Merge master

13 files changed, 1565 insertions, 87 deletions

diff --git a/include/grpcpp/impl/codegen/byte_buffer.h b/include/grpcpp/impl/codegen/byte_buffer.h
index abba5549b8..a77e36dfc5 100644
--- a/include/grpcpp/impl/codegen/byte_buffer.h
+++ b/include/grpcpp/impl/codegen/byte_buffer.h
@@ -45,8 +45,10 @@ template <class ServiceType, class RequestType, class ResponseType>
 class RpcMethodHandler;
 template <class ServiceType, class RequestType, class ResponseType>
 class ServerStreamingHandler;
-template <class ServiceType, class RequestType, class ResponseType>
+template <class RequestType, class ResponseType>
 class CallbackUnaryHandler;
+template <class RequestType, class ResponseType>
+class CallbackServerStreamingHandler;
 template <StatusCode code>
 class ErrorMethodHandler;
 template <class R>
@@ -91,7 +93,9 @@ class ByteBuffer final {
   }
 
   /// Constuct a byte buffer by referencing elements of existing buffer
-  /// \a buf. Wrapper of core function grpc_byte_buffer_copy
+  /// \a buf. Wrapper of core function grpc_byte_buffer_copy . This is not
+  /// a deep copy; it is just a referencing. As a result, its performance is
+  /// size-independent.
   ByteBuffer(const ByteBuffer& buf);
 
   ~ByteBuffer() {
@@ -100,6 +104,9 @@ class ByteBuffer final {
     }
   }
 
+  /// Wrapper of core function grpc_byte_buffer_copy . This is not
+  /// a deep copy; it is just a referencing. As a result, its performance is
+  /// size-independent.
   ByteBuffer& operator=(const ByteBuffer&);
 
   /// Dump (read) the buffer contents into \a slices.
@@ -115,7 +122,9 @@ class ByteBuffer final {
 
   /// Make a duplicate copy of the internals of this byte
   /// buffer so that we have our own owned version of it.
-  /// bbuf.Duplicate(); is equivalent to bbuf=bbuf; but is actually readable
+  /// bbuf.Duplicate(); is equivalent to bbuf=bbuf; but is actually readable.
+  /// This is not a deep copy; it is a referencing and its performance
+  /// is size-independent.
   void Duplicate() {
     buffer_ = g_core_codegen_interface->grpc_byte_buffer_copy(buffer_);
   }
@@ -156,8 +165,10 @@ class ByteBuffer final {
   friend class internal::RpcMethodHandler;
   template <class ServiceType, class RequestType, class ResponseType>
   friend class internal::ServerStreamingHandler;
-  template <class ServiceType, class RequestType, class ResponseType>
+  template <class RequestType, class ResponseType>
   friend class internal::CallbackUnaryHandler;
+  template <class RequestType, class ResponseType>
+  friend class ::grpc::internal::CallbackServerStreamingHandler;
   template <StatusCode code>
   friend class internal::ErrorMethodHandler;
   template <class R>
diff --git a/include/grpcpp/impl/codegen/call_op_set.h b/include/grpcpp/impl/codegen/call_op_set.h
index ac3ba17bd9..3db9f48bff 100644
--- a/include/grpcpp/impl/codegen/call_op_set.h
+++ b/include/grpcpp/impl/codegen/call_op_set.h
@@ -343,6 +343,9 @@ class CallOpSendMessage {
       // We had already registered failed_send_ earlier. No need to do it again.
     }
     send_buf_.Clear();
+    // The contents of the SendMessage value that was previously set
+    // has had its references stolen by core's operations
+    interceptor_methods->SetSendMessage(nullptr);
   }
 
   void SetHijackingState(InterceptorBatchMethodsImpl* interceptor_methods) {
diff --git a/include/grpcpp/impl/codegen/callback_common.h b/include/grpcpp/impl/codegen/callback_common.h
index 51367cf550..a3c8c41246 100644
--- a/include/grpcpp/impl/codegen/callback_common.h
+++ b/include/grpcpp/impl/codegen/callback_common.h
@@ -32,6 +32,8 @@ namespace grpc {
 namespace internal {
 
 /// An exception-safe way of invoking a user-specified callback function
+// TODO(vjpai): decide whether it is better for this to take a const lvalue
+//              parameter or an rvalue parameter, or if it even matters
 template <class Func, class... Args>
 void CatchingCallback(Func&& func, Args&&... args) {
 #if GRPC_ALLOW_EXCEPTIONS
@@ -45,6 +47,20 @@ void CatchingCallback(Func&& func, Args&&... args) {
 #endif  // GRPC_ALLOW_EXCEPTIONS
 }
 
+template <class ReturnType, class Func, class... Args>
+ReturnType* CatchingReactorCreator(Func&& func, Args&&... args) {
+#if GRPC_ALLOW_EXCEPTIONS
+  try {
+    return func(std::forward<Args>(args)...);
+  } catch (...) {
+    // fail the RPC, don't crash the library
+    return nullptr;
+  }
+#else   // GRPC_ALLOW_EXCEPTIONS
+  return func(std::forward<Args>(args)...);
+#endif  // GRPC_ALLOW_EXCEPTIONS
+}
+
 // The contract on these tags is that they are single-shot. They must be
 // constructed and then fired at exactly one point. There is no expectation
 // that they can be reused without reconstruction.
@@ -145,18 +161,19 @@ class CallbackWithSuccessTag
   // or on a tag that has been Set before unless the tag has been cleared.
   void Set(grpc_call* call, std::function<void(bool)> f,
            CompletionQueueTag* ops) {
+    GPR_CODEGEN_ASSERT(call_ == nullptr);
+    g_core_codegen_interface->grpc_call_ref(call);
     call_ = call;
     func_ = std::move(f);
     ops_ = ops;
-    g_core_codegen_interface->grpc_call_ref(call);
     functor_run = &CallbackWithSuccessTag::StaticRun;
   }
 
   void Clear() {
     if (call_ != nullptr) {
-      func_ = nullptr;
       grpc_call* call = call_;
       call_ = nullptr;
+      func_ = nullptr;
       g_core_codegen_interface->grpc_call_unref(call);
     }
   }
@@ -182,11 +199,11 @@ class CallbackWithSuccessTag
   }
   void Run(bool ok) {
     void* ignored = ops_;
-    bool new_ok = ok;
     // Allow a "false" return value from FinalizeResult to silence the
     // callback, just as it silences a CQ tag in the async cases
-    bool do_callback = ops_->FinalizeResult(&ignored, &new_ok);
-    GPR_CODEGEN_ASSERT(ignored == ops_);
+    auto* ops = ops_;
+    bool do_callback = ops_->FinalizeResult(&ignored, &ok);
+    GPR_CODEGEN_ASSERT(ignored == ops);
 
     if (do_callback) {
       CatchingCallback(func_, ok);
diff --git a/include/grpcpp/impl/codegen/channel_interface.h b/include/grpcpp/impl/codegen/channel_interface.h
index 6ec1ffb8c7..5353f5feaa 100644
--- a/include/grpcpp/impl/codegen/channel_interface.h
+++ b/include/grpcpp/impl/codegen/channel_interface.h
@@ -21,7 +21,6 @@
 
 #include <grpc/impl/codegen/connectivity_state.h>
 #include <grpcpp/impl/codegen/call.h>
-#include <grpcpp/impl/codegen/client_context.h>
 #include <grpcpp/impl/codegen/status.h>
 #include <grpcpp/impl/codegen/time.h>
 
@@ -53,6 +52,12 @@ template <class W, class R>
 class ClientAsyncReaderWriterFactory;
 template <class R>
 class ClientAsyncResponseReaderFactory;
+template <class W, class R>
+class ClientCallbackReaderWriterFactory;
+template <class R>
+class ClientCallbackReaderFactory;
+template <class W>
+class ClientCallbackWriterFactory;
 class InterceptedChannel;
 }  // namespace internal
 
@@ -106,6 +111,12 @@ class ChannelInterface {
   friend class ::grpc::internal::ClientAsyncReaderWriterFactory;
   template <class R>
   friend class ::grpc::internal::ClientAsyncResponseReaderFactory;
+  template <class W, class R>
+  friend class ::grpc::internal::ClientCallbackReaderWriterFactory;
+  template <class R>
+  friend class ::grpc::internal::ClientCallbackReaderFactory;
+  template <class W>
+  friend class ::grpc::internal::ClientCallbackWriterFactory;
   template <class InputMessage, class OutputMessage>
   friend class ::grpc::internal::BlockingUnaryCallImpl;
   template <class InputMessage, class OutputMessage>
diff --git a/include/grpcpp/impl/codegen/client_callback.h b/include/grpcpp/impl/codegen/client_callback.h
index 4baa819091..66cf9b7754 100644
--- a/include/grpcpp/impl/codegen/client_callback.h
+++ b/include/grpcpp/impl/codegen/client_callback.h
@@ -22,6 +22,7 @@
 #include <functional>
 
 #include <grpcpp/impl/codegen/call.h>
+#include <grpcpp/impl/codegen/call_op_set.h>
 #include <grpcpp/impl/codegen/callback_common.h>
 #include <grpcpp/impl/codegen/channel_interface.h>
 #include <grpcpp/impl/codegen/config.h>
@@ -88,6 +89,660 @@ class CallbackUnaryCallImpl {
     call.PerformOps(ops);
   }
 };
+}  // namespace internal
+
+namespace experimental {
+
+// Forward declarations
+template <class Request, class Response>
+class ClientBidiReactor;
+template <class Response>
+class ClientReadReactor;
+template <class Request>
+class ClientWriteReactor;
+
+// NOTE: The streaming objects are not actually implemented in the public API.
+//       These interfaces are provided for mocking only. Typical applications
+//       will interact exclusively with the reactors that they define.
+template <class Request, class Response>
+class ClientCallbackReaderWriter {
+ public:
+  virtual ~ClientCallbackReaderWriter() {}
+  virtual void StartCall() = 0;
+  virtual void Write(const Request* req, WriteOptions options) = 0;
+  virtual void WritesDone() = 0;
+  virtual void Read(Response* resp) = 0;
+
+ protected:
+  void BindReactor(ClientBidiReactor<Request, Response>* reactor) {
+    reactor->BindStream(this);
+  }
+};
+
+template <class Response>
+class ClientCallbackReader {
+ public:
+  virtual ~ClientCallbackReader() {}
+  virtual void StartCall() = 0;
+  virtual void Read(Response* resp) = 0;
+
+ protected:
+  void BindReactor(ClientReadReactor<Response>* reactor) {
+    reactor->BindReader(this);
+  }
+};
+
+template <class Request>
+class ClientCallbackWriter {
+ public:
+  virtual ~ClientCallbackWriter() {}
+  virtual void StartCall() = 0;
+  void Write(const Request* req) { Write(req, WriteOptions()); }
+  virtual void Write(const Request* req, WriteOptions options) = 0;
+  void WriteLast(const Request* req, WriteOptions options) {
+    Write(req, options.set_last_message());
+  }
+  virtual void WritesDone() = 0;
+
+ protected:
+  void BindReactor(ClientWriteReactor<Request>* reactor) {
+    reactor->BindWriter(this);
+  }
+};
+
+// The user must implement this reactor interface with reactions to each event
+// type that gets called by the library. An empty reaction is provided by
+// default
+template <class Request, class Response>
+class ClientBidiReactor {
+ public:
+  virtual ~ClientBidiReactor() {}
+  virtual void OnDone(const Status& s) {}
+  virtual void OnReadInitialMetadataDone(bool ok) {}
+  virtual void OnReadDone(bool ok) {}
+  virtual void OnWriteDone(bool ok) {}
+  virtual void OnWritesDoneDone(bool ok) {}
+
+  void StartCall() { stream_->StartCall(); }
+  void StartRead(Response* resp) { stream_->Read(resp); }
+  void StartWrite(const Request* req) { StartWrite(req, WriteOptions()); }
+  void StartWrite(const Request* req, WriteOptions options) {
+    stream_->Write(req, std::move(options));
+  }
+  void StartWriteLast(const Request* req, WriteOptions options) {
+    StartWrite(req, std::move(options.set_last_message()));
+  }
+  void StartWritesDone() { stream_->WritesDone(); }
+
+ private:
+  friend class ClientCallbackReaderWriter<Request, Response>;
+  void BindStream(ClientCallbackReaderWriter<Request, Response>* stream) {
+    stream_ = stream;
+  }
+  ClientCallbackReaderWriter<Request, Response>* stream_;
+};
+
+template <class Response>
+class ClientReadReactor {
+ public:
+  virtual ~ClientReadReactor() {}
+  virtual void OnDone(const Status& s) {}
+  virtual void OnReadInitialMetadataDone(bool ok) {}
+  virtual void OnReadDone(bool ok) {}
+
+  void StartCall() { reader_->StartCall(); }
+  void StartRead(Response* resp) { reader_->Read(resp); }
+
+ private:
+  friend class ClientCallbackReader<Response>;
+  void BindReader(ClientCallbackReader<Response>* reader) { reader_ = reader; }
+  ClientCallbackReader<Response>* reader_;
+};
+
+template <class Request>
+class ClientWriteReactor {
+ public:
+  virtual ~ClientWriteReactor() {}
+  virtual void OnDone(const Status& s) {}
+  virtual void OnReadInitialMetadataDone(bool ok) {}
+  virtual void OnWriteDone(bool ok) {}
+  virtual void OnWritesDoneDone(bool ok) {}
+
+  void StartCall() { writer_->StartCall(); }
+  void StartWrite(const Request* req) { StartWrite(req, WriteOptions()); }
+  void StartWrite(const Request* req, WriteOptions options) {
+    writer_->Write(req, std::move(options));
+  }
+  void StartWriteLast(const Request* req, WriteOptions options) {
+    StartWrite(req, std::move(options.set_last_message()));
+  }
+  void StartWritesDone() { writer_->WritesDone(); }
+
+ private:
+  friend class ClientCallbackWriter<Request>;
+  void BindWriter(ClientCallbackWriter<Request>* writer) { writer_ = writer; }
+  ClientCallbackWriter<Request>* writer_;
+};
+
+}  // namespace experimental
+
+namespace internal {
+
+// Forward declare factory classes for friendship
+template <class Request, class Response>
+class ClientCallbackReaderWriterFactory;
+template <class Response>
+class ClientCallbackReaderFactory;
+template <class Request>
+class ClientCallbackWriterFactory;
+
+template <class Request, class Response>
+class ClientCallbackReaderWriterImpl
+    : public ::grpc::experimental::ClientCallbackReaderWriter<Request,
+                                                              Response> {
+ public:
+  // always allocated against a call arena, no memory free required
+  static void operator delete(void* ptr, std::size_t size) {
+    assert(size == sizeof(ClientCallbackReaderWriterImpl));
+  }
+
+  // This operator should never be called as the memory should be freed as part
+  // of the arena destruction. It only exists to provide a matching operator
+  // delete to the operator new so that some compilers will not complain (see
+  // https://github.com/grpc/grpc/issues/11301) Note at the time of adding this
+  // there are no tests catching the compiler warning.
+  static void operator delete(void*, void*) { assert(0); }
+
+  void MaybeFinish() {
+    if (--callbacks_outstanding_ == 0) {
+      Status s = std::move(finish_status_);
+      auto* reactor = reactor_;
+      auto* call = call_.call();
+      this->~ClientCallbackReaderWriterImpl();
+      g_core_codegen_interface->grpc_call_unref(call);
+      reactor->OnDone(s);
+    }
+  }
+
+  void StartCall() override {
+    // This call initiates two batches, plus any backlog, each with a callback
+    // 1. Send initial metadata (unless corked) + recv initial metadata
+    // 2. Any read backlog
+    // 3. Recv trailing metadata, on_completion callback
+    // 4. Any write backlog
+    // 5. See if the call can finish (if other callbacks were triggered already)
+    started_ = true;
+
+    start_tag_.Set(call_.call(),
+                   [this](bool ok) {
+                     reactor_->OnReadInitialMetadataDone(ok);
+                     MaybeFinish();
+                   },
+                   &start_ops_);
+    if (!start_corked_) {
+      start_ops_.SendInitialMetadata(&context_->send_initial_metadata_,
+                                     context_->initial_metadata_flags());
+    }
+    start_ops_.RecvInitialMetadata(context_);
+    start_ops_.set_core_cq_tag(&start_tag_);
+    call_.PerformOps(&start_ops_);
+
+    // Also set up the read and write tags so that they don't have to be set up
+    // each time
+    write_tag_.Set(call_.call(),
+                   [this](bool ok) {
+                     reactor_->OnWriteDone(ok);
+                     MaybeFinish();
+                   },
+                   &write_ops_);
+    write_ops_.set_core_cq_tag(&write_tag_);
+
+    read_tag_.Set(call_.call(),
+                  [this](bool ok) {
+                    reactor_->OnReadDone(ok);
+                    MaybeFinish();
+                  },
+                  &read_ops_);
+    read_ops_.set_core_cq_tag(&read_tag_);
+    if (read_ops_at_start_) {
+      call_.PerformOps(&read_ops_);
+    }
+
+    finish_tag_.Set(call_.call(), [this](bool ok) { MaybeFinish(); },
+                    &finish_ops_);
+    finish_ops_.ClientRecvStatus(context_, &finish_status_);
+    finish_ops_.set_core_cq_tag(&finish_tag_);
+    call_.PerformOps(&finish_ops_);
+
+    if (write_ops_at_start_) {
+      call_.PerformOps(&write_ops_);
+    }
+
+    if (writes_done_ops_at_start_) {
+      call_.PerformOps(&writes_done_ops_);
+    }
+    MaybeFinish();
+  }
+
+  void Read(Response* msg) override {
+    read_ops_.RecvMessage(msg);
+    callbacks_outstanding_++;
+    if (started_) {
+      call_.PerformOps(&read_ops_);
+    } else {
+      read_ops_at_start_ = true;
+    }
+  }
+
+  void Write(const Request* msg, WriteOptions options) override {
+    if (start_corked_) {
+      write_ops_.SendInitialMetadata(&context_->send_initial_metadata_,
+                                     context_->initial_metadata_flags());
+      start_corked_ = false;
+    }
+    // TODO(vjpai): don't assert
+    GPR_CODEGEN_ASSERT(write_ops_.SendMessage(*msg).ok());
+
+    if (options.is_last_message()) {
+      options.set_buffer_hint();
+      write_ops_.ClientSendClose();
+    }
+    callbacks_outstanding_++;
+    if (started_) {
+      call_.PerformOps(&write_ops_);
+    } else {
+      write_ops_at_start_ = true;
+    }
+  }
+  void WritesDone() override {
+    if (start_corked_) {
+      writes_done_ops_.SendInitialMetadata(&context_->send_initial_metadata_,
+                                           context_->initial_metadata_flags());
+      start_corked_ = false;
+    }
+    writes_done_ops_.ClientSendClose();
+    writes_done_tag_.Set(call_.call(),
+                         [this](bool ok) {
+                           reactor_->OnWritesDoneDone(ok);
+                           MaybeFinish();
+                         },
+                         &writes_done_ops_);
+    writes_done_ops_.set_core_cq_tag(&writes_done_tag_);
+    callbacks_outstanding_++;
+    if (started_) {
+      call_.PerformOps(&writes_done_ops_);
+    } else {
+      writes_done_ops_at_start_ = true;
+    }
+  }
+
+ private:
+  friend class ClientCallbackReaderWriterFactory<Request, Response>;
+
+  ClientCallbackReaderWriterImpl(
+      Call call, ClientContext* context,
+      ::grpc::experimental::ClientBidiReactor<Request, Response>* reactor)
+      : context_(context),
+        call_(call),
+        reactor_(reactor),
+        start_corked_(context_->initial_metadata_corked_) {
+    this->BindReactor(reactor);
+  }
+
+  ClientContext* context_;
+  Call call_;
+  ::grpc::experimental::ClientBidiReactor<Request, Response>* reactor_;
+
+  CallOpSet<CallOpSendInitialMetadata, CallOpRecvInitialMetadata> start_ops_;
+  CallbackWithSuccessTag start_tag_;
+  bool start_corked_;
+
+  CallOpSet<CallOpClientRecvStatus> finish_ops_;
+  CallbackWithSuccessTag finish_tag_;
+  Status finish_status_;
+
+  CallOpSet<CallOpSendInitialMetadata, CallOpSendMessage, CallOpClientSendClose>
+      write_ops_;
+  CallbackWithSuccessTag write_tag_;
+  bool write_ops_at_start_{false};
+
+  CallOpSet<CallOpSendInitialMetadata, CallOpClientSendClose> writes_done_ops_;
+  CallbackWithSuccessTag writes_done_tag_;
+  bool writes_done_ops_at_start_{false};
+
+  CallOpSet<CallOpRecvMessage<Response>> read_ops_;
+  CallbackWithSuccessTag read_tag_;
+  bool read_ops_at_start_{false};
+
+  // Minimum of 3 callbacks to pre-register for StartCall, start, and finish
+  std::atomic_int callbacks_outstanding_{3};
+  bool started_{false};
+};
+
+template <class Request, class Response>
+class ClientCallbackReaderWriterFactory {
+ public:
+  static void Create(
+      ChannelInterface* channel, const ::grpc::internal::RpcMethod& method,
+      ClientContext* context,
+      ::grpc::experimental::ClientBidiReactor<Request, Response>* reactor) {
+    Call call = channel->CreateCall(method, context, channel->CallbackCQ());
+
+    g_core_codegen_interface->grpc_call_ref(call.call());
+    new (g_core_codegen_interface->grpc_call_arena_alloc(
+        call.call(), sizeof(ClientCallbackReaderWriterImpl<Request, Response>)))
+        ClientCallbackReaderWriterImpl<Request, Response>(call, context,
+                                                          reactor);
+  }
+};
+
+template <class Response>
+class ClientCallbackReaderImpl
+    : public ::grpc::experimental::ClientCallbackReader<Response> {
+ public:
+  // always allocated against a call arena, no memory free required
+  static void operator delete(void* ptr, std::size_t size) {
+    assert(size == sizeof(ClientCallbackReaderImpl));
+  }
+
+  // This operator should never be called as the memory should be freed as part
+  // of the arena destruction. It only exists to provide a matching operator
+  // delete to the operator new so that some compilers will not complain (see
+  // https://github.com/grpc/grpc/issues/11301) Note at the time of adding this
+  // there are no tests catching the compiler warning.
+  static void operator delete(void*, void*) { assert(0); }
+
+  void MaybeFinish() {
+    if (--callbacks_outstanding_ == 0) {
+      Status s = std::move(finish_status_);
+      auto* reactor = reactor_;
+      auto* call = call_.call();
+      this->~ClientCallbackReaderImpl();
+      g_core_codegen_interface->grpc_call_unref(call);
+      reactor->OnDone(s);
+    }
+  }
+
+  void StartCall() override {
+    // This call initiates two batches, plus any backlog, each with a callback
+    // 1. Send initial metadata (unless corked) + recv initial metadata
+    // 2. Any backlog
+    // 3. Recv trailing metadata, on_completion callback
+    // 4. See if the call can finish (if other callbacks were triggered already)
+    started_ = true;
+
+    start_tag_.Set(call_.call(),
+                   [this](bool ok) {
+                     reactor_->OnReadInitialMetadataDone(ok);
+                     MaybeFinish();
+                   },
+                   &start_ops_);
+    start_ops_.SendInitialMetadata(&context_->send_initial_metadata_,
+                                   context_->initial_metadata_flags());
+    start_ops_.RecvInitialMetadata(context_);
+    start_ops_.set_core_cq_tag(&start_tag_);
+    call_.PerformOps(&start_ops_);
+
+    // Also set up the read tag so it doesn't have to be set up each time
+    read_tag_.Set(call_.call(),
+                  [this](bool ok) {
+                    reactor_->OnReadDone(ok);
+                    MaybeFinish();
+                  },
+                  &read_ops_);
+    read_ops_.set_core_cq_tag(&read_tag_);
+    if (read_ops_at_start_) {
+      call_.PerformOps(&read_ops_);
+    }
+
+    finish_tag_.Set(call_.call(), [this](bool ok) { MaybeFinish(); },
+                    &finish_ops_);
+    finish_ops_.ClientRecvStatus(context_, &finish_status_);
+    finish_ops_.set_core_cq_tag(&finish_tag_);
+    call_.PerformOps(&finish_ops_);
+
+    MaybeFinish();
+  }
+
+  void Read(Response* msg) override {
+    read_ops_.RecvMessage(msg);
+    callbacks_outstanding_++;
+    if (started_) {
+      call_.PerformOps(&read_ops_);
+    } else {
+      read_ops_at_start_ = true;
+    }
+  }
+
+ private:
+  friend class ClientCallbackReaderFactory<Response>;
+
+  template <class Request>
+  ClientCallbackReaderImpl(
+      Call call, ClientContext* context, Request* request,
+      ::grpc::experimental::ClientReadReactor<Response>* reactor)
+      : context_(context), call_(call), reactor_(reactor) {
+    this->BindReactor(reactor);
+    // TODO(vjpai): don't assert
+    GPR_CODEGEN_ASSERT(start_ops_.SendMessage(*request).ok());
+    start_ops_.ClientSendClose();
+  }
+
+  ClientContext* context_;
+  Call call_;
+  ::grpc::experimental::ClientReadReactor<Response>* reactor_;
+
+  CallOpSet<CallOpSendInitialMetadata, CallOpSendMessage, CallOpClientSendClose,
+            CallOpRecvInitialMetadata>
+      start_ops_;
+  CallbackWithSuccessTag start_tag_;
+
+  CallOpSet<CallOpClientRecvStatus> finish_ops_;
+  CallbackWithSuccessTag finish_tag_;
+  Status finish_status_;
+
+  CallOpSet<CallOpRecvMessage<Response>> read_ops_;
+  CallbackWithSuccessTag read_tag_;
+  bool read_ops_at_start_{false};
+
+  // Minimum of 3 callbacks to pre-register for StartCall, start, and finish
+  std::atomic_int callbacks_outstanding_{3};
+  bool started_{false};
+};
+
+template <class Response>
+class ClientCallbackReaderFactory {
+ public:
+  template <class Request>
+  static void Create(
+      ChannelInterface* channel, const ::grpc::internal::RpcMethod& method,
+      ClientContext* context, const Request* request,
+      ::grpc::experimental::ClientReadReactor<Response>* reactor) {
+    Call call = channel->CreateCall(method, context, channel->CallbackCQ());
+
+    g_core_codegen_interface->grpc_call_ref(call.call());
+    new (g_core_codegen_interface->grpc_call_arena_alloc(
+        call.call(), sizeof(ClientCallbackReaderImpl<Response>)))
+        ClientCallbackReaderImpl<Response>(call, context, request, reactor);
+  }
+};
+
+template <class Request>
+class ClientCallbackWriterImpl
+    : public ::grpc::experimental::ClientCallbackWriter<Request> {
+ public:
+  // always allocated against a call arena, no memory free required
+  static void operator delete(void* ptr, std::size_t size) {
+    assert(size == sizeof(ClientCallbackWriterImpl));
+  }
+
+  // This operator should never be called as the memory should be freed as part
+  // of the arena destruction. It only exists to provide a matching operator
+  // delete to the operator new so that some compilers will not complain (see
+  // https://github.com/grpc/grpc/issues/11301) Note at the time of adding this
+  // there are no tests catching the compiler warning.
+  static void operator delete(void*, void*) { assert(0); }
+
+  void MaybeFinish() {
+    if (--callbacks_outstanding_ == 0) {
+      Status s = std::move(finish_status_);
+      auto* reactor = reactor_;
+      auto* call = call_.call();
+      this->~ClientCallbackWriterImpl();
+      g_core_codegen_interface->grpc_call_unref(call);
+      reactor->OnDone(s);
+    }
+  }
+
+  void StartCall() override {
+    // This call initiates two batches, plus any backlog, each with a callback
+    // 1. Send initial metadata (unless corked) + recv initial metadata
+    // 2. Recv trailing metadata, on_completion callback
+    // 3. Any backlog
+    // 4. See if the call can finish (if other callbacks were triggered already)
+    started_ = true;
+
+    start_tag_.Set(call_.call(),
+                   [this](bool ok) {
+                     reactor_->OnReadInitialMetadataDone(ok);
+                     MaybeFinish();
+                   },
+                   &start_ops_);
+    if (!start_corked_) {
+      start_ops_.SendInitialMetadata(&context_->send_initial_metadata_,
+                                     context_->initial_metadata_flags());
+    }
+    start_ops_.RecvInitialMetadata(context_);
+    start_ops_.set_core_cq_tag(&start_tag_);
+    call_.PerformOps(&start_ops_);
+
+    // Also set up the read and write tags so that they don't have to be set up
+    // each time
+    write_tag_.Set(call_.call(),
+                   [this](bool ok) {
+                     reactor_->OnWriteDone(ok);
+                     MaybeFinish();
+                   },
+                   &write_ops_);
+    write_ops_.set_core_cq_tag(&write_tag_);
+
+    finish_tag_.Set(call_.call(), [this](bool ok) { MaybeFinish(); },
+                    &finish_ops_);
+    finish_ops_.ClientRecvStatus(context_, &finish_status_);
+    finish_ops_.set_core_cq_tag(&finish_tag_);
+    call_.PerformOps(&finish_ops_);
+
+    if (write_ops_at_start_) {
+      call_.PerformOps(&write_ops_);
+    }
+
+    if (writes_done_ops_at_start_) {
+      call_.PerformOps(&writes_done_ops_);
+    }
+
+    MaybeFinish();
+  }
+
+  void Write(const Request* msg, WriteOptions options) override {
+    if (start_corked_) {
+      write_ops_.SendInitialMetadata(&context_->send_initial_metadata_,
+                                     context_->initial_metadata_flags());
+      start_corked_ = false;
+    }
+    // TODO(vjpai): don't assert
+    GPR_CODEGEN_ASSERT(write_ops_.SendMessage(*msg).ok());
+
+    if (options.is_last_message()) {
+      options.set_buffer_hint();
+      write_ops_.ClientSendClose();
+    }
+    callbacks_outstanding_++;
+    if (started_) {
+      call_.PerformOps(&write_ops_);
+    } else {
+      write_ops_at_start_ = true;
+    }
+  }
+  void WritesDone() override {
+    if (start_corked_) {
+      writes_done_ops_.SendInitialMetadata(&context_->send_initial_metadata_,
+                                           context_->initial_metadata_flags());
+      start_corked_ = false;
+    }
+    writes_done_ops_.ClientSendClose();
+    writes_done_tag_.Set(call_.call(),
+                         [this](bool ok) {
+                           reactor_->OnWritesDoneDone(ok);
+                           MaybeFinish();
+                         },
+                         &writes_done_ops_);
+    writes_done_ops_.set_core_cq_tag(&writes_done_tag_);
+    callbacks_outstanding_++;
+    if (started_) {
+      call_.PerformOps(&writes_done_ops_);
+    } else {
+      writes_done_ops_at_start_ = true;
+    }
+  }
+
+ private:
+  friend class ClientCallbackWriterFactory<Request>;
+
+  template <class Response>
+  ClientCallbackWriterImpl(
+      Call call, ClientContext* context, Response* response,
+      ::grpc::experimental::ClientWriteReactor<Request>* reactor)
+      : context_(context),
+        call_(call),
+        reactor_(reactor),
+        start_corked_(context_->initial_metadata_corked_) {
+    this->BindReactor(reactor);
+    finish_ops_.RecvMessage(response);
+    finish_ops_.AllowNoMessage();
+  }
+
+  ClientContext* context_;
+  Call call_;
+  ::grpc::experimental::ClientWriteReactor<Request>* reactor_;
+
+  CallOpSet<CallOpSendInitialMetadata, CallOpRecvInitialMetadata> start_ops_;
+  CallbackWithSuccessTag start_tag_;
+  bool start_corked_;
+
+  CallOpSet<CallOpGenericRecvMessage, CallOpClientRecvStatus> finish_ops_;
+  CallbackWithSuccessTag finish_tag_;
+  Status finish_status_;
+
+  CallOpSet<CallOpSendInitialMetadata, CallOpSendMessage, CallOpClientSendClose>
+      write_ops_;
+  CallbackWithSuccessTag write_tag_;
+  bool write_ops_at_start_{false};
+
+  CallOpSet<CallOpSendInitialMetadata, CallOpClientSendClose> writes_done_ops_;
+  CallbackWithSuccessTag writes_done_tag_;
+  bool writes_done_ops_at_start_{false};
+
+  // Minimum of 3 callbacks to pre-register for StartCall, start, and finish
+  std::atomic_int callbacks_outstanding_{3};
+  bool started_{false};
+};
+
+template <class Request>
+class ClientCallbackWriterFactory {
+ public:
+  template <class Response>
+  static void Create(
+      ChannelInterface* channel, const ::grpc::internal::RpcMethod& method,
+      ClientContext* context, Response* response,
+      ::grpc::experimental::ClientWriteReactor<Request>* reactor) {
+    Call call = channel->CreateCall(method, context, channel->CallbackCQ());
+
+    g_core_codegen_interface->grpc_call_ref(call.call());
+    new (g_core_codegen_interface->grpc_call_arena_alloc(
+        call.call(), sizeof(ClientCallbackWriterImpl<Request>)))
+        ClientCallbackWriterImpl<Request>(call, context, response, reactor);
+  }
+};
 
 }  // namespace internal
 }  // namespace grpc
diff --git a/include/grpcpp/impl/codegen/client_context.h b/include/grpcpp/impl/codegen/client_context.h
index 75b955e760..0a71f3d9b6 100644
--- a/include/grpcpp/impl/codegen/client_context.h
+++ b/include/grpcpp/impl/codegen/client_context.h
@@ -46,6 +46,7 @@
 #include <grpcpp/impl/codegen/core_codegen_interface.h>
 #include <grpcpp/impl/codegen/create_auth_context.h>
 #include <grpcpp/impl/codegen/metadata_map.h>
+#include <grpcpp/impl/codegen/rpc_method.h>
 #include <grpcpp/impl/codegen/security/auth_context.h>
 #include <grpcpp/impl/codegen/slice.h>
 #include <grpcpp/impl/codegen/status.h>
@@ -71,6 +72,12 @@ template <class InputMessage, class OutputMessage>
 class BlockingUnaryCallImpl;
 template <class InputMessage, class OutputMessage>
 class CallbackUnaryCallImpl;
+template <class Request, class Response>
+class ClientCallbackReaderWriterImpl;
+template <class Response>
+class ClientCallbackReaderImpl;
+template <class Request>
+class ClientCallbackWriterImpl;
 }  // namespace internal
 
 template <class R>
@@ -162,6 +169,8 @@ class InteropClientContextInspector;
 /// (see \a grpc::CreateCustomChannel).
 ///
 /// \warning ClientContext instances should \em not be reused across rpcs.
+/// \warning The ClientContext instance used for creating an rpc must remain
+///          alive and valid for the lifetime of the rpc.
 class ClientContext {
  public:
   ClientContext();
@@ -394,6 +403,12 @@ class ClientContext {
   friend class ::grpc::internal::BlockingUnaryCallImpl;
   template <class InputMessage, class OutputMessage>
   friend class ::grpc::internal::CallbackUnaryCallImpl;
+  template <class Request, class Response>
+  friend class ::grpc::internal::ClientCallbackReaderWriterImpl;
+  template <class Response>
+  friend class ::grpc::internal::ClientCallbackReaderImpl;
+  template <class Request>
+  friend class ::grpc::internal::ClientCallbackWriterImpl;
 
   // Used by friend class CallOpClientRecvStatus
   void set_debug_error_string(const grpc::string& debug_error_string) {
@@ -404,12 +419,13 @@ class ClientContext {
   void set_call(grpc_call* call, const std::shared_ptr<Channel>& channel);
 
   experimental::ClientRpcInfo* set_client_rpc_info(
-      const char* method, grpc::ChannelInterface* channel,
+      const char* method, internal::RpcMethod::RpcType type,
+      grpc::ChannelInterface* channel,
       const std::vector<
           std::unique_ptr<experimental::ClientInterceptorFactoryInterface>>&
           creators,
       size_t interceptor_pos) {
-    rpc_info_ = experimental::ClientRpcInfo(this, method, channel);
+    rpc_info_ = experimental::ClientRpcInfo(this, type, method, channel);
     rpc_info_.RegisterInterceptors(creators, interceptor_pos);
     return &rpc_info_;
   }
diff --git a/include/grpcpp/impl/codegen/client_interceptor.h b/include/grpcpp/impl/codegen/client_interceptor.h
index f69c99ab22..2bae11a251 100644
--- a/include/grpcpp/impl/codegen/client_interceptor.h
+++ b/include/grpcpp/impl/codegen/client_interceptor.h
@@ -23,6 +23,7 @@
 #include <vector>
 
 #include <grpcpp/impl/codegen/interceptor.h>
+#include <grpcpp/impl/codegen/rpc_method.h>
 #include <grpcpp/impl/codegen/string_ref.h>
 
 namespace grpc {
@@ -52,23 +53,56 @@ extern experimental::ClientInterceptorFactoryInterface*
 namespace experimental {
 class ClientRpcInfo {
  public:
-  ClientRpcInfo() {}
+  // TODO(yashykt): Stop default-constructing ClientRpcInfo and remove UNKNOWN
+  //                from the list of possible Types.
+  enum class Type {
+    UNARY,
+    CLIENT_STREAMING,
+    SERVER_STREAMING,
+    BIDI_STREAMING,
+    UNKNOWN  // UNKNOWN is not API and will be removed later
+  };
 
   ~ClientRpcInfo(){};
 
   ClientRpcInfo(const ClientRpcInfo&) = delete;
   ClientRpcInfo(ClientRpcInfo&&) = default;
-  ClientRpcInfo& operator=(ClientRpcInfo&&) = default;
 
   // Getter methods
-  const char* method() { return method_; }
+  const char* method() const { return method_; }
   ChannelInterface* channel() { return channel_; }
   grpc::ClientContext* client_context() { return ctx_; }
+  Type type() const { return type_; }
 
  private:
-  ClientRpcInfo(grpc::ClientContext* ctx, const char* method,
-                grpc::ChannelInterface* channel)
-      : ctx_(ctx), method_(method), channel_(channel) {}
+  static_assert(Type::UNARY ==
+                    static_cast<Type>(internal::RpcMethod::NORMAL_RPC),
+                "violated expectation about Type enum");
+  static_assert(Type::CLIENT_STREAMING ==
+                    static_cast<Type>(internal::RpcMethod::CLIENT_STREAMING),
+                "violated expectation about Type enum");
+  static_assert(Type::SERVER_STREAMING ==
+                    static_cast<Type>(internal::RpcMethod::SERVER_STREAMING),
+                "violated expectation about Type enum");
+  static_assert(Type::BIDI_STREAMING ==
+                    static_cast<Type>(internal::RpcMethod::BIDI_STREAMING),
+                "violated expectation about Type enum");
+
+  // Default constructor should only be used by ClientContext
+  ClientRpcInfo() = default;
+
+  // Constructor will only be called from ClientContext
+  ClientRpcInfo(grpc::ClientContext* ctx, internal::RpcMethod::RpcType type,
+                const char* method, grpc::ChannelInterface* channel)
+      : ctx_(ctx),
+        type_(static_cast<Type>(type)),
+        method_(method),
+        channel_(channel) {}
+
+  // Move assignment should only be used by ClientContext
+  // TODO(yashykt): Delete move assignment
+  ClientRpcInfo& operator=(ClientRpcInfo&&) = default;
+
   // Runs interceptor at pos \a pos.
   void RunInterceptor(
       experimental::InterceptorBatchMethods* interceptor_methods, size_t pos) {
@@ -97,6 +131,8 @@ class ClientRpcInfo {
   }
 
   grpc::ClientContext* ctx_ = nullptr;
+  // TODO(yashykt): make type_ const once move-assignment is deleted
+  Type type_{Type::UNKNOWN};
   const char* method_ = nullptr;
   grpc::ChannelInterface* channel_ = nullptr;
   std::vector<std::unique_ptr<experimental::Interceptor>> interceptors_;
diff --git a/include/grpcpp/impl/codegen/client_unary_call.h b/include/grpcpp/impl/codegen/client_unary_call.h
index b1c80764f2..5151839412 100644
--- a/include/grpcpp/impl/codegen/client_unary_call.h
+++ b/include/grpcpp/impl/codegen/client_unary_call.h
@@ -69,13 +69,17 @@ class BlockingUnaryCallImpl {
     ops.ClientSendClose();
     ops.ClientRecvStatus(context, &status_);
     call.PerformOps(&ops);
-    if (cq.Pluck(&ops)) {
-      if (!ops.got_message && status_.ok()) {
-        status_ = Status(StatusCode::UNIMPLEMENTED,
-                         "No message returned for unary request");
-      }
-    } else {
-      GPR_CODEGEN_ASSERT(!status_.ok());
+    cq.Pluck(&ops);
+    // Some of the ops might fail. If the ops fail in the core layer, status
+    // would reflect the error. But, if the ops fail in the C++ layer, the
+    // status would still be the same as the one returned by gRPC Core. This can
+    // happen if deserialization of the message fails.
+    // TODO(yashykt): If deserialization fails, but the status received is OK,
+    // then it might be a good idea to change the status to something better
+    // than StatusCode::UNIMPLEMENTED to reflect this.
+    if (!ops.got_message && status_.ok()) {
+      status_ = Status(StatusCode::UNIMPLEMENTED,
+                       "No message returned for unary request");
     }
   }
   Status status() { return status_; }
diff --git a/include/grpcpp/impl/codegen/completion_queue.h b/include/grpcpp/impl/codegen/completion_queue.h
index d603c7c700..fb38788f7d 100644
--- a/include/grpcpp/impl/codegen/completion_queue.h
+++ b/include/grpcpp/impl/codegen/completion_queue.h
@@ -307,8 +307,7 @@ class CompletionQueue : private GrpcLibraryCodegen {
       void* ignored = tag;
       if (tag->FinalizeResult(&ignored, &ok)) {
         GPR_CODEGEN_ASSERT(ignored == tag);
-        // Ignore mutations by FinalizeResult: Pluck returns the C API status
-        return ev.success != 0;
+        return ok;
       }
     }
   }
diff --git a/include/grpcpp/impl/codegen/server_callback.h b/include/grpcpp/impl/codegen/server_callback.h
index b866fc16dc..1854f6ef2f 100644
--- a/include/grpcpp/impl/codegen/server_callback.h
+++ b/include/grpcpp/impl/codegen/server_callback.h
@@ -19,7 +19,9 @@
 #ifndef GRPCPP_IMPL_CODEGEN_SERVER_CALLBACK_H
 #define GRPCPP_IMPL_CODEGEN_SERVER_CALLBACK_H
 
+#include <atomic>
 #include <functional>
+#include <type_traits>
 
 #include <grpcpp/impl/codegen/call.h>
 #include <grpcpp/impl/codegen/call_op_set.h>
@@ -32,19 +34,33 @@
 
 namespace grpc {
 
-// forward declarations
+// Declare base class of all reactors as internal
 namespace internal {
-template <class ServiceType, class RequestType, class ResponseType>
-class CallbackUnaryHandler;
+
+class ServerReactor {
+ public:
+  virtual ~ServerReactor() = default;
+  virtual void OnDone() {}
+  virtual void OnCancel() {}
+};
+
 }  // namespace internal
 
 namespace experimental {
 
+// Forward declarations
+template <class Request, class Response>
+class ServerReadReactor;
+template <class Request, class Response>
+class ServerWriteReactor;
+template <class Request, class Response>
+class ServerBidiReactor;
+
 // For unary RPCs, the exposed controller class is only an interface
 // and the actual implementation is an internal class.
 class ServerCallbackRpcController {
  public:
-  virtual ~ServerCallbackRpcController() {}
+  virtual ~ServerCallbackRpcController() = default;
 
   // The method handler must call this function when it is done so that
   // the library knows to free its resources
@@ -55,18 +71,193 @@ class ServerCallbackRpcController {
   virtual void SendInitialMetadata(std::function<void(bool)>) = 0;
 };
 
+// NOTE: The actual streaming object classes are provided
+// as API only to support mocking. There are no implementations of
+// these class interfaces in the API.
+template <class Request>
+class ServerCallbackReader {
+ public:
+  virtual ~ServerCallbackReader() {}
+  virtual void Finish(Status s) = 0;
+  virtual void SendInitialMetadata() = 0;
+  virtual void Read(Request* msg) = 0;
+
+ protected:
+  template <class Response>
+  void BindReactor(ServerReadReactor<Request, Response>* reactor) {
+    reactor->BindReader(this);
+  }
+};
+
+template <class Response>
+class ServerCallbackWriter {
+ public:
+  virtual ~ServerCallbackWriter() {}
+
+  virtual void Finish(Status s) = 0;
+  virtual void SendInitialMetadata() = 0;
+  virtual void Write(const Response* msg, WriteOptions options) = 0;
+  virtual void WriteAndFinish(const Response* msg, WriteOptions options,
+                              Status s) {
+    // Default implementation that can/should be overridden
+    Write(msg, std::move(options));
+    Finish(std::move(s));
+  };
+
+ protected:
+  template <class Request>
+  void BindReactor(ServerWriteReactor<Request, Response>* reactor) {
+    reactor->BindWriter(this);
+  }
+};
+
+template <class Request, class Response>
+class ServerCallbackReaderWriter {
+ public:
+  virtual ~ServerCallbackReaderWriter() {}
+
+  virtual void Finish(Status s) = 0;
+  virtual void SendInitialMetadata() = 0;
+  virtual void Read(Request* msg) = 0;
+  virtual void Write(const Response* msg, WriteOptions options) = 0;
+  virtual void WriteAndFinish(const Response* msg, WriteOptions options,
+                              Status s) {
+    // Default implementation that can/should be overridden
+    Write(msg, std::move(options));
+    Finish(std::move(s));
+  };
+
+ protected:
+  void BindReactor(ServerBidiReactor<Request, Response>* reactor) {
+    reactor->BindStream(this);
+  }
+};
+
+// The following classes are reactors that are to be implemented
+// by the user, returned as the result of the method handler for
+// a callback method, and activated by the call to OnStarted
+template <class Request, class Response>
+class ServerBidiReactor : public internal::ServerReactor {
+ public:
+  ~ServerBidiReactor() = default;
+  virtual void OnStarted(ServerContext*) {}
+  virtual void OnSendInitialMetadataDone(bool ok) {}
+  virtual void OnReadDone(bool ok) {}
+  virtual void OnWriteDone(bool ok) {}
+
+  void StartSendInitialMetadata() { stream_->SendInitialMetadata(); }
+  void StartRead(Request* msg) { stream_->Read(msg); }
+  void StartWrite(const Response* msg) { StartWrite(msg, WriteOptions()); }
+  void StartWrite(const Response* msg, WriteOptions options) {
+    stream_->Write(msg, std::move(options));
+  }
+  void StartWriteAndFinish(const Response* msg, WriteOptions options,
+                           Status s) {
+    stream_->WriteAndFinish(msg, std::move(options), std::move(s));
+  }
+  void StartWriteLast(const Response* msg, WriteOptions options) {
+    StartWrite(msg, std::move(options.set_last_message()));
+  }
+  void Finish(Status s) { stream_->Finish(std::move(s)); }
+
+ private:
+  friend class ServerCallbackReaderWriter<Request, Response>;
+  void BindStream(ServerCallbackReaderWriter<Request, Response>* stream) {
+    stream_ = stream;
+  }
+
+  ServerCallbackReaderWriter<Request, Response>* stream_;
+};
+
+template <class Request, class Response>
+class ServerReadReactor : public internal::ServerReactor {
+ public:
+  ~ServerReadReactor() = default;
+  virtual void OnStarted(ServerContext*, Response* resp) {}
+  virtual void OnSendInitialMetadataDone(bool ok) {}
+  virtual void OnReadDone(bool ok) {}
+
+  void StartSendInitialMetadata() { reader_->SendInitialMetadata(); }
+  void StartRead(Request* msg) { reader_->Read(msg); }
+  void Finish(Status s) { reader_->Finish(std::move(s)); }
+
+ private:
+  friend class ServerCallbackReader<Request>;
+  void BindReader(ServerCallbackReader<Request>* reader) { reader_ = reader; }
+
+  ServerCallbackReader<Request>* reader_;
+};
+
+template <class Request, class Response>
+class ServerWriteReactor : public internal::ServerReactor {
+ public:
+  ~ServerWriteReactor() = default;
+  virtual void OnStarted(ServerContext*, const Request* req) {}
+  virtual void OnSendInitialMetadataDone(bool ok) {}
+  virtual void OnWriteDone(bool ok) {}
+
+  void StartSendInitialMetadata() { writer_->SendInitialMetadata(); }
+  void StartWrite(const Response* msg) { StartWrite(msg, WriteOptions()); }
+  void StartWrite(const Response* msg, WriteOptions options) {
+    writer_->Write(msg, std::move(options));
+  }
+  void StartWriteAndFinish(const Response* msg, WriteOptions options,
+                           Status s) {
+    writer_->WriteAndFinish(msg, std::move(options), std::move(s));
+  }
+  void StartWriteLast(const Response* msg, WriteOptions options) {
+    StartWrite(msg, std::move(options.set_last_message()));
+  }
+  void Finish(Status s) { writer_->Finish(std::move(s)); }
+
+ private:
+  friend class ServerCallbackWriter<Response>;
+  void BindWriter(ServerCallbackWriter<Response>* writer) { writer_ = writer; }
+
+  ServerCallbackWriter<Response>* writer_;
+};
+
 }  // namespace experimental
 
 namespace internal {
 
-template <class ServiceType, class RequestType, class ResponseType>
+template <class Request, class Response>
+class UnimplementedReadReactor
+    : public experimental::ServerReadReactor<Request, Response> {
+ public:
+  void OnDone() override { delete this; }
+  void OnStarted(ServerContext*, Response*) override {
+    this->Finish(Status(StatusCode::UNIMPLEMENTED, ""));
+  }
+};
+
+template <class Request, class Response>
+class UnimplementedWriteReactor
+    : public experimental::ServerWriteReactor<Request, Response> {
+ public:
+  void OnDone() override { delete this; }
+  void OnStarted(ServerContext*, const Request*) override {
+    this->Finish(Status(StatusCode::UNIMPLEMENTED, ""));
+  }
+};
+
+template <class Request, class Response>
+class UnimplementedBidiReactor
+    : public experimental::ServerBidiReactor<Request, Response> {
+ public:
+  void OnDone() override { delete this; }
+  void OnStarted(ServerContext*) override {
+    this->Finish(Status(StatusCode::UNIMPLEMENTED, ""));
+  }
+};
+
+template <class RequestType, class ResponseType>
 class CallbackUnaryHandler : public MethodHandler {
  public:
   CallbackUnaryHandler(
       std::function<void(ServerContext*, const RequestType*, ResponseType*,
                          experimental::ServerCallbackRpcController*)>
-          func,
-      ServiceType* service)
+          func)
       : func_(func) {}
   void RunHandler(const HandlerParameter& param) final {
     // Arena allocate a controller structure (that includes request/response)
@@ -81,9 +272,8 @@ class CallbackUnaryHandler : public MethodHandler {
 
     if (status.ok()) {
       // Call the actual function handler and expect the user to call finish
-      CatchingCallback(std::move(func_), param.server_context,
-                       controller->request(), controller->response(),
-                       controller);
+      CatchingCallback(func_, param.server_context, controller->request(),
+                       controller->response(), controller);
     } else {
       // if deserialization failed, we need to fail the call
       controller->Finish(status);
@@ -117,79 +307,579 @@ class CallbackUnaryHandler : public MethodHandler {
       : public experimental::ServerCallbackRpcController {
    public:
     void Finish(Status s) override {
-      finish_tag_.Set(
-          call_.call(),
-          [this](bool) {
-            grpc_call* call = call_.call();
-            auto call_requester = std::move(call_requester_);
-            this->~ServerCallbackRpcControllerImpl();  // explicitly call
-                                                       // destructor
-            g_core_codegen_interface->grpc_call_unref(call);
-            call_requester();
-          },
-          &finish_buf_);
+      finish_tag_.Set(call_.call(), [this](bool) { MaybeDone(); },
+                      &finish_ops_);
       if (!ctx_->sent_initial_metadata_) {
-        finish_buf_.SendInitialMetadata(&ctx_->initial_metadata_,
+        finish_ops_.SendInitialMetadata(&ctx_->initial_metadata_,
                                         ctx_->initial_metadata_flags());
         if (ctx_->compression_level_set()) {
-          finish_buf_.set_compression_level(ctx_->compression_level());
+          finish_ops_.set_compression_level(ctx_->compression_level());
         }
         ctx_->sent_initial_metadata_ = true;
       }
       // The response is dropped if the status is not OK.
       if (s.ok()) {
-        finish_buf_.ServerSendStatus(&ctx_->trailing_metadata_,
-                                     finish_buf_.SendMessage(resp_));
+        finish_ops_.ServerSendStatus(&ctx_->trailing_metadata_,
+                                     finish_ops_.SendMessage(resp_));
       } else {
-        finish_buf_.ServerSendStatus(&ctx_->trailing_metadata_, s);
+        finish_ops_.ServerSendStatus(&ctx_->trailing_metadata_, s);
       }
-      finish_buf_.set_core_cq_tag(&finish_tag_);
-      call_.PerformOps(&finish_buf_);
+      finish_ops_.set_core_cq_tag(&finish_tag_);
+      call_.PerformOps(&finish_ops_);
     }
 
     void SendInitialMetadata(std::function<void(bool)> f) override {
       GPR_CODEGEN_ASSERT(!ctx_->sent_initial_metadata_);
-
-      meta_tag_.Set(call_.call(), std::move(f), &meta_buf_);
-      meta_buf_.SendInitialMetadata(&ctx_->initial_metadata_,
+      callbacks_outstanding_++;
+      // TODO(vjpai): Consider taking f as a move-capture if we adopt C++14
+      //              and if performance of this operation matters
+      meta_tag_.Set(call_.call(),
+                    [this, f](bool ok) {
+                      f(ok);
+                      MaybeDone();
+                    },
+                    &meta_ops_);
+      meta_ops_.SendInitialMetadata(&ctx_->initial_metadata_,
                                     ctx_->initial_metadata_flags());
       if (ctx_->compression_level_set()) {
-        meta_buf_.set_compression_level(ctx_->compression_level());
+        meta_ops_.set_compression_level(ctx_->compression_level());
       }
       ctx_->sent_initial_metadata_ = true;
-      meta_buf_.set_core_cq_tag(&meta_tag_);
-      call_.PerformOps(&meta_buf_);
+      meta_ops_.set_core_cq_tag(&meta_tag_);
+      call_.PerformOps(&meta_ops_);
     }
 
    private:
-    template <class SrvType, class ReqType, class RespType>
-    friend class CallbackUnaryHandler;
+    friend class CallbackUnaryHandler<RequestType, ResponseType>;
 
     ServerCallbackRpcControllerImpl(ServerContext* ctx, Call* call,
-                                    RequestType* req,
+                                    const RequestType* req,
                                     std::function<void()> call_requester)
         : ctx_(ctx),
           call_(*call),
           req_(req),
-          call_requester_(std::move(call_requester)) {}
+          call_requester_(std::move(call_requester)) {
+      ctx_->BeginCompletionOp(call, [this](bool) { MaybeDone(); }, nullptr);
+    }
 
     ~ServerCallbackRpcControllerImpl() { req_->~RequestType(); }
 
-    RequestType* request() { return req_; }
+    const RequestType* request() { return req_; }
     ResponseType* response() { return &resp_; }
 
-    CallOpSet<CallOpSendInitialMetadata> meta_buf_;
+    void MaybeDone() {
+      if (--callbacks_outstanding_ == 0) {
+        grpc_call* call = call_.call();
+        auto call_requester = std::move(call_requester_);
+        this->~ServerCallbackRpcControllerImpl();  // explicitly call destructor
+        g_core_codegen_interface->grpc_call_unref(call);
+        call_requester();
+      }
+    }
+
+    CallOpSet<CallOpSendInitialMetadata> meta_ops_;
     CallbackWithSuccessTag meta_tag_;
     CallOpSet<CallOpSendInitialMetadata, CallOpSendMessage,
               CallOpServerSendStatus>
-        finish_buf_;
+        finish_ops_;
     CallbackWithSuccessTag finish_tag_;
 
     ServerContext* ctx_;
     Call call_;
-    RequestType* req_;
+    const RequestType* req_;
     ResponseType resp_;
     std::function<void()> call_requester_;
+    std::atomic_int callbacks_outstanding_{
+        2};  // reserve for Finish and CompletionOp
+  };
+};
+
+template <class RequestType, class ResponseType>
+class CallbackClientStreamingHandler : public MethodHandler {
+ public:
+  CallbackClientStreamingHandler(
+      std::function<
+          experimental::ServerReadReactor<RequestType, ResponseType>*()>
+          func)
+      : func_(std::move(func)) {}
+  void RunHandler(const HandlerParameter& param) final {
+    // Arena allocate a reader structure (that includes response)
+    g_core_codegen_interface->grpc_call_ref(param.call->call());
+
+    experimental::ServerReadReactor<RequestType, ResponseType>* reactor =
+        param.status.ok()
+            ? CatchingReactorCreator<
+                  experimental::ServerReadReactor<RequestType, ResponseType>>(
+                  func_)
+            : nullptr;
+
+    if (reactor == nullptr) {
+      // if deserialization or reactor creator failed, we need to fail the call
+      reactor = new UnimplementedReadReactor<RequestType, ResponseType>;
+    }
+
+    auto* reader = new (g_core_codegen_interface->grpc_call_arena_alloc(
+        param.call->call(), sizeof(ServerCallbackReaderImpl)))
+        ServerCallbackReaderImpl(param.server_context, param.call,
+                                 std::move(param.call_requester), reactor);
+
+    reader->BindReactor(reactor);
+    reactor->OnStarted(param.server_context, reader->response());
+    reader->MaybeDone();
+  }
+
+ private:
+  std::function<experimental::ServerReadReactor<RequestType, ResponseType>*()>
+      func_;
+
+  class ServerCallbackReaderImpl
+      : public experimental::ServerCallbackReader<RequestType> {
+   public:
+    void Finish(Status s) override {
+      finish_tag_.Set(call_.call(), [this](bool) { MaybeDone(); },
+                      &finish_ops_);
+      if (!ctx_->sent_initial_metadata_) {
+        finish_ops_.SendInitialMetadata(&ctx_->initial_metadata_,
+                                        ctx_->initial_metadata_flags());
+        if (ctx_->compression_level_set()) {
+          finish_ops_.set_compression_level(ctx_->compression_level());
+        }
+        ctx_->sent_initial_metadata_ = true;
+      }
+      // The response is dropped if the status is not OK.
+      if (s.ok()) {
+        finish_ops_.ServerSendStatus(&ctx_->trailing_metadata_,
+                                     finish_ops_.SendMessage(resp_));
+      } else {
+        finish_ops_.ServerSendStatus(&ctx_->trailing_metadata_, s);
+      }
+      finish_ops_.set_core_cq_tag(&finish_tag_);
+      call_.PerformOps(&finish_ops_);
+    }
+
+    void SendInitialMetadata() override {
+      GPR_CODEGEN_ASSERT(!ctx_->sent_initial_metadata_);
+      callbacks_outstanding_++;
+      meta_tag_.Set(call_.call(),
+                    [this](bool ok) {
+                      reactor_->OnSendInitialMetadataDone(ok);
+                      MaybeDone();
+                    },
+                    &meta_ops_);
+      meta_ops_.SendInitialMetadata(&ctx_->initial_metadata_,
+                                    ctx_->initial_metadata_flags());
+      if (ctx_->compression_level_set()) {
+        meta_ops_.set_compression_level(ctx_->compression_level());
+      }
+      ctx_->sent_initial_metadata_ = true;
+      meta_ops_.set_core_cq_tag(&meta_tag_);
+      call_.PerformOps(&meta_ops_);
+    }
+
+    void Read(RequestType* req) override {
+      callbacks_outstanding_++;
+      read_ops_.RecvMessage(req);
+      call_.PerformOps(&read_ops_);
+    }
+
+   private:
+    friend class CallbackClientStreamingHandler<RequestType, ResponseType>;
+
+    ServerCallbackReaderImpl(
+        ServerContext* ctx, Call* call, std::function<void()> call_requester,
+        experimental::ServerReadReactor<RequestType, ResponseType>* reactor)
+        : ctx_(ctx),
+          call_(*call),
+          call_requester_(std::move(call_requester)),
+          reactor_(reactor) {
+      ctx_->BeginCompletionOp(call, [this](bool) { MaybeDone(); }, reactor);
+      read_tag_.Set(call_.call(),
+                    [this](bool ok) {
+                      reactor_->OnReadDone(ok);
+                      MaybeDone();
+                    },
+                    &read_ops_);
+      read_ops_.set_core_cq_tag(&read_tag_);
+    }
+
+    ~ServerCallbackReaderImpl() {}
+
+    ResponseType* response() { return &resp_; }
+
+    void MaybeDone() {
+      if (--callbacks_outstanding_ == 0) {
+        reactor_->OnDone();
+        grpc_call* call = call_.call();
+        auto call_requester = std::move(call_requester_);
+        this->~ServerCallbackReaderImpl();  // explicitly call destructor
+        g_core_codegen_interface->grpc_call_unref(call);
+        call_requester();
+      }
+    }
+
+    CallOpSet<CallOpSendInitialMetadata> meta_ops_;
+    CallbackWithSuccessTag meta_tag_;
+    CallOpSet<CallOpSendInitialMetadata, CallOpSendMessage,
+              CallOpServerSendStatus>
+        finish_ops_;
+    CallbackWithSuccessTag finish_tag_;
+    CallOpSet<CallOpRecvMessage<RequestType>> read_ops_;
+    CallbackWithSuccessTag read_tag_;
+
+    ServerContext* ctx_;
+    Call call_;
+    ResponseType resp_;
+    std::function<void()> call_requester_;
+    experimental::ServerReadReactor<RequestType, ResponseType>* reactor_;
+    std::atomic_int callbacks_outstanding_{
+        3};  // reserve for OnStarted, Finish, and CompletionOp
+  };
+};
+
+template <class RequestType, class ResponseType>
+class CallbackServerStreamingHandler : public MethodHandler {
+ public:
+  CallbackServerStreamingHandler(
+      std::function<
+          experimental::ServerWriteReactor<RequestType, ResponseType>*()>
+          func)
+      : func_(std::move(func)) {}
+  void RunHandler(const HandlerParameter& param) final {
+    // Arena allocate a writer structure
+    g_core_codegen_interface->grpc_call_ref(param.call->call());
+
+    experimental::ServerWriteReactor<RequestType, ResponseType>* reactor =
+        param.status.ok()
+            ? CatchingReactorCreator<
+                  experimental::ServerWriteReactor<RequestType, ResponseType>>(
+                  func_)
+            : nullptr;
+
+    if (reactor == nullptr) {
+      // if deserialization or reactor creator failed, we need to fail the call
+      reactor = new UnimplementedWriteReactor<RequestType, ResponseType>;
+    }
+
+    auto* writer = new (g_core_codegen_interface->grpc_call_arena_alloc(
+        param.call->call(), sizeof(ServerCallbackWriterImpl)))
+        ServerCallbackWriterImpl(param.server_context, param.call,
+                                 static_cast<RequestType*>(param.request),
+                                 std::move(param.call_requester), reactor);
+    writer->BindReactor(reactor);
+    reactor->OnStarted(param.server_context, writer->request());
+    writer->MaybeDone();
+  }
+
+  void* Deserialize(grpc_call* call, grpc_byte_buffer* req,
+                    Status* status) final {
+    ByteBuffer buf;
+    buf.set_buffer(req);
+    auto* request = new (g_core_codegen_interface->grpc_call_arena_alloc(
+        call, sizeof(RequestType))) RequestType();
+    *status = SerializationTraits<RequestType>::Deserialize(&buf, request);
+    buf.Release();
+    if (status->ok()) {
+      return request;
+    }
+    request->~RequestType();
+    return nullptr;
+  }
+
+ private:
+  std::function<experimental::ServerWriteReactor<RequestType, ResponseType>*()>
+      func_;
+
+  class ServerCallbackWriterImpl
+      : public experimental::ServerCallbackWriter<ResponseType> {
+   public:
+    void Finish(Status s) override {
+      finish_tag_.Set(call_.call(), [this](bool) { MaybeDone(); },
+                      &finish_ops_);
+      finish_ops_.set_core_cq_tag(&finish_tag_);
+
+      if (!ctx_->sent_initial_metadata_) {
+        finish_ops_.SendInitialMetadata(&ctx_->initial_metadata_,
+                                        ctx_->initial_metadata_flags());
+        if (ctx_->compression_level_set()) {
+          finish_ops_.set_compression_level(ctx_->compression_level());
+        }
+        ctx_->sent_initial_metadata_ = true;
+      }
+      finish_ops_.ServerSendStatus(&ctx_->trailing_metadata_, s);
+      call_.PerformOps(&finish_ops_);
+    }
+
+    void SendInitialMetadata() override {
+      GPR_CODEGEN_ASSERT(!ctx_->sent_initial_metadata_);
+      callbacks_outstanding_++;
+      meta_tag_.Set(call_.call(),
+                    [this](bool ok) {
+                      reactor_->OnSendInitialMetadataDone(ok);
+                      MaybeDone();
+                    },
+                    &meta_ops_);
+      meta_ops_.SendInitialMetadata(&ctx_->initial_metadata_,
+                                    ctx_->initial_metadata_flags());
+      if (ctx_->compression_level_set()) {
+        meta_ops_.set_compression_level(ctx_->compression_level());
+      }
+      ctx_->sent_initial_metadata_ = true;
+      meta_ops_.set_core_cq_tag(&meta_tag_);
+      call_.PerformOps(&meta_ops_);
+    }
+
+    void Write(const ResponseType* resp, WriteOptions options) override {
+      callbacks_outstanding_++;
+      if (options.is_last_message()) {
+        options.set_buffer_hint();
+      }
+      if (!ctx_->sent_initial_metadata_) {
+        write_ops_.SendInitialMetadata(&ctx_->initial_metadata_,
+                                       ctx_->initial_metadata_flags());
+        if (ctx_->compression_level_set()) {
+          write_ops_.set_compression_level(ctx_->compression_level());
+        }
+        ctx_->sent_initial_metadata_ = true;
+      }
+      // TODO(vjpai): don't assert
+      GPR_CODEGEN_ASSERT(write_ops_.SendMessage(*resp, options).ok());
+      call_.PerformOps(&write_ops_);
+    }
+
+    void WriteAndFinish(const ResponseType* resp, WriteOptions options,
+                        Status s) override {
+      // This combines the write into the finish callback
+      // Don't send any message if the status is bad
+      if (s.ok()) {
+        // TODO(vjpai): don't assert
+        GPR_CODEGEN_ASSERT(finish_ops_.SendMessage(*resp, options).ok());
+      }
+      Finish(std::move(s));
+    }
+
+   private:
+    friend class CallbackServerStreamingHandler<RequestType, ResponseType>;
+
+    ServerCallbackWriterImpl(
+        ServerContext* ctx, Call* call, const RequestType* req,
+        std::function<void()> call_requester,
+        experimental::ServerWriteReactor<RequestType, ResponseType>* reactor)
+        : ctx_(ctx),
+          call_(*call),
+          req_(req),
+          call_requester_(std::move(call_requester)),
+          reactor_(reactor) {
+      ctx_->BeginCompletionOp(call, [this](bool) { MaybeDone(); }, reactor);
+      write_tag_.Set(call_.call(),
+                     [this](bool ok) {
+                       reactor_->OnWriteDone(ok);
+                       MaybeDone();
+                     },
+                     &write_ops_);
+      write_ops_.set_core_cq_tag(&write_tag_);
+    }
+    ~ServerCallbackWriterImpl() { req_->~RequestType(); }
+
+    const RequestType* request() { return req_; }
+
+    void MaybeDone() {
+      if (--callbacks_outstanding_ == 0) {
+        reactor_->OnDone();
+        grpc_call* call = call_.call();
+        auto call_requester = std::move(call_requester_);
+        this->~ServerCallbackWriterImpl();  // explicitly call destructor
+        g_core_codegen_interface->grpc_call_unref(call);
+        call_requester();
+      }
+    }
+
+    CallOpSet<CallOpSendInitialMetadata> meta_ops_;
+    CallbackWithSuccessTag meta_tag_;
+    CallOpSet<CallOpSendInitialMetadata, CallOpSendMessage,
+              CallOpServerSendStatus>
+        finish_ops_;
+    CallbackWithSuccessTag finish_tag_;
+    CallOpSet<CallOpSendInitialMetadata, CallOpSendMessage> write_ops_;
+    CallbackWithSuccessTag write_tag_;
+
+    ServerContext* ctx_;
+    Call call_;
+    const RequestType* req_;
+    std::function<void()> call_requester_;
+    experimental::ServerWriteReactor<RequestType, ResponseType>* reactor_;
+    std::atomic_int callbacks_outstanding_{
+        3};  // reserve for OnStarted, Finish, and CompletionOp
+  };
+};
+
+template <class RequestType, class ResponseType>
+class CallbackBidiHandler : public MethodHandler {
+ public:
+  CallbackBidiHandler(
+      std::function<
+          experimental::ServerBidiReactor<RequestType, ResponseType>*()>
+          func)
+      : func_(std::move(func)) {}
+  void RunHandler(const HandlerParameter& param) final {
+    g_core_codegen_interface->grpc_call_ref(param.call->call());
+
+    experimental::ServerBidiReactor<RequestType, ResponseType>* reactor =
+        param.status.ok()
+            ? CatchingReactorCreator<
+                  experimental::ServerBidiReactor<RequestType, ResponseType>>(
+                  func_)
+            : nullptr;
+
+    if (reactor == nullptr) {
+      // if deserialization or reactor creator failed, we need to fail the call
+      reactor = new UnimplementedBidiReactor<RequestType, ResponseType>;
+    }
+
+    auto* stream = new (g_core_codegen_interface->grpc_call_arena_alloc(
+        param.call->call(), sizeof(ServerCallbackReaderWriterImpl)))
+        ServerCallbackReaderWriterImpl(param.server_context, param.call,
+                                       std::move(param.call_requester),
+                                       reactor);
+
+    stream->BindReactor(reactor);
+    reactor->OnStarted(param.server_context);
+    stream->MaybeDone();
+  }
+
+ private:
+  std::function<experimental::ServerBidiReactor<RequestType, ResponseType>*()>
+      func_;
+
+  class ServerCallbackReaderWriterImpl
+      : public experimental::ServerCallbackReaderWriter<RequestType,
+                                                        ResponseType> {
+   public:
+    void Finish(Status s) override {
+      finish_tag_.Set(call_.call(), [this](bool) { MaybeDone(); },
+                      &finish_ops_);
+      finish_ops_.set_core_cq_tag(&finish_tag_);
+
+      if (!ctx_->sent_initial_metadata_) {
+        finish_ops_.SendInitialMetadata(&ctx_->initial_metadata_,
+                                        ctx_->initial_metadata_flags());
+        if (ctx_->compression_level_set()) {
+          finish_ops_.set_compression_level(ctx_->compression_level());
+        }
+        ctx_->sent_initial_metadata_ = true;
+      }
+      finish_ops_.ServerSendStatus(&ctx_->trailing_metadata_, s);
+      call_.PerformOps(&finish_ops_);
+    }
+
+    void SendInitialMetadata() override {
+      GPR_CODEGEN_ASSERT(!ctx_->sent_initial_metadata_);
+      callbacks_outstanding_++;
+      meta_tag_.Set(call_.call(),
+                    [this](bool ok) {
+                      reactor_->OnSendInitialMetadataDone(ok);
+                      MaybeDone();
+                    },
+                    &meta_ops_);
+      meta_ops_.SendInitialMetadata(&ctx_->initial_metadata_,
+                                    ctx_->initial_metadata_flags());
+      if (ctx_->compression_level_set()) {
+        meta_ops_.set_compression_level(ctx_->compression_level());
+      }
+      ctx_->sent_initial_metadata_ = true;
+      meta_ops_.set_core_cq_tag(&meta_tag_);
+      call_.PerformOps(&meta_ops_);
+    }
+
+    void Write(const ResponseType* resp, WriteOptions options) override {
+      callbacks_outstanding_++;
+      if (options.is_last_message()) {
+        options.set_buffer_hint();
+      }
+      if (!ctx_->sent_initial_metadata_) {
+        write_ops_.SendInitialMetadata(&ctx_->initial_metadata_,
+                                       ctx_->initial_metadata_flags());
+        if (ctx_->compression_level_set()) {
+          write_ops_.set_compression_level(ctx_->compression_level());
+        }
+        ctx_->sent_initial_metadata_ = true;
+      }
+      // TODO(vjpai): don't assert
+      GPR_CODEGEN_ASSERT(write_ops_.SendMessage(*resp, options).ok());
+      call_.PerformOps(&write_ops_);
+    }
+
+    void WriteAndFinish(const ResponseType* resp, WriteOptions options,
+                        Status s) override {
+      // Don't send any message if the status is bad
+      if (s.ok()) {
+        // TODO(vjpai): don't assert
+        GPR_CODEGEN_ASSERT(finish_ops_.SendMessage(*resp, options).ok());
+      }
+      Finish(std::move(s));
+    }
+
+    void Read(RequestType* req) override {
+      callbacks_outstanding_++;
+      read_ops_.RecvMessage(req);
+      call_.PerformOps(&read_ops_);
+    }
+
+   private:
+    friend class CallbackBidiHandler<RequestType, ResponseType>;
+
+    ServerCallbackReaderWriterImpl(
+        ServerContext* ctx, Call* call, std::function<void()> call_requester,
+        experimental::ServerBidiReactor<RequestType, ResponseType>* reactor)
+        : ctx_(ctx),
+          call_(*call),
+          call_requester_(std::move(call_requester)),
+          reactor_(reactor) {
+      ctx_->BeginCompletionOp(call, [this](bool) { MaybeDone(); }, reactor);
+      write_tag_.Set(call_.call(),
+                     [this](bool ok) {
+                       reactor_->OnWriteDone(ok);
+                       MaybeDone();
+                     },
+                     &write_ops_);
+      write_ops_.set_core_cq_tag(&write_tag_);
+      read_tag_.Set(call_.call(),
+                    [this](bool ok) {
+                      reactor_->OnReadDone(ok);
+                      MaybeDone();
+                    },
+                    &read_ops_);
+      read_ops_.set_core_cq_tag(&read_tag_);
+    }
+    ~ServerCallbackReaderWriterImpl() {}
+
+    void MaybeDone() {
+      if (--callbacks_outstanding_ == 0) {
+        reactor_->OnDone();
+        grpc_call* call = call_.call();
+        auto call_requester = std::move(call_requester_);
+        this->~ServerCallbackReaderWriterImpl();  // explicitly call destructor
+        g_core_codegen_interface->grpc_call_unref(call);
+        call_requester();
+      }
+    }
+
+    CallOpSet<CallOpSendInitialMetadata> meta_ops_;
+    CallbackWithSuccessTag meta_tag_;
+    CallOpSet<CallOpSendInitialMetadata, CallOpSendMessage,
+              CallOpServerSendStatus>
+        finish_ops_;
+    CallbackWithSuccessTag finish_tag_;
+    CallOpSet<CallOpSendInitialMetadata, CallOpSendMessage> write_ops_;
+    CallbackWithSuccessTag write_tag_;
+    CallOpSet<CallOpRecvMessage<RequestType>> read_ops_;
+    CallbackWithSuccessTag read_tag_;
+
+    ServerContext* ctx_;
+    Call call_;
+    std::function<void()> call_requester_;
+    experimental::ServerBidiReactor<RequestType, ResponseType>* reactor_;
+    std::atomic_int callbacks_outstanding_{
+        3};  // reserve for OnStarted, Finish, and CompletionOp
   };
 };
 
diff --git a/include/grpcpp/impl/codegen/server_context.h b/include/grpcpp/impl/codegen/server_context.h
index 82ee862f61..ccb5925e7d 100644
--- a/include/grpcpp/impl/codegen/server_context.h
+++ b/include/grpcpp/impl/codegen/server_context.h
@@ -66,13 +66,20 @@ template <class ServiceType, class RequestType, class ResponseType>
 class ServerStreamingHandler;
 template <class ServiceType, class RequestType, class ResponseType>
 class BidiStreamingHandler;
-template <class ServiceType, class RequestType, class ResponseType>
+template <class RequestType, class ResponseType>
 class CallbackUnaryHandler;
+template <class RequestType, class ResponseType>
+class CallbackClientStreamingHandler;
+template <class RequestType, class ResponseType>
+class CallbackServerStreamingHandler;
+template <class RequestType, class ResponseType>
+class CallbackBidiHandler;
 template <class Streamer, bool WriteNeeded>
 class TemplatedBidiStreamingHandler;
 template <StatusCode code>
 class ErrorMethodHandler;
 class Call;
+class ServerReactor;
 }  // namespace internal
 
 class CompletionQueue;
@@ -270,8 +277,14 @@ class ServerContext {
   friend class ::grpc::internal::ServerStreamingHandler;
   template <class Streamer, bool WriteNeeded>
   friend class ::grpc::internal::TemplatedBidiStreamingHandler;
-  template <class ServiceType, class RequestType, class ResponseType>
+  template <class RequestType, class ResponseType>
   friend class ::grpc::internal::CallbackUnaryHandler;
+  template <class RequestType, class ResponseType>
+  friend class ::grpc::internal::CallbackClientStreamingHandler;
+  template <class RequestType, class ResponseType>
+  friend class ::grpc::internal::CallbackServerStreamingHandler;
+  template <class RequestType, class ResponseType>
+  friend class ::grpc::internal::CallbackBidiHandler;
   template <StatusCode code>
   friend class internal::ErrorMethodHandler;
   friend class ::grpc::ClientContext;
@@ -282,7 +295,9 @@ class ServerContext {
 
   class CompletionOp;
 
-  void BeginCompletionOp(internal::Call* call, bool callback);
+  void BeginCompletionOp(internal::Call* call,
+                         std::function<void(bool)> callback,
+                         internal::ServerReactor* reactor);
   /// Return the tag queued by BeginCompletionOp()
   internal::CompletionQueueTag* GetCompletionOpTag();
 
@@ -299,12 +314,12 @@ class ServerContext {
   uint32_t initial_metadata_flags() const { return 0; }
 
   experimental::ServerRpcInfo* set_server_rpc_info(
-      const char* method,
+      const char* method, internal::RpcMethod::RpcType type,
       const std::vector<
           std::unique_ptr<experimental::ServerInterceptorFactoryInterface>>&
           creators) {
     if (creators.size() != 0) {
-      rpc_info_ = new experimental::ServerRpcInfo(this, method);
+      rpc_info_ = new experimental::ServerRpcInfo(this, method, type);
       rpc_info_->RegisterInterceptors(creators);
     }
     return rpc_info_;
diff --git a/include/grpcpp/impl/codegen/server_interceptor.h b/include/grpcpp/impl/codegen/server_interceptor.h
index 5fb5df28b7..afc3c198cc 100644
--- a/include/grpcpp/impl/codegen/server_interceptor.h
+++ b/include/grpcpp/impl/codegen/server_interceptor.h
@@ -23,6 +23,7 @@
 #include <vector>
 
 #include <grpcpp/impl/codegen/interceptor.h>
+#include <grpcpp/impl/codegen/rpc_method.h>
 #include <grpcpp/impl/codegen/string_ref.h>
 
 namespace grpc {
@@ -44,19 +45,36 @@ class ServerInterceptorFactoryInterface {
 
 class ServerRpcInfo {
  public:
+  enum class Type { UNARY, CLIENT_STREAMING, SERVER_STREAMING, BIDI_STREAMING };
+
   ~ServerRpcInfo(){};
 
   ServerRpcInfo(const ServerRpcInfo&) = delete;
-  ServerRpcInfo(ServerRpcInfo&&) = default;
-  ServerRpcInfo& operator=(ServerRpcInfo&&) = default;
+  ServerRpcInfo(ServerRpcInfo&&) = delete;
+  ServerRpcInfo& operator=(ServerRpcInfo&&) = delete;
 
   // Getter methods
-  const char* method() { return method_; }
+  const char* method() const { return method_; }
+  Type type() const { return type_; }
   grpc::ServerContext* server_context() { return ctx_; }
 
  private:
-  ServerRpcInfo(grpc::ServerContext* ctx, const char* method)
-      : ctx_(ctx), method_(method) {
+  static_assert(Type::UNARY ==
+                    static_cast<Type>(internal::RpcMethod::NORMAL_RPC),
+                "violated expectation about Type enum");
+  static_assert(Type::CLIENT_STREAMING ==
+                    static_cast<Type>(internal::RpcMethod::CLIENT_STREAMING),
+                "violated expectation about Type enum");
+  static_assert(Type::SERVER_STREAMING ==
+                    static_cast<Type>(internal::RpcMethod::SERVER_STREAMING),
+                "violated expectation about Type enum");
+  static_assert(Type::BIDI_STREAMING ==
+                    static_cast<Type>(internal::RpcMethod::BIDI_STREAMING),
+                "violated expectation about Type enum");
+
+  ServerRpcInfo(grpc::ServerContext* ctx, const char* method,
+                internal::RpcMethod::RpcType type)
+      : ctx_(ctx), method_(method), type_(static_cast<Type>(type)) {
     ref_.store(1);
   }
 
@@ -86,6 +104,7 @@ class ServerRpcInfo {
 
   grpc::ServerContext* ctx_ = nullptr;
   const char* method_ = nullptr;
+  const Type type_;
   std::atomic_int ref_;
   std::vector<std::unique_ptr<experimental::Interceptor>> interceptors_;
 
diff --git a/include/grpcpp/impl/codegen/server_interface.h b/include/grpcpp/impl/codegen/server_interface.h
index 55c94f4d2f..e0e2629827 100644
--- a/include/grpcpp/impl/codegen/server_interface.h
+++ b/include/grpcpp/impl/codegen/server_interface.h
@@ -174,13 +174,14 @@ class ServerInterface : public internal::CallHook {
     bool done_intercepting_;
   };
 
+  /// RegisteredAsyncRequest is not part of the C++ API
   class RegisteredAsyncRequest : public BaseAsyncRequest {
    public:
     RegisteredAsyncRequest(ServerInterface* server, ServerContext* context,
                            internal::ServerAsyncStreamingInterface* stream,
                            CompletionQueue* call_cq,
                            ServerCompletionQueue* notification_cq, void* tag,
-                           const char* name);
+                           const char* name, internal::RpcMethod::RpcType type);
 
     virtual bool FinalizeResult(void** tag, bool* status) override {
       /* If we are done intercepting, then there is nothing more for us to do */
@@ -189,7 +190,7 @@ class ServerInterface : public internal::CallHook {
       }
       call_wrapper_ = internal::Call(
           call_, server_, call_cq_, server_->max_receive_message_size(),
-          context_->set_server_rpc_info(name_,
+          context_->set_server_rpc_info(name_, type_,
                                         *server_->interceptor_creators()));
       return BaseAsyncRequest::FinalizeResult(tag, status);
     }
@@ -198,6 +199,7 @@ class ServerInterface : public internal::CallHook {
     void IssueRequest(void* registered_method, grpc_byte_buffer** payload,
                       ServerCompletionQueue* notification_cq);
     const char* name_;
+    const internal::RpcMethod::RpcType type_;
   };
 
   class NoPayloadAsyncRequest final : public RegisteredAsyncRequest {
@@ -207,9 +209,9 @@ class ServerInterface : public internal::CallHook {
                           internal::ServerAsyncStreamingInterface* stream,
                           CompletionQueue* call_cq,
                           ServerCompletionQueue* notification_cq, void* tag)
-        : RegisteredAsyncRequest(server, context, stream, call_cq,
-                                 notification_cq, tag,
-                                 registered_method->name()) {
+        : RegisteredAsyncRequest(
+              server, context, stream, call_cq, notification_cq, tag,
+              registered_method->name(), registered_method->method_type()) {
       IssueRequest(registered_method->server_tag(), nullptr, notification_cq);
     }
 
@@ -225,9 +227,9 @@ class ServerInterface : public internal::CallHook {
                         CompletionQueue* call_cq,
                         ServerCompletionQueue* notification_cq, void* tag,
                         Message* request)
-        : RegisteredAsyncRequest(server, context, stream, call_cq,
-                                 notification_cq, tag,
-                                 registered_method->name()),
+        : RegisteredAsyncRequest(
+              server, context, stream, call_cq, notification_cq, tag,
+              registered_method->name(), registered_method->method_type()),
           registered_method_(registered_method),
           server_(server),
           context_(context),