIX_SOCKET
+
+#include "src/core/client_config/resolvers/unix_resolver_posix.h"
+
+#include <string.h>
+#include <sys/un.h>
+
+#include <grpc/support/alloc.h>
+#include <grpc/support/string_util.h>
+
+#include "src/core/client_config/lb_policies/pick_first.h"
+#include "src/core/iomgr/resolve_address.h"
+#include "src/core/support/string.h"
+
+typedef struct {
+  /** base class: must be first */
+  grpc_resolver base;
+  /** refcount */
+  gpr_refcount refs;
+  /** subchannel factory */
+  grpc_subchannel_factory *subchannel_factory;
+  /** load balancing policy factory */
+  grpc_lb_policy *(*lb_policy_factory)(grpc_subchannel **subchannels,
+                                       size_t num_subchannels);
+
+  /** the address that we've 'resolved' */
+  struct sockaddr_un addr;
+  int addr_len;
+
+  /** mutex guarding the rest of the state */
+  gpr_mu mu;
+  /** have we published? */
+  int published;
+  /** pending next completion, or NULL */
+  grpc_iomgr_closure *next_completion;
+  /** target config address for next completion */
+  grpc_client_config **target_config;
+} unix_resolver;
+
+static void unix_destroy(grpc_resolver *r);
+
+static void unix_maybe_finish_next_locked(unix_resolver *r);
+
+static void unix_shutdown(grpc_resolver *r);
+static void unix_channel_saw_error(grpc_resolver *r,
+                                   struct sockaddr *failing_address,
+                                   int failing_address_len);
+static void unix_next(grpc_resolver *r, grpc_client_config **target_config,
+                      grpc_iomgr_closure *on_complete);
+
+static const grpc_resolver_vtable unix_resolver_vtable = {
+    unix_destroy, unix_shutdown, unix_channel_saw_error, unix_next};
+
+static void unix_shutdown(grpc_resolver *resolver) {
+  unix_resolver *r = (unix_resolver *)resolver;
+  gpr_mu_lock(&r->mu);
+  if (r->next_completion != NULL) {
+    *r->target_config = NULL;
+    /* TODO(ctiller): add delayed callback */
+    grpc_iomgr_add_callback(r->next_completion);
+    r->next_completion = NULL;
+  }
+  gpr_mu_unlock(&r->mu);
+}
+
+static void unix_channel_saw_error(grpc_resolver *resolver, struct sockaddr *sa,
+                                   int len) {}
+
+static void unix_next(grpc_resolver *resolver,
+                      grpc_client_config **target_config,
+                      grpc_iomgr_closure *on_complete) {
+  unix_resolver *r = (unix_resolver *)resolver;
+  gpr_mu_lock(&r->mu);
+  GPR_ASSERT(!r->next_completion);
+  r->next_completion = on_complete;
+  r->target_config = target_config;
+  unix_maybe_finish_next_locked(r);
+  gpr_mu_unlock(&r->mu);
+}
+
+static void unix_maybe_finish_next_locked(unix_resolver *r) {
+  grpc_client_config *cfg;
+  grpc_lb_policy *lb_policy;
+  grpc_subchannel *subchannel;
+  grpc_subchannel_args args;
+
+  if (r->next_completion != NULL && !r->published) {
+    cfg = grpc_client_config_create();
+    memset(&args, 0, sizeof(args));
+    args.addr = (struct sockaddr *)&r->addr;
+    args.addr_len = r->addr_len;
+    subchannel =
+        grpc_subchannel_factory_create_subchannel(r->subchannel_factory, &args);
+    lb_policy = r->lb_policy_factory(&subchannel, 1);
+    grpc_client_config_set_lb_policy(cfg, lb_policy);
+    GRPC_LB_POLICY_UNREF(lb_policy, "unix");
+    r->published = 1;
+    *r->target_config = cfg;
+    grpc_iomgr_add_callback(r->next_completion);
+    r->next_completion = NULL;
+  }
+}
+
+static void unix_destroy(grpc_resolver *gr) {
+  unix_resolver *r = (unix_resolver *)gr;
+  gpr_mu_destroy(&r->mu);
+  grpc_subchannel_factory_unref(r->subchannel_factory);
+  gpr_free(r);
+}
+
+static grpc_resolver *unix_create(
+    grpc_uri *uri,
+    grpc_lb_policy *(*lb_policy_factory)(grpc_subchannel **subchannels,
+                                         size_t num_subchannels),
+    grpc_subchannel_factory *subchannel_factory) {
+  unix_resolver *r;
+
+  if (0 != strcmp(uri->authority, "")) {
+    gpr_log(GPR_ERROR, "authority based uri's not supported");
+    return NULL;
+  }
+
+  r = gpr_malloc(sizeof(unix_resolver));
+  memset(r, 0, sizeof(*r));
+  gpr_ref_init(&r->refs, 1);
+  gpr_mu_init(&r->mu);
+  grpc_resolver_init(&r->base, &unix_resolver_vtable);
+  r->subchannel_factory = subchannel_factory;
+  r->lb_policy_factory = lb_policy_factory;
+
+  r->addr.sun_family = AF_UNIX;
+  strcpy(r->addr.sun_path, uri->path);
+  r->addr_len = strlen(r->addr.sun_path) + sizeof(r->addr.sun_family) + 1;
+
+  grpc_subchannel_factory_ref(subchannel_factory);
+  return &r->base;
+}
+
+/*
+ * FACTORY
+ */
+
+static void unix_factory_ref(grpc_resolver_factory *factory) {}
+
+static void unix_factory_unref(grpc_resolver_factory *factory) {}
+
+static grpc_resolver *unix_factory_create_resolver(
+    grpc_resolver_factory *factory, grpc_uri *uri,
+    grpc_subchannel_factory *subchannel_factory) {
+  return unix_create(uri, grpc_create_pick_first_lb_policy, subchannel_factory);
+}
+
+static const grpc_resolver_factory_vtable unix_factory_vtable = {
+    unix_factory_ref, unix_factory_unref, unix_factory_create_resolver};
+static grpc_resolver_factory unix_resolver_factory = {&unix_factory_vtable};
+
+grpc_resolver_factory *grpc_unix_resolver_factory_create() {
+  return &unix_resolver_factory;
+}
+
+#endif
diff --git a/src/core/client_config/resolvers/unix_resolver_posix.h b/src/core/client_config/resolvers/unix_resolver_posix.h
new file mode 100644
index 0000000000..57ace59e21
--- /dev/null
+++ b/src/core/client_config/resolvers/unix_resolver_posix.h
@@ -0,0 +1,44 @@
+/*
+ *
+ * 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.
+ *
+ */
+
+#ifndef GRPC_INTERNAL_CORE_CLIENT_CONFIG_RESOLVERS_UNIX_RESOLVER_H
+#define GRPC_INTERNAL_CORE_CLIENT_CONFIG_RESOLVERS_UNIX_RESOLVER_H
+
+#include <grpc/support/port_platform.h>
+
+#include "src/core/client_config/resolver_factory.h"
+
+/** Create a unix resolver factory */
+grpc_resolver_factory *grpc_unix_resolver_factory_create(void);
+
+#endif /* GRPC_INTERNAL_CORE_CLIENT_CONFIG_RESOLVERS_UNIX_RESOLVER_H */
diff --git a/src/core/client_config/subchannel.c b/src/core/client_config/subchannel.c
new file mode 100644
index 0000000000..6cf9062ab0
--- /dev/null
+++ b/src/core/client_config/subchannel.c
@@ -0,0 +1,659 @@
+/*
+ *
+ * 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.
+ *
+ */
+
+#include "src/core/client_config/subchannel.h"
+
+#include <string.h>
+
+#include <grpc/support/alloc.h>
+
+#include "src/core/channel/channel_args.h"
+#include "src/core/channel/connected_channel.h"
+#include "src/core/iomgr/alarm.h"
+#include "src/core/transport/connectivity_state.h"
+
+typedef struct {
+  /* all fields protected by subchannel->mu */
+  /** refcount */
+  int refs;
+  /** parent subchannel */
+  grpc_subchannel *subchannel;
+} connection;
+
+typedef struct {
+  grpc_iomgr_closure closure;
+  size_t version;
+  grpc_subchannel *subchannel;
+  grpc_connectivity_state connectivity_state;
+} state_watcher;
+
+typedef struct waiting_for_connect {
+  struct waiting_for_connect *next;
+  grpc_iomgr_closure *notify;
+  grpc_pollset *pollset;
+  grpc_subchannel_call **target;
+  grpc_subchannel *subchannel;
+  grpc_iomgr_closure continuation;
+} waiting_for_connect;
+
+struct grpc_subchannel {
+  grpc_connector *connector;
+
+  /** non-transport related channel filters */
+  const grpc_channel_filter **filters;
+  size_t num_filters;
+  /** channel arguments */
+  grpc_channel_args *args;
+  /** address to connect to */
+  struct sockaddr *addr;
+  size_t addr_len;
+  /** metadata context */
+  grpc_mdctx *mdctx;
+  /** master channel - the grpc_channel instance that ultimately owns
+      this channel_data via its channel stack.
+      We occasionally use this to bump the refcount on the master channel
+      to keep ourselves alive through an asynchronous operation. */
+  grpc_channel *master;
+  /** have we seen a disconnection? */
+  int disconnected;
+
+  /** set during connection */
+  grpc_connect_out_args connecting_result;
+
+  /** callback for connection finishing */
+  grpc_iomgr_closure connected;
+
+  /** pollset_set tracking who's interested in a connection
+      being setup */
+  grpc_pollset_set pollset_set;
+
+  /** mutex protecting remaining elements */
+  gpr_mu mu;
+
+  /** active connection */
+  connection *active;
+  /** version number for the active connection */
+  size_t active_version;
+  /** refcount */
+  int refs;
+  /** are we connecting */
+  int connecting;
+  /** things waiting for a connection */
+  waiting_for_connect *waiting;
+  /** connectivity state tracking */
+  grpc_connectivity_state_tracker state_tracker;
+
+  /** next connect attempt time */
+  gpr_timespec next_attempt;
+  /** amount to backoff each failure */
+  gpr_timespec backoff_delta;
+  /** do we have an active alarm? */
+  int have_alarm;
+  /** our alarm */
+  grpc_alarm alarm;
+};
+
+struct grpc_subchannel_call {
+  connection *connection;
+  gpr_refcount refs;
+};
+
+#define SUBCHANNEL_CALL_TO_CALL_STACK(call) ((grpc_call_stack *)((call) + 1))
+#define CHANNEL_STACK_FROM_CONNECTION(con) ((grpc_channel_stack *)((con) + 1))
+
+static grpc_subchannel_call *create_call(connection *con);
+static void connectivity_state_changed_locked(grpc_subchannel *c);
+static grpc_connectivity_state compute_connectivity_locked(grpc_subchannel *c);
+static gpr_timespec compute_connect_deadline(grpc_subchannel *c);
+static void subchannel_connected(void *subchannel, int iomgr_success);
+
+static void subchannel_ref_locked(
+    grpc_subchannel *c GRPC_SUBCHANNEL_REF_EXTRA_ARGS);
+static int subchannel_unref_locked(
+    grpc_subchannel *c GRPC_SUBCHANNEL_REF_EXTRA_ARGS) GRPC_MUST_USE_RESULT;
+static void connection_ref_locked(connection *c GRPC_SUBCHANNEL_REF_EXTRA_ARGS);
+static grpc_subchannel *connection_unref_locked(
+    connection *c GRPC_SUBCHANNEL_REF_EXTRA_ARGS) GRPC_MUST_USE_RESULT;
+static void subchannel_destroy(grpc_subchannel *c);
+
+#ifdef GRPC_SUBCHANNEL_REFCOUNT_DEBUG
+#define SUBCHANNEL_REF_LOCKED(p, r) \
+  subchannel_ref_locked((p), __FILE__, __LINE__, (r))
+#define SUBCHANNEL_UNREF_LOCKED(p, r) \
+  subchannel_unref_locked((p), __FILE__, __LINE__, (r))
+#define CONNECTION_REF_LOCKED(p, r) \
+  connection_ref_locked((p), __FILE__, __LINE__, (r))
+#define CONNECTION_UNREF_LOCKED(p, r) \
+  connection_unref_locked((p), __FILE__, __LINE__, (r))
+#define REF_PASS_ARGS , file, line, reason
+#define REF_LOG(name, p)                                                  \
+  gpr_log(file, line, GPR_LOG_SEVERITY_DEBUG, "%s: %p   ref %d -> %d %s", \
+          (name), (p), (p)->refs, (p)->refs + 1, reason)
+#define UNREF_LOG(name, p)                                                \
+  gpr_log(file, line, GPR_LOG_SEVERITY_DEBUG, "%s: %p unref %d -> %d %s", \
+          (name), (p), (p)->refs, (p)->refs - 1, reason)
+#else
+#define SUBCHANNEL_REF_LOCKED(p, r) subchannel_ref_locked((p))
+#define SUBCHANNEL_UNREF_LOCKED(p, r) subchannel_unref_locked((p))
+#define CONNECTION_REF_LOCKED(p, r) connection_ref_locked((p))
+#define CONNECTION_UNREF_LOCKED(p, r) connection_unref_locked((p))
+#define REF_PASS_ARGS
+#define REF_LOG(name, p) \
+  do {                   \
+  } while (0)
+#define UNREF_LOG(name, p) \
+  do {                     \
+  } while (0)
+#endif
+
+/*
+ * connection implementation
+ */
+
+static void connection_destroy(connection *c) {
+  GPR_ASSERT(c->refs == 0);
+  grpc_channel_stack_destroy(CHANNEL_STACK_FROM_CONNECTION(c));
+  gpr_free(c);
+}
+
+static void connection_ref_locked(
+    connection *c GRPC_SUBCHANNEL_REF_EXTRA_ARGS) {
+  REF_LOG("CONNECTION", c);
+  subchannel_ref_locked(c->subchannel REF_PASS_ARGS);
+  ++c->refs;
+}
+
+static grpc_subchannel *connection_unref_locked(
+    connection *c GRPC_SUBCHANNEL_REF_EXTRA_ARGS) {
+  grpc_subchannel *destroy = NULL;
+  UNREF_LOG("CONNECTION", c);
+  if (subchannel_unref_locked(c->subchannel REF_PASS_ARGS)) {
+    destroy = c->subchannel;
+  }
+  if (--c->refs == 0 && c->subchannel->active != c) {
+    connection_destroy(c);
+  }
+  return destroy;
+}
+
+/*
+ * grpc_subchannel implementation
+ */
+
+static void subchannel_ref_locked(
+    grpc_subchannel *c GRPC_SUBCHANNEL_REF_EXTRA_ARGS) {
+  REF_LOG("SUBCHANNEL", c);
+  ++c->refs;
+}
+
+static int subchannel_unref_locked(
+    grpc_subchannel *c GRPC_SUBCHANNEL_REF_EXTRA_ARGS) {
+  UNREF_LOG("SUBCHANNEL", c);
+  return --c->refs == 0;
+}
+
+void grpc_subchannel_ref(grpc_subchannel *c GRPC_SUBCHANNEL_REF_EXTRA_ARGS) {
+  gpr_mu_lock(&c->mu);
+  subchannel_ref_locked(c REF_PASS_ARGS);
+  gpr_mu_unlock(&c->mu);
+}
+
+void grpc_subchannel_unref(grpc_subchannel *c GRPC_SUBCHANNEL_REF_EXTRA_ARGS) {
+  int destroy;
+  gpr_mu_lock(&c->mu);
+  destroy = subchannel_unref_locked(c REF_PASS_ARGS);
+  gpr_mu_unlock(&c->mu);
+  if (destroy) subchannel_destroy(c);
+}
+
+static void subchannel_destroy(grpc_subchannel *c) {
+  if (c->active != NULL) {
+    connection_destroy(c->active);
+  }
+  gpr_free(c->filters);
+  grpc_channel_args_destroy(c->args);
+  gpr_free(c->addr);
+  grpc_mdctx_unref(c->mdctx);
+  grpc_pollset_set_destroy(&c->pollset_set);
+  grpc_connectivity_state_destroy(&c->state_tracker);
+  grpc_connector_unref(c->connector);
+  gpr_free(c);
+}
+
+void grpc_subchannel_add_interested_party(grpc_subchannel *c,
+                                          grpc_pollset *pollset) {
+  grpc_pollset_set_add_pollset(&c->pollset_set, pollset);
+}
+
+void grpc_subchannel_del_interested_party(grpc_subchannel *c,
+                                          grpc_pollset *pollset) {
+  grpc_pollset_set_del_pollset(&c->pollset_set, pollset);
+}
+
+grpc_subchannel *grpc_subchannel_create(grpc_connector *connector,
+                                        grpc_subchannel_args *args) {
+  grpc_subchannel *c = gpr_malloc(sizeof(*c));
+  memset(c, 0, sizeof(*c));
+  c->refs = 1;
+  c->connector = connector;
+  grpc_connector_ref(c->connector);
+  c->num_filters = args->filter_count;
+  c->filters = gpr_malloc(sizeof(grpc_channel_filter *) * c->num_filters);
+  memcpy(c->filters, args->filters,
+         sizeof(grpc_channel_filter *) * c->num_filters);
+  c->addr = gpr_malloc(args->addr_len);
+  memcpy(c->addr, args->addr, args->addr_len);
+  c->addr_len = args->addr_len;
+  c->args = grpc_channel_args_copy(args->args);
+  c->mdctx = args->mdctx;
+  c->master = args->master;
+  grpc_mdctx_ref(c->mdctx);
+  grpc_pollset_set_init(&c->pollset_set);
+  grpc_iomgr_closure_init(&c->connected, subchannel_connected, c);
+  grpc_connectivity_state_init(&c->state_tracker, GRPC_CHANNEL_IDLE);
+  gpr_mu_init(&c->mu);
+  return c;
+}
+
+static void continue_connect(grpc_subchannel *c) {
+  grpc_connect_in_args args;
+
+  args.interested_parties = &c->pollset_set;
+  args.addr = c->addr;
+  args.addr_len = c->addr_len;
+  args.deadline = compute_connect_deadline(c);
+  args.channel_args = c->args;
+  args.metadata_context = c->mdctx;
+
+  grpc_connector_connect(c->connector, &args, &c->connecting_result,
+                         &c->connected);
+}
+
+static void start_connect(grpc_subchannel *c) {
+  gpr_timespec now = gpr_now();
+  c->next_attempt = now;
+  c->backoff_delta = gpr_time_from_seconds(1);
+
+  continue_connect(c);
+}
+
+static void continue_creating_call(void *arg, int iomgr_success) {
+  waiting_for_connect *w4c = arg;
+  grpc_subchannel_create_call(w4c->subchannel, w4c->pollset, w4c->target,
+                              w4c->notify);
+  GRPC_SUBCHANNEL_UNREF(w4c->subchannel, "waiting_for_connect");
+  gpr_free(w4c);
+}
+
+void grpc_subchannel_create_call(grpc_subchannel *c, grpc_pollset *pollset,
+                                 grpc_subchannel_call **target,
+                                 grpc_iomgr_closure *notify) {
+  connection *con;
+  gpr_mu_lock(&c->mu);
+  if (c->active != NULL) {
+    con = c->active;
+    CONNECTION_REF_LOCKED(con, "call");
+    gpr_mu_unlock(&c->mu);
+
+    *target = create_call(con);
+    notify->cb(notify->cb_arg, 1);
+  } else {
+    waiting_for_connect *w4c = gpr_malloc(sizeof(*w4c));
+    w4c->next = c->waiting;
+    w4c->notify = notify;
+    w4c->pollset = pollset;
+    w4c->target = target;
+    w4c->subchannel = c;
+    /* released when clearing w4c */
+    SUBCHANNEL_REF_LOCKED(c, "waiting_for_connect");
+    grpc_iomgr_closure_init(&w4c->continuation, continue_creating_call, w4c);
+    c->waiting = w4c;
+    grpc_subchannel_add_interested_party(c, pollset);
+    if (!c->connecting) {
+      c->connecting = 1;
+      connectivity_state_changed_locked(c);
+      /* released by connection */
+      SUBCHANNEL_REF_LOCKED(c, "connecting");
+      gpr_mu_unlock(&c->mu);
+
+      start_connect(c);
+    } else {
+      gpr_mu_unlock(&c->mu);
+    }
+  }
+}
+
+grpc_connectivity_state grpc_subchannel_check_connectivity(grpc_subchannel *c) {
+  grpc_connectivity_state state;
+  gpr_mu_lock(&c->mu);
+  state = grpc_connectivity_state_check(&c->state_tracker);
+  gpr_mu_unlock(&c->mu);
+  return state;
+}
+
+void grpc_subchannel_notify_on_state_change(grpc_subchannel *c,
+                                            grpc_connectivity_state *state,
+                                            grpc_iomgr_closure *notify) {
+  int do_connect = 0;
+  gpr_mu_lock(&c->mu);
+  if (grpc_connectivity_state_notify_on_state_change(&c->state_tracker, state,
+                                                     notify)) {
+    do_connect = 1;
+    c->connecting = 1;
+    /* released by connection */
+    SUBCHANNEL_REF_LOCKED(c, "connecting");
+    connectivity_state_changed_locked(c);
+  }
+  gpr_mu_unlock(&c->mu);
+  if (do_connect) {
+    start_connect(c);
+  }
+}
+
+void grpc_subchannel_process_transport_op(grpc_subchannel *c,
+                                          grpc_transport_op *op) {
+  connection *con = NULL;
+  grpc_subchannel *destroy;
+  int cancel_alarm = 0;
+  gpr_mu_lock(&c->mu);
+  if (op->disconnect) {
+    c->disconnected = 1;
+    connectivity_state_changed_locked(c);
+    if (c->have_alarm) {
+      cancel_alarm = 1;
+    }
+  }
+  if (c->active != NULL) {
+    con = c->active;
+    CONNECTION_REF_LOCKED(con, "transport-op");
+  }
+  gpr_mu_unlock(&c->mu);
+
+  if (con != NULL) {
+    grpc_channel_stack *channel_stack = CHANNEL_STACK_FROM_CONNECTION(con);
+    grpc_channel_element *top_elem =
+        grpc_channel_stack_element(channel_stack, 0);
+    top_elem->filter->start_transport_op(top_elem, op);
+
+    gpr_mu_lock(&c->mu);
+    destroy = CONNECTION_UNREF_LOCKED(con, "transport-op");
+    gpr_mu_unlock(&c->mu);
+    if (destroy) {
+      subchannel_destroy(destroy);
+    }
+  }
+
+  if (cancel_alarm) {
+    grpc_alarm_cancel(&c->alarm);
+  }
+}
+
+static void on_state_changed(void *p, int iomgr_success) {
+  state_watcher *sw = p;
+  grpc_subchannel *c = sw->subchannel;
+  gpr_mu *mu = &c->mu;
+  int destroy;
+  grpc_transport_op op;
+  grpc_channel_element *elem;
+  connection *destroy_connection = NULL;
+
+  gpr_mu_lock(mu);
+
+  /* if we failed or there is a version number mismatch, just leave
+     this closure */
+  if (!iomgr_success || sw->subchannel->active_version != sw->version) {
+    goto done;
+  }
+
+  switch (sw->connectivity_state) {
+    case GRPC_CHANNEL_CONNECTING:
+    case GRPC_CHANNEL_READY:
+    case GRPC_CHANNEL_IDLE:
+      /* all is still good: keep watching */
+      memset(&op, 0, sizeof(op));
+      op.connectivity_state = &sw->connectivity_state;
+      op.on_connectivity_state_change = &sw->closure;
+      elem = grpc_channel_stack_element(
+          CHANNEL_STACK_FROM_CONNECTION(c->active), 0);
+      elem->filter->start_transport_op(elem, &op);
+      /* early out */
+      gpr_mu_unlock(mu);
+      return;
+    case GRPC_CHANNEL_FATAL_FAILURE:
+    case GRPC_CHANNEL_TRANSIENT_FAILURE:
+      /* things have gone wrong, deactivate and enter idle */
+      if (sw->subchannel->active->refs == 0) {
+        destroy_connection = sw->subchannel->active;
+      }
+      sw->subchannel->active = NULL;
+      grpc_connectivity_state_set(&c->state_tracker,
+                                  GRPC_CHANNEL_TRANSIENT_FAILURE);
+      break;
+  }
+
+done:
+  connectivity_state_changed_locked(c);
+  destroy = SUBCHANNEL_UNREF_LOCKED(c, "state_watcher");
+  gpr_free(sw);
+  gpr_mu_unlock(mu);
+  if (destroy) {
+    subchannel_destroy(c);
+  }
+  if (destroy_connection != NULL) {
+    connection_destroy(destroy_connection);
+  }
+}
+
+static void publish_transport(grpc_subchannel *c) {
+  size_t channel_stack_size;
+  connection *con;
+  grpc_channel_stack *stk;
+  size_t num_filters;
+  const grpc_channel_filter **filters;
+  waiting_for_connect *w4c;
+  grpc_transport_op op;
+  state_watcher *sw;
+  connection *destroy_connection = NULL;
+  grpc_channel_element *elem;
+
+  /* build final filter list */
+  num_filters = c->num_filters + c->connecting_result.num_filters + 1;
+  filters = gpr_malloc(sizeof(*filters) * num_filters);
+  memcpy(filters, c->filters, sizeof(*filters) * c->num_filters);
+  memcpy(filters + c->num_filters, c->connecting_result.filters,
+         sizeof(*filters) * c->connecting_result.num_filters);
+  filters[num_filters - 1] = &grpc_connected_channel_filter;
+
+  /* construct channel stack */
+  channel_stack_size = grpc_channel_stack_size(filters, num_filters);
+  con = gpr_malloc(sizeof(connection) + channel_stack_size);
+  stk = (grpc_channel_stack *)(con + 1);
+  con->refs = 0;
+  con->subchannel = c;
+  grpc_channel_stack_init(filters, num_filters, c->master, c->args, c->mdctx,
+                          stk);
+  grpc_connected_channel_bind_transport(stk, c->connecting_result.transport);
+  gpr_free(c->connecting_result.filters);
+  memset(&c->connecting_result, 0, sizeof(c->connecting_result));
+
+  /* initialize state watcher */
+  sw = gpr_malloc(sizeof(*sw));
+  grpc_iomgr_closure_init(&sw->closure, on_state_changed, sw);
+  sw->subchannel = c;
+  sw->connectivity_state = GRPC_CHANNEL_READY;
+
+  gpr_mu_lock(&c->mu);
+
+  if (c->disconnected) {
+    gpr_mu_unlock(&c->mu);
+    gpr_free(sw);
+    gpr_free(filters);
+    grpc_channel_stack_destroy(stk);
+    return;
+  }
+
+  /* publish */
+  if (c->active != NULL && c->active->refs == 0) {
+    destroy_connection = c->active;
+  }
+  c->active = con;
+  c->active_version++;
+  sw->version = c->active_version;
+  c->connecting = 0;
+
+  /* watch for changes; subchannel ref for connecting is donated
+     to the state watcher */
+  memset(&op, 0, sizeof(op));
+  op.connectivity_state = &sw->connectivity_state;
+  op.on_connectivity_state_change = &sw->closure;
+  SUBCHANNEL_REF_LOCKED(c, "state_watcher");
+  GPR_ASSERT(!SUBCHANNEL_UNREF_LOCKED(c, "connecting"));
+  elem =
+      grpc_channel_stack_element(CHANNEL_STACK_FROM_CONNECTION(c->active), 0);
+  elem->filter->start_transport_op(elem, &op);
+
+  /* signal completion */
+  connectivity_state_changed_locked(c);
+  while ((w4c = c->waiting)) {
+    c->waiting = w4c->next;
+    grpc_iomgr_add_callback(&w4c->continuation);
+  }
+
+  gpr_mu_unlock(&c->mu);
+
+  gpr_free(filters);
+
+  if (destroy_connection != NULL) {
+    connection_destroy(destroy_connection);
+  }
+}
+
+static void on_alarm(void *arg, int iomgr_success) {
+  grpc_subchannel *c = arg;
+  gpr_mu_lock(&c->mu);
+  c->have_alarm = 0;
+  if (c->disconnected) {
+    iomgr_success = 0;
+  }
+  connectivity_state_changed_locked(c);
+  gpr_mu_unlock(&c->mu);
+  if (iomgr_success) {
+    continue_connect(c);
+  } else {
+    GRPC_SUBCHANNEL_UNREF(c, "connecting");
+  }
+}
+
+static void subchannel_connected(void *arg, int iomgr_success) {
+  grpc_subchannel *c = arg;
+  if (c->connecting_result.transport != NULL) {
+    publish_transport(c);
+  } else {
+    gpr_mu_lock(&c->mu);
+    connectivity_state_changed_locked(c);
+    GPR_ASSERT(!c->have_alarm);
+    c->have_alarm = 1;
+    c->next_attempt = gpr_time_add(c->next_attempt, c->backoff_delta);
+    c->backoff_delta = gpr_time_add(c->backoff_delta, c->backoff_delta);
+    grpc_alarm_init(&c->alarm, c->next_attempt, on_alarm, c, gpr_now());
+    gpr_mu_unlock(&c->mu);
+  }
+}
+
+static gpr_timespec compute_connect_deadline(grpc_subchannel *c) {
+  return gpr_time_add(c->next_attempt, c->backoff_delta);
+}
+
+static grpc_connectivity_state compute_connectivity_locked(grpc_subchannel *c) {
+  if (c->disconnected) {
+    return GRPC_CHANNEL_FATAL_FAILURE;
+  }
+  if (c->connecting) {
+    if (c->have_alarm) {
+      return GRPC_CHANNEL_TRANSIENT_FAILURE;
+    }
+    return GRPC_CHANNEL_CONNECTING;
+  }
+  if (c->active) {
+    return GRPC_CHANNEL_READY;
+  }
+  return GRPC_CHANNEL_IDLE;
+}
+
+static void connectivity_state_changed_locked(grpc_subchannel *c) {
+  grpc_connectivity_state current = compute_connectivity_locked(c);
+  grpc_connectivity_state_set(&c->state_tracker, current);
+}
+
+/*
+ * grpc_subchannel_call implementation
+ */
+
+void grpc_subchannel_call_ref(
+    grpc_subchannel_call *c GRPC_SUBCHANNEL_REF_EXTRA_ARGS) {
+  gpr_ref(&c->refs);
+}
+
+void grpc_subchannel_call_unref(
+    grpc_subchannel_call *c GRPC_SUBCHANNEL_REF_EXTRA_ARGS) {
+  if (gpr_unref(&c->refs)) {
+    gpr_mu *mu = &c->connection->subchannel->mu;
+    grpc_subchannel *destroy;
+    grpc_call_stack_destroy(SUBCHANNEL_CALL_TO_CALL_STACK(c));
+    gpr_mu_lock(mu);
+    destroy = CONNECTION_UNREF_LOCKED(c->connection, "call");
+    gpr_mu_unlock(mu);
+    gpr_free(c);
+    if (destroy != NULL) {
+      subchannel_destroy(destroy);
+    }
+  }
+}
+
+void grpc_subchannel_call_process_op(grpc_subchannel_call *call,
+                                     grpc_transport_stream_op *op) {
+  grpc_call_stack *call_stack = SUBCHANNEL_CALL_TO_CALL_STACK(call);
+  grpc_call_element *top_elem = grpc_call_stack_element(call_stack, 0);
+  top_elem->filter->start_transport_stream_op(top_elem, op);
+}
+
+grpc_subchannel_call *create_call(connection *con) {
+  grpc_channel_stack *chanstk = CHANNEL_STACK_FROM_CONNECTION(con);
+  grpc_subchannel_call *call =
+      gpr_malloc(sizeof(grpc_subchannel_call) + chanstk->call_stack_size);
+  grpc_call_stack *callstk = SUBCHANNEL_CALL_TO_CALL_STACK(call);
+  call->connection = con;
+  gpr_ref_init(&call->refs, 1);
+  grpc_call_stack_init(chanstk, NULL, NULL, callstk);
+  return call;
+}
diff --git a/src/core/client_config/subchannel.h b/src/core/client_config/subchannel.h
new file mode 100644
index 0000000000..a23a623277
--- /dev/null
+++ b/src/core/client_config/subchannel.h
@@ -0,0 +1,124 @@
+/*
+ *
+ * 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.
+ *
+ */
+
+#ifndef GRPC_INTERNAL_CORE_CLIENT_CONFIG_SUBCHANNEL_H
+#define GRPC_INTERNAL_CORE_CLIENT_CONFIG_SUBCHANNEL_H
+
+#include "src/core/channel/channel_stack.h"
+#include "src/core/client_config/connector.h"
+
+/** A (sub-)channel that knows how to connect to exactly one target
+    address. Provides a target for load balancing. */
+typedef struct grpc_subchannel grpc_subchannel;
+typedef struct grpc_subchannel_call grpc_subchannel_call;
+typedef struct grpc_subchannel_args grpc_subchannel_args;
+
+#ifdef GRPC_SUBCHANNEL_REFCOUNT_DEBUG
+#define GRPC_SUBCHANNEL_REF(p, r) \
+  grpc_subchannel_ref((p), __FILE__, __LINE__, (r))
+#define GRPC_SUBCHANNEL_UNREF(p, r) \
+  grpc_subchannel_unref((p), __FILE__, __LINE__, (r))
+#define GRPC_SUBCHANNEL_CALL_REF(p, r) \
+  grpc_subchannel_call_ref((p), __FILE__, __LINE__, (r))
+#define GRPC_SUBCHANNEL_CALL_UNREF(p, r) \
+  grpc_subchannel_call_unref((p), __FILE__, __LINE__, (r))
+#define GRPC_SUBCHANNEL_REF_EXTRA_ARGS \
+  , const char *file, int line, const char *reason
+#else
+#define GRPC_SUBCHANNEL_REF(p, r) grpc_subchannel_ref((p))
+#define GRPC_SUBCHANNEL_UNREF(p, r) grpc_subchannel_unref((p))
+#define GRPC_SUBCHANNEL_CALL_REF(p, r) grpc_subchannel_call_ref((p))
+#define GRPC_SUBCHANNEL_CALL_UNREF(p, r) grpc_subchannel_call_unref((p))
+#define GRPC_SUBCHANNEL_REF_EXTRA_ARGS
+#endif
+
+void grpc_subchannel_ref(
+    grpc_subchannel *channel GRPC_SUBCHANNEL_REF_EXTRA_ARGS);
+void grpc_subchannel_unref(
+    grpc_subchannel *channel GRPC_SUBCHANNEL_REF_EXTRA_ARGS);
+void grpc_subchannel_call_ref(
+    grpc_subchannel_call *call GRPC_SUBCHANNEL_REF_EXTRA_ARGS);
+void grpc_subchannel_call_unref(
+    grpc_subchannel_call *call GRPC_SUBCHANNEL_REF_EXTRA_ARGS);
+
+/** construct a call (possibly asynchronously) */
+void grpc_subchannel_create_call(grpc_subchannel *subchannel,
+                                 grpc_pollset *pollset,
+                                 grpc_subchannel_call **target,
+                                 grpc_iomgr_closure *notify);
+
+/** process a transport level op */
+void grpc_subchannel_process_transport_op(grpc_subchannel *subchannel,
+                                          grpc_transport_op *op);
+
+/** poll the current connectivity state of a channel */
+grpc_connectivity_state grpc_subchannel_check_connectivity(
+    grpc_subchannel *channel);
+
+/** call notify when the connectivity state of a channel changes from *state.
+    Updates *state with the new state of the channel */
+void grpc_subchannel_notify_on_state_change(grpc_subchannel *channel,
+                                            grpc_connectivity_state *state,
+                                            grpc_iomgr_closure *notify);
+
+void grpc_subchannel_add_interested_party(grpc_subchannel *channel,
+                                          grpc_pollset *pollset);
+void grpc_subchannel_del_interested_party(grpc_subchannel *channel,
+                                          grpc_pollset *pollset);
+
+/** continue processing a transport op */
+void grpc_subchannel_call_process_op(grpc_subchannel_call *subchannel_call,
+                                     grpc_transport_stream_op *op);
+
+struct grpc_subchannel_args {
+  /** Channel filters for this channel - wrapped factories will likely
+      want to mutate this */
+  const grpc_channel_filter **filters;
+  /** The number of filters in the above array */
+  size_t filter_count;
+  /** Channel arguments to be supplied to the newly created channel */
+  const grpc_channel_args *args;
+  /** Address to connect to */
+  struct sockaddr *addr;
+  size_t addr_len;
+  /** metadata context to use */
+  grpc_mdctx *mdctx;
+  /** master channel */
+  grpc_channel *master;
+};
+
+/** create a subchannel given a connector */
+grpc_subchannel *grpc_subchannel_create(grpc_connector *connector,
+                                        grpc_subchannel_args *args);
+
+#endif /* GRPC_INTERNAL_CORE_CLIENT_CONFIG_SUBCHANNEL_H */
diff --git a/src/core/client_config/subchannel_factory.c b/src/core/client_config/subchannel_factory.c
new file mode 100644
index 0000000000..f71386594c
--- /dev/null
+++ b/src/core/client_config/subchannel_factory.c
@@ -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.
+ *
+ */
+
+#include "src/core/client_config/subchannel_factory.h"
+
+void grpc_subchannel_factory_ref(grpc_subchannel_factory *factory) {
+  factory->vtable->ref(factory);
+}
+void grpc_subchannel_factory_unref(grpc_subchannel_factory *factory) {
+  factory->vtable->unref(factory);
+}
+
+grpc_subchannel *grpc_subchannel_factory_create_subchannel(
+    grpc_subchannel_factory *factory, grpc_subchannel_args *args) {
+  return factory->vtable->create_subchannel(factory, args);
+}
diff --git a/src/core/channel/child_channel.h b/src/core/client_config/subchannel_factory.h
index 556a1c731c..d7eae1c964 100644
--- a/src/core/channel/child_channel.h
+++ b/src/core/client_config/subchannel_factory.h
@@ -31,35 +31,33 @@
  *
  */
 
-#ifndef GRPC_INTERNAL_CORE_CHANNEL_CHILD_CHANNEL_H
-#define GRPC_INTERNAL_CORE_CHANNEL_CHILD_CHANNEL_H
+#ifndef GRPC_INTERNAL_CORE_CLIENT_CONFIG_SUBCHANNEL_FACTORY_H
+#define GRPC_INTERNAL_CORE_CLIENT_CONFIG_SUBCHANNEL_FACTORY_H
 
 #include "src/core/channel/channel_stack.h"
+#include "src/core/client_config/subchannel.h"
 
-/* helper for filters that need to host child channel stacks... handles
-   lifetime and upwards propagation cleanly */
+typedef struct grpc_subchannel_factory grpc_subchannel_factory;
+typedef struct grpc_subchannel_factory_vtable grpc_subchannel_factory_vtable;
 
-extern const grpc_channel_filter grpc_child_channel_top_filter;
+/** Constructor for new configured channels.
+    Creating decorators around this type is encouraged to adapt behavior. */
+struct grpc_subchannel_factory {
+  const grpc_subchannel_factory_vtable *vtable;
+};
 
-typedef grpc_channel_stack grpc_child_channel;
-typedef grpc_call_stack grpc_child_call;
+struct grpc_subchannel_factory_vtable {
+  void (*ref)(grpc_subchannel_factory *factory);
+  void (*unref)(grpc_subchannel_factory *factory);
+  grpc_subchannel *(*create_subchannel)(grpc_subchannel_factory *factory,
+                                        grpc_subchannel_args *args);
+};
 
-/* filters[0] must be &grpc_child_channel_top_filter */
-grpc_child_channel *grpc_child_channel_create(
-    grpc_channel_element *parent, const grpc_channel_filter **filters,
-    size_t filter_count, const grpc_channel_args *args,
-    grpc_mdctx *metadata_context);
-void grpc_child_channel_handle_op(grpc_child_channel *channel,
-                                  grpc_channel_op *op);
-grpc_channel_element *grpc_child_channel_get_bottom_element(
-    grpc_child_channel *channel);
-void grpc_child_channel_destroy(grpc_child_channel *channel,
-                                int wait_for_callbacks);
+void grpc_subchannel_factory_ref(grpc_subchannel_factory *factory);
+void grpc_subchannel_factory_unref(grpc_subchannel_factory *factory);
 
-grpc_child_call *grpc_child_channel_create_call(grpc_child_channel *channel,
-                                                grpc_call_element *parent,
-                                                grpc_transport_op *initial_op);
-grpc_call_element *grpc_child_call_get_top_element(grpc_child_call *call);
-void grpc_child_call_destroy(grpc_child_call *call);
+/** Create a new grpc_subchannel */
+grpc_subchannel *grpc_subchannel_factory_create_subchannel(
+    grpc_subchannel_factory *factory, grpc_subchannel_args *args);
 
-#endif /* GRPC_INTERNAL_CORE_CHANNEL_CHILD_CHANNEL_H */
+#endif /* GRPC_INTERNAL_CORE_CLIENT_CONFIG_SUBCHANNEL_FACTORY_H */
diff --git a/src/core/client_config/uri_parser.c b/src/core/client_config/uri_parser.c
new file mode 100644
index 0000000000..776a255923
--- /dev/null
+++ b/src/core/client_config/uri_parser.c
@@ -0,0 +1,149 @@
+/*
+ *
+ * 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.
+ *
+ */
+
+#include "src/core/client_config/uri_parser.h"
+
+#include <string.h>
+
+#include <grpc/support/alloc.h>
+#include <grpc/support/log.h>
+#include <grpc/support/string_util.h>
+
+static grpc_uri *bad_uri(const char *uri_text, int pos, const char *section,
+                         int suppress_errors) {
+  char *line_prefix;
+  int pfx_len;
+
+  if (!suppress_errors) {
+    gpr_asprintf(&line_prefix, "bad uri.%s: '", section);
+    pfx_len = strlen(line_prefix) + pos;
+    gpr_log(GPR_ERROR, "%s%s'", line_prefix, uri_text);
+    gpr_free(line_prefix);
+
+    line_prefix = gpr_malloc(pfx_len + 1);
+    memset(line_prefix, ' ', pfx_len);
+    line_prefix[pfx_len] = 0;
+    gpr_log(GPR_ERROR, "%s^ here", line_prefix);
+    gpr_free(line_prefix);
+  }
+
+  return NULL;
+}
+
+static char *copy_fragment(const char *src, int begin, int end) {
+  char *out = gpr_malloc(end - begin + 1);
+  memcpy(out, src + begin, end - begin);
+  out[end - begin] = 0;
+  return out;
+}
+
+grpc_uri *grpc_uri_parse(const char *uri_text, int suppress_errors) {
+  grpc_uri *uri;
+  int scheme_begin = 0;
+  int scheme_end = -1;
+  int authority_begin = -1;
+  int authority_end = -1;
+  int path_begin = -1;
+  int path_end = -1;
+  int i;
+
+  for (i = scheme_begin; uri_text[i] != 0; i++) {
+    if (uri_text[i] == ':') {
+      scheme_end = i;
+      break;
+    }
+    if (uri_text[i] >= 'a' && uri_text[i] <= 'z') continue;
+    if (uri_text[i] >= 'A' && uri_text[i] <= 'Z') continue;
+    if (i != scheme_begin) {
+      if (uri_text[i] >= '0' && uri_text[i] <= '9') continue;
+      if (uri_text[i] == '+') continue;
+      if (uri_text[i] == '-') continue;
+      if (uri_text[i] == '.') continue;
+    }
+    break;
+  }
+  if (scheme_end == -1) {
+    return bad_uri(uri_text, i, "scheme", suppress_errors);
+  }
+
+  if (uri_text[scheme_end + 1] == '/' && uri_text[scheme_end + 2] == '/') {
+    authority_begin = scheme_end + 3;
+    for (i = authority_begin; uri_text[i] != 0; i++) {
+      if (uri_text[i] == '/') {
+        authority_end = i;
+      }
+      if (uri_text[i] == '?') {
+        return bad_uri(uri_text, i, "query_not_supported", suppress_errors);
+      }
+      if (uri_text[i] == '#') {
+        return bad_uri(uri_text, i, "fragment_not_supported", suppress_errors);
+      }
+    }
+    if (authority_end == -1 && uri_text[i] == 0) {
+      authority_end = i;
+    }
+    if (authority_end == -1) {
+      return bad_uri(uri_text, i, "authority", suppress_errors);
+    }
+    /* TODO(ctiller): parse the authority correctly */
+    path_begin = authority_end;
+  } else {
+    path_begin = scheme_end + 1;
+  }
+
+  for (i = path_begin; uri_text[i] != 0; i++) {
+    if (uri_text[i] == '?') {
+      return bad_uri(uri_text, i, "query_not_supported", suppress_errors);
+    }
+    if (uri_text[i] == '#') {
+      return bad_uri(uri_text, i, "fragment_not_supported", suppress_errors);
+    }
+  }
+  path_end = i;
+
+  uri = gpr_malloc(sizeof(*uri));
+  memset(uri, 0, sizeof(*uri));
+  uri->scheme = copy_fragment(uri_text, scheme_begin, scheme_end);
+  uri->authority = copy_fragment(uri_text, authority_begin, authority_end);
+  uri->path = copy_fragment(uri_text, path_begin, path_end);
+
+  return uri;
+}
+
+void grpc_uri_destroy(grpc_uri *uri) {
+  if (!uri) return;
+  gpr_free(uri->scheme);
+  gpr_free(uri->authority);
+  gpr_free(uri->path);
+  gpr_free(uri);
+}
diff --git a/src/core/client_config/uri_parser.h b/src/core/client_config/uri_parser.h
new file mode 100644
index 0000000000..ce4e6aecb0
--- /dev/null
+++ b/src/core/client_config/uri_parser.h
@@ -0,0 +1,49 @@
+/*
+ *
+ * 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.
+ *
+ */
+
+#ifndef GRPC_INTERNAL_CORE_CLIENT_CONFIG_URI_PARSER_H
+#define GRPC_INTERNAL_CORE_CLIENT_CONFIG_URI_PARSER_H
+
+typedef struct {
+  char *scheme;
+  char *authority;
+  char *path;
+} grpc_uri;
+
+/** parse a uri, return NULL on failure */
+grpc_uri *grpc_uri_parse(const char *uri_text, int suppress_errors);
+
+/** destroy a uri */
+void grpc_uri_destroy(grpc_uri *uri);
+
+#endif
diff --git a/src/core/httpcli/httpcli.c b/src/core/httpcli/httpcli.c
index 914355a408..3f5557e08e 100644
--- a/src/core/httpcli/httpcli.c
+++ b/src/core/httpcli/httpcli.c
@@ -198,7 +198,7 @@ static void on_connected(void *arg, grpc_endpoint *tcp) {
                GRPC_SECURITY_OK);
     grpc_setup_secure_transport(&sc->base, tcp, on_secure_transport_setup_done,
                                 req);
-    grpc_security_connector_unref(&sc->base);
+    GRPC_SECURITY_CONNECTOR_UNREF(&sc->base, "httpcli");
   } else {
     start_write(req);
   }
diff --git a/src/core/iomgr/alarm.h b/src/core/iomgr/alarm.h
index e5262e2199..c067a0b8a3 100644
--- a/src/core/iomgr/alarm.h
+++ b/src/core/iomgr/alarm.h
@@ -41,9 +41,9 @@
 typedef struct grpc_alarm {
   gpr_timespec deadline;
   gpr_uint32 heap_index; /* INVALID_HEAP_INDEX if not in heap */
+  int triggered;
   struct grpc_alarm *next;
   struct grpc_alarm *prev;
-  int triggered;
   grpc_iomgr_cb_func cb;
   void *cb_arg;
 } grpc_alarm;
diff --git a/src/core/iomgr/fd_posix.c b/src/core/iomgr/fd_posix.c
index 632d2a4609..6ad377ce1c 100644
--- a/src/core/iomgr/fd_posix.c
+++ b/src/core/iomgr/fd_posix.c
@@ -116,7 +116,7 @@ static void destroy(grpc_fd *fd) {
 #define UNREF_BY(fd, n, reason) unref_by(fd, n, reason, __FILE__, __LINE__)
 static void ref_by(grpc_fd *fd, int n, const char *reason, const char *file,
                    int line) {
-  gpr_log(GPR_DEBUG, "FD %d %p  ref %d %d -> %d [%s; %s:%d]", fd->fd, fd, n,
+  gpr_log(GPR_DEBUG, "FD %d %p   ref %d %d -> %d [%s; %s:%d]", fd->fd, fd, n,
           gpr_atm_no_barrier_load(&fd->refst),
           gpr_atm_no_barrier_load(&fd->refst) + n, reason, file, line);
 #else
@@ -198,7 +198,8 @@ static void wake_all_watchers_locked(grpc_fd *fd) {
 }
 
 static int has_watchers(grpc_fd *fd) {
-  return fd->read_watcher != NULL || fd->write_watcher != NULL || fd->inactive_watcher_root.next != &fd->inactive_watcher_root;
+  return fd->read_watcher != NULL || fd->write_watcher != NULL ||
+         fd->inactive_watcher_root.next != &fd->inactive_watcher_root;
 }
 
 void grpc_fd_orphan(grpc_fd *fd, grpc_iomgr_closure *on_done,
diff --git a/src/core/iomgr/iocp_windows.h b/src/core/iomgr/iocp_windows.h
index 4503fdd55e..9df6476917 100644
--- a/src/core/iomgr/iocp_windows.h
+++ b/src/core/iomgr/iocp_windows.h
@@ -34,7 +34,6 @@
 #ifndef GRPC_INTERNAL_CORE_IOMGR_IOCP_WINDOWS_H
 #define GRPC_INTERNAL_CORE_IOMGR_IOCP_WINDOWS_H
 
-#include <windows.h>
 #include <grpc/support/sync.h>
 
 #include "src/core/iomgr/socket_windows.h"
diff --git a/src/core/iomgr/iomgr.c b/src/core/iomgr/iomgr.c
index c47528aa94..c507e7c26a 100644
--- a/src/core/iomgr/iomgr.c
+++ b/src/core/iomgr/iomgr.c
@@ -158,7 +158,7 @@ void grpc_iomgr_shutdown(void) {
                 "memory leaks are likely",
                 count_objects());
         for (obj = g_root_object.next; obj != &g_root_object; obj = obj->next) {
-          gpr_log(GPR_DEBUG, "LEAKED OBJECT: %s", obj->name);
+          gpr_log(GPR_DEBUG, "LEAKED OBJECT: %s %p", obj->name, obj);
         }
         break;
       }
@@ -177,8 +177,8 @@ void grpc_iomgr_shutdown(void) {
 }
 
 void grpc_iomgr_register_object(grpc_iomgr_object *obj, const char *name) {
-  gpr_mu_lock(&g_mu);
   obj->name = gpr_strdup(name);
+  gpr_mu_lock(&g_mu);
   obj->next = &g_root_object;
   obj->prev = obj->next->prev;
   obj->next->prev = obj->prev->next = obj;
@@ -189,9 +189,9 @@ void grpc_iomgr_unregister_object(grpc_iomgr_object *obj) {
   gpr_mu_lock(&g_mu);
   obj->next->prev = obj->prev;
   obj->prev->next = obj->next;
-  gpr_free(obj->name);
   gpr_cv_signal(&g_rcv);
   gpr_mu_unlock(&g_mu);
+  gpr_free(obj->name);
 }
 
 void grpc_iomgr_closure_init(grpc_iomgr_closure *closure, grpc_iomgr_cb_func cb,
@@ -201,9 +201,21 @@ void grpc_iomgr_closure_init(grpc_iomgr_closure *closure, grpc_iomgr_cb_func cb,
   closure->next = NULL;
 }
 
+static void assert_not_scheduled_locked(grpc_iomgr_closure *closure) {
+#ifndef NDEBUG
+  grpc_iomgr_closure *c;
+
+  for (c = g_cbs_head; c; c = c->next) {
+    GPR_ASSERT(c != closure);
+  }
+#endif
+}
+
 void grpc_iomgr_add_delayed_callback(grpc_iomgr_closure *closure, int success) {
   closure->success = success;
+  GPR_ASSERT(closure->cb);
   gpr_mu_lock(&g_mu);
+  assert_not_scheduled_locked(closure);
   closure->next = NULL;
   if (!g_cbs_tail) {
     g_cbs_head = g_cbs_tail = closure;
diff --git a/src/core/iomgr/pollset_posix.c b/src/core/iomgr/pollset_posix.c
index 15ed8e75e6..12496440de 100644
--- a/src/core/iomgr/pollset_posix.c
+++ b/src/core/iomgr/pollset_posix.c
@@ -249,7 +249,8 @@ static void basic_do_promote(void *args, int success) {
   pollset->in_flight_cbs--;
   if (pollset->shutting_down) {
     /* We don't care about this pollset anymore. */
-    if (pollset->in_flight_cbs == 0 && pollset->counter == 0) {
+    if (pollset->in_flight_cbs == 0 && pollset->counter == 0 && !pollset->called_shutdown) {
+      pollset->called_shutdown = 1;
       do_shutdown_cb = 1;
     }
   } else if (grpc_fd_is_orphaned(fd)) {
diff --git a/src/core/iomgr/pollset_set_posix.c b/src/core/iomgr/pollset_set_posix.c
index 005e938398..5ff7df1dcd 100644
--- a/src/core/iomgr/pollset_set_posix.c
+++ b/src/core/iomgr/pollset_set_posix.c
@@ -114,7 +114,7 @@ void grpc_pollset_set_del_fd(grpc_pollset_set *pollset_set, grpc_fd *fd) {
     if (pollset_set->fds[i] == fd) {
       pollset_set->fd_count--;
       GPR_SWAP(grpc_fd *, pollset_set->fds[i],
-               pollset_set->fds[pollset_set->pollset_count]);
+               pollset_set->fds[pollset_set->fd_count]);
       GRPC_FD_UNREF(fd, "pollset_set");
       break;
     }
diff --git a/src/core/iomgr/pollset_windows.h b/src/core/iomgr/pollset_windows.h
index 57a2907926..c9b8d3f374 100644
--- a/src/core/iomgr/pollset_windows.h
+++ b/src/core/iomgr/pollset_windows.h
@@ -34,7 +34,6 @@
 #ifndef GRPC_INTERNAL_CORE_IOMGR_POLLSET_WINDOWS_H
 #define GRPC_INTERNAL_CORE_IOMGR_POLLSET_WINDOWS_H
 
-#include <windows.h>
 #include <grpc/support/sync.h>
 
 #include "src/core/iomgr/socket_windows.h"
diff --git a/src/core/iomgr/sockaddr_win32.h b/src/core/iomgr/sockaddr_win32.h
index c0385ea614..be55db805a 100644
--- a/src/core/iomgr/sockaddr_win32.h
+++ b/src/core/iomgr/sockaddr_win32.h
@@ -34,8 +34,8 @@
 #ifndef GRPC_INTERNAL_CORE_IOMGR_SOCKADDR_WIN32_H
 #define GRPC_INTERNAL_CORE_IOMGR_SOCKADDR_WIN32_H
 
-#include <ws2tcpip.h>
 #include <winsock2.h>
+#include <ws2tcpip.h>
 #include <mswsock.h>
 
 #ifdef __MINGW32__
diff --git a/src/core/iomgr/socket_windows.h b/src/core/iomgr/socket_windows.h
index 7080919af0..346fde8edd 100644
--- a/src/core/iomgr/socket_windows.h
+++ b/src/core/iomgr/socket_windows.h
@@ -34,7 +34,8 @@
 #ifndef GRPC_INTERNAL_CORE_IOMGR_SOCKET_WINDOWS_H
 #define GRPC_INTERNAL_CORE_IOMGR_SOCKET_WINDOWS_H
 
-#include <windows.h>
+#include <grpc/support/port_platform.h>
+#include <winsock2.h>
 
 #include <grpc/support/sync.h>
 #include <grpc/support/atm.h>
diff --git a/src/core/iomgr/tcp_client_posix.c b/src/core/iomgr/tcp_client_posix.c
index bbf7711588..d981aaf028 100644
--- a/src/core/iomgr/tcp_client_posix.c
+++ b/src/core/iomgr/tcp_client_posix.c
@@ -63,6 +63,7 @@ typedef struct {
   grpc_alarm alarm;
   int refs;
   grpc_iomgr_closure write_closure;
+  grpc_pollset_set *interested_parties;
 } async_connect;
 
 static int prepare_socket(const struct sockaddr *addr, int fd) {
@@ -152,6 +153,7 @@ static void on_writable(void *acp, int success) {
         goto finish;
       }
     } else {
+      grpc_pollset_set_del_fd(ac->interested_parties, ac->fd);
       ep = grpc_tcp_create(ac->fd, GRPC_TCP_DEFAULT_READ_SLICE_SIZE);
       goto finish;
     }
@@ -165,6 +167,7 @@ static void on_writable(void *acp, int success) {
 finish:
   gpr_mu_lock(&ac->mu);
   if (!ep) {
+    grpc_pollset_set_del_fd(ac->interested_parties, ac->fd);
     grpc_fd_orphan(ac->fd, NULL, "tcp_client_orphan");
   }
   done = (--ac->refs == 0);
@@ -240,6 +243,7 @@ void grpc_tcp_client_connect(void (*cb)(void *arg, grpc_endpoint *ep),
   ac->cb = cb;
   ac->cb_arg = arg;
   ac->fd = fdobj;
+  ac->interested_parties = interested_parties;
   gpr_mu_init(&ac->mu);
   ac->refs = 2;
   ac->write_closure.cb = on_writable;
diff --git a/src/core/security/client_auth_filter.c b/src/core/security/client_auth_filter.c
index e9bd45db68..f8d18d9b17 100644
--- a/src/core/security/client_auth_filter.c
+++ b/src/core/security/client_auth_filter.c
@@ -58,7 +58,7 @@ typedef struct {
      so that work can progress when this call wants work to
      progress */
   grpc_pollset *pollset;
-  grpc_transport_op op;
+  grpc_transport_stream_op op;
   size_t op_md_idx;
   int sent_initial_metadata;
   grpc_linked_mdelem md_links[MAX_CREDENTIALS_METADATA_COUNT];
@@ -77,7 +77,7 @@ typedef struct {
 static void bubble_up_error(grpc_call_element *elem, const char *error_msg) {
   call_data *calld = elem->call_data;
   channel_data *chand = elem->channel_data;
-  grpc_transport_op_add_cancellation(
+  grpc_transport_stream_op_add_cancellation(
       &calld->op, GRPC_STATUS_UNAUTHENTICATED,
       grpc_mdstr_from_string(chand->md_ctx, error_msg));
   grpc_call_next_op(elem, &calld->op);
@@ -90,7 +90,7 @@ static void on_credentials_metadata(void *user_data,
   grpc_call_element *elem = (grpc_call_element *)user_data;
   call_data *calld = elem->call_data;
   channel_data *chand = elem->channel_data;
-  grpc_transport_op *op = &calld->op;
+  grpc_transport_stream_op *op = &calld->op;
   grpc_metadata_batch *mdb;
   size_t i;
   if (status != GRPC_CREDENTIALS_OK) {
@@ -131,7 +131,7 @@ static char *build_service_url(const char *url_scheme, call_data *calld) {
 }
 
 static void send_security_metadata(grpc_call_element *elem,
-                                   grpc_transport_op *op) {
+                                   grpc_transport_stream_op *op) {
   call_data *calld = elem->call_data;
   channel_data *chand = elem->channel_data;
   grpc_client_security_context *ctx =
@@ -193,7 +193,7 @@ static void on_host_checked(void *user_data, grpc_security_status status) {
    op contains type and call direction information, in addition to the data
    that is being sent or received. */
 static void auth_start_transport_op(grpc_call_element *elem,
-                                    grpc_transport_op *op) {
+                                    grpc_transport_stream_op *op) {
   /* grab pointers to our data from the call element */
   call_data *calld = elem->call_data;
   channel_data *chand = elem->channel_data;
@@ -253,17 +253,10 @@ static void auth_start_transport_op(grpc_call_element *elem,
   grpc_call_next_op(elem, op);
 }
 
-/* Called on special channel events, such as disconnection or new incoming
-   calls on the server */
-static void channel_op(grpc_channel_element *elem,
-                       grpc_channel_element *from_elem, grpc_channel_op *op) {
-  grpc_channel_next_op(elem, op);
-}
-
 /* Constructor for call_data */
 static void init_call_elem(grpc_call_element *elem,
                            const void *server_transport_data,
-                           grpc_transport_op *initial_op) {
+                           grpc_transport_stream_op *initial_op) {
   call_data *calld = elem->call_data;
   calld->creds = NULL;
   calld->host = NULL;
@@ -287,7 +280,7 @@ static void destroy_call_elem(grpc_call_element *elem) {
 }
 
 /* Constructor for channel_data */
-static void init_channel_elem(grpc_channel_element *elem,
+static void init_channel_elem(grpc_channel_element *elem, grpc_channel *master,
                               const grpc_channel_args *args,
                               grpc_mdctx *metadata_context, int is_first,
                               int is_last) {
@@ -298,14 +291,14 @@ static void init_channel_elem(grpc_channel_element *elem,
   /* The first and the last filters tend to be implemented differently to
      handle the case that there's no 'next' filter to call on the up or down
      path */
-  GPR_ASSERT(!is_first);
   GPR_ASSERT(!is_last);
   GPR_ASSERT(sc != NULL);
 
   /* initialize members */
   GPR_ASSERT(sc->is_client_side);
   chand->security_connector =
-      (grpc_channel_security_connector *)grpc_security_connector_ref(sc);
+      (grpc_channel_security_connector *)GRPC_SECURITY_CONNECTOR_REF(
+          sc, "client_auth_filter");
   chand->md_ctx = metadata_context;
   chand->authority_string = grpc_mdstr_from_string(chand->md_ctx, ":authority");
   chand->path_string = grpc_mdstr_from_string(chand->md_ctx, ":path");
@@ -318,7 +311,8 @@ static void destroy_channel_elem(grpc_channel_element *elem) {
   /* grab pointers to our data from the channel element */
   channel_data *chand = elem->channel_data;
   grpc_channel_security_connector *ctx = chand->security_connector;
-  if (ctx != NULL) grpc_security_connector_unref(&ctx->base);
+  if (ctx != NULL)
+    GRPC_SECURITY_CONNECTOR_UNREF(&ctx->base, "client_auth_filter");
   if (chand->authority_string != NULL) {
     grpc_mdstr_unref(chand->authority_string);
   }
@@ -334,6 +328,6 @@ static void destroy_channel_elem(grpc_channel_element *elem) {
 }
 
 const grpc_channel_filter grpc_client_auth_filter = {
-    auth_start_transport_op, channel_op,           sizeof(call_data),
+    auth_start_transport_op, grpc_channel_next_op, sizeof(call_data),
     init_call_elem,          destroy_call_elem,    sizeof(channel_data),
     init_channel_elem,       destroy_channel_elem, "client-auth"};
diff --git a/src/core/security/credentials.c b/src/core/security/credentials.c
index cf663faf2d..e79e9ce351 100644
--- a/src/core/security/credentials.c
+++ b/src/core/security/credentials.c
@@ -225,7 +225,7 @@ static grpc_security_status ssl_create_security_connector(
   arg.type = GRPC_ARG_STRING;
   arg.key = GRPC_ARG_HTTP2_SCHEME;
   arg.value.string = "https";
-  *new_args = grpc_channel_args_copy_and_add(args, &arg);
+  *new_args = grpc_channel_args_copy_and_add(args, &arg, 1);
   return status;
 }
 
diff --git a/src/core/security/secure_transport_setup.c b/src/core/security/secure_transport_setup.c
index 1b39ab141e..731b382f09 100644
--- a/src/core/security/secure_transport_setup.c
+++ b/src/core/security/secure_transport_setup.c
@@ -74,7 +74,7 @@ static void secure_transport_setup_done(grpc_secure_transport_setup *s,
   if (s->handshaker != NULL) tsi_handshaker_destroy(s->handshaker);
   if (s->handshake_buffer != NULL) gpr_free(s->handshake_buffer);
   gpr_slice_buffer_destroy(&s->left_overs);
-  grpc_security_connector_unref(s->connector);
+  GRPC_SECURITY_CONNECTOR_UNREF(s->connector, "secure_transport_setup");
   gpr_free(s);
 }
 
@@ -234,8 +234,9 @@ static void on_handshake_data_received_from_peer(
                          gpr_slice_split_tail(&slices[i], consumed_slice_size));
     gpr_slice_unref(slices[i]); /* split_tail above increments refcount. */
   }
-  gpr_slice_buffer_addn(&s->left_overs, &slices[i + 1],
-                        num_left_overs - (size_t)has_left_overs_in_current_slice);
+  gpr_slice_buffer_addn(
+      &s->left_overs, &slices[i + 1],
+      num_left_overs - (size_t)has_left_overs_in_current_slice);
   check_peer(s);
 }
 
@@ -275,7 +276,8 @@ void grpc_setup_secure_transport(grpc_security_connector *connector,
     secure_transport_setup_done(s, 0);
     return;
   }
-  s->connector = grpc_security_connector_ref(connector);
+  s->connector =
+      GRPC_SECURITY_CONNECTOR_REF(connector, "secure_transport_setup");
   s->handshake_buffer_size = GRPC_INITIAL_HANDSHAKE_BUFFER_SIZE;
   s->handshake_buffer = gpr_malloc(s->handshake_buffer_size);
   s->endpoint = nonsecure_endpoint;
diff --git a/src/core/security/security_connector.c b/src/core/security/security_connector.c
index 34cb0395a2..f6e423eb27 100644
--- a/src/core/security/security_connector.c
+++ b/src/core/security/security_connector.c
@@ -84,12 +84,12 @@ static const char *ssl_cipher_suites(void) {
 /* -- Common methods. -- */
 
 /* Returns the first property with that name. */
-const tsi_peer_property *tsi_peer_get_property_by_name(
-    const tsi_peer *peer, const char *name) {
+const tsi_peer_property *tsi_peer_get_property_by_name(const tsi_peer *peer,
+                                                       const char *name) {
   size_t i;
   if (peer == NULL) return NULL;
   for (i = 0; i < peer->property_count; i++) {
-    const tsi_peer_property* property = &peer->properties[i];
+    const tsi_peer_property *property = &peer->properties[i];
     if (name == NULL && property->name == NULL) {
       return property;
     }
@@ -124,24 +124,44 @@ grpc_security_status grpc_channel_security_connector_check_call_host(
   return sc->check_call_host(sc, host, cb, user_data);
 }
 
-void grpc_security_connector_unref(grpc_security_connector *sc) {
-  if (sc == NULL) return;
-  if (gpr_unref(&sc->refcount)) sc->vtable->destroy(sc);
-}
-
+#ifdef GRPC_SECURITY_CONNECTOR_REFCOUNT_DEBUG
+grpc_security_connector *grpc_security_connector_ref(
+    grpc_security_connector *sc, const char *file, int line,
+    const char *reason) {
+  if (sc == NULL) return NULL;
+  gpr_log(file, line, GPR_LOG_SEVERITY_DEBUG,
+          "SECURITY_CONNECTOR:%p   ref %d -> %d %s", sc,
+          (int)sc->refcount.count, (int)sc->refcount.count + 1, reason);
+#else
 grpc_security_connector *grpc_security_connector_ref(
     grpc_security_connector *sc) {
   if (sc == NULL) return NULL;
+#endif
   gpr_ref(&sc->refcount);
   return sc;
 }
 
+#ifdef GRPC_SECURITY_CONNECTOR_REFCOUNT_DEBUG
+void grpc_security_connector_unref(grpc_security_connector *sc,
+                                   const char *file, int line,
+                                   const char *reason) {
+  if (sc == NULL) return;
+  gpr_log(file, line, GPR_LOG_SEVERITY_DEBUG,
+          "SECURITY_CONNECTOR:%p unref %d -> %d %s", sc,
+          (int)sc->refcount.count, (int)sc->refcount.count - 1, reason);
+#else
+void grpc_security_connector_unref(grpc_security_connector *sc) {
+  if (sc == NULL) return;
+#endif
+  if (gpr_unref(&sc->refcount)) sc->vtable->destroy(sc);
+}
+
 static void connector_pointer_arg_destroy(void *p) {
-  grpc_security_connector_unref(p);
+  GRPC_SECURITY_CONNECTOR_UNREF(p, "connector_pointer_arg");
 }
 
 static void *connector_pointer_arg_copy(void *p) {
-  return grpc_security_connector_ref(p);
+  return GRPC_SECURITY_CONNECTOR_REF(p, "connector_pointer_arg");
 }
 
 grpc_arg grpc_security_connector_to_arg(grpc_security_connector *sc) {
@@ -580,7 +600,8 @@ grpc_security_status grpc_ssl_channel_security_connector_create(
       config->pem_private_key, config->pem_private_key_size,
       config->pem_cert_chain, config->pem_cert_chain_size, pem_root_certs,
       pem_root_certs_size, ssl_cipher_suites(), alpn_protocol_strings,
-      alpn_protocol_string_lengths, (uint16_t)num_alpn_protocols, &c->handshaker_factory);
+      alpn_protocol_string_lengths, (uint16_t)num_alpn_protocols,
+      &c->handshaker_factory);
   if (result != TSI_OK) {
     gpr_log(GPR_ERROR, "Handshaker factory creation failed with %s.",
             tsi_result_to_string(result));
@@ -633,8 +654,8 @@ grpc_security_status grpc_ssl_server_security_connector_create(
       (const unsigned char **)config->pem_cert_chains,
       config->pem_cert_chains_sizes, config->num_key_cert_pairs,
       config->pem_root_certs, config->pem_root_certs_size, ssl_cipher_suites(),
-      alpn_protocol_strings, alpn_protocol_string_lengths, (uint16_t)num_alpn_protocols,
-      &c->handshaker_factory);
+      alpn_protocol_strings, alpn_protocol_string_lengths,
+      (uint16_t)num_alpn_protocols, &c->handshaker_factory);
   if (result != TSI_OK) {
     gpr_log(GPR_ERROR, "Handshaker factory creation failed with %s.",
             tsi_result_to_string(result));
diff --git a/src/core/security/security_connector.h b/src/core/security/security_connector.h
index ee3057b43b..a4c723f026 100644
--- a/src/core/security/security_connector.h
+++ b/src/core/security/security_connector.h
@@ -80,12 +80,25 @@ struct grpc_security_connector {
   grpc_auth_context *auth_context; /* Populated after the peer is checked. */
 };
 
-/* Increments the refcount. */
+/* Refcounting. */
+#ifdef GRPC_SECURITY_CONNECTOR_REFCOUNT_DEBUG
+#define GRPC_SECURITY_CONNECTOR_REF(p, r) \
+  grpc_security_connector_ref((p), __FILE__, __LINE__, (r))
+#define GRPC_SECURITY_CONNECTOR_UNREF(p, r) \
+  grpc_security_connector_unref((p), __FILE__, __LINE__, (r))
 grpc_security_connector *grpc_security_connector_ref(
-    grpc_security_connector *sc);
-
-/* Decrements the refcount and destroys the object if it reaches 0. */
-void grpc_security_connector_unref(grpc_security_connector *sc);
+    grpc_security_connector *policy, const char *file, int line,
+    const char *reason);
+void grpc_security_connector_unref(grpc_security_connector *policy,
+                                   const char *file, int line,
+                                   const char *reason);
+#else
+#define GRPC_SECURITY_CONNECTOR_REF(p, r) grpc_security_connector_ref((p))
+#define GRPC_SECURITY_CONNECTOR_UNREF(p, r) grpc_security_connector_unref((p))
+grpc_security_connector *grpc_security_connector_ref(
+    grpc_security_connector *policy);
+void grpc_security_connector_unref(grpc_security_connector *policy);
+#endif
 
 /* Handshake creation. */
 grpc_security_status grpc_security_connector_create_handshaker(
@@ -172,9 +185,9 @@ typedef struct {
   specific error code otherwise.
 */
 grpc_security_status grpc_ssl_channel_security_connector_create(
-    grpc_credentials *request_metadata_creds,
-    const grpc_ssl_config *config, const char *target_name,
-    const char *overridden_target_name, grpc_channel_security_connector **sc);
+    grpc_credentials *request_metadata_creds, const grpc_ssl_config *config,
+    const char *target_name, const char *overridden_target_name,
+    grpc_channel_security_connector **sc);
 
 /* Gets the default ssl roots. */
 size_t grpc_get_default_ssl_roots(const unsigned char **pem_root_certs);
@@ -200,8 +213,8 @@ grpc_security_status grpc_ssl_server_security_connector_create(
     const grpc_ssl_server_config *config, grpc_security_connector **sc);
 
 /* Util. */
-const tsi_peer_property *tsi_peer_get_property_by_name(
-    const tsi_peer *peer, const char *name);
+const tsi_peer_property *tsi_peer_get_property_by_name(const tsi_peer *peer,
+                                                       const char *name);
 
 /* Exposed for testing only. */
 grpc_auth_context *tsi_ssl_peer_to_auth_context(const tsi_peer *peer);
diff --git a/src/core/security/server_auth_filter.c b/src/core/security/server_auth_filter.c
index b8639287a5..10eef6d237 100644
--- a/src/core/security/server_auth_filter.c
+++ b/src/core/security/server_auth_filter.c
@@ -51,24 +51,17 @@ typedef struct channel_data {
    op contains type and call direction information, in addition to the data
    that is being sent or received. */
 static void auth_start_transport_op(grpc_call_element *elem,
-                                    grpc_transport_op *op) {
+                                    grpc_transport_stream_op *op) {
   /* TODO(jboeuf): Get the metadata and get a new context from it. */
 
   /* pass control down the stack */
   grpc_call_next_op(elem, op);
 }
 
-/* Called on special channel events, such as disconnection or new incoming
-   calls on the server */
-static void channel_op(grpc_channel_element *elem,
-                       grpc_channel_element *from_elem, grpc_channel_op *op) {
-  grpc_channel_next_op(elem, op);
-}
-
 /* Constructor for call_data */
 static void init_call_elem(grpc_call_element *elem,
                            const void *server_transport_data,
-                           grpc_transport_op *initial_op) {
+                           grpc_transport_stream_op *initial_op) {
   /* grab pointers to our data from the call element */
   call_data *calld = elem->call_data;
   channel_data *chand = elem->channel_data;
@@ -95,11 +88,10 @@ static void init_call_elem(grpc_call_element *elem,
 }
 
 /* Destructor for call_data */
-static void destroy_call_elem(grpc_call_element *elem) {
-}
+static void destroy_call_elem(grpc_call_element *elem) {}
 
 /* Constructor for channel_data */
-static void init_channel_elem(grpc_channel_element *elem,
+static void init_channel_elem(grpc_channel_element *elem, grpc_channel *master,
                               const grpc_channel_args *args, grpc_mdctx *mdctx,
                               int is_first, int is_last) {
   grpc_security_connector *sc = grpc_find_security_connector_in_args(args);
@@ -115,17 +107,19 @@ static void init_channel_elem(grpc_channel_element *elem,
 
   /* initialize members */
   GPR_ASSERT(!sc->is_client_side);
-  chand->security_connector = grpc_security_connector_ref(sc);
+  chand->security_connector =
+      GRPC_SECURITY_CONNECTOR_REF(sc, "server_auth_filter");
 }
 
 /* Destructor for channel data */
 static void destroy_channel_elem(grpc_channel_element *elem) {
   /* grab pointers to our data from the channel element */
   channel_data *chand = elem->channel_data;
-  grpc_security_connector_unref(chand->security_connector);
+  GRPC_SECURITY_CONNECTOR_UNREF(chand->security_connector,
+                                "server_auth_filter");
 }
 
 const grpc_channel_filter grpc_server_auth_filter = {
-    auth_start_transport_op, channel_op, sizeof(call_data), init_call_elem,
-    destroy_call_elem, sizeof(channel_data), init_channel_elem,
-    destroy_channel_elem, "server-auth"};
+    auth_start_transport_op, grpc_channel_next_op, sizeof(call_data),
+    init_call_elem,          destroy_call_elem,    sizeof(channel_data),
+    init_channel_elem,       destroy_channel_elem, "server-auth"};
diff --git a/src/core/security/server_secure_chttp2.c b/src/core/security/server_secure_chttp2.c
index 53afa1caad..8a7ada07af 100644
--- a/src/core/security/server_secure_chttp2.c
+++ b/src/core/security/server_secure_chttp2.c
@@ -70,38 +70,39 @@ static void state_unref(grpc_server_secure_state *state) {
     gpr_mu_lock(&state->mu);
     gpr_mu_unlock(&state->mu);
     /* clean up */
-    grpc_security_connector_unref(state->sc);
+    GRPC_SECURITY_CONNECTOR_UNREF(state->sc, "server");
     gpr_free(state);
   }
 }
 
-static grpc_transport_setup_result setup_transport(void *statep,
-                                                   grpc_transport *transport,
-                                                   grpc_mdctx *mdctx) {
+static void setup_transport(void *statep, grpc_transport *transport,
+                            grpc_mdctx *mdctx) {
   static grpc_channel_filter const *extra_filters[] = {
       &grpc_server_auth_filter, &grpc_http_server_filter};
   grpc_server_secure_state *state = statep;
-  grpc_transport_setup_result result;
   grpc_arg connector_arg = grpc_security_connector_to_arg(state->sc);
   grpc_channel_args *args_copy = grpc_channel_args_copy_and_add(
-      grpc_server_get_channel_args(state->server), &connector_arg);
-  result = grpc_server_setup_transport(state->server, transport, extra_filters,
-                                       GPR_ARRAY_SIZE(extra_filters), mdctx,
-                                       args_copy);
+      grpc_server_get_channel_args(state->server), &connector_arg, 1);
+  grpc_server_setup_transport(state->server, transport, extra_filters,
+                              GPR_ARRAY_SIZE(extra_filters), mdctx, args_copy);
   grpc_channel_args_destroy(args_copy);
-  return result;
 }
 
 static void on_secure_transport_setup_done(void *statep,
                                            grpc_security_status status,
                                            grpc_endpoint *secure_endpoint) {
   grpc_server_secure_state *state = statep;
+  grpc_transport *transport;
+  grpc_mdctx *mdctx;
   if (status == GRPC_SECURITY_OK) {
     gpr_mu_lock(&state->mu);
     if (!state->is_shutdown) {
-      grpc_create_chttp2_transport(
-          setup_transport, state, grpc_server_get_channel_args(state->server),
-          secure_endpoint, NULL, 0, grpc_mdctx_create(), 0);
+      mdctx = grpc_mdctx_create();
+      transport = grpc_create_chttp2_transport(
+          grpc_server_get_channel_args(state->server), secure_endpoint, mdctx,
+          0);
+      setup_transport(state, transport, mdctx);
+      grpc_chttp2_transport_start_reading(transport, NULL, 0);
     } else {
       /* We need to consume this here, because the server may already have gone
        * away. */
@@ -220,7 +221,7 @@ int grpc_server_add_secure_http2_port(grpc_server *server, const char *addr,
 /* Error path: cleanup and return */
 error:
   if (sc) {
-    grpc_security_connector_unref(sc);
+    GRPC_SECURITY_CONNECTOR_UNREF(sc, "server");
   }
   if (resolved) {
     grpc_resolved_addresses_destroy(resolved);
diff --git a/src/core/support/cpu_windows.c b/src/core/support/cpu_windows.c
index 107a7b85f0..ce32eb0a9d 100644
--- a/src/core/support/cpu_windows.c
+++ b/src/core/support/cpu_windows.c
@@ -34,7 +34,6 @@
 #include <grpc/support/port_platform.h>
 
 #ifdef GPR_WIN32
-#include <windows.h>
 #include <grpc/support/log.h>
 
 unsigned gpr_cpu_num_cores(void) {
diff --git a/src/core/support/log_linux.c b/src/core/support/log_linux.c
index 48349d2c83..7937466b79 100644
--- a/src/core/support/log_linux.c
+++ b/src/core/support/log_linux.c
@@ -43,7 +43,9 @@
 
 #ifdef GPR_LINUX
 
+#include <grpc/support/alloc.h>
 #include <grpc/support/log.h>
+#include <grpc/support/string_util.h>
 #include <grpc/support/time.h>
 #include <stdio.h>
 #include <stdarg.h>
@@ -71,6 +73,7 @@ void gpr_log(const char *file, int line, gpr_log_severity severity,
 
 void gpr_default_log(gpr_log_func_args *args) {
   char *final_slash;
+  char *prefix;
   const char *display_file;
   char time_buffer[64];
   gpr_timespec now = gpr_now();
@@ -89,10 +92,12 @@ void gpr_default_log(gpr_log_func_args *args) {
     strcpy(time_buffer, "error:strftime");
   }
 
-  fprintf(stderr, "%s%s.%09d %7ld %s:%d] %s\n",
+  gpr_asprintf(&prefix, "%s%s.%09d %7tu %s:%d]",
           gpr_log_severity_string(args->severity), time_buffer,
-          (int)(now.tv_nsec), gettid(), display_file, args->line,
-          args->message);
+          (int)(now.tv_nsec), gettid(), display_file, args->line);
+
+  fprintf(stderr, "%-60s %s\n", prefix, args->message);
+  gpr_free(prefix);
 }
 
 #endif
diff --git a/src/core/support/string_win32.c b/src/core/support/string_win32.c
index 6d1d6337a9..27b9f3637a 100644
--- a/src/core/support/string_win32.c
+++ b/src/core/support/string_win32.c
@@ -37,7 +37,6 @@
 
 #ifdef GPR_WIN32
 
-#include <windows.h>
 #include <stdio.h>
 #include <stdarg.h>
 #include <string.h>
diff --git a/src/core/support/string_win32.h b/src/core/support/string_win32.h
index 0bc3247d9d..1260aa55c1 100644
--- a/src/core/support/string_win32.h
+++ b/src/core/support/string_win32.h
@@ -38,8 +38,6 @@
 
 #ifdef GPR_WIN32
 
-#include <windows.h>
-
 /* These allocate new strings using gpr_malloc to convert from and to utf-8. */
 LPTSTR gpr_char_to_tchar(LPCSTR input);
 LPSTR gpr_tchar_to_char(LPCTSTR input);
diff --git a/src/core/support/sync_win32.c b/src/core/support/sync_win32.c
index cc31d9b052..72f39f8d46 100644
--- a/src/core/support/sync_win32.c
+++ b/src/core/support/sync_win32.c
@@ -37,9 +37,6 @@
 
 #ifdef GPR_WIN32
 
-#undef _WIN32_WINNT
-#define _WIN32_WINNT 0x0600
-#include <windows.h>
 #include <grpc/support/log.h>
 #include <grpc/support/sync.h>
 #include <grpc/support/time.h>
diff --git a/src/core/support/thd_win32.c b/src/core/support/thd_win32.c
index 3cc798293a..4fa3907444 100644
--- a/src/core/support/thd_win32.c
+++ b/src/core/support/thd_win32.c
@@ -37,7 +37,6 @@
 
 #ifdef GPR_WIN32
 
-#include <windows.h>
 #include <string.h>
 #include <grpc/support/alloc.h>
 #include <grpc/support/log.h>
diff --git a/src/core/support/time_win32.c b/src/core/support/time_win32.c
index f4443b5c2d..9db267c01b 100644
--- a/src/core/support/time_win32.c
+++ b/src/core/support/time_win32.c
@@ -39,7 +39,6 @@
 
 #include <grpc/support/time.h>
 #include <sys/timeb.h>
-#include <windows.h>
 
 gpr_timespec gpr_now(void) {
   gpr_timespec now_tv;
diff --git a/src/core/surface/call.c b/src/core/surface/call.c
index 181617fff8..fc09137b67 100644
--- a/src/core/surface/call.c
+++ b/src/core/surface/call.c
@@ -76,14 +76,14 @@ typedef struct {
 typedef struct {
   /* Overall status of the operation: starts OK, may degrade to
      non-OK */
-  int success;
-  /* Completion function to call at the end of the operation */
-  grpc_ioreq_completion_func on_complete;
-  void *user_data;
+  gpr_uint8 success;
   /* a bit mask of which request ops are needed (1u << opid) */
   gpr_uint16 need_mask;
   /* a bit mask of which request ops are now completed */
   gpr_uint16 complete_mask;
+  /* Completion function to call at the end of the operation */
+  grpc_ioreq_completion_func on_complete;
+  void *user_data;
 } reqinfo_master;
 
 /* Status data for a request can come from several sources; this
@@ -262,8 +262,8 @@ struct grpc_call {
 static void set_deadline_alarm(grpc_call *call, gpr_timespec deadline);
 static void call_on_done_recv(void *call, int success);
 static void call_on_done_send(void *call, int success);
-static int fill_send_ops(grpc_call *call, grpc_transport_op *op);
-static void execute_op(grpc_call *call, grpc_transport_op *op);
+static int fill_send_ops(grpc_call *call, grpc_transport_stream_op *op);
+static void execute_op(grpc_call *call, grpc_transport_stream_op *op);
 static void recv_metadata(grpc_call *call, grpc_metadata_batch *metadata);
 static void finish_read_ops(grpc_call *call);
 static grpc_call_error cancel_with_status(grpc_call *c, grpc_status_code status,
@@ -279,8 +279,8 @@ grpc_call *grpc_call_create(grpc_channel *channel, grpc_completion_queue *cq,
                             size_t add_initial_metadata_count,
                             gpr_timespec send_deadline) {
   size_t i;
-  grpc_transport_op initial_op;
-  grpc_transport_op *initial_op_ptr = NULL;
+  grpc_transport_stream_op initial_op;
+  grpc_transport_stream_op *initial_op_ptr = NULL;
   grpc_channel_stack *channel_stack = grpc_channel_get_channel_stack(channel);
   grpc_call *call =
       gpr_malloc(sizeof(grpc_call) + channel_stack->call_stack_size);
@@ -464,12 +464,11 @@ static int need_more_data(grpc_call *call) {
          (is_op_live(call, GRPC_IOREQ_RECV_CLOSE) &&
           grpc_bbq_empty(&call->incoming_queue)) ||
          (call->write_state == WRITE_STATE_INITIAL && !call->is_client) ||
-         (call->cancel_with_status != GRPC_STATUS_OK) ||
-         call->destroy_called;
+         (call->cancel_with_status != GRPC_STATUS_OK) || call->destroy_called;
 }
 
 static void unlock(grpc_call *call) {
-  grpc_transport_op op;
+  grpc_transport_stream_op op;
   completed_request completed_requests[GRPC_IOREQ_OP_COUNT];
   int completing_requests = 0;
   int start_op = 0;
@@ -888,7 +887,7 @@ static void copy_byte_buffer_to_stream_ops(grpc_byte_buffer *byte_buffer,
   }
 }
 
-static int fill_send_ops(grpc_call *call, grpc_transport_op *op) {
+static int fill_send_ops(grpc_call *call, grpc_transport_stream_op *op) {
   grpc_ioreq_data data;
   gpr_uint32 flags;
   grpc_metadata_batch mdb;
@@ -1144,7 +1143,7 @@ static void finished_loose_op_allocated(void *alloc, int success) {
   gpr_free(args);
 }
 
-static void execute_op(grpc_call *call, grpc_transport_op *op) {
+static void execute_op(grpc_call *call, grpc_transport_stream_op *op) {
   grpc_call_element *elem;
 
   GPR_ASSERT(op->on_consumed == NULL);
@@ -1155,14 +1154,15 @@ static void execute_op(grpc_call *call, grpc_transport_op *op) {
     } else {
       finished_loose_op_allocated_args *args = gpr_malloc(sizeof(*args));
       args->call = call;
-      grpc_iomgr_closure_init(&args->closure, finished_loose_op_allocated, args);
+      grpc_iomgr_closure_init(&args->closure, finished_loose_op_allocated,
+                              args);
       op->on_consumed = &args->closure;
     }
   }
 
   elem = CALL_ELEM_FROM_CALL(call, 0);
   op->context = call->context;
-  elem->filter->start_transport_op(elem, op);
+  elem->filter->start_transport_stream_op(elem, op);
 }
 
 grpc_call *grpc_call_from_top_element(grpc_call_element *elem) {
@@ -1229,13 +1229,13 @@ static gpr_uint32 decode_compression(grpc_mdelem *md) {
   } else {
     gpr_uint32 parsed_clevel_bytes;
     if (gpr_parse_bytes_to_uint32(grpc_mdstr_as_c_string(md->value),
-                                   GPR_SLICE_LENGTH(md->value->slice),
-                                   &parsed_clevel_bytes)) {
+                                  GPR_SLICE_LENGTH(md->value->slice),
+                                  &parsed_clevel_bytes)) {
       /* the following cast is safe, as a gpr_uint32 should be able to hold all
        * possible values of the grpc_compression_level enum */
-      clevel = (grpc_compression_level) parsed_clevel_bytes;
+      clevel = (grpc_compression_level)parsed_clevel_bytes;
     } else {
-      clevel = GRPC_COMPRESS_LEVEL_NONE;  /* could not parse, no compression */
+      clevel = GRPC_COMPRESS_LEVEL_NONE; /* could not parse, no compression */
     }
     grpc_mdelem_set_user_data(md, destroy_compression,
                               (void *)(gpr_intptr)(clevel + COMPRESS_OFFSET));
@@ -1258,7 +1258,8 @@ static void recv_metadata(grpc_call *call, grpc_metadata_batch *md) {
       set_status_code(call, STATUS_FROM_WIRE, decode_status(md));
     } else if (key == grpc_channel_get_message_string(call->channel)) {
       set_status_details(call, STATUS_FROM_WIRE, grpc_mdstr_ref(md->value));
-    } else if (key == grpc_channel_get_compresssion_level_string(call->channel)) {
+    } else if (key ==
+               grpc_channel_get_compresssion_level_string(call->channel)) {
       set_decode_compression_level(call, decode_compression(md));
     } else {
       dest = &call->buffered_metadata[is_trailing];
diff --git a/src/core/surface/call.h b/src/core/surface/call.h
index fb3662b50d..3b6f9c942e 100644
--- a/src/core/surface/call.h
+++ b/src/core/surface/call.h
@@ -78,8 +78,8 @@ typedef union {
 
 typedef struct {
   grpc_ioreq_op op;
-  grpc_ioreq_data data;
   gpr_uint32 flags; /**< A copy of the write flags from grpc_op */
+  grpc_ioreq_data data;
 } grpc_ioreq;
 
 typedef void (*grpc_ioreq_completion_func)(grpc_call *call, int success,
diff --git a/src/core/surface/channel.c b/src/core/surface/channel.c
index a3c4dcebc1..f8151c121c 100644
--- a/src/core/surface/channel.c
+++ b/src/core/surface/channel.c
@@ -39,7 +39,6 @@
 #include "src/core/iomgr/iomgr.h"
 #include "src/core/support/string.h"
 #include "src/core/surface/call.h"
-#include "src/core/surface/client.h"
 #include "src/core/surface/init.h"
 #include <grpc/support/alloc.h>
 #include <grpc/support/log.h>
@@ -94,9 +93,8 @@ grpc_channel *grpc_channel_create_from_filters(
   grpc_channel *channel = gpr_malloc(size);
   GPR_ASSERT(grpc_is_initialized() && "call grpc_init()");
   channel->is_client = is_client;
-  /* decremented by grpc_channel_destroy, and grpc_client_channel_closed if
-   * is_client */
-  gpr_ref_init(&channel->refs, 1 + is_client);
+  /* decremented by grpc_channel_destroy */
+  gpr_ref_init(&channel->refs, 1);
   channel->metadata_context = mdctx;
   channel->grpc_status_string = grpc_mdstr_from_string(mdctx, "grpc-status");
   channel->grpc_compression_level_string =
@@ -111,8 +109,6 @@ grpc_channel *grpc_channel_create_from_filters(
   }
   channel->path_string = grpc_mdstr_from_string(mdctx, ":path");
   channel->authority_string = grpc_mdstr_from_string(mdctx, ":authority");
-  grpc_channel_stack_init(filters, num_filters, args, channel->metadata_context,
-                          CHANNEL_STACK_FROM_CHANNEL(channel));
   gpr_mu_init(&channel->registered_call_mu);
   channel->registered_calls = NULL;
 
@@ -133,6 +129,10 @@ grpc_channel *grpc_channel_create_from_filters(
     }
   }
 
+  grpc_channel_stack_init(filters, num_filters, channel, args,
+                          channel->metadata_context,
+                          CHANNEL_STACK_FROM_CHANNEL(channel));
+
   return channel;
 }
 
@@ -239,28 +239,16 @@ void grpc_channel_internal_unref(grpc_channel *channel) {
 }
 
 void grpc_channel_destroy(grpc_channel *channel) {
-  grpc_channel_op op;
+  grpc_transport_op op;
   grpc_channel_element *elem;
-
+  memset(&op, 0, sizeof(op));
+  op.disconnect = 1;
   elem = grpc_channel_stack_element(CHANNEL_STACK_FROM_CHANNEL(channel), 0);
-
-  op.type = GRPC_CHANNEL_GOAWAY;
-  op.dir = GRPC_CALL_DOWN;
-  op.data.goaway.status = GRPC_STATUS_OK;
-  op.data.goaway.message = gpr_slice_from_copied_string("Client disconnect");
-  elem->filter->channel_op(elem, NULL, &op);
-
-  op.type = GRPC_CHANNEL_DISCONNECT;
-  op.dir = GRPC_CALL_DOWN;
-  elem->filter->channel_op(elem, NULL, &op);
+  elem->filter->start_transport_op(elem, &op);
 
   GRPC_CHANNEL_INTERNAL_UNREF(channel, "channel");
 }
 
-void grpc_client_channel_closed(grpc_channel_element *elem) {
-  GRPC_CHANNEL_INTERNAL_UNREF(CHANNEL_FROM_TOP_ELEM(elem), "closed");
-}
-
 grpc_channel_stack *grpc_channel_get_channel_stack(grpc_channel *channel) {
   return CHANNEL_STACK_FROM_CHANNEL(channel);
 }
@@ -277,7 +265,6 @@ grpc_mdstr *grpc_channel_get_compresssion_level_string(grpc_channel *channel) {
   return channel->grpc_compression_level_string;
 }
 
-
 grpc_mdelem *grpc_channel_get_reffed_status_elem(grpc_channel *channel, int i) {
   if (i >= 0 && i < NUM_CACHED_STATUS_ELEMS) {
     return grpc_mdelem_ref(channel->grpc_status_elem[i]);
diff --git a/src/core/surface/channel.h b/src/core/surface/channel.h
index 3c04676b43..71f8a55731 100644
--- a/src/core/surface/channel.h
+++ b/src/core/surface/channel.h
@@ -35,6 +35,7 @@
 #define GRPC_INTERNAL_CORE_SURFACE_CHANNEL_H
 
 #include "src/core/channel/channel_stack.h"
+#include "src/core/client_config/subchannel_factory.h"
 
 grpc_channel *grpc_channel_create_from_filters(
     const grpc_channel_filter **filters, size_t count,
@@ -57,8 +58,6 @@ grpc_mdstr *grpc_channel_get_compresssion_level_string(grpc_channel *channel);
 grpc_mdstr *grpc_channel_get_message_string(grpc_channel *channel);
 gpr_uint32 grpc_channel_get_max_message_length(grpc_channel *channel);
 
-void grpc_client_channel_closed(grpc_channel_element *elem);
-
 #ifdef GRPC_CHANNEL_REF_COUNT_DEBUG
 void grpc_channel_internal_ref(grpc_channel *channel, const char *reason);
 void grpc_channel_internal_unref(grpc_channel *channel, const char *reason);
diff --git a/src/core/surface/channel_create.c b/src/core/surface/channel_create.c
index d069a04a9a..e205f0a9f8 100644
--- a/src/core/surface/channel_create.c
+++ b/src/core/surface/channel_create.c
@@ -31,159 +31,120 @@
  *
  */
 
-#include "src/core/iomgr/sockaddr.h"
-
 #include <grpc/grpc.h>
 
 #include <stdlib.h>
 #include <string.h>
 
-#include "src/core/channel/census_filter.h"
+#include <grpc/support/alloc.h>
+
 #include "src/core/channel/channel_args.h"
 #include "src/core/channel/client_channel.h"
-#include "src/core/channel/client_setup.h"
-#include "src/core/channel/connected_channel.h"
 #include "src/core/channel/http_client_filter.h"
-#include "src/core/iomgr/endpoint.h"
-#include "src/core/iomgr/resolve_address.h"
+#include "src/core/client_config/resolver_registry.h"
 #include "src/core/iomgr/tcp_client.h"
 #include "src/core/surface/channel.h"
-#include "src/core/surface/client.h"
-#include "src/core/support/string.h"
 #include "src/core/transport/chttp2_transport.h"
-#include <grpc/support/alloc.h>
-#include <grpc/support/log.h>
-#include <grpc/support/string_util.h>
-#include <grpc/support/sync.h>
-#include <grpc/support/useful.h>
-
-typedef struct setup setup;
 
-/* A single setup request (started via initiate) */
 typedef struct {
-  grpc_client_setup_request *cs_request;
-  setup *setup;
-  /* Resolved addresses, or null if resolution not yet completed */
-  grpc_resolved_addresses *resolved;
-  /* which address in resolved should we pick for the next connection attempt */
-  size_t resolved_index;
-} request;
-
-/* Global setup logic (may be running many simultaneous setup requests, but
-   with only one 'active' */
-struct setup {
-  const char *target;
-  grpc_transport_setup_callback setup_callback;
-  void *setup_user_data;
-};
-
-static int maybe_try_next_resolved(request *r);
-
-static void done(request *r, int was_successful) {
-  grpc_client_setup_request_finish(r->cs_request, was_successful);
-  if (r->resolved) {
-    grpc_resolved_addresses_destroy(r->resolved);
-  }
-  gpr_free(r);
+  grpc_connector base;
+  gpr_refcount refs;
+
+  grpc_iomgr_closure *notify;
+  grpc_connect_in_args args;
+  grpc_connect_out_args *result;
+} connector;
+
+static void connector_ref(grpc_connector *con) {
+  connector *c = (connector *)con;
+  gpr_ref(&c->refs);
 }
 
-/* connection callback: tcp is either valid, or null on error */
-static void on_connect(void *rp, grpc_endpoint *tcp) {
-  request *r = rp;
-
-  if (!grpc_client_setup_request_should_continue(r->cs_request, "on_connect")) {
-    if (tcp) {
-      grpc_endpoint_shutdown(tcp);
-      grpc_endpoint_destroy(tcp);
-    }
-    done(r, 0);
-    return;
+static void connector_unref(grpc_connector *con) {
+  connector *c = (connector *)con;
+  if (gpr_unref(&c->refs)) {
+    gpr_free(c);
   }
+}
 
-  if (!tcp) {
-    if (!maybe_try_next_resolved(r)) {
-      done(r, 0);
-      return;
-    } else {
-      return;
-    }
-  } else if (grpc_client_setup_cb_begin(r->cs_request, "on_connect")) {
-    grpc_create_chttp2_transport(
-        r->setup->setup_callback, r->setup->setup_user_data,
-        grpc_client_setup_get_channel_args(r->cs_request), tcp, NULL, 0,
-        grpc_client_setup_get_mdctx(r->cs_request), 1);
-    grpc_client_setup_cb_end(r->cs_request, "on_connect");
-    done(r, 1);
-    return;
+static void connected(void *arg, grpc_endpoint *tcp) {
+  connector *c = arg;
+  grpc_iomgr_closure *notify;
+  if (tcp != NULL) {
+    c->result->transport = grpc_create_chttp2_transport(
+        c->args.channel_args, tcp, c->args.metadata_context, 1);
+    grpc_chttp2_transport_start_reading(c->result->transport, NULL, 0);
+    GPR_ASSERT(c->result->transport);
+    c->result->filters = gpr_malloc(sizeof(grpc_channel_filter *));
+    c->result->filters[0] = &grpc_http_client_filter;
+    c->result->num_filters = 1;
   } else {
-    done(r, 0);
+    memset(c->result, 0, sizeof(*c->result));
   }
+  notify = c->notify;
+  c->notify = NULL;
+  grpc_iomgr_add_callback(notify);
 }
 
-/* attempt to connect to the next available resolved address */
-static int maybe_try_next_resolved(request *r) {
-  grpc_resolved_address *addr;
-  if (!r->resolved) return 0;
-  if (r->resolved_index == r->resolved->naddrs) return 0;
-  addr = &r->resolved->addrs[r->resolved_index++];
-  grpc_tcp_client_connect(
-      on_connect, r, grpc_client_setup_get_interested_parties(r->cs_request),
-      (struct sockaddr *)&addr->addr, addr->len,
-      grpc_client_setup_request_deadline(r->cs_request));
-  return 1;
+static void connector_connect(grpc_connector *con,
+                              const grpc_connect_in_args *args,
+                              grpc_connect_out_args *result,
+                              grpc_iomgr_closure *notify) {
+  connector *c = (connector *)con;
+  GPR_ASSERT(c->notify == NULL);
+  GPR_ASSERT(notify->cb);
+  c->notify = notify;
+  c->args = *args;
+  c->result = result;
+  grpc_tcp_client_connect(connected, c, args->interested_parties, args->addr,
+                          args->addr_len, args->deadline);
 }
 
-/* callback for when our target address has been resolved */
-static void on_resolved(void *rp, grpc_resolved_addresses *resolved) {
-  request *r = rp;
-
-  /* if we're not still the active request, abort */
-  if (!grpc_client_setup_request_should_continue(r->cs_request,
-                                                 "on_resolved")) {
-    if (resolved) {
-      grpc_resolved_addresses_destroy(resolved);
-    }
-    done(r, 0);
-    return;
-  }
+static const grpc_connector_vtable connector_vtable = {
+    connector_ref, connector_unref, connector_connect};
 
-  if (!resolved) {
-    done(r, 0);
-    return;
-  } else {
-    r->resolved = resolved;
-    r->resolved_index = 0;
-    if (!maybe_try_next_resolved(r)) {
-      done(r, 0);
-    }
-  }
+typedef struct {
+  grpc_subchannel_factory base;
+  gpr_refcount refs;
+  grpc_mdctx *mdctx;
+  grpc_channel_args *merge_args;
+} subchannel_factory;
+
+static void subchannel_factory_ref(grpc_subchannel_factory *scf) {
+  subchannel_factory *f = (subchannel_factory *)scf;
+  gpr_ref(&f->refs);
 }
 
-static void initiate_setup(void *sp, grpc_client_setup_request *cs_request) {
-  request *r = gpr_malloc(sizeof(request));
-  r->setup = sp;
-  r->cs_request = cs_request;
-  r->resolved = NULL;
-  r->resolved_index = 0;
-  /* TODO(klempner): Make grpc_resolve_address respect deadline */
-  grpc_resolve_address(r->setup->target, "http", on_resolved, r);
+static void subchannel_factory_unref(grpc_subchannel_factory *scf) {
+  subchannel_factory *f = (subchannel_factory *)scf;
+  if (gpr_unref(&f->refs)) {
+    grpc_channel_args_destroy(f->merge_args);
+    grpc_mdctx_unref(f->mdctx);
+    gpr_free(f);
+  }
 }
 
-static void done_setup(void *sp) {
-  setup *s = sp;
-  gpr_free((void *)s->target);
-  gpr_free(s);
+static grpc_subchannel *subchannel_factory_create_subchannel(
+    grpc_subchannel_factory *scf, grpc_subchannel_args *args) {
+  subchannel_factory *f = (subchannel_factory *)scf;
+  connector *c = gpr_malloc(sizeof(*c));
+  grpc_channel_args *final_args =
+      grpc_channel_args_merge(args->args, f->merge_args);
+  grpc_subchannel *s;
+  memset(c, 0, sizeof(*c));
+  c->base.vtable = &connector_vtable;
+  gpr_ref_init(&c->refs, 1);
+  args->mdctx = f->mdctx;
+  args->args = final_args;
+  s = grpc_subchannel_create(&c->base, args);
+  grpc_connector_unref(&c->base);
+  grpc_channel_args_destroy(final_args);
+  return s;
 }
 
-static grpc_transport_setup_result complete_setup(void *channel_stack,
-                                                  grpc_transport *transport,
-                                                  grpc_mdctx *mdctx) {
-  static grpc_channel_filter const *extra_filters[] = {
-      &grpc_http_client_filter};
-  return grpc_client_channel_transport_setup_complete(
-      channel_stack, transport, extra_filters, GPR_ARRAY_SIZE(extra_filters),
-      mdctx);
-}
+static const grpc_subchannel_factory_vtable subchannel_factory_vtable = {
+    subchannel_factory_ref, subchannel_factory_unref,
+    subchannel_factory_create_subchannel};
 
 /* Create a client channel:
    Asynchronously: - resolve target
@@ -191,28 +152,36 @@ static grpc_transport_setup_result complete_setup(void *channel_stack,
                    - perform handshakes */
 grpc_channel *grpc_channel_create(const char *target,
                                   const grpc_channel_args *args) {
-  setup *s = gpr_malloc(sizeof(setup));
-  grpc_mdctx *mdctx = grpc_mdctx_create();
   grpc_channel *channel = NULL;
 #define MAX_FILTERS 3
   const grpc_channel_filter *filters[MAX_FILTERS];
+  grpc_resolver *resolver;
+  subchannel_factory *f;
+  grpc_mdctx *mdctx = grpc_mdctx_create();
   int n = 0;
-  filters[n++] = &grpc_client_surface_filter;
   /* TODO(census)
   if (grpc_channel_args_is_census_enabled(args)) {
     filters[n++] = &grpc_client_census_filter;
     } */
   filters[n++] = &grpc_client_channel_filter;
   GPR_ASSERT(n <= MAX_FILTERS);
-  channel = grpc_channel_create_from_filters(filters, n, args, mdctx, 1);
 
-  s->target = gpr_strdup(target);
-  s->setup_callback = complete_setup;
-  s->setup_user_data = grpc_channel_get_channel_stack(channel);
+  f = gpr_malloc(sizeof(*f));
+  f->base.vtable = &subchannel_factory_vtable;
+  gpr_ref_init(&f->refs, 1);
+  grpc_mdctx_ref(mdctx);
+  f->mdctx = mdctx;
+  f->merge_args = grpc_channel_args_copy(args);
+  resolver = grpc_resolver_create(target, &f->base);
+  if (!resolver) {
+    return NULL;
+  }
 
-  grpc_client_setup_create_and_attach(grpc_channel_get_channel_stack(channel),
-                                      args, mdctx, initiate_setup, done_setup,
-                                      s);
+  channel = grpc_channel_create_from_filters(filters, n, args, mdctx, 1);
+  grpc_client_channel_set_resolver(grpc_channel_get_channel_stack(channel),
+                                   resolver);
+  GRPC_RESOLVER_UNREF(resolver, "create");
+  grpc_subchannel_factory_unref(&f->base);
 
   return channel;
 }
diff --git a/src/core/surface/client.c b/src/core/surface/client.c
deleted file mode 100644
index 8ac4dd1e0e..0000000000
--- a/src/core/surface/client.c
+++ /dev/null
@@ -1,89 +0,0 @@
-/*
- *
- * 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.
- *
- */
-
-#include "src/core/surface/client.h"
-
-#include "src/core/surface/call.h"
-#include "src/core/surface/channel.h"
-#include "src/core/support/string.h"
-#include <grpc/support/alloc.h>
-#include <grpc/support/log.h>
-
-typedef struct { void *unused; } call_data;
-
-typedef struct { void *unused; } channel_data;
-
-static void client_start_transport_op(grpc_call_element *elem,
-                                      grpc_transport_op *op) {
-  GRPC_CALL_LOG_OP(GPR_INFO, elem, op);
-  grpc_call_next_op(elem, op);
-}
-
-static void channel_op(grpc_channel_element *elem,
-                       grpc_channel_element *from_elem, grpc_channel_op *op) {
-  switch (op->type) {
-    case GRPC_ACCEPT_CALL:
-      gpr_log(GPR_ERROR, "Client cannot accept new calls");
-      break;
-    case GRPC_TRANSPORT_CLOSED:
-      grpc_client_channel_closed(elem);
-      break;
-    case GRPC_TRANSPORT_GOAWAY:
-      gpr_slice_unref(op->data.goaway.message);
-      break;
-    default:
-      GPR_ASSERT(op->dir == GRPC_CALL_DOWN);
-      grpc_channel_next_op(elem, op);
-  }
-}
-
-static void init_call_elem(grpc_call_element *elem,
-                           const void *transport_server_data,
-                           grpc_transport_op *initial_op) {}
-
-static void destroy_call_elem(grpc_call_element *elem) {}
-
-static void init_channel_elem(grpc_channel_element *elem,
-                              const grpc_channel_args *args, grpc_mdctx *mdctx,
-                              int is_first, int is_last) {
-  GPR_ASSERT(is_first);
-  GPR_ASSERT(!is_last);
-}
-
-static void destroy_channel_elem(grpc_channel_element *elem) {}
-
-const grpc_channel_filter grpc_client_surface_filter = {
-    client_start_transport_op, channel_op, sizeof(call_data), init_call_elem,
-    destroy_call_elem, sizeof(channel_data), init_channel_elem,
-    destroy_channel_elem, "client",
-};
diff --git a/src/core/surface/init.c b/src/core/surface/init.c
index ca61a38a35..3847ded28c 100644
--- a/src/core/surface/init.c
+++ b/src/core/surface/init.c
@@ -31,9 +31,13 @@
  *
  */
 
+#include <grpc/support/port_platform.h>
+
 #include <grpc/census.h>
 #include <grpc/grpc.h>
 #include "src/core/channel/channel_stack.h"
+#include "src/core/client_config/resolver_registry.h"
+#include "src/core/client_config/resolvers/dns_resolver.h"
 #include "src/core/debug/trace.h"
 #include "src/core/iomgr/iomgr.h"
 #include "src/core/profiling/timers.h"
@@ -42,6 +46,10 @@
 #include "src/core/surface/surface_trace.h"
 #include "src/core/transport/chttp2_transport.h"
 
+#ifdef GPR_POSIX_SOCKET
+#include "src/core/client_config/resolvers/unix_resolver_posix.h"
+#endif
+
 static gpr_once g_basic_init = GPR_ONCE_INIT;
 static gpr_mu g_init_mu;
 static int g_initializations;
@@ -56,6 +64,11 @@ void grpc_init(void) {
 
   gpr_mu_lock(&g_init_mu);
   if (++g_initializations == 1) {
+    grpc_resolver_registry_init("dns:///");
+    grpc_register_resolver_type("dns", grpc_dns_resolver_factory_create());
+#ifdef GPR_POSIX_SOCKET
+    grpc_register_resolver_type("unix", grpc_unix_resolver_factory_create());
+#endif
     grpc_register_tracer("channel", &grpc_trace_channel);
     grpc_register_tracer("surface", &grpc_surface_trace);
     grpc_register_tracer("http", &grpc_http_trace);
@@ -79,6 +92,7 @@ void grpc_shutdown(void) {
     census_shutdown();
     grpc_timers_global_destroy();
     grpc_tracer_shutdown();
+    grpc_resolver_registry_shutdown();
   }
   gpr_mu_unlock(&g_init_mu);
 }
diff --git a/src/core/surface/lame_client.c b/src/core/surface/lame_client.c
index 85e1ab5554..3dd56fe5a9 100644
--- a/src/core/surface/lame_client.c
+++ b/src/core/surface/lame_client.c
@@ -49,16 +49,16 @@ typedef struct {
 
 typedef struct { grpc_mdctx *mdctx; } channel_data;
 
-static void lame_start_transport_op(grpc_call_element *elem,
-                                    grpc_transport_op *op) {
+static void lame_start_transport_stream_op(grpc_call_element *elem,
+                                           grpc_transport_stream_op *op) {
   call_data *calld = elem->call_data;
   channel_data *chand = elem->channel_data;
   GRPC_CALL_LOG_OP(GPR_INFO, elem, op);
-  if (op->send_ops) {
+  if (op->send_ops != NULL) {
     grpc_stream_ops_unref_owned_objects(op->send_ops->ops, op->send_ops->nops);
     op->on_done_send->cb(op->on_done_send->cb_arg, 0);
   }
-  if (op->recv_ops) {
+  if (op->recv_ops != NULL) {
     char tmp[GPR_LTOA_MIN_BUFSIZE];
     grpc_metadata_batch mdb;
     gpr_ltoa(GRPC_STATUS_UNKNOWN, tmp);
@@ -77,36 +77,35 @@ static void lame_start_transport_op(grpc_call_element *elem,
     *op->recv_state = GRPC_STREAM_CLOSED;
     op->on_done_recv->cb(op->on_done_recv->cb_arg, 1);
   }
-  if (op->on_consumed) {
+  if (op->on_consumed != NULL) {
     op->on_consumed->cb(op->on_consumed->cb_arg, 0);
   }
 }
 
-static void channel_op(grpc_channel_element *elem,
-                       grpc_channel_element *from_elem, grpc_channel_op *op) {
-  switch (op->type) {
-    case GRPC_CHANNEL_GOAWAY:
-      gpr_slice_unref(op->data.goaway.message);
-      break;
-    case GRPC_CHANNEL_DISCONNECT:
-      grpc_client_channel_closed(elem);
-      break;
-    default:
-      break;
+static void lame_start_transport_op(grpc_channel_element *elem,
+                                    grpc_transport_op *op) {
+  if (op->on_connectivity_state_change) {
+    GPR_ASSERT(*op->connectivity_state != GRPC_CHANNEL_FATAL_FAILURE);
+    *op->connectivity_state = GRPC_CHANNEL_FATAL_FAILURE;
+    op->on_connectivity_state_change->cb(
+        op->on_connectivity_state_change->cb_arg, 1);
+  }
+  if (op->on_consumed != NULL) {
+    op->on_consumed->cb(op->on_consumed->cb_arg, 1);
   }
 }
 
 static void init_call_elem(grpc_call_element *elem,
                            const void *transport_server_data,
-                           grpc_transport_op *initial_op) {
+                           grpc_transport_stream_op *initial_op) {
   if (initial_op) {
-    grpc_transport_op_finish_with_failure(initial_op);
+    grpc_transport_stream_op_finish_with_failure(initial_op);
   }
 }
 
 static void destroy_call_elem(grpc_call_element *elem) {}
 
-static void init_channel_elem(grpc_channel_element *elem,
+static void init_channel_elem(grpc_channel_element *elem, grpc_channel *master,
                               const grpc_channel_args *args, grpc_mdctx *mdctx,
                               int is_first, int is_last) {
   channel_data *chand = elem->channel_data;
@@ -118,9 +117,15 @@ static void init_channel_elem(grpc_channel_element *elem,
 static void destroy_channel_elem(grpc_channel_element *elem) {}
 
 static const grpc_channel_filter lame_filter = {
-    lame_start_transport_op, channel_op,           sizeof(call_data),
-    init_call_elem,          destroy_call_elem,    sizeof(channel_data),
-    init_channel_elem,       destroy_channel_elem, "lame-client",
+    lame_start_transport_stream_op,
+    lame_start_transport_op,
+    sizeof(call_data),
+    init_call_elem,
+    destroy_call_elem,
+    sizeof(channel_data),
+    init_channel_elem,
+    destroy_channel_elem,
+    "lame-client",
 };
 
 grpc_channel *grpc_lame_client_channel_create(void) {
diff --git a/src/core/surface/secure_channel_create.c b/src/core/surface/secure_channel_create.c
index fae3e4e90a..34ee3f8400 100644
--- a/src/core/surface/secure_channel_create.c
+++ b/src/core/surface/secure_channel_create.c
@@ -31,177 +31,147 @@
  *
  */
 
-#include "src/core/iomgr/sockaddr.h"
-
 #include <grpc/grpc.h>
 
 #include <stdlib.h>
 #include <string.h>
 
-#include "src/core/channel/census_filter.h"
+#include <grpc/support/alloc.h>
+
 #include "src/core/channel/channel_args.h"
 #include "src/core/channel/client_channel.h"
-#include "src/core/channel/client_setup.h"
-#include "src/core/channel/connected_channel.h"
 #include "src/core/channel/http_client_filter.h"
-#include "src/core/iomgr/resolve_address.h"
+#include "src/core/client_config/resolver_registry.h"
 #include "src/core/iomgr/tcp_client.h"
 #include "src/core/security/auth_filters.h"
 #include "src/core/security/credentials.h"
 #include "src/core/security/secure_transport_setup.h"
-#include "src/core/support/string.h"
 #include "src/core/surface/channel.h"
-#include "src/core/surface/client.h"
 #include "src/core/transport/chttp2_transport.h"
-#include <grpc/grpc_security.h>
-#include <grpc/support/alloc.h>
-#include <grpc/support/log.h>
-#include <grpc/support/string_util.h>
-#include <grpc/support/sync.h>
-#include <grpc/support/useful.h>
 #include "src/core/tsi/transport_security_interface.h"
 
-typedef struct setup setup;
-
-/* A single setup request (started via initiate) */
 typedef struct {
-  grpc_client_setup_request *cs_request;
-  setup *setup;
-  /* Resolved addresses, or null if resolution not yet completed. */
-  grpc_resolved_addresses *resolved;
-  /* which address in resolved should we pick for the next connection attempt */
-  size_t resolved_index;
-} request;
+  grpc_connector base;
+  gpr_refcount refs;
 
-struct setup {
   grpc_channel_security_connector *security_connector;
-  const char *target;
-  grpc_transport_setup_callback setup_callback;
-  void *setup_user_data;
-};
 
-static int maybe_try_next_resolved(request *r);
+  grpc_iomgr_closure *notify;
+  grpc_connect_in_args args;
+  grpc_connect_out_args *result;
+} connector;
 
-static void done(request *r, int was_successful) {
-  grpc_client_setup_request_finish(r->cs_request, was_successful);
-  if (r->resolved) {
-    grpc_resolved_addresses_destroy(r->resolved);
+static void connector_ref(grpc_connector *con) {
+  connector *c = (connector *)con;
+  gpr_ref(&c->refs);
+}
+
+static void connector_unref(grpc_connector *con) {
+  connector *c = (connector *)con;
+  if (gpr_unref(&c->refs)) {
+    gpr_free(c);
   }
-  gpr_free(r);
 }
 
-static void on_secure_transport_setup_done(void *rp,
+static void on_secure_transport_setup_done(void *arg,
                                            grpc_security_status status,
                                            grpc_endpoint *secure_endpoint) {
-  request *r = rp;
+  connector *c = arg;
+  grpc_iomgr_closure *notify;
   if (status != GRPC_SECURITY_OK) {
     gpr_log(GPR_ERROR, "Secure transport setup failed with error %d.", status);
-    done(r, 0);
-  } else if (grpc_client_setup_cb_begin(r->cs_request,
-                                        "on_secure_transport_setup_done")) {
-    grpc_create_chttp2_transport(
-        r->setup->setup_callback, r->setup->setup_user_data,
-        grpc_client_setup_get_channel_args(r->cs_request), secure_endpoint,
-        NULL, 0, grpc_client_setup_get_mdctx(r->cs_request), 1);
-    grpc_client_setup_cb_end(r->cs_request, "on_secure_transport_setup_done");
-    done(r, 1);
+    memset(c->result, 0, sizeof(*c->result));
   } else {
-    done(r, 0);
+    c->result->transport = grpc_create_chttp2_transport(
+        c->args.channel_args, secure_endpoint, c->args.metadata_context, 1);
+    grpc_chttp2_transport_start_reading(c->result->transport, NULL, 0);
+    c->result->filters = gpr_malloc(sizeof(grpc_channel_filter *) * 2);
+    c->result->filters[0] = &grpc_client_auth_filter;
+    c->result->filters[1] = &grpc_http_client_filter;
+    c->result->num_filters = 2;
   }
+  notify = c->notify;
+  c->notify = NULL;
+  grpc_iomgr_add_callback(notify);
 }
 
-/* connection callback: tcp is either valid, or null on error */
-static void on_connect(void *rp, grpc_endpoint *tcp) {
-  request *r = rp;
-
-  if (!grpc_client_setup_request_should_continue(r->cs_request,
-                                                 "on_connect.secure")) {
-    if (tcp) {
-      grpc_endpoint_shutdown(tcp);
-      grpc_endpoint_destroy(tcp);
-    }
-    done(r, 0);
-    return;
-  }
-
-  if (!tcp) {
-    if (!maybe_try_next_resolved(r)) {
-      done(r, 0);
-      return;
-    } else {
-      return;
-    }
+static void connected(void *arg, grpc_endpoint *tcp) {
+  connector *c = arg;
+  grpc_iomgr_closure *notify;
+  if (tcp != NULL) {
+    grpc_setup_secure_transport(&c->security_connector->base, tcp,
+                                on_secure_transport_setup_done, c);
   } else {
-    grpc_setup_secure_transport(&r->setup->security_connector->base, tcp,
-                                on_secure_transport_setup_done, r);
+    memset(c->result, 0, sizeof(*c->result));
+    notify = c->notify;
+    c->notify = NULL;
+    grpc_iomgr_add_callback(notify);
   }
 }
 
-/* attempt to connect to the next available resolved address */
-static int maybe_try_next_resolved(request *r) {
-  grpc_resolved_address *addr;
-  if (!r->resolved) return 0;
-  if (r->resolved_index == r->resolved->naddrs) return 0;
-  addr = &r->resolved->addrs[r->resolved_index++];
-  grpc_tcp_client_connect(
-      on_connect, r, grpc_client_setup_get_interested_parties(r->cs_request),
-      (struct sockaddr *)&addr->addr, addr->len,
-      grpc_client_setup_request_deadline(r->cs_request));
-  return 1;
+static void connector_connect(grpc_connector *con,
+                              const grpc_connect_in_args *args,
+                              grpc_connect_out_args *result,
+                              grpc_iomgr_closure *notify) {
+  connector *c = (connector *)con;
+  GPR_ASSERT(c->notify == NULL);
+  GPR_ASSERT(notify->cb);
+  c->notify = notify;
+  c->args = *args;
+  c->result = result;
+  grpc_tcp_client_connect(connected, c, args->interested_parties, args->addr,
+                          args->addr_len, args->deadline);
 }
 
-/* callback for when our target address has been resolved */
-static void on_resolved(void *rp, grpc_resolved_addresses *resolved) {
-  request *r = rp;
+static const grpc_connector_vtable connector_vtable = {
+    connector_ref, connector_unref, connector_connect};
 
-  /* if we're not still the active request, abort */
-  if (!grpc_client_setup_request_should_continue(r->cs_request,
-                                                 "on_resolved.secure")) {
-    if (resolved) {
-      grpc_resolved_addresses_destroy(resolved);
-    }
-    done(r, 0);
-    return;
-  }
+typedef struct {
+  grpc_subchannel_factory base;
+  gpr_refcount refs;
+  grpc_mdctx *mdctx;
+  grpc_channel_args *merge_args;
+  grpc_channel_security_connector *security_connector;
+} subchannel_factory;
 
-  if (!resolved) {
-    done(r, 0);
-    return;
-  } else {
-    r->resolved = resolved;
-    r->resolved_index = 0;
-    if (!maybe_try_next_resolved(r)) {
-      done(r, 0);
-    }
-  }
+static void subchannel_factory_ref(grpc_subchannel_factory *scf) {
+  subchannel_factory *f = (subchannel_factory *)scf;
+  gpr_ref(&f->refs);
 }
 
-static void initiate_setup(void *sp, grpc_client_setup_request *cs_request) {
-  request *r = gpr_malloc(sizeof(request));
-  r->setup = sp;
-  r->cs_request = cs_request;
-  r->resolved = NULL;
-  r->resolved_index = 0;
-  /* TODO(klempner): Make grpc_resolve_address respect deadline */
-  grpc_resolve_address(r->setup->target, "https", on_resolved, r);
+static void subchannel_factory_unref(grpc_subchannel_factory *scf) {
+  subchannel_factory *f = (subchannel_factory *)scf;
+  if (gpr_unref(&f->refs)) {
+    GRPC_SECURITY_CONNECTOR_UNREF(&f->security_connector->base,
+                                  "subchannel_factory");
+    grpc_channel_args_destroy(f->merge_args);
+    grpc_mdctx_unref(f->mdctx);
+    gpr_free(f);
+  }
 }
 
-static void done_setup(void *sp) {
-  setup *s = sp;
-  gpr_free((void *)s->target);
-  grpc_security_connector_unref(&s->security_connector->base);
-  gpr_free(s);
+static grpc_subchannel *subchannel_factory_create_subchannel(
+    grpc_subchannel_factory *scf, grpc_subchannel_args *args) {
+  subchannel_factory *f = (subchannel_factory *)scf;
+  connector *c = gpr_malloc(sizeof(*c));
+  grpc_channel_args *final_args =
+      grpc_channel_args_merge(args->args, f->merge_args);
+  grpc_subchannel *s;
+  memset(c, 0, sizeof(*c));
+  c->base.vtable = &connector_vtable;
+  c->security_connector = f->security_connector;
+  gpr_ref_init(&c->refs, 1);
+  args->mdctx = f->mdctx;
+  args->args = final_args;
+  s = grpc_subchannel_create(&c->base, args);
+  grpc_connector_unref(&c->base);
+  grpc_channel_args_destroy(final_args);
+  return s;
 }
 
-static grpc_transport_setup_result complete_setup(void *channel_stack,
-                                                  grpc_transport *transport,
-                                                  grpc_mdctx *mdctx) {
-  static grpc_channel_filter const *extra_filters[] = {
-      &grpc_client_auth_filter, &grpc_http_client_filter};
-  return grpc_client_channel_transport_setup_complete(
-      channel_stack, transport, extra_filters, GPR_ARRAY_SIZE(extra_filters),
-      mdctx);
-}
+static const grpc_subchannel_factory_vtable subchannel_factory_vtable = {
+    subchannel_factory_ref, subchannel_factory_unref,
+    subchannel_factory_create_subchannel};
 
 /* Create a secure client channel:
    Asynchronously: - resolve target
@@ -210,13 +180,14 @@ static grpc_transport_setup_result complete_setup(void *channel_stack,
 grpc_channel *grpc_secure_channel_create(grpc_credentials *creds,
                                          const char *target,
                                          const grpc_channel_args *args) {
-  setup *s;
   grpc_channel *channel;
   grpc_arg connector_arg;
   grpc_channel_args *args_copy;
   grpc_channel_args *new_args_from_connector;
   grpc_channel_security_connector *connector;
   grpc_mdctx *mdctx;
+  grpc_resolver *resolver;
+  subchannel_factory *f;
 #define MAX_FILTERS 3
   const grpc_channel_filter *filters[MAX_FILTERS];
   int n = 0;
@@ -233,30 +204,41 @@ grpc_channel *grpc_secure_channel_create(grpc_credentials *creds,
   }
   mdctx = grpc_mdctx_create();
 
-  s = gpr_malloc(sizeof(setup));
   connector_arg = grpc_security_connector_to_arg(&connector->base);
   args_copy = grpc_channel_args_copy_and_add(
       new_args_from_connector != NULL ? new_args_from_connector : args,
-      &connector_arg);
-  filters[n++] = &grpc_client_surface_filter;
+      &connector_arg, 1);
   /* TODO(census)
   if (grpc_channel_args_is_census_enabled(args)) {
     filters[n++] = &grpc_client_census_filter;
     } */
   filters[n++] = &grpc_client_channel_filter;
   GPR_ASSERT(n <= MAX_FILTERS);
+
+  f = gpr_malloc(sizeof(*f));
+  f->base.vtable = &subchannel_factory_vtable;
+  gpr_ref_init(&f->refs, 1);
+  grpc_mdctx_ref(mdctx);
+  f->mdctx = mdctx;
+  GRPC_SECURITY_CONNECTOR_REF(&connector->base, "subchannel_factory");
+  f->security_connector = connector;
+  f->merge_args = grpc_channel_args_copy(args_copy);
+  resolver = grpc_resolver_create(target, &f->base);
+  if (!resolver) {
+    return NULL;
+  }
+
   channel = grpc_channel_create_from_filters(filters, n, args_copy, mdctx, 1);
+  grpc_client_channel_set_resolver(grpc_channel_get_channel_stack(channel),
+                                   resolver);
+  GRPC_RESOLVER_UNREF(resolver, "create");
+  grpc_subchannel_factory_unref(&f->base);
+  GRPC_SECURITY_CONNECTOR_UNREF(&connector->base, "channel_create");
+
   grpc_channel_args_destroy(args_copy);
   if (new_args_from_connector != NULL) {
     grpc_channel_args_destroy(new_args_from_connector);
   }
 
-  s->target = gpr_strdup(target);
-  s->setup_callback = complete_setup;
-  s->setup_user_data = grpc_channel_get_channel_stack(channel);
-  s->security_connector = connector;
-  grpc_client_setup_create_and_attach(grpc_channel_get_channel_stack(channel),
-                                      args, mdctx, initiate_setup, done_setup,
-                                      s);
   return channel;
 }
diff --git a/src/core/surface/server.c b/src/core/surface/server.c
index 13ec5bee94..f29d47c17c 100644
--- a/src/core/surface/server.c
+++ b/src/core/surface/server.c
@@ -115,6 +115,7 @@ typedef struct channel_registered_method {
 struct channel_data {
   grpc_server *server;
   size_t num_calls;
+  grpc_connectivity_state connectivity_state;
   grpc_channel *channel;
   grpc_mdstr *path_key;
   grpc_mdstr *authority_key;
@@ -125,6 +126,7 @@ struct channel_data {
   gpr_uint32 registered_method_slots;
   gpr_uint32 registered_method_max_probes;
   grpc_iomgr_closure finish_destroy_channel_closure;
+  grpc_iomgr_closure channel_connectivity_changed;
 };
 
 typedef struct shutdown_tag {
@@ -149,7 +151,7 @@ struct grpc_server {
      before mu_call. This is currently used in shutdown processing
      (grpc_server_shutdown_and_notify and maybe_finish_shutdown) */
   gpr_mu mu_global; /* mutex for server and channel state */
-  gpr_mu mu_call; /* mutex for call-specific state */
+  gpr_mu mu_call;   /* mutex for call-specific state */
 
   registered_method *registered_methods;
   requested_call_array requested_calls;
@@ -200,18 +202,101 @@ struct call_data {
   call_link links[CALL_LIST_COUNT];
 };
 
+typedef struct {
+  grpc_channel **channels;
+  grpc_channel **disconnects;
+  size_t num_channels;
+  size_t num_disconnects;
+} channel_broadcaster;
+
 #define SERVER_FROM_CALL_ELEM(elem) \
   (((channel_data *)(elem)->channel_data)->server)
 
 static void begin_call(grpc_server *server, call_data *calld,
                        requested_call *rc);
 static void fail_call(grpc_server *server, requested_call *rc);
-static void shutdown_channel(channel_data *chand, int send_goaway,
-                             int send_disconnect);
 /* Before calling maybe_finish_shutdown, we must hold mu_global and not
    hold mu_call */
 static void maybe_finish_shutdown(grpc_server *server);
 
+/* channel broadcaster */
+
+/* assumes server locked */
+static void channel_broadcaster_init(grpc_server *s, channel_broadcaster *cb) {
+  channel_data *c;
+  size_t count = 0;
+  size_t dc_count = 0;
+  for (c = s->root_channel_data.next; c != &s->root_channel_data; c = c->next) {
+    count++;
+    if (c->num_calls == 0) {
+      dc_count++;
+    }
+  }
+  cb->num_channels = count;
+  cb->num_disconnects = dc_count;
+  cb->channels = gpr_malloc(sizeof(*cb->channels) * cb->num_channels);
+  cb->disconnects = gpr_malloc(sizeof(*cb->channels) * cb->num_disconnects);
+  count = 0;
+  dc_count = 0;
+  for (c = s->root_channel_data.next; c != &s->root_channel_data; c = c->next) {
+    cb->channels[count++] = c->channel;
+    GRPC_CHANNEL_INTERNAL_REF(c->channel, "broadcast");
+    if (c->num_calls == 0) {
+      cb->disconnects[dc_count++] = c->channel;
+      GRPC_CHANNEL_INTERNAL_REF(c->channel, "broadcast-disconnect");
+    }
+  }
+}
+
+struct shutdown_cleanup_args {
+  grpc_iomgr_closure closure;
+  gpr_slice slice;
+};
+
+static void shutdown_cleanup(void *arg, int iomgr_status_ignored) {
+  struct shutdown_cleanup_args *a = arg;
+  gpr_slice_unref(a->slice);
+  gpr_free(a);
+}
+
+static void send_shutdown(grpc_channel *channel, int send_goaway,
+                          int send_disconnect) {
+  grpc_transport_op op;
+  struct shutdown_cleanup_args *sc;
+  grpc_channel_element *elem;
+
+  memset(&op, 0, sizeof(op));
+  op.send_goaway = send_goaway;
+  sc = gpr_malloc(sizeof(*sc));
+  sc->slice = gpr_slice_from_copied_string("Server shutdown");
+  op.goaway_message = &sc->slice;
+  op.goaway_status = GRPC_STATUS_OK;
+  op.disconnect = send_disconnect;
+  grpc_iomgr_closure_init(&sc->closure, shutdown_cleanup, sc);
+  op.on_consumed = &sc->closure;
+
+  elem = grpc_channel_stack_element(grpc_channel_get_channel_stack(channel), 0);
+  elem->filter->start_transport_op(elem, &op);
+}
+
+static void channel_broadcaster_shutdown(channel_broadcaster *cb,
+                                         int send_goaway, int send_disconnect) {
+  size_t i;
+
+  for (i = 0; i < cb->num_channels; i++) {
+    send_shutdown(cb->channels[i], 1, 0);
+    GRPC_CHANNEL_INTERNAL_UNREF(cb->channels[i], "broadcast");
+  }
+  for (i = 0; i < cb->num_disconnects; i++) {
+    send_shutdown(cb->disconnects[i], 0, 1);
+    GRPC_CHANNEL_INTERNAL_UNREF(cb->channels[i], "broadcast-disconnect");
+  }
+  gpr_free(cb->channels);
+  gpr_free(cb->disconnects);
+}
+
+/* call list */
+
 static int call_list_join(call_data **root, call_data *call, call_list list) {
   GPR_ASSERT(!call->root[list]);
   call->root[list] = root;
@@ -456,12 +541,14 @@ static grpc_mdelem *server_filter(void *user_data, grpc_mdelem *md) {
   return md;
 }
 
-static void decrement_call_count(channel_data *chand) {
+static int decrement_call_count(channel_data *chand) {
+  int disconnect = 0;
   chand->num_calls--;
   if (0 == chand->num_calls && chand->server->shutdown) {
-    shutdown_channel(chand, 0, 1);
+    disconnect = 1;
   }
   maybe_finish_shutdown(chand->server);
+  return disconnect;
 }
 
 static void server_on_recv(void *ptr, int success) {
@@ -469,6 +556,7 @@ static void server_on_recv(void *ptr, int success) {
   call_data *calld = elem->call_data;
   channel_data *chand = elem->channel_data;
   int remove_res;
+  int disconnect = 0;
 
   if (success && !calld->got_initial_metadata) {
     size_t i;
@@ -517,16 +605,24 @@ static void server_on_recv(void *ptr, int success) {
       gpr_mu_unlock(&chand->server->mu_call);
       gpr_mu_lock(&chand->server->mu_global);
       if (remove_res) {
-        decrement_call_count(chand);
+        disconnect = decrement_call_count(chand);
+        if (disconnect) {
+          GRPC_CHANNEL_INTERNAL_REF(chand->channel, "send-disconnect");
+        }
       }
       gpr_mu_unlock(&chand->server->mu_global);
+      if (disconnect) {
+        send_shutdown(chand->channel, 0, 1);
+        GRPC_CHANNEL_INTERNAL_UNREF(chand->channel, "send-disconnect");
+      }
       break;
   }
 
   calld->on_done_recv->cb(calld->on_done_recv->cb_arg, success);
 }
 
-static void server_mutate_op(grpc_call_element *elem, grpc_transport_op *op) {
+static void server_mutate_op(grpc_call_element *elem,
+                             grpc_transport_stream_op *op) {
   call_data *calld = elem->call_data;
 
   if (op->recv_ops) {
@@ -538,92 +634,43 @@ static void server_mutate_op(grpc_call_element *elem, grpc_transport_op *op) {
   }
 }
 
-static void server_start_transport_op(grpc_call_element *elem,
-                                      grpc_transport_op *op) {
+static void server_start_transport_stream_op(grpc_call_element *elem,
+                                             grpc_transport_stream_op *op) {
   GRPC_CALL_LOG_OP(GPR_INFO, elem, op);
   server_mutate_op(elem, op);
   grpc_call_next_op(elem, op);
 }
 
-static void channel_op(grpc_channel_element *elem,
-                       grpc_channel_element *from_elem, grpc_channel_op *op) {
-  channel_data *chand = elem->channel_data;
-  grpc_server *server = chand->server;
-
-  switch (op->type) {
-    case GRPC_ACCEPT_CALL:
-      /* create a call */
-      grpc_call_create(chand->channel, NULL,
-                       op->data.accept_call.transport_server_data, NULL, 0,
-                       gpr_inf_future);
-      break;
-    case GRPC_TRANSPORT_CLOSED:
-      /* if the transport is closed for a server channel, we destroy the
-         channel */
-      gpr_mu_lock(&server->mu_global);
-      server_ref(server);
-      destroy_channel(chand);
-      gpr_mu_unlock(&server->mu_global);
-      server_unref(server);
-      break;
-    case GRPC_TRANSPORT_GOAWAY:
-      gpr_slice_unref(op->data.goaway.message);
-      break;
-    default:
-      GPR_ASSERT(op->dir == GRPC_CALL_DOWN);
-      grpc_channel_next_op(elem, op);
-      break;
-  }
+static void accept_stream(void *cd, grpc_transport *transport,
+                          const void *transport_server_data) {
+  channel_data *chand = cd;
+  /* create a call */
+  grpc_call_create(chand->channel, NULL, transport_server_data, NULL, 0,
+                   gpr_inf_future);
 }
 
-typedef struct {
-  channel_data *chand;
-  int send_goaway;
-  int send_disconnect;
-  grpc_iomgr_closure finish_shutdown_channel_closure;
-} shutdown_channel_args;
-
-static void finish_shutdown_channel(void *p, int success) {
-  shutdown_channel_args *sca = p;
-  grpc_channel_op op;
-
-  if (sca->send_goaway) {
-    op.type = GRPC_CHANNEL_GOAWAY;
-    op.dir = GRPC_CALL_DOWN;
-    op.data.goaway.status = GRPC_STATUS_OK;
-    op.data.goaway.message = gpr_slice_from_copied_string("Server shutdown");
-    channel_op(grpc_channel_stack_element(
-                   grpc_channel_get_channel_stack(sca->chand->channel), 0),
-               NULL, &op);
-  }
-  if (sca->send_disconnect) {
-    op.type = GRPC_CHANNEL_DISCONNECT;
-    op.dir = GRPC_CALL_DOWN;
-    channel_op(grpc_channel_stack_element(
-                   grpc_channel_get_channel_stack(sca->chand->channel), 0),
-               NULL, &op);
+static void channel_connectivity_changed(void *cd, int iomgr_status_ignored) {
+  channel_data *chand = cd;
+  grpc_server *server = chand->server;
+  if (chand->connectivity_state != GRPC_CHANNEL_FATAL_FAILURE) {
+    grpc_transport_op op;
+    memset(&op, 0, sizeof(op));
+    op.on_connectivity_state_change = &chand->channel_connectivity_changed,
+    op.connectivity_state = &chand->connectivity_state;
+    grpc_channel_next_op(grpc_channel_stack_element(
+                             grpc_channel_get_channel_stack(chand->channel), 0),
+                         &op);
+  } else {
+    gpr_mu_lock(&server->mu_global);
+    destroy_channel(chand);
+    gpr_mu_unlock(&server->mu_global);
+    GRPC_CHANNEL_INTERNAL_UNREF(chand->channel, "connectivity");
   }
-  GRPC_CHANNEL_INTERNAL_UNREF(sca->chand->channel, "shutdown");
-
-  gpr_free(sca);
-}
-
-static void shutdown_channel(channel_data *chand, int send_goaway,
-                             int send_disconnect) {
-  shutdown_channel_args *sca;
-  GRPC_CHANNEL_INTERNAL_REF(chand->channel, "shutdown");
-  sca = gpr_malloc(sizeof(shutdown_channel_args));
-  sca->chand = chand;
-  sca->send_goaway = send_goaway;
-  sca->send_disconnect = send_disconnect;
-  sca->finish_shutdown_channel_closure.cb = finish_shutdown_channel;
-  sca->finish_shutdown_channel_closure.cb_arg = sca;
-  grpc_iomgr_add_callback(&sca->finish_shutdown_channel_closure);
 }
 
 static void init_call_elem(grpc_call_element *elem,
                            const void *server_transport_data,
-                           grpc_transport_op *initial_op) {
+                           grpc_transport_stream_op *initial_op) {
   call_data *calld = elem->call_data;
   channel_data *chand = elem->channel_data;
   memset(calld, 0, sizeof(call_data));
@@ -672,7 +719,7 @@ static void destroy_call_elem(grpc_call_element *elem) {
   server_unref(chand->server);
 }
 
-static void init_channel_elem(grpc_channel_element *elem,
+static void init_channel_elem(grpc_channel_element *elem, grpc_channel *master,
                               const grpc_channel_args *args,
                               grpc_mdctx *metadata_context, int is_first,
                               int is_last) {
@@ -686,6 +733,9 @@ static void init_channel_elem(grpc_channel_element *elem,
   chand->authority_key = grpc_mdstr_from_string(metadata_context, ":authority");
   chand->next = chand->prev = chand;
   chand->registered_methods = NULL;
+  chand->connectivity_state = GRPC_CHANNEL_IDLE;
+  grpc_iomgr_closure_init(&chand->channel_connectivity_changed,
+                          channel_connectivity_changed, chand);
 }
 
 static void destroy_channel_elem(grpc_channel_element *elem) {
@@ -716,8 +766,8 @@ static void destroy_channel_elem(grpc_channel_element *elem) {
 }
 
 static const grpc_channel_filter server_surface_filter = {
-    server_start_transport_op,
-    channel_op,
+    server_start_transport_stream_op,
+    grpc_channel_next_op,
     sizeof(call_data),
     init_call_elem,
     destroy_call_elem,
@@ -831,10 +881,10 @@ void grpc_server_start(grpc_server *server) {
   }
 }
 
-grpc_transport_setup_result grpc_server_setup_transport(
-    grpc_server *s, grpc_transport *transport,
-    grpc_channel_filter const **extra_filters, size_t num_extra_filters,
-    grpc_mdctx *mdctx, const grpc_channel_args *args) {
+void grpc_server_setup_transport(grpc_server *s, grpc_transport *transport,
+                                 grpc_channel_filter const **extra_filters,
+                                 size_t num_extra_filters, grpc_mdctx *mdctx,
+                                 const grpc_channel_args *args) {
   size_t num_filters = s->channel_filter_count + num_extra_filters + 1;
   grpc_channel_filter const **filters =
       gpr_malloc(sizeof(grpc_channel_filter *) * num_filters);
@@ -851,7 +901,7 @@ grpc_transport_setup_result grpc_server_setup_transport(
   gpr_uint32 slots;
   gpr_uint32 probes;
   gpr_uint32 max_probes = 0;
-  grpc_transport_setup_result result;
+  grpc_transport_op op;
 
   for (i = 0; i < s->channel_filter_count; i++) {
     filters[i] = s->channel_filters[i];
@@ -862,7 +912,9 @@ grpc_transport_setup_result grpc_server_setup_transport(
   filters[i] = &grpc_connected_channel_filter;
 
   for (i = 0; i < s->cq_count; i++) {
-    grpc_transport_add_to_pollset(transport, grpc_cq_pollset(s->cqs[i]));
+    memset(&op, 0, sizeof(op));
+    op.bind_pollset = grpc_cq_pollset(s->cqs[i]);
+    grpc_transport_perform_op(transport, &op);
   }
 
   channel =
@@ -903,8 +955,8 @@ grpc_transport_setup_result grpc_server_setup_transport(
     chand->registered_method_max_probes = max_probes;
   }
 
-  result = grpc_connected_channel_bind_transport(
-      grpc_channel_get_channel_stack(channel), transport);
+  grpc_connected_channel_bind_transport(grpc_channel_get_channel_stack(channel),
+                                        transport);
 
   gpr_mu_lock(&s->mu_global);
   chand->next = &s->root_channel_data;
@@ -914,17 +966,23 @@ grpc_transport_setup_result grpc_server_setup_transport(
 
   gpr_free(filters);
 
-  return result;
+  GRPC_CHANNEL_INTERNAL_REF(channel, "connectivity");
+  memset(&op, 0, sizeof(op));
+  op.set_accept_stream = accept_stream;
+  op.set_accept_stream_user_data = chand;
+  op.on_connectivity_state_change = &chand->channel_connectivity_changed;
+  op.connectivity_state = &chand->connectivity_state;
+  grpc_transport_perform_op(transport, &op);
 }
 
 void grpc_server_shutdown_and_notify(grpc_server *server,
                                      grpc_completion_queue *cq, void *tag) {
   listener *l;
   requested_call_array requested_calls;
-  channel_data *c;
   size_t i;
   registered_method *rm;
   shutdown_tag *sdt;
+  channel_broadcaster broadcaster;
 
   /* lock, and gather up some stuff to do */
   gpr_mu_lock(&server->mu_global);
@@ -940,10 +998,7 @@ void grpc_server_shutdown_and_notify(grpc_server *server,
     return;
   }
 
-  for (c = server->root_channel_data.next; c != &server->root_channel_data;
-       c = c->next) {
-    shutdown_channel(c, 1, c->num_calls == 0);
-  }
+  channel_broadcaster_init(server, &broadcaster);
 
   /* collect all unregistered then registered calls */
   gpr_mu_lock(&server->mu_call);
@@ -981,6 +1036,8 @@ void grpc_server_shutdown_and_notify(grpc_server *server,
   for (l = server->listeners; l; l = l->next) {
     l->destroy(server, l->arg);
   }
+
+  channel_broadcaster_shutdown(&broadcaster, 1, 0);
 }
 
 void grpc_server_listener_destroy_done(void *s) {
@@ -1181,6 +1238,8 @@ static void begin_call(grpc_server *server, call_data *calld,
   calld->cq_new = rc->cq_for_notification;
   switch (rc->type) {
     case BATCH_CALL:
+      GPR_ASSERT(calld->host != NULL);
+      GPR_ASSERT(calld->path != NULL);
       cpstr(&rc->data.batch.details->host,
             &rc->data.batch.details->host_capacity, calld->host);
       cpstr(&rc->data.batch.details->method,
diff --git a/src/core/surface/server.h b/src/core/surface/server.h
index 91a1a2a7f6..2899c6dea3 100644
--- a/src/core/surface/server.h
+++ b/src/core/surface/server.h
@@ -55,10 +55,10 @@ void grpc_server_listener_destroy_done(void *server);
 
 /* Setup a transport - creates a channel stack, binds the transport to the
    server */
-grpc_transport_setup_result grpc_server_setup_transport(
-    grpc_server *server, grpc_transport *transport,
-    grpc_channel_filter const **extra_filters, size_t num_extra_filters,
-    grpc_mdctx *mdctx, const grpc_channel_args *args);
+void grpc_server_setup_transport(grpc_server *server, grpc_transport *transport,
+                                 grpc_channel_filter const **extra_filters,
+                                 size_t num_extra_filters, grpc_mdctx *mdctx,
+                                 const grpc_channel_args *args);
 
 const grpc_channel_args *grpc_server_get_channel_args(grpc_server *server);
 
diff --git a/src/core/surface/server_chttp2.c b/src/core/surface/server_chttp2.c
index 7e49a531df..78c53466b3 100644
--- a/src/core/surface/server_chttp2.c
+++ b/src/core/surface/server_chttp2.c
@@ -42,14 +42,13 @@
 #include <grpc/support/log.h>
 #include <grpc/support/useful.h>
 
-static grpc_transport_setup_result setup_transport(void *server,
-                                                   grpc_transport *transport,
-                                                   grpc_mdctx *mdctx) {
+static void setup_transport(void *server, grpc_transport *transport,
+                            grpc_mdctx *mdctx) {
   static grpc_channel_filter const *extra_filters[] = {
       &grpc_http_server_filter};
-  return grpc_server_setup_transport(server, transport, extra_filters,
-                                     GPR_ARRAY_SIZE(extra_filters), mdctx,
-                                     grpc_server_get_channel_args(server));
+  grpc_server_setup_transport(server, transport, extra_filters,
+                              GPR_ARRAY_SIZE(extra_filters), mdctx,
+                              grpc_server_get_channel_args(server));
 }
 
 static void new_transport(void *server, grpc_endpoint *tcp) {
@@ -60,9 +59,11 @@ static void new_transport(void *server, grpc_endpoint *tcp) {
    * (as in server_secure_chttp2.c) needs to add synchronization to avoid this
    * case.
    */
-  grpc_create_chttp2_transport(setup_transport, server,
-                               grpc_server_get_channel_args(server), tcp, NULL,
-                               0, grpc_mdctx_create(), 0);
+  grpc_mdctx *mdctx = grpc_mdctx_create();
+  grpc_transport *transport = grpc_create_chttp2_transport(
+      grpc_server_get_channel_args(server), tcp, mdctx, 0);
+  setup_transport(server, transport, mdctx);
+  grpc_chttp2_transport_start_reading(transport, NULL, 0);
 }
 
 /* Server callback: start listening on our ports */
diff --git a/src/core/transport/chttp2/incoming_metadata.c b/src/core/transport/chttp2/incoming_metadata.c
index a4b7174329..68e0912b9c 100644
--- a/src/core/transport/chttp2/incoming_metadata.c
+++ b/src/core/transport/chttp2/incoming_metadata.c
@@ -124,6 +124,7 @@ void grpc_incoming_metadata_buffer_move_to_referencing_sopb(
     sopb->ops[i].data.metadata.list.tail =
         (void *)(delta + (gpr_intptr)sopb->ops[i].data.metadata.list.tail);
   }
+  src->count = 0;
 }
 
 void grpc_chttp2_incoming_metadata_buffer_postprocess_sopb_and_begin_live_op(
diff --git a/src/core/transport/chttp2/internal.h b/src/core/transport/chttp2/internal.h
index 02c94744ee..7f98a5bd71 100644
--- a/src/core/transport/chttp2/internal.h
+++ b/src/core/transport/chttp2/internal.h
@@ -34,7 +34,6 @@
 #ifndef GRPC_INTERNAL_CORE_CHTTP2_INTERNAL_H
 #define GRPC_INTERNAL_CORE_CHTTP2_INTERNAL_H
 
-#include "src/core/transport/transport_impl.h"
 #include "src/core/iomgr/endpoint.h"
 #include "src/core/transport/chttp2/frame.h"
 #include "src/core/transport/chttp2/frame_data.h"
@@ -47,6 +46,8 @@
 #include "src/core/transport/chttp2/incoming_metadata.h"
 #include "src/core/transport/chttp2/stream_encoder.h"
 #include "src/core/transport/chttp2/stream_map.h"
+#include "src/core/transport/connectivity_state.h"
+#include "src/core/transport/transport_impl.h"
 
 typedef struct grpc_chttp2_transport grpc_chttp2_transport;
 typedef struct grpc_chttp2_stream grpc_chttp2_stream;
@@ -62,6 +63,7 @@ typedef enum {
   GRPC_CHTTP2_LIST_WRITABLE_WINDOW_UPDATE,
   GRPC_CHTTP2_LIST_PARSING_SEEN,
   GRPC_CHTTP2_LIST_CLOSED_WAITING_FOR_PARSING,
+  GRPC_CHTTP2_LIST_CANCELLED_WAITING_FOR_WRITING,
   GRPC_CHTTP2_LIST_INCOMING_WINDOW_UPDATED,
   /** streams that are waiting to start because there are too many concurrent
       streams on the connection */
@@ -134,12 +136,6 @@ typedef struct {
   grpc_chttp2_stream *prev;
 } grpc_chttp2_stream_link;
 
-typedef enum {
-  GRPC_CHTTP2_ERROR_STATE_NONE,
-  GRPC_CHTTP2_ERROR_STATE_SEEN,
-  GRPC_CHTTP2_ERROR_STATE_NOTIFIED
-} grpc_chttp2_error_state;
-
 /* We keep several sets of connection wide parameters */
 typedef enum {
   /* The settings our peer has asked for (and we have acked) */
@@ -165,7 +161,8 @@ typedef struct {
   /** data to write next write */
   gpr_slice_buffer qbuf;
   /** queued callbacks */
-  grpc_iomgr_closure *pending_closures;
+  grpc_iomgr_closure *pending_closures_head;
+  grpc_iomgr_closure *pending_closures_tail;
 
   /** window available for us to send to peer */
   gpr_uint32 outgoing_window;
@@ -174,6 +171,9 @@ typedef struct {
   /** how much window would we like to have for incoming_window */
   gpr_uint32 connection_window_target;
 
+  /** have we seen a goaway */
+  gpr_uint8 seen_goaway;
+
   /** is this transport a client? */
   gpr_uint8 is_client;
   /** are the local settings dirty and need to be sent? */
@@ -185,10 +185,6 @@ typedef struct {
   /** settings values */
   gpr_uint32 settings[GRPC_NUM_SETTING_SETS][GRPC_CHTTP2_NUM_SETTINGS];
 
-  /** has there been a connection level error, and have we notified
-      anyone about it? */
-  grpc_chttp2_error_state error_state;
-
   /** what is the next stream id to be allocated by this peer?
       copied to next_stream_id in parsing when parsing commences */
   gpr_uint32 next_stream_id;
@@ -204,13 +200,6 @@ typedef struct {
   /** concurrent stream count: updated when not parsing,
       so this is a strict over-estimation on the client */
   gpr_uint32 concurrent_stream_count;
-
-  /** is there a goaway available? (boolean) */
-  grpc_chttp2_error_state goaway_state;
-  /** what is the debug text of the goaway? */
-  gpr_slice goaway_text;
-  /** what is the status code of the goaway? */
-  grpc_status_code goaway_error;
 } grpc_chttp2_transport_global;
 
 typedef struct {
@@ -343,14 +332,13 @@ struct grpc_chttp2_transport {
   grpc_chttp2_stream **accepting_stream;
 
   struct {
-    /** is a thread currently performing channel callbacks */
-    gpr_uint8 executing;
-    /** transport channel-level callback */
-    const grpc_transport_callbacks *cb;
-    /** user data for cb calls */
-    void *cb_user_data;
-    /** closure for notifying transport closure */
-    grpc_iomgr_closure notify_closed;
+    /* accept stream callback */
+    void (*accept_stream)(void *user_data, grpc_transport *transport,
+                          const void *server_data);
+    void *accept_stream_user_data;
+
+    /** connectivity tracking */
+    grpc_connectivity_state_tracker state_tracker;
   } channel_callback;
 };
 
@@ -539,6 +527,13 @@ int grpc_chttp2_list_pop_closed_waiting_for_parsing(
     grpc_chttp2_transport_global *transport_global,
     grpc_chttp2_stream_global **stream_global);
 
+void grpc_chttp2_list_add_cancelled_waiting_for_writing(
+    grpc_chttp2_transport_global *transport_global,
+    grpc_chttp2_stream_global *stream_global);
+int grpc_chttp2_list_pop_cancelled_waiting_for_writing(
+    grpc_chttp2_transport_global *transport_global,
+    grpc_chttp2_stream_global **stream_global);
+
 void grpc_chttp2_list_add_read_write_state_changed(
     grpc_chttp2_transport_global *transport_global,
     grpc_chttp2_stream_global *stream_global);
diff --git a/src/core/transport/chttp2/stream_lists.c b/src/core/transport/chttp2/stream_lists.c
index c6ba12fca8..85691b32d2 100644
--- a/src/core/transport/chttp2/stream_lists.c
+++ b/src/core/transport/chttp2/stream_lists.c
@@ -222,7 +222,9 @@ int grpc_chttp2_list_pop_writable_window_update_stream(
 void grpc_chttp2_list_remove_writable_window_update_stream(
     grpc_chttp2_transport_global *transport_global,
     grpc_chttp2_stream_global *stream_global) {
-  stream_list_maybe_remove(TRANSPORT_FROM_GLOBAL(transport_global), STREAM_FROM_GLOBAL(stream_global), GRPC_CHTTP2_LIST_WRITABLE_WINDOW_UPDATE);
+  stream_list_maybe_remove(TRANSPORT_FROM_GLOBAL(transport_global),
+                           STREAM_FROM_GLOBAL(stream_global),
+                           GRPC_CHTTP2_LIST_WRITABLE_WINDOW_UPDATE);
 }
 
 void grpc_chttp2_list_add_parsing_seen_stream(
@@ -282,6 +284,24 @@ int grpc_chttp2_list_pop_closed_waiting_for_parsing(
   return r;
 }
 
+void grpc_chttp2_list_add_cancelled_waiting_for_writing(
+    grpc_chttp2_transport_global *transport_global,
+    grpc_chttp2_stream_global *stream_global) {
+  stream_list_add(TRANSPORT_FROM_GLOBAL(transport_global),
+                  STREAM_FROM_GLOBAL(stream_global),
+                  GRPC_CHTTP2_LIST_CANCELLED_WAITING_FOR_WRITING);
+}
+
+int grpc_chttp2_list_pop_cancelled_waiting_for_writing(
+    grpc_chttp2_transport_global *transport_global,
+    grpc_chttp2_stream_global **stream_global) {
+  grpc_chttp2_stream *stream;
+  int r = stream_list_pop(TRANSPORT_FROM_GLOBAL(transport_global), &stream,
+                          GRPC_CHTTP2_LIST_CANCELLED_WAITING_FOR_WRITING);
+  *stream_global = &stream->global;
+  return r;
+}
+
 void grpc_chttp2_list_add_incoming_window_updated(
     grpc_chttp2_transport_global *transport_global,
     grpc_chttp2_stream_global *stream_global) {
diff --git a/src/core/transport/chttp2/writing.c b/src/core/transport/chttp2/writing.c
index fdcc300099..a78654334e 100644
--- a/src/core/transport/chttp2/writing.c
+++ b/src/core/transport/chttp2/writing.c
@@ -97,12 +97,8 @@ int grpc_chttp2_unlocking_check_writes(
       grpc_chttp2_list_add_writing_stream(transport_writing, stream_writing);
     }
 
-    /* we should either exhaust window or have no ops left, but not both */
-    if (stream_global->outgoing_sopb->nops == 0) {
-      stream_global->outgoing_sopb = NULL;
-      grpc_chttp2_schedule_closure(transport_global,
-                                   stream_global->send_done_closure, 1);
-    } else if (stream_global->outgoing_window > 0) {
+    if (stream_global->outgoing_window > 0 &&
+        stream_global->outgoing_sopb->nops != 0) {
       grpc_chttp2_list_add_writable_stream(transport_global, stream_global);
     }
   }
@@ -201,6 +197,11 @@ void grpc_chttp2_cleanup_writing(
 
   while (grpc_chttp2_list_pop_written_stream(
       transport_global, transport_writing, &stream_global, &stream_writing)) {
+    if (stream_global->outgoing_sopb->nops == 0) {
+      stream_global->outgoing_sopb = NULL;
+      grpc_chttp2_schedule_closure(transport_global,
+                                   stream_global->send_done_closure, 1);
+    }
     if (stream_writing->send_closed != GRPC_DONT_SEND_CLOSED) {
       stream_global->write_state = GRPC_WRITE_STATE_SENT_CLOSE;
       if (!transport_global->is_client) {
diff --git a/src/core/transport/chttp2_transport.c b/src/core/transport/chttp2_transport.c
index 5cc4d9b876..923a3a7a9b 100644
--- a/src/core/transport/chttp2_transport.c
+++ b/src/core/transport/chttp2_transport.c
@@ -37,18 +37,19 @@
 #include <stdio.h>
 #include <string.h>
 
+#include <grpc/support/alloc.h>
+#include <grpc/support/log.h>
+#include <grpc/support/slice_buffer.h>
+#include <grpc/support/string_util.h>
+#include <grpc/support/useful.h>
+
 #include "src/core/profiling/timers.h"
 #include "src/core/support/string.h"
 #include "src/core/transport/chttp2/http2_errors.h"
+#include "src/core/transport/chttp2/internal.h"
 #include "src/core/transport/chttp2/status_conversion.h"
 #include "src/core/transport/chttp2/timeout_encoding.h"
-#include "src/core/transport/chttp2/internal.h"
 #include "src/core/transport/transport_impl.h"
-#include <grpc/support/alloc.h>
-#include <grpc/support/log.h>
-#include <grpc/support/slice_buffer.h>
-#include <grpc/support/string_util.h>
-#include <grpc/support/useful.h>
 
 #define DEFAULT_WINDOW 65535
 #define DEFAULT_CONNECTION_WINDOW_TARGET (1024 * 1024)
@@ -79,13 +80,11 @@ static const grpc_transport_vtable vtable;
 static void lock(grpc_chttp2_transport *t);
 static void unlock(grpc_chttp2_transport *t);
 
-static void unlock_check_channel_callbacks(grpc_chttp2_transport *t);
 static void unlock_check_read_write_state(grpc_chttp2_transport *t);
 
 /* forward declarations of various callbacks that we'll build closures around */
 static void writing_action(void *t, int iomgr_success_ignored);
 static void reading_action(void *t, int iomgr_success_ignored);
-static void notify_closed(void *t, int iomgr_success_ignored);
 
 /** Set a transport level setting, and push it to our peer */
 static void push_setting(grpc_chttp2_transport *t, grpc_chttp2_setting_id id,
@@ -99,9 +98,9 @@ static void recv_data(void *tp, gpr_slice *slices, size_t nslices,
 static void drop_connection(grpc_chttp2_transport *t);
 
 /** Perform a transport_op */
-static void perform_op_locked(grpc_chttp2_transport_global *transport_global,
-                              grpc_chttp2_stream_global *stream_global,
-                              grpc_transport_op *op);
+static void perform_stream_op_locked(
+    grpc_chttp2_transport_global *transport_global,
+    grpc_chttp2_stream_global *stream_global, grpc_transport_stream_op *op);
 
 /** Cancel a stream: coming from the transport API */
 static void cancel_from_api(grpc_chttp2_transport_global *transport_global,
@@ -116,6 +115,10 @@ static void add_to_pollset_locked(grpc_chttp2_transport *t,
 static void maybe_start_some_streams(
     grpc_chttp2_transport_global *transport_global);
 
+static void connectivity_state_set(
+    grpc_chttp2_transport_global *transport_global,
+    grpc_connectivity_state state);
+
 /*
  * CONSTRUCTION/DESTRUCTION/REFCOUNTING
  */
@@ -148,6 +151,7 @@ static void destruct_transport(grpc_chttp2_transport *t) {
 
   grpc_chttp2_stream_map_destroy(&t->parsing_stream_map);
   grpc_chttp2_stream_map_destroy(&t->new_stream_map);
+  grpc_connectivity_state_destroy(&t->channel_callback.state_tracker);
 
   gpr_mu_unlock(&t->mu);
   gpr_mu_destroy(&t->mu);
@@ -196,13 +200,11 @@ static void ref_transport(grpc_chttp2_transport *t) { gpr_ref(&t->refs); }
 #endif
 
 static void init_transport(grpc_chttp2_transport *t,
-                           grpc_transport_setup_callback setup, void *arg,
                            const grpc_channel_args *channel_args,
-                           grpc_endpoint *ep, gpr_slice *slices, size_t nslices,
-                           grpc_mdctx *mdctx, int is_client) {
+                           grpc_endpoint *ep, grpc_mdctx *mdctx,
+                           int is_client) {
   size_t i;
   int j;
-  grpc_transport_setup_result sr;
 
   GPR_ASSERT(strlen(GRPC_CHTTP2_CLIENT_CONNECT_STRING) ==
              GRPC_CHTTP2_CLIENT_CONNECT_STRLEN);
@@ -217,7 +219,6 @@ static void init_transport(grpc_chttp2_transport *t,
   grpc_mdctx_ref(mdctx);
   t->metadata_context = mdctx;
   t->endpoint_reading = 1;
-  t->global.error_state = GRPC_CHTTP2_ERROR_STATE_NONE;
   t->global.next_stream_id = is_client ? 1 : 2;
   t->global.is_client = is_client;
   t->global.outgoing_window = DEFAULT_WINDOW;
@@ -231,6 +232,8 @@ static void init_transport(grpc_chttp2_transport *t,
   t->parsing.deframe_state =
       is_client ? GRPC_DTS_FH_0 : GRPC_DTS_CLIENT_PREFIX_0;
   t->writing.is_client = is_client;
+  grpc_connectivity_state_init(&t->channel_callback.state_tracker,
+                               GRPC_CHANNEL_READY);
 
   gpr_slice_buffer_init(&t->global.qbuf);
 
@@ -243,7 +246,6 @@ static void init_transport(grpc_chttp2_transport *t,
   grpc_chttp2_goaway_parser_init(&t->parsing.goaway_parser);
   grpc_chttp2_hpack_parser_init(&t->parsing.hpack_parser, t->metadata_context);
 
-  grpc_iomgr_closure_init(&t->channel_callback.notify_closed, notify_closed, t);
   if (is_client) {
     gpr_slice_buffer_add(
         &t->global.qbuf,
@@ -309,24 +311,6 @@ static void init_transport(grpc_chttp2_transport *t,
       }
     }
   }
-
-  gpr_mu_lock(&t->mu);
-  t->channel_callback.executing = 1;
-  REF_TRANSPORT(t, "init"); /* matches unref at end of this function */
-  gpr_mu_unlock(&t->mu);
-
-  sr = setup(arg, &t->base, t->metadata_context);
-
-  lock(t);
-  t->channel_callback.cb = sr.callbacks;
-  t->channel_callback.cb_user_data = sr.user_data;
-  t->channel_callback.executing = 0;
-  unlock(t);
-
-  REF_TRANSPORT(t, "recv_data"); /* matches unref inside recv_data */
-  recv_data(t, slices, nslices, GRPC_ENDPOINT_CB_OK);
-
-  UNREF_TRANSPORT(t, "init");
 }
 
 static void destroy_transport(grpc_transport *gt) {
@@ -343,31 +327,16 @@ static void destroy_transport(grpc_transport *gt) {
 static void close_transport_locked(grpc_chttp2_transport *t) {
   if (!t->closed) {
     t->closed = 1;
+    connectivity_state_set(&t->global, GRPC_CHANNEL_FATAL_FAILURE);
     if (t->ep) {
       grpc_endpoint_shutdown(t->ep);
     }
   }
 }
 
-static void close_transport(grpc_transport *gt) {
-  grpc_chttp2_transport *t = (grpc_chttp2_transport *)gt;
-  gpr_mu_lock(&t->mu);
-  close_transport_locked(t);
-  gpr_mu_unlock(&t->mu);
-}
-
-static void goaway(grpc_transport *gt, grpc_status_code status,
-                   gpr_slice debug_data) {
-  grpc_chttp2_transport *t = (grpc_chttp2_transport *)gt;
-  lock(t);
-  grpc_chttp2_goaway_append(t->global.last_incoming_stream_id,
-                            grpc_chttp2_grpc_status_to_http2_error(status),
-                            debug_data, &t->global.qbuf);
-  unlock(t);
-}
-
 static int init_stream(grpc_transport *gt, grpc_stream *gs,
-                       const void *server_data, grpc_transport_op *initial_op) {
+                       const void *server_data,
+                       grpc_transport_stream_op *initial_op) {
   grpc_chttp2_transport *t = (grpc_chttp2_transport *)gt;
   grpc_chttp2_stream *s = (grpc_chttp2_stream *)gs;
 
@@ -397,7 +366,7 @@ static int init_stream(grpc_transport *gt, grpc_stream *gs,
     s->global.in_stream_map = 1;
   }
 
-  if (initial_op) perform_op_locked(&t->global, &s->global, initial_op);
+  if (initial_op) perform_stream_op_locked(&t->global, &s->global, initial_op);
   unlock(t);
 
   return 0;
@@ -455,8 +424,8 @@ grpc_chttp2_stream_parsing *grpc_chttp2_parsing_accept_stream(
   grpc_chttp2_transport *t = TRANSPORT_FROM_PARSING(transport_parsing);
   GPR_ASSERT(t->accepting_stream == NULL);
   t->accepting_stream = &accepting;
-  t->channel_callback.cb->accept_stream(t->channel_callback.cb_user_data,
-                                        &t->base, (void *)(gpr_uintptr)id);
+  t->channel_callback.accept_stream(t->channel_callback.accept_stream_user_data,
+                                    &t->base, (void *)(gpr_uintptr)id);
   t->accepting_stream = NULL;
   return &accepting->parsing;
 }
@@ -477,17 +446,16 @@ static void unlock(grpc_chttp2_transport *t) {
   grpc_iomgr_closure *run_closures;
 
   unlock_check_read_write_state(t);
-  if (!t->writing_active && t->global.error_state == GRPC_CHTTP2_ERROR_STATE_NONE &&
+  if (!t->writing_active && !t->closed &&
       grpc_chttp2_unlocking_check_writes(&t->global, &t->writing)) {
     t->writing_active = 1;
     REF_TRANSPORT(t, "writing");
     grpc_chttp2_schedule_closure(&t->global, &t->writing_action, 1);
   }
-  /* unlock_check_parser(t); */
-  unlock_check_channel_callbacks(t);
 
-  run_closures = t->global.pending_closures;
-  t->global.pending_closures = NULL;
+  run_closures = t->global.pending_closures_head;
+  t->global.pending_closures_head = NULL;
+  t->global.pending_closures_tail = NULL;
 
   gpr_mu_unlock(&t->mu);
 
@@ -553,15 +521,13 @@ static void writing_action(void *gt, int iomgr_success_ignored) {
 void grpc_chttp2_add_incoming_goaway(
     grpc_chttp2_transport_global *transport_global, gpr_uint32 goaway_error,
     gpr_slice goaway_text) {
-  char *msg = gpr_hexdump((char*)GPR_SLICE_START_PTR(goaway_text), GPR_SLICE_LENGTH(goaway_text), GPR_HEXDUMP_PLAINTEXT);
+  char *msg = gpr_hexdump((char *)GPR_SLICE_START_PTR(goaway_text),
+                          GPR_SLICE_LENGTH(goaway_text), GPR_HEXDUMP_PLAINTEXT);
+  gpr_log(GPR_DEBUG, "got goaway [%d]: %s", goaway_error, msg);
   gpr_free(msg);
-  if (transport_global->goaway_state == GRPC_CHTTP2_ERROR_STATE_NONE) {
-    transport_global->goaway_state = GRPC_CHTTP2_ERROR_STATE_SEEN;
-    transport_global->goaway_text = goaway_text;
-    transport_global->goaway_error = goaway_error;
-  } else {
-    gpr_slice_unref(goaway_text);
-  }
+  gpr_slice_unref(goaway_text);
+  transport_global->seen_goaway = 1;
+  connectivity_state_set(transport_global, GRPC_CHANNEL_FATAL_FAILURE);
 }
 
 static void maybe_start_some_streams(
@@ -586,9 +552,7 @@ static void maybe_start_some_streams(
     transport_global->next_stream_id += 2;
 
     if (transport_global->next_stream_id >= MAX_CLIENT_STREAM_ID) {
-      grpc_chttp2_add_incoming_goaway(
-          transport_global, GRPC_CHTTP2_NO_ERROR,
-          gpr_slice_from_copied_string("Exceeded sequence number limit"));
+      connectivity_state_set(transport_global, GRPC_CHANNEL_TRANSIENT_FAILURE);
     }
 
     stream_global->outgoing_window =
@@ -614,9 +578,9 @@ static void maybe_start_some_streams(
   }
 }
 
-static void perform_op_locked(grpc_chttp2_transport_global *transport_global,
-                              grpc_chttp2_stream_global *stream_global,
-                              grpc_transport_op *op) {
+static void perform_stream_op_locked(
+    grpc_chttp2_transport_global *transport_global,
+    grpc_chttp2_stream_global *stream_global, grpc_transport_stream_op *op) {
   if (op->cancel_with_status != GRPC_STATUS_OK) {
     cancel_from_api(transport_global, stream_global, op->cancel_with_status);
   }
@@ -673,21 +637,19 @@ static void perform_op_locked(grpc_chttp2_transport_global *transport_global,
   }
 }
 
-static void perform_op(grpc_transport *gt, grpc_stream *gs,
-                       grpc_transport_op *op) {
+static void perform_stream_op(grpc_transport *gt, grpc_stream *gs,
+                              grpc_transport_stream_op *op) {
   grpc_chttp2_transport *t = (grpc_chttp2_transport *)gt;
   grpc_chttp2_stream *s = (grpc_chttp2_stream *)gs;
 
   lock(t);
-  perform_op_locked(&t->global, &s->global, op);
+  perform_stream_op_locked(&t->global, &s->global, op);
   unlock(t);
 }
 
-static void send_ping(grpc_transport *gt, grpc_iomgr_closure *on_recv) {
-  grpc_chttp2_transport *t = (grpc_chttp2_transport *)gt;
+static void send_ping_locked(grpc_chttp2_transport *t,
+                             grpc_iomgr_closure *on_recv) {
   grpc_chttp2_outstanding_ping *p = gpr_malloc(sizeof(*p));
-
-  lock(t);
   p->next = &t->global.pings;
   p->prev = p->next->prev;
   p->prev->next = p->next->prev = p;
@@ -701,6 +663,48 @@ static void send_ping(grpc_transport *gt, grpc_iomgr_closure *on_recv) {
   p->id[7] = t->global.ping_counter & 0xff;
   p->on_recv = on_recv;
   gpr_slice_buffer_add(&t->global.qbuf, grpc_chttp2_ping_create(0, p->id));
+}
+
+static void perform_transport_op(grpc_transport *gt, grpc_transport_op *op) {
+  grpc_chttp2_transport *t = (grpc_chttp2_transport *)gt;
+
+  lock(t);
+
+  if (op->on_consumed) {
+    grpc_chttp2_schedule_closure(&t->global, op->on_consumed, 1);
+  }
+
+  if (op->on_connectivity_state_change) {
+    grpc_connectivity_state_notify_on_state_change(
+        &t->channel_callback.state_tracker, op->connectivity_state,
+        op->on_connectivity_state_change);
+  }
+
+  if (op->send_goaway) {
+    grpc_chttp2_goaway_append(
+        t->global.last_incoming_stream_id,
+        grpc_chttp2_grpc_status_to_http2_error(op->goaway_status),
+        gpr_slice_ref(*op->goaway_message), &t->global.qbuf);
+  }
+
+  if (op->set_accept_stream != NULL) {
+    t->channel_callback.accept_stream = op->set_accept_stream;
+    t->channel_callback.accept_stream_user_data =
+        op->set_accept_stream_user_data;
+  }
+
+  if (op->bind_pollset) {
+    add_to_pollset_locked(t, op->bind_pollset);
+  }
+
+  if (op->send_ping) {
+    send_ping_locked(t, op->send_ping);
+  }
+
+  if (op->disconnect) {
+    close_transport_locked(t);
+  }
+
   unlock(t);
 }
 
@@ -730,9 +734,8 @@ static void remove_stream(grpc_chttp2_transport *t, gpr_uint32 id) {
     grpc_chttp2_parsing_become_skip_parser(&t->parsing);
   }
 
-  new_stream_count =
-      grpc_chttp2_stream_map_size(&t->parsing_stream_map) +
-      grpc_chttp2_stream_map_size(&t->new_stream_map);
+  new_stream_count = grpc_chttp2_stream_map_size(&t->parsing_stream_map) +
+                     grpc_chttp2_stream_map_size(&t->new_stream_map);
   if (new_stream_count != t->global.concurrent_stream_count) {
     t->global.concurrent_stream_count = new_stream_count;
     maybe_start_some_streams(&t->global);
@@ -759,20 +762,35 @@ static void unlock_check_read_write_state(grpc_chttp2_transport *t) {
     }
   }
 
+  if (!t->writing_active) {
+    while (grpc_chttp2_list_pop_cancelled_waiting_for_writing(transport_global,
+                                                              &stream_global)) {
+      grpc_chttp2_list_add_read_write_state_changed(transport_global,
+                                                    stream_global);
+    }
+  }
+
   while (grpc_chttp2_list_pop_read_write_state_changed(transport_global,
                                                        &stream_global)) {
     if (stream_global->cancelled) {
-      stream_global->write_state = GRPC_WRITE_STATE_SENT_CLOSE;
-      stream_global->read_closed = 1;
-      if (!stream_global->published_cancelled) {
-        char buffer[GPR_LTOA_MIN_BUFSIZE];
-        gpr_ltoa(stream_global->cancelled_status, buffer);
-        grpc_chttp2_incoming_metadata_buffer_add(&stream_global->incoming_metadata,
-          grpc_mdelem_from_strings(t->metadata_context, "grpc-status", buffer));
-        grpc_chttp2_incoming_metadata_buffer_place_metadata_batch_into(
-          &stream_global->incoming_metadata,
-          &stream_global->incoming_sopb);
-        stream_global->published_cancelled = 1;
+      if (t->writing_active &&
+          stream_global->write_state != GRPC_WRITE_STATE_SENT_CLOSE) {
+        grpc_chttp2_list_add_cancelled_waiting_for_writing(transport_global,
+                                                           stream_global);
+      } else {
+        stream_global->write_state = GRPC_WRITE_STATE_SENT_CLOSE;
+        stream_global->read_closed = 1;
+        if (!stream_global->published_cancelled) {
+          char buffer[GPR_LTOA_MIN_BUFSIZE];
+          gpr_ltoa(stream_global->cancelled_status, buffer);
+          grpc_chttp2_incoming_metadata_buffer_add(
+              &stream_global->incoming_metadata,
+              grpc_mdelem_from_strings(t->metadata_context, "grpc-status",
+                                       buffer));
+          grpc_chttp2_incoming_metadata_buffer_place_metadata_batch_into(
+              &stream_global->incoming_metadata, &stream_global->incoming_sopb);
+          stream_global->published_cancelled = 1;
+        }
       }
     }
     if (stream_global->write_state == GRPC_WRITE_STATE_SENT_CLOSE &&
@@ -820,10 +838,10 @@ static void cancel_from_api(grpc_chttp2_transport_global *transport_global,
   stream_global->cancelled = 1;
   stream_global->cancelled_status = status;
   if (stream_global->id != 0) {
-    gpr_slice_buffer_add(&transport_global->qbuf,
-                         grpc_chttp2_rst_stream_create(
-                             stream_global->id,
-                             grpc_chttp2_grpc_status_to_http2_error(status)));
+    gpr_slice_buffer_add(
+        &transport_global->qbuf,
+        grpc_chttp2_rst_stream_create(
+            stream_global->id, grpc_chttp2_grpc_status_to_http2_error(status)));
   }
   grpc_chttp2_list_add_read_write_state_changed(transport_global,
                                                 stream_global);
@@ -840,9 +858,6 @@ static void end_all_the_calls(grpc_chttp2_transport *t) {
 }
 
 static void drop_connection(grpc_chttp2_transport *t) {
-  if (t->global.error_state == GRPC_CHTTP2_ERROR_STATE_NONE) {
-    t->global.error_state = GRPC_CHTTP2_ERROR_STATE_SEEN;
-  }
   close_transport_locked(t);
   end_all_the_calls(t);
 }
@@ -900,7 +915,7 @@ static void recv_data(void *tp, gpr_slice *slices, size_t nslices,
       lock(t);
       i = 0;
       GPR_ASSERT(!t->parsing_active);
-      if (t->global.error_state == GRPC_CHTTP2_ERROR_STATE_NONE) {
+      if (!t->closed) {
         t->parsing_active = 1;
         /* merge stream lists */
         grpc_chttp2_stream_map_move_into(&t->new_stream_map,
@@ -918,7 +933,8 @@ static void recv_data(void *tp, gpr_slice *slices, size_t nslices,
         /* merge stream lists */
         grpc_chttp2_stream_map_move_into(&t->new_stream_map,
                                          &t->parsing_stream_map);
-        t->global.concurrent_stream_count = grpc_chttp2_stream_map_size(&t->parsing_stream_map);
+        t->global.concurrent_stream_count =
+            grpc_chttp2_stream_map_size(&t->parsing_stream_map);
         if (t->parsing.initial_window_update != 0) {
           grpc_chttp2_stream_map_for_each(&t->parsing_stream_map,
                                           update_global_window, t);
@@ -952,76 +968,33 @@ static void reading_action(void *pt, int iomgr_success_ignored) {
  * CALLBACK LOOP
  */
 
-typedef struct {
-  grpc_chttp2_transport *t;
-  gpr_uint32 error;
-  gpr_slice text;
-  grpc_iomgr_closure closure;
-} notify_goaways_args;
-
-static void notify_goaways(void *p, int iomgr_success_ignored) {
-  notify_goaways_args *a = p;
-  grpc_chttp2_transport *t = a->t;
-
-  t->channel_callback.cb->goaway(t->channel_callback.cb_user_data, &t->base,
-                                 a->error, a->text);
-
-  gpr_free(a);
-
-  lock(t);
-  t->channel_callback.executing = 0;
-  unlock(t);
-
-  UNREF_TRANSPORT(t, "notify_goaways");
+static void schedule_closure_for_connectivity(void *a,
+                                              grpc_iomgr_closure *closure) {
+  grpc_chttp2_schedule_closure(a, closure, 1);
 }
 
-static void notify_closed(void *gt, int iomgr_success_ignored) {
-  grpc_chttp2_transport *t = gt;
-  t->channel_callback.cb->closed(t->channel_callback.cb_user_data, &t->base);
-
-  lock(t);
-  t->channel_callback.executing = 0;
-  unlock(t);
-
-  UNREF_TRANSPORT(t, "notify_closed");
-}
-
-static void unlock_check_channel_callbacks(grpc_chttp2_transport *t) {
-  if (t->channel_callback.executing) {
-    return;
-  }
-  if (t->global.goaway_state != GRPC_CHTTP2_ERROR_STATE_NONE) {
-    if (t->global.goaway_state == GRPC_CHTTP2_ERROR_STATE_SEEN &&
-        t->global.error_state != GRPC_CHTTP2_ERROR_STATE_NOTIFIED) {
-      notify_goaways_args *a = gpr_malloc(sizeof(*a));
-      a->t = t;
-      a->error = t->global.goaway_error;
-      a->text = t->global.goaway_text;
-      t->global.goaway_state = GRPC_CHTTP2_ERROR_STATE_NOTIFIED;
-      t->channel_callback.executing = 1;
-      grpc_iomgr_closure_init(&a->closure, notify_goaways, a);
-      REF_TRANSPORT(t, "notify_goaways");
-      grpc_chttp2_schedule_closure(&t->global, &a->closure, 1);
-      return;
-    } else if (t->global.goaway_state != GRPC_CHTTP2_ERROR_STATE_NOTIFIED) {
-      return;
-    }
-  }
-  if (t->global.error_state == GRPC_CHTTP2_ERROR_STATE_SEEN) {
-    t->global.error_state = GRPC_CHTTP2_ERROR_STATE_NOTIFIED;
-    t->channel_callback.executing = 1;
-    REF_TRANSPORT(t, "notify_closed");
-    grpc_chttp2_schedule_closure(&t->global, &t->channel_callback.notify_closed,
-                                 1);
-  }
+static void connectivity_state_set(
+    grpc_chttp2_transport_global *transport_global,
+    grpc_connectivity_state state) {
+  GRPC_CHTTP2_IF_TRACING(
+      gpr_log(GPR_DEBUG, "set connectivity_state=%d", state));
+  grpc_connectivity_state_set_with_scheduler(
+      &TRANSPORT_FROM_GLOBAL(transport_global)->channel_callback.state_tracker,
+      state, schedule_closure_for_connectivity, transport_global);
 }
 
 void grpc_chttp2_schedule_closure(
     grpc_chttp2_transport_global *transport_global, grpc_iomgr_closure *closure,
     int success) {
   closure->success = success;
-  closure->next = transport_global->pending_closures;
-  transport_global->pending_closures = closure;
+  if (transport_global->pending_closures_tail == NULL) {
+    transport_global->pending_closures_head =
+        transport_global->pending_closures_tail = closure;
+  } else {
+    transport_global->pending_closures_tail->next = closure;
+    transport_global->pending_closures_tail = closure;
+  }
+  closure->next = NULL;
 }
 
 /*
@@ -1035,13 +1008,6 @@ static void add_to_pollset_locked(grpc_chttp2_transport *t,
   }
 }
 
-static void add_to_pollset(grpc_transport *gt, grpc_pollset *pollset) {
-  grpc_chttp2_transport *t = (grpc_chttp2_transport *)gt;
-  lock(t);
-  add_to_pollset_locked(t, pollset);
-  unlock(t);
-}
-
 /*
  * TRACING
  */
@@ -1077,23 +1043,21 @@ void grpc_chttp2_flowctl_trace(const char *file, int line, const char *reason,
  * INTEGRATION GLUE
  */
 
-static const grpc_transport_vtable vtable = {sizeof(grpc_chttp2_stream),
-                                             init_stream,
-                                             perform_op,
-                                             add_to_pollset,
-                                             destroy_stream,
-                                             goaway,
-                                             close_transport,
-                                             send_ping,
-                                             destroy_transport};
-
-void grpc_create_chttp2_transport(grpc_transport_setup_callback setup,
-                                  void *arg,
-                                  const grpc_channel_args *channel_args,
-                                  grpc_endpoint *ep, gpr_slice *slices,
-                                  size_t nslices, grpc_mdctx *mdctx,
-                                  int is_client) {
+static const grpc_transport_vtable vtable = {
+    sizeof(grpc_chttp2_stream), init_stream,    perform_stream_op,
+    perform_transport_op,       destroy_stream, destroy_transport};
+
+grpc_transport *grpc_create_chttp2_transport(
+    const grpc_channel_args *channel_args, grpc_endpoint *ep, grpc_mdctx *mdctx,
+    int is_client) {
   grpc_chttp2_transport *t = gpr_malloc(sizeof(grpc_chttp2_transport));
-  init_transport(t, setup, arg, channel_args, ep, slices, nslices, mdctx,
-                 is_client);
+  init_transport(t, channel_args, ep, mdctx, is_client);
+  return &t->base;
+}
+
+void grpc_chttp2_transport_start_reading(grpc_transport *transport,
+                                         gpr_slice *slices, size_t nslices) {
+  grpc_chttp2_transport *t = (grpc_chttp2_transport *)transport;
+  REF_TRANSPORT(t, "recv_data"); /* matches unref inside recv_data */
+  recv_data(t, slices, nslices, GRPC_ENDPOINT_CB_OK);
 }
diff --git a/src/core/transport/chttp2_transport.h b/src/core/transport/chttp2_transport.h
index 18e19f03af..fa0d6e4151 100644
--- a/src/core/transport/chttp2_transport.h
+++ b/src/core/transport/chttp2_transport.h
@@ -40,11 +40,11 @@
 extern int grpc_http_trace;
 extern int grpc_flowctl_trace;
 
-void grpc_create_chttp2_transport(grpc_transport_setup_callback setup,
-                                  void *arg,
-                                  const grpc_channel_args *channel_args,
-                                  grpc_endpoint *ep, gpr_slice *slices,
-                                  size_t nslices, grpc_mdctx *metadata_context,
-                                  int is_client);
+grpc_transport *grpc_create_chttp2_transport(
+    const grpc_channel_args *channel_args, grpc_endpoint *ep,
+    grpc_mdctx *metadata_context, int is_client);
+
+void grpc_chttp2_transport_start_reading(grpc_transport *transport,
+                                         gpr_slice *slices, size_t nslices);
 
 #endif /* GRPC_INTERNAL_CORE_TRANSPORT_CHTTP2_TRANSPORT_H */
diff --git a/src/core/transport/connectivity_state.c b/src/core/transport/connectivity_state.c
new file mode 100644
index 0000000000..1091ceae44
--- /dev/null
+++ b/src/core/transport/connectivity_state.c
@@ -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.
+ *
+ */
+
+#include "src/core/transport/connectivity_state.h"
+#include <grpc/support/alloc.h>
+#include <grpc/support/log.h>
+
+void grpc_connectivity_state_init(grpc_connectivity_state_tracker *tracker,
+                                  grpc_connectivity_state init_state) {
+  tracker->current_state = init_state;
+  tracker->watchers = NULL;
+}
+
+void grpc_connectivity_state_destroy(grpc_connectivity_state_tracker *tracker) {
+  grpc_connectivity_state_watcher *w;
+  while ((w = tracker->watchers)) {
+    tracker->watchers = w->next;
+
+    if (GRPC_CHANNEL_FATAL_FAILURE != *w->current) {
+      *w->current = GRPC_CHANNEL_FATAL_FAILURE;
+      grpc_iomgr_add_callback(w->notify);
+    } else {
+      grpc_iomgr_add_delayed_callback(w->notify, 0);
+    }
+    gpr_free(w);
+  }
+}
+
+grpc_connectivity_state grpc_connectivity_state_check(
+    grpc_connectivity_state_tracker *tracker) {
+  return tracker->current_state;
+}
+
+int grpc_connectivity_state_notify_on_state_change(
+    grpc_connectivity_state_tracker *tracker, grpc_connectivity_state *current,
+    grpc_iomgr_closure *notify) {
+  if (tracker->current_state != *current) {
+    *current = tracker->current_state;
+    grpc_iomgr_add_callback(notify);
+  } else {
+    grpc_connectivity_state_watcher *w = gpr_malloc(sizeof(*w));
+    w->current = current;
+    w->notify = notify;
+    w->next = tracker->watchers;
+    tracker->watchers = w;
+  }
+  return tracker->current_state == GRPC_CHANNEL_IDLE;
+}
+
+void grpc_connectivity_state_set_with_scheduler(
+    grpc_connectivity_state_tracker *tracker, grpc_connectivity_state state,
+    void (*scheduler)(void *arg, grpc_iomgr_closure *closure), void *arg) {
+  grpc_connectivity_state_watcher *new = NULL;
+  grpc_connectivity_state_watcher *w;
+  if (tracker->current_state == state) {
+    return;
+  }
+  tracker->current_state = state;
+  while ((w = tracker->watchers)) {
+    tracker->watchers = w->next;
+
+    if (state != *w->current) {
+      *w->current = state;
+      scheduler(arg, w->notify);
+      gpr_free(w);
+    } else {
+      w->next = new;
+      new = w;
+    }
+  }
+  tracker->watchers = new;
+}
+
+static void default_scheduler(void *ignored, grpc_iomgr_closure *closure) {
+  grpc_iomgr_add_callback(closure);
+}
+
+void grpc_connectivity_state_set(grpc_connectivity_state_tracker *tracker,
+                                 grpc_connectivity_state state) {
+  grpc_connectivity_state_set_with_scheduler(tracker, state, default_scheduler,
+                                             NULL);
+}
diff --git a/src/core/transport/connectivity_state.h b/src/core/transport/connectivity_state.h
new file mode 100644
index 0000000000..bbdcbcb069
--- /dev/null
+++ b/src/core/transport/connectivity_state.h
@@ -0,0 +1,74 @@
+/*
+ *
+ * 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.
+ *
+ */
+
+#ifndef GRPC_INTERNAL_CORE_TRANSPORT_CONNECTIVITY_STATE_H
+#define GRPC_INTERNAL_CORE_TRANSPORT_CONNECTIVITY_STATE_H
+
+#include <grpc/grpc.h>
+#include "src/core/iomgr/iomgr.h"
+
+typedef struct grpc_connectivity_state_watcher {
+  /** we keep watchers in a linked list */
+  struct grpc_connectivity_state_watcher *next;
+  /** closure to notify on change */
+  grpc_iomgr_closure *notify;
+  /** the current state as believed by the watcher */
+  grpc_connectivity_state *current;
+} grpc_connectivity_state_watcher;
+
+typedef struct {
+  /** current connectivity state */
+  grpc_connectivity_state current_state;
+  /** all our watchers */
+  grpc_connectivity_state_watcher *watchers;
+} grpc_connectivity_state_tracker;
+
+void grpc_connectivity_state_init(grpc_connectivity_state_tracker *tracker,
+                                  grpc_connectivity_state init_state);
+void grpc_connectivity_state_destroy(grpc_connectivity_state_tracker *tracker);
+
+void grpc_connectivity_state_set(grpc_connectivity_state_tracker *tracker,
+                                 grpc_connectivity_state state);
+void grpc_connectivity_state_set_with_scheduler(
+    grpc_connectivity_state_tracker *tracker, grpc_connectivity_state state,
+    void (*scheduler)(void *arg, grpc_iomgr_closure *closure), void *arg);
+
+grpc_connectivity_state grpc_connectivity_state_check(
+    grpc_connectivity_state_tracker *tracker);
+
+/** Return 1 if the channel should start connecting, 0 otherwise */
+int grpc_connectivity_state_notify_on_state_change(
+    grpc_connectivity_state_tracker *tracker, grpc_connectivity_state *current,
+    grpc_iomgr_closure *notify);
+
+#endif /* GRPC_INTERNAL_CORE_TRANSPORT_CONNECTIVITY_STATE_H */
diff --git a/src/core/transport/stream_op.h b/src/core/transport/stream_op.h
index 842fc932b9..964d39d14f 100644
--- a/src/core/transport/stream_op.h
+++ b/src/core/transport/stream_op.h
@@ -41,7 +41,7 @@
 #include "src/core/transport/metadata.h"
 
 /* this many stream ops are inlined into a sopb before allocating */
-#define GRPC_SOPB_INLINE_ELEMENTS 16
+#define GRPC_SOPB_INLINE_ELEMENTS 4
 
 /* Operations that can be performed on a stream.
    Used by grpc_stream_op. */
diff --git a/src/core/transport/transport.c b/src/core/transport/transport.c
index 39d7b701f2..fe565944ed 100644
--- a/src/core/transport/transport.c
+++ b/src/core/transport/transport.c
@@ -38,34 +38,26 @@ size_t grpc_transport_stream_size(grpc_transport *transport) {
   return transport->vtable->sizeof_stream;
 }
 
-void grpc_transport_goaway(grpc_transport *transport, grpc_status_code status,
-                           gpr_slice message) {
-  transport->vtable->goaway(transport, status, message);
-}
-
-void grpc_transport_close(grpc_transport *transport) {
-  transport->vtable->close(transport);
-}
-
 void grpc_transport_destroy(grpc_transport *transport) {
   transport->vtable->destroy(transport);
 }
 
 int grpc_transport_init_stream(grpc_transport *transport, grpc_stream *stream,
                                const void *server_data,
-                               grpc_transport_op *initial_op) {
+                               grpc_transport_stream_op *initial_op) {
   return transport->vtable->init_stream(transport, stream, server_data,
                                         initial_op);
 }
 
-void grpc_transport_perform_op(grpc_transport *transport, grpc_stream *stream,
-                               grpc_transport_op *op) {
-  transport->vtable->perform_op(transport, stream, op);
+void grpc_transport_perform_stream_op(grpc_transport *transport,
+                                      grpc_stream *stream,
+                                      grpc_transport_stream_op *op) {
+  transport->vtable->perform_stream_op(transport, stream, op);
 }
 
-void grpc_transport_add_to_pollset(grpc_transport *transport,
-                                   grpc_pollset *pollset) {
-  transport->vtable->add_to_pollset(transport, pollset);
+void grpc_transport_perform_op(grpc_transport *transport,
+                               grpc_transport_op *op) {
+  transport->vtable->perform_op(transport, op);
 }
 
 void grpc_transport_destroy_stream(grpc_transport *transport,
@@ -73,29 +65,8 @@ void grpc_transport_destroy_stream(grpc_transport *transport,
   transport->vtable->destroy_stream(transport, stream);
 }
 
-void grpc_transport_ping(grpc_transport *transport, grpc_iomgr_closure *cb) {
-  transport->vtable->ping(transport, cb);
-}
-
-void grpc_transport_setup_cancel(grpc_transport_setup *setup) {
-  setup->vtable->cancel(setup);
-}
-
-void grpc_transport_setup_initiate(grpc_transport_setup *setup) {
-  setup->vtable->initiate(setup);
-}
-
-void grpc_transport_setup_add_interested_party(grpc_transport_setup *setup,
-                                               grpc_pollset *pollset) {
-  setup->vtable->add_interested_party(setup, pollset);
-}
-
-void grpc_transport_setup_del_interested_party(grpc_transport_setup *setup,
-                                               grpc_pollset *pollset) {
-  setup->vtable->del_interested_party(setup, pollset);
-}
-
-void grpc_transport_op_finish_with_failure(grpc_transport_op *op) {
+void grpc_transport_stream_op_finish_with_failure(
+    grpc_transport_stream_op *op) {
   if (op->send_ops) {
     op->on_done_send->cb(op->on_done_send->cb_arg, 0);
   }
@@ -107,9 +78,9 @@ void grpc_transport_op_finish_with_failure(grpc_transport_op *op) {
   }
 }
 
-void grpc_transport_op_add_cancellation(grpc_transport_op *op,
-                                        grpc_status_code status,
-                                        grpc_mdstr *message) {
+void grpc_transport_stream_op_add_cancellation(grpc_transport_stream_op *op,
+                                               grpc_status_code status,
+                                               grpc_mdstr *message) {
   if (op->cancel_with_status == GRPC_STATUS_OK) {
     op->cancel_with_status = status;
   }
diff --git a/src/core/transport/transport.h b/src/core/transport/transport.h
index a2c41c47af..579bcc943f 100644
--- a/src/core/transport/transport.h
+++ b/src/core/transport/transport.h
@@ -43,7 +43,6 @@
 
 /* forward declarations */
 typedef struct grpc_transport grpc_transport;
-typedef struct grpc_transport_callbacks grpc_transport_callbacks;
 
 /* grpc_stream doesn't actually exist. It's used as a typesafe
    opaque pointer for whatever data the transport wants to track
@@ -62,8 +61,9 @@ typedef enum grpc_stream_state {
   GRPC_STREAM_CLOSED
 } grpc_stream_state;
 
-/* Transport op: a set of operations to perform on a transport */
-typedef struct grpc_transport_op {
+/* Transport stream op: a set of operations to perform on a transport
+   against a single stream */
+typedef struct grpc_transport_stream_op {
   grpc_iomgr_closure *on_consumed;
 
   grpc_stream_op_buffer *send_ops;
@@ -80,32 +80,32 @@ typedef struct grpc_transport_op {
 
   /* Indexes correspond to grpc_context_index enum values */
   grpc_call_context_element *context;
-} grpc_transport_op;
+} grpc_transport_stream_op;
 
-/* Callbacks made from the transport to the upper layers of grpc. */
-struct grpc_transport_callbacks {
-  /* Initialize a new stream on behalf of the transport.
-     Must result in a call to
-     grpc_transport_init_stream(transport, ..., request) in the same call
-     stack.
-     Must not result in any other calls to the transport.
-
-     Arguments:
-       user_data     - the transport user data set at transport creation time
-       transport     - the grpc_transport instance making this call
-       request       - request parameters for this stream (owned by the caller)
-       server_data   - opaque transport dependent argument that should be passed
-                       to grpc_transport_init_stream
-     */
-  void (*accept_stream)(void *user_data, grpc_transport *transport,
-                        const void *server_data);
-
-  void (*goaway)(void *user_data, grpc_transport *transport,
-                 grpc_status_code status, gpr_slice debug);
-
-  /* The transport has been closed */
-  void (*closed)(void *user_data, grpc_transport *transport);
-};
+/** Transport op: a set of operations to perform on a transport as a whole */
+typedef struct grpc_transport_op {
+  /** called when processing of this op is done */
+  grpc_iomgr_closure *on_consumed;
+  /** connectivity monitoring */
+  grpc_iomgr_closure *on_connectivity_state_change;
+  grpc_connectivity_state *connectivity_state;
+  /** should the transport be disconnected */
+  int disconnect;
+  /** should we send a goaway? */
+  int send_goaway;
+  /** what should the goaway contain? */
+  grpc_status_code goaway_status;
+  gpr_slice *goaway_message;
+  /** set the callback for accepting new streams;
+      this is a permanent callback, unlike the other one-shot closures */
+  void (*set_accept_stream)(void *user_data, grpc_transport *transport,
+                            const void *server_data);
+  void *set_accept_stream_user_data;
+  /** add this transport to a pollset */
+  grpc_pollset *bind_pollset;
+  /** send a ping, call this back if not NULL */
+  grpc_iomgr_closure *send_ping;
+} grpc_transport_op;
 
 /* Returns the amount of memory required to store a grpc_stream for this
    transport */
@@ -122,7 +122,7 @@ size_t grpc_transport_stream_size(grpc_transport *transport);
                    supplied from the accept_stream callback function */
 int grpc_transport_init_stream(grpc_transport *transport, grpc_stream *stream,
                                const void *server_data,
-                               grpc_transport_op *initial_op);
+                               grpc_transport_stream_op *initial_op);
 
 /* Destroy transport data for a stream.
 
@@ -137,17 +137,13 @@ int grpc_transport_init_stream(grpc_transport *transport, grpc_stream *stream,
 void grpc_transport_destroy_stream(grpc_transport *transport,
                                    grpc_stream *stream);
 
-void grpc_transport_op_finish_with_failure(grpc_transport_op *op);
-
-void grpc_transport_op_add_cancellation(grpc_transport_op *op,
-                                        grpc_status_code status,
-                                        grpc_mdstr *message);
+void grpc_transport_stream_op_finish_with_failure(grpc_transport_stream_op *op);
 
-/* TODO(ctiller): remove this */
-void grpc_transport_add_to_pollset(grpc_transport *transport,
-                                   grpc_pollset *pollset);
+void grpc_transport_stream_op_add_cancellation(grpc_transport_stream_op *op,
+                                               grpc_status_code status,
+                                               grpc_mdstr *message);
 
-char *grpc_transport_op_string(grpc_transport_op *op);
+char *grpc_transport_stream_op_string(grpc_transport_stream_op *op);
 
 /* Send a batch of operations on a transport
 
@@ -157,8 +153,12 @@ char *grpc_transport_op_string(grpc_transport_op *op);
      transport - the transport on which to initiate the stream
      stream    - the stream on which to send the operations. This must be
                  non-NULL and previously initialized by the same transport.
-     op        - a grpc_transport_op specifying the op to perform */
-void grpc_transport_perform_op(grpc_transport *transport, grpc_stream *stream,
+     op        - a grpc_transport_stream_op specifying the op to perform */
+void grpc_transport_perform_stream_op(grpc_transport *transport,
+                                      grpc_stream *stream,
+                                      grpc_transport_stream_op *op);
+
+void grpc_transport_perform_op(grpc_transport *transport,
                                grpc_transport_op *op);
 
 /* Send a ping on a transport
@@ -176,52 +176,4 @@ void grpc_transport_close(grpc_transport *transport);
 /* Destroy the transport */
 void grpc_transport_destroy(grpc_transport *transport);
 
-/* Return type for grpc_transport_setup_callback */
-typedef struct grpc_transport_setup_result {
-  void *user_data;
-  const grpc_transport_callbacks *callbacks;
-} grpc_transport_setup_result;
-
-/* Given a transport, return callbacks for that transport. Used to finalize
-   setup as a transport is being created */
-typedef grpc_transport_setup_result (*grpc_transport_setup_callback)(
-    void *setup_arg, grpc_transport *transport, grpc_mdctx *mdctx);
-
-typedef struct grpc_transport_setup grpc_transport_setup;
-typedef struct grpc_transport_setup_vtable grpc_transport_setup_vtable;
-
-struct grpc_transport_setup_vtable {
-  void (*initiate)(grpc_transport_setup *setup);
-  void (*add_interested_party)(grpc_transport_setup *setup,
-                               grpc_pollset *pollset);
-  void (*del_interested_party)(grpc_transport_setup *setup,
-                               grpc_pollset *pollset);
-  void (*cancel)(grpc_transport_setup *setup);
-};
-
-/* Transport setup is an asynchronous utility interface for client channels to
-   establish connections. It's transport agnostic. */
-struct grpc_transport_setup {
-  const grpc_transport_setup_vtable *vtable;
-};
-
-/* Initiate transport setup: e.g. for TCP+DNS trigger a resolve of the name
-   given at transport construction time, create the tcp connection, perform
-   handshakes, and call some grpc_transport_setup_result function provided at
-   setup construction time.
-   This *may* be implemented as a no-op if the setup process monitors something
-   continuously. */
-void grpc_transport_setup_initiate(grpc_transport_setup *setup);
-
-void grpc_transport_setup_add_interested_party(grpc_transport_setup *setup,
-                                               grpc_pollset *pollset);
-void grpc_transport_setup_del_interested_party(grpc_transport_setup *setup,
-                                               grpc_pollset *pollset);
-
-/* Cancel transport setup. After this returns, no new transports should be
-   created, and all pending transport setup callbacks should be completed.
-   After this call completes, setup should be considered invalid (this can be
-   used as a destruction call by setup). */
-void grpc_transport_setup_cancel(grpc_transport_setup *setup);
-
 #endif /* GRPC_INTERNAL_CORE_TRANSPORT_TRANSPORT_H */
diff --git a/src/core/transport/transport_impl.h b/src/core/transport/transport_impl.h
index c51951b7a7..515721dfb6 100644
--- a/src/core/transport/transport_impl.h
+++ b/src/core/transport/transport_impl.h
@@ -43,28 +43,19 @@ typedef struct grpc_transport_vtable {
 
   /* implementation of grpc_transport_init_stream */
   int (*init_stream)(grpc_transport *self, grpc_stream *stream,
-                     const void *server_data, grpc_transport_op *initial_op);
+                     const void *server_data,
+                     grpc_transport_stream_op *initial_op);
 
-  /* implementation of grpc_transport_send_batch */
-  void (*perform_op)(grpc_transport *self, grpc_stream *stream,
-                     grpc_transport_op *op);
+  /* implementation of grpc_transport_perform_stream_op */
+  void (*perform_stream_op)(grpc_transport *self, grpc_stream *stream,
+                            grpc_transport_stream_op *op);
 
-  /* implementation of grpc_transport_add_to_pollset */
-  void (*add_to_pollset)(grpc_transport *self, grpc_pollset *pollset);
+  /* implementation of grpc_transport_perform_op */
+  void (*perform_op)(grpc_transport *self, grpc_transport_op *op);
 
   /* implementation of grpc_transport_destroy_stream */
   void (*destroy_stream)(grpc_transport *self, grpc_stream *stream);
 
-  /* implementation of grpc_transport_goaway */
-  void (*goaway)(grpc_transport *self, grpc_status_code status,
-                 gpr_slice debug_data);
-
-  /* implementation of grpc_transport_close */
-  void (*close)(grpc_transport *self);
-
-  /* implementation of grpc_transport_ping */
-  void (*ping)(grpc_transport *self, grpc_iomgr_closure *cb);
-
   /* implementation of grpc_transport_destroy */
   void (*destroy)(grpc_transport *self);
 } grpc_transport_vtable;
diff --git a/src/core/transport/transport_op_string.c b/src/core/transport/transport_op_string.c
index a408b75790..1ffdb5be94 100644
--- a/src/core/transport/transport_op_string.c
+++ b/src/core/transport/transport_op_string.c
@@ -107,7 +107,7 @@ char *grpc_sopb_string(grpc_stream_op_buffer *sopb) {
   return out;
 }
 
-char *grpc_transport_op_string(grpc_transport_op *op) {
+char *grpc_transport_stream_op_string(grpc_transport_stream_op *op) {
   char *tmp;
   char *out;
   int first = 1;
@@ -146,6 +146,13 @@ char *grpc_transport_op_string(grpc_transport_op *op) {
     gpr_strvec_add(&b, tmp);
   }
 
+  if (op->on_consumed != NULL) {
+    if (!first) gpr_strvec_add(&b, gpr_strdup(" "));
+    first = 0;
+    gpr_asprintf(&tmp, "ON_CONSUMED:%p", op->on_consumed);
+    gpr_strvec_add(&b, tmp);
+  }
+
   out = gpr_strvec_flatten(&b, NULL);
   gpr_strvec_destroy(&b);
 
@@ -153,8 +160,8 @@ char *grpc_transport_op_string(grpc_transport_op *op) {
 }
 
 void grpc_call_log_op(char *file, int line, gpr_log_severity severity,
-                      grpc_call_element *elem, grpc_transport_op *op) {
-  char *str = grpc_transport_op_string(op);
+                      grpc_call_element *elem, grpc_transport_stream_op *op) {
+  char *str = grpc_transport_stream_op_string(op);
   gpr_log(file, line, severity, "OP[%s:%p]: %s", elem->filter->name, elem, str);
   gpr_free(str);
 }