diff --git a/include/grpc++/impl/codegen/async_stream.h b/include/grpc++/impl/codegen/async_stream.h
index a607a4710605f1028e4e7a17cdf67b49411979bc..70a8b3931204342dd430161cd7deaa93226f080a 100644
--- a/include/grpc++/impl/codegen/async_stream.h
+++ b/include/grpc++/impl/codegen/async_stream.h
@@ -298,8 +298,16 @@ class ClientAsyncReaderWriter GRPC_FINAL
 };
 
 template <class W, class R>
-class ServerAsyncReader GRPC_FINAL : public ServerAsyncStreamingInterface,
-                                     public AsyncReaderInterface<R> {
+class ServerAsyncReaderInterface : public ServerAsyncStreamingInterface,
+                                   public AsyncReaderInterface<R> {
+ public:
+  virtual void Finish(const W& msg, const Status& status, void* tag) = 0;
+
+  virtual void FinishWithError(const Status& status, void* tag) = 0;
+};
+
+template <class W, class R>
+class ServerAsyncReader GRPC_FINAL : public ServerAsyncReaderInterface<W, R> {
  public:
   explicit ServerAsyncReader(ServerContext* ctx)
       : call_(nullptr, nullptr, nullptr), ctx_(ctx) {}
@@ -320,7 +328,7 @@ class ServerAsyncReader GRPC_FINAL : public ServerAsyncStreamingInterface,
     call_.PerformOps(&read_ops_);
   }
 
-  void Finish(const W& msg, const Status& status, void* tag) {
+  void Finish(const W& msg, const Status& status, void* tag) GRPC_OVERRIDE {
     finish_ops_.set_output_tag(tag);
     if (!ctx_->sent_initial_metadata_) {
       finish_ops_.SendInitialMetadata(ctx_->initial_metadata_,
@@ -337,7 +345,7 @@ class ServerAsyncReader GRPC_FINAL : public ServerAsyncStreamingInterface,
     call_.PerformOps(&finish_ops_);
   }
 
-  void FinishWithError(const Status& status, void* tag) {
+  void FinishWithError(const Status& status, void* tag) GRPC_OVERRIDE {
     GPR_CODEGEN_ASSERT(!status.ok());
     finish_ops_.set_output_tag(tag);
     if (!ctx_->sent_initial_metadata_) {
@@ -362,8 +370,14 @@ class ServerAsyncReader GRPC_FINAL : public ServerAsyncStreamingInterface,
 };
 
 template <class W>
-class ServerAsyncWriter GRPC_FINAL : public ServerAsyncStreamingInterface,
-                                     public AsyncWriterInterface<W> {
+class ServerAsyncWriterInterface : public ServerAsyncStreamingInterface,
+                                   public AsyncWriterInterface<W> {
+ public:
+  virtual void Finish(const Status& status, void* tag) = 0;
+};
+
+template <class W>
+class ServerAsyncWriter GRPC_FINAL : public ServerAsyncWriterInterface<W> {
  public:
   explicit ServerAsyncWriter(ServerContext* ctx)
       : call_(nullptr, nullptr, nullptr), ctx_(ctx) {}
@@ -390,7 +404,7 @@ class ServerAsyncWriter GRPC_FINAL : public ServerAsyncStreamingInterface,
     call_.PerformOps(&write_ops_);
   }
 
-  void Finish(const Status& status, void* tag) {
+  void Finish(const Status& status, void* tag) GRPC_OVERRIDE {
     finish_ops_.set_output_tag(tag);
     if (!ctx_->sent_initial_metadata_) {
       finish_ops_.SendInitialMetadata(ctx_->initial_metadata_,
@@ -413,9 +427,16 @@ class ServerAsyncWriter GRPC_FINAL : public ServerAsyncStreamingInterface,
 
 /// Server-side interface for asynchronous bi-directional streaming.
 template <class W, class R>
-class ServerAsyncReaderWriter GRPC_FINAL : public ServerAsyncStreamingInterface,
-                                           public AsyncWriterInterface<W>,
-                                           public AsyncReaderInterface<R> {
+class ServerAsyncReaderWriterInterface : public ServerAsyncStreamingInterface,
+                                         public AsyncWriterInterface<W>,
+                                         public AsyncReaderInterface<R> {
+ public:
+  virtual void Finish(const Status& status, void* tag) = 0;
+};
+
+template <class W, class R>
+class ServerAsyncReaderWriter GRPC_FINAL
+    : public ServerAsyncReaderWriterInterface<W, R> {
  public:
   explicit ServerAsyncReaderWriter(ServerContext* ctx)
       : call_(nullptr, nullptr, nullptr), ctx_(ctx) {}
@@ -448,7 +469,7 @@ class ServerAsyncReaderWriter GRPC_FINAL : public ServerAsyncStreamingInterface,
     call_.PerformOps(&write_ops_);
   }
 
-  void Finish(const Status& status, void* tag) {
+  void Finish(const Status& status, void* tag) GRPC_OVERRIDE {
     finish_ops_.set_output_tag(tag);
     if (!ctx_->sent_initial_metadata_) {
       finish_ops_.SendInitialMetadata(ctx_->initial_metadata_,
diff --git a/include/grpc++/impl/codegen/impl/async_stream.h b/include/grpc++/impl/codegen/impl/async_stream.h
index 8f99e7eea43f695ea4deca22be5ecd9c19e71a27..7d7a9568077a3a74e4ab997ab0a3265aecaf0782 100644
--- a/include/grpc++/impl/codegen/impl/async_stream.h
+++ b/include/grpc++/impl/codegen/impl/async_stream.h
@@ -295,8 +295,16 @@ class ClientAsyncReaderWriter GRPC_FINAL
 };
 
 template <class W, class R>
-class ServerAsyncReader GRPC_FINAL : public ServerAsyncStreamingInterface,
-                                     public AsyncReaderInterface<R> {
+class ServerAsyncReaderInterface : public ServerAsyncStreamingInterface,
+                                   public AsyncReaderInterface<R> {
+ public:
+  virtual void Finish(const W& msg, const Status& status, void* tag) = 0;
+
+  virtual void FinishWithError(const Status& status, void* tag) = 0;
+};
+
+template <class W, class R>
+class ServerAsyncReader GRPC_FINAL : public ServerAsyncReaderInterface<W, R> {
  public:
   explicit ServerAsyncReader(ServerContext* ctx)
       : call_(nullptr, nullptr, nullptr), ctx_(ctx) {}
@@ -316,7 +324,7 @@ class ServerAsyncReader GRPC_FINAL : public ServerAsyncStreamingInterface,
     call_.PerformOps(&read_ops_);
   }
 
-  void Finish(const W& msg, const Status& status, void* tag) {
+  void Finish(const W& msg, const Status& status, void* tag) GRPC_OVERRIDE {
     finish_ops_.set_output_tag(tag);
     if (!ctx_->sent_initial_metadata_) {
       finish_ops_.SendInitialMetadata(ctx_->initial_metadata_);
@@ -332,7 +340,7 @@ class ServerAsyncReader GRPC_FINAL : public ServerAsyncStreamingInterface,
     call_.PerformOps(&finish_ops_);
   }
 
-  void FinishWithError(const Status& status, void* tag) {
+  void FinishWithError(const Status& status, void* tag) GRPC_OVERRIDE {
     GPR_CODEGEN_ASSERT(!status.ok());
     finish_ops_.set_output_tag(tag);
     if (!ctx_->sent_initial_metadata_) {
@@ -356,8 +364,14 @@ class ServerAsyncReader GRPC_FINAL : public ServerAsyncStreamingInterface,
 };
 
 template <class W>
-class ServerAsyncWriter GRPC_FINAL : public ServerAsyncStreamingInterface,
-                                     public AsyncWriterInterface<W> {
+class ServerAsyncWriterInterface : public ServerAsyncStreamingInterface,
+                                   public AsyncWriterInterface<W> {
+ public:
+  virtual void Finish(const Status& status, void* tag) = 0;
+};
+
+template <class W>
+class ServerAsyncWriter GRPC_FINAL : public ServerAsyncWriterInterface<W> {
  public:
   explicit ServerAsyncWriter(ServerContext* ctx)
       : call_(nullptr, nullptr, nullptr), ctx_(ctx) {}
@@ -382,7 +396,7 @@ class ServerAsyncWriter GRPC_FINAL : public ServerAsyncStreamingInterface,
     call_.PerformOps(&write_ops_);
   }
 
-  void Finish(const Status& status, void* tag) {
+  void Finish(const Status& status, void* tag) GRPC_OVERRIDE {
     finish_ops_.set_output_tag(tag);
     if (!ctx_->sent_initial_metadata_) {
       finish_ops_.SendInitialMetadata(ctx_->initial_metadata_);
@@ -404,9 +418,16 @@ class ServerAsyncWriter GRPC_FINAL : public ServerAsyncStreamingInterface,
 
 /// Server-side interface for asynchronous bi-directional streaming.
 template <class W, class R>
-class ServerAsyncReaderWriter GRPC_FINAL : public ServerAsyncStreamingInterface,
-                                           public AsyncWriterInterface<W>,
-                                           public AsyncReaderInterface<R> {
+class ServerAsyncReaderWriterInterface : public ServerAsyncStreamingInterface,
+                                         public AsyncWriterInterface<W>,
+                                         public AsyncReaderInterface<R> {
+ public:
+  virtual void Finish(const Status& status, void* tag) = 0;
+};
+
+template <class W, class R>
+class ServerAsyncReaderWriter GRPC_FINAL
+    : public ServerAsyncReaderWriterInterface<W, R> {
  public:
   explicit ServerAsyncReaderWriter(ServerContext* ctx)
       : call_(nullptr, nullptr, nullptr), ctx_(ctx) {}
@@ -437,7 +458,7 @@ class ServerAsyncReaderWriter GRPC_FINAL : public ServerAsyncStreamingInterface,
     call_.PerformOps(&write_ops_);
   }
 
-  void Finish(const Status& status, void* tag) {
+  void Finish(const Status& status, void* tag) GRPC_OVERRIDE {
     finish_ops_.set_output_tag(tag);
     if (!ctx_->sent_initial_metadata_) {
       finish_ops_.SendInitialMetadata(ctx_->initial_metadata_);