Support for python grpc - continuing the work from the pull request #4270 #4705 (#5613)

* Support for python grpc

* add few fixes

* Fixes build

* Fix python generator

* Add tests

* Fix grpc python test

* Fix tests and add incomplete python generator

* Fix python generator

* Add python generator methods

* Fix Appveyor build

* grpc python support v0.1

* Update tests

* update grpctest

* Remove duplicated code and fix a brace

* tests for flatbuffers grpc python

* Updated tests + removed SerializeToString, From String

* remove pickle import

* include missing files in ci - BUILD and generated test result

5 files changed, 958 insertions, 0 deletions

diff --git a/grpc/src/compiler/python_generator.cc b/grpc/src/compiler/python_generator.cc
new file mode 100644
index 00000000..4bc2fb5e
--- /dev/null
+++ b/grpc/src/compiler/python_generator.cc
@@ -0,0 +1,639 @@
+/*
+ *
+ * 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 <algorithm>
+#include <cassert>
+#include <cctype>
+#include <cstring>
+#include <fstream>
+#include <iostream>
+#include <map>
+#include <memory>
+#include <ostream>
+#include <set>
+#include <sstream>
+#include <tuple>
+#include <vector>
+
+#include "flatbuffers/util.h"
+#include "src/compiler/python_generator.h"
+#include "src/compiler/python_private_generator.h"
+
+using std::make_pair;
+using std::map;
+using std::pair;
+using std::replace;
+using std::tuple;
+using std::vector;
+using std::set;
+
+namespace grpc_python_generator {
+
+grpc::string generator_file_name;
+
+typedef map<grpc::string, grpc::string> StringMap;
+typedef vector<grpc::string> StringVector;
+typedef tuple<grpc::string, grpc::string> StringPair;
+typedef set<StringPair> StringPairSet;
+
+// Provides RAII indentation handling. Use as:
+// {
+//   IndentScope raii_my_indent_var_name_here(my_py_printer);
+//   // constructor indented my_py_printer
+//   ...
+//   // destructor called at end of scope, un-indenting my_py_printer
+// }
+class IndentScope {
+ public:
+  explicit IndentScope(grpc_generator::Printer* printer) : printer_(printer) {
+    printer_->Indent();
+  }
+
+  ~IndentScope() { printer_->Outdent(); }
+
+ private:
+  grpc_generator::Printer* printer_;
+};
+
+inline grpc::string StringReplace(grpc::string str, const grpc::string& from,
+                                  const grpc::string& to, bool replace_all) {
+  size_t pos = 0;
+
+  do {
+    pos = str.find(from, pos);
+    if (pos == grpc::string::npos) {
+      break;
+    }
+    str.replace(pos, from.length(), to);
+    pos += to.length();
+  } while (replace_all);
+
+  return str;
+}
+
+inline grpc::string StringReplace(grpc::string str, const grpc::string& from,
+                                  const grpc::string& to) {
+  return StringReplace(str, from, to, true);
+}
+
+grpc::string ModuleName(const grpc::string& filename,
+                        const grpc::string& import_prefix) {
+  grpc::string basename = flatbuffers::StripExtension(filename);
+  basename = StringReplace(basename, "-", "_");
+  basename = StringReplace(basename, "/", ".");
+  return import_prefix + basename + "_fb";
+}
+
+grpc::string ModuleAlias(const grpc::string& filename,
+                         const grpc::string& import_prefix) {
+  grpc::string module_name = ModuleName(filename, import_prefix);
+  // We can't have dots in the module name, so we replace each with _dot_.
+  // But that could lead to a collision between a.b and a_dot_b, so we also
+  // duplicate each underscore.
+  module_name = StringReplace(module_name, "_", "__");
+  module_name = StringReplace(module_name, ".", "_dot_");
+  return module_name;
+}
+
+PrivateGenerator::PrivateGenerator(const GeneratorConfiguration& config_,
+                                   const grpc_generator::File* file_)
+    : config(config_), file(file_) {}
+
+void PrivateGenerator::PrintBetaServicer(const grpc_generator::Service* service,
+                                         grpc_generator::Printer* out) {
+  StringMap service_dict;
+  service_dict["Service"] = service->name();
+  out->Print("\n\n");
+  out->Print(service_dict, "class Beta$Service$Servicer(object):\n");
+  {
+    IndentScope raii_class_indent(out);
+    out->Print(
+        "\"\"\"The Beta API is deprecated for 0.15.0 and later.\n"
+        "\nIt is recommended to use the GA API (classes and functions in this\n"
+        "file not marked beta) for all further purposes. This class was "
+        "generated\n"
+        "only to ease transition from grpcio<0.15.0 to "
+        "grpcio>=0.15.0.\"\"\"\n");
+    for (int i = 0; i < service->method_count(); ++i) {
+      auto method = service->method(i);
+      grpc::string arg_name =
+          method->ClientStreaming() ? "request_iterator" : "request";
+      StringMap method_dict;
+      method_dict["Method"] = method->name();
+      method_dict["ArgName"] = arg_name;
+      out->Print(method_dict, "def $Method$(self, $ArgName$, context):\n");
+      {
+        IndentScope raii_method_indent(out);
+        out->Print("context.code(beta_interfaces.StatusCode.UNIMPLEMENTED)\n");
+      }
+    }
+  }
+}
+
+void PrivateGenerator::PrintBetaStub(const grpc_generator::Service* service,
+                                     grpc_generator::Printer* out) {
+  StringMap service_dict;
+  service_dict["Service"] = service->name();
+  out->Print("\n\n");
+  out->Print(service_dict, "class Beta$Service$Stub(object):\n");
+  {
+    IndentScope raii_class_indent(out);
+    out->Print(
+        "\"\"\"The Beta API is deprecated for 0.15.0 and later.\n"
+        "\nIt is recommended to use the GA API (classes and functions in this\n"
+        "file not marked beta) for all further purposes. This class was "
+        "generated\n"
+        "only to ease transition from grpcio<0.15.0 to "
+        "grpcio>=0.15.0.\"\"\"\n");
+    for (int i = 0; i < service->method_count(); ++i) {
+      auto method = service->method(i);
+      grpc::string arg_name =
+          method->ClientStreaming() ? "request_iterator" : "request";
+      StringMap method_dict;
+      method_dict["Method"] = method->name();
+      method_dict["ArgName"] = arg_name;
+      out->Print(method_dict,
+                 "def $Method$(self, $ArgName$, timeout, metadata=None, "
+                 "with_call=False, protocol_options=None):\n");
+      {
+        IndentScope raii_method_indent(out);
+        out->Print("raise NotImplementedError()\n");
+      }
+      if (!method->ServerStreaming()) {
+        out->Print(method_dict, "$Method$.future = None\n");
+      }
+    }
+  }
+}
+
+void PrivateGenerator::PrintBetaServerFactory(
+    const grpc::string& package_qualified_service_name,
+    const grpc_generator::Service* service, grpc_generator::Printer* out) {
+  StringMap service_dict;
+  service_dict["Service"] = service->name();
+  out->Print("\n\n");
+  out->Print(service_dict,
+             "def beta_create_$Service$_server(servicer, pool=None, "
+             "pool_size=None, default_timeout=None, maximum_timeout=None):\n");
+  {
+    IndentScope raii_create_server_indent(out);
+    out->Print(
+        "\"\"\"The Beta API is deprecated for 0.15.0 and later.\n"
+        "\nIt is recommended to use the GA API (classes and functions in this\n"
+        "file not marked beta) for all further purposes. This function was\n"
+        "generated only to ease transition from grpcio<0.15.0 to grpcio>=0.15.0"
+        "\"\"\"\n");
+    StringMap method_implementation_constructors;
+    StringMap input_message_modules_and_classes;
+    StringMap output_message_modules_and_classes;
+    for (int i = 0; i < service->method_count(); ++i) {
+      auto method = service->method(i);
+      const grpc::string method_implementation_constructor =
+          grpc::string(method->ClientStreaming() ? "stream_" : "unary_") +
+          grpc::string(method->ServerStreaming() ? "stream_" : "unary_") +
+          "inline";
+      grpc::string input_message_module_and_class = method->get_fb_builder();
+      grpc::string output_message_module_and_class = method->get_fb_builder();
+      method_implementation_constructors.insert(
+          make_pair(method->name(), method_implementation_constructor));
+      input_message_modules_and_classes.insert(
+          make_pair(method->name(), input_message_module_and_class));
+      output_message_modules_and_classes.insert(
+          make_pair(method->name(), output_message_module_and_class));
+    }
+    StringMap method_dict;
+    method_dict["PackageQualifiedServiceName"] = package_qualified_service_name;
+//    out->Print("request_deserializers = {\n");
+//    for (StringMap::iterator name_and_input_module_class_pair =
+//             input_message_modules_and_classes.begin();
+//         name_and_input_module_class_pair !=
+//         input_message_modules_and_classes.end();
+//         name_and_input_module_class_pair++) {
+//      method_dict["MethodName"] = name_and_input_module_class_pair->first;
+//      method_dict["InputTypeModuleAndClass"] =
+//          name_and_input_module_class_pair->second;
+//      IndentScope raii_indent(out);
+//      out->Print(method_dict,
+//                 "(\'$PackageQualifiedServiceName$\', \'$MethodName$\'): "
+//                 "$InputTypeModuleAndClass$.FromString,\n");
+//    }
+//    out->Print("}\n");
+//    out->Print("response_serializers = {\n");
+//    for (StringMap::iterator name_and_output_module_class_pair =
+//             output_message_modules_and_classes.begin();
+//         name_and_output_module_class_pair !=
+//         output_message_modules_and_classes.end();
+//         name_and_output_module_class_pair++) {
+//      method_dict["MethodName"] = name_and_output_module_class_pair->first;
+//      method_dict["OutputTypeModuleAndClass"] =
+//          name_and_output_module_class_pair->second;
+//      IndentScope raii_indent(out);
+//      out->Print(method_dict,
+//                 "(\'$PackageQualifiedServiceName$\', \'$MethodName$\'): "
+//                 "$OutputTypeModuleAndClass$.SerializeToString,\n");
+//    }
+//    out->Print("}\n");
+    out->Print("method_implementations = {\n");
+    for (StringMap::iterator name_and_implementation_constructor =
+             method_implementation_constructors.begin();
+         name_and_implementation_constructor !=
+         method_implementation_constructors.end();
+         name_and_implementation_constructor++) {
+      method_dict["Method"] = name_and_implementation_constructor->first;
+      method_dict["Constructor"] = name_and_implementation_constructor->second;
+      IndentScope raii_descriptions_indent(out);
+      const grpc::string method_name =
+          name_and_implementation_constructor->first;
+      out->Print(method_dict,
+                 "(\'$PackageQualifiedServiceName$\', \'$Method$\'): "
+                 "face_utilities.$Constructor$(servicer.$Method$),\n");
+    }
+    out->Print("}\n");
+    out->Print(
+        "server_options = beta_implementations.server_options("
+        "thread_pool=pool, thread_pool_size=pool_size, "
+        "default_timeout=default_timeout, "
+        "maximum_timeout=maximum_timeout)\n");
+    out->Print(
+        "return beta_implementations.server(method_implementations, "
+        "options=server_options)\n");
+        //"request_deserializers=request_deserializers, "
+        //"response_serializers=response_serializers, "
+  }
+}
+
+void PrivateGenerator::PrintBetaStubFactory(
+    const grpc::string& package_qualified_service_name,
+    const grpc_generator::Service* service, grpc_generator::Printer* out) {
+  StringMap dict;
+  dict["Service"] = service->name();
+  out->Print("\n\n");
+  out->Print(dict,
+             "def beta_create_$Service$_stub(channel, host=None,"
+             " metadata_transformer=None, pool=None, pool_size=None):\n");
+  {
+    IndentScope raii_create_server_indent(out);
+    out->Print(
+        "\"\"\"The Beta API is deprecated for 0.15.0 and later.\n"
+        "\nIt is recommended to use the GA API (classes and functions in this\n"
+        "file not marked beta) for all further purposes. This function was\n"
+        "generated only to ease transition from grpcio<0.15.0 to grpcio>=0.15.0"
+        "\"\"\"\n");
+    StringMap method_cardinalities;
+    StringMap input_message_modules_and_classes;
+    StringMap output_message_modules_and_classes;
+    for (int i = 0; i < service->method_count(); ++i) {
+      auto method = service->method(i);
+      const grpc::string method_cardinality =
+          grpc::string(method->ClientStreaming() ? "STREAM" : "UNARY") +
+          "_" +
+          grpc::string(method->ServerStreaming() ? "STREAM" : "UNARY");
+      grpc::string input_message_module_and_class = method->get_fb_builder();
+      grpc::string output_message_module_and_class = method->get_fb_builder();
+      method_cardinalities.insert(
+          make_pair(method->name(), method_cardinality));
+      input_message_modules_and_classes.insert(
+          make_pair(method->name(), input_message_module_and_class));
+      output_message_modules_and_classes.insert(
+          make_pair(method->name(), output_message_module_and_class));
+    }
+    StringMap method_dict;
+    method_dict["PackageQualifiedServiceName"] = package_qualified_service_name;
+//    out->Print("request_serializers = {\n");
+//    for (StringMap::iterator name_and_input_module_class_pair =
+//             input_message_modules_and_classes.begin();
+//         name_and_input_module_class_pair !=
+//         input_message_modules_and_classes.end();
+//         name_and_input_module_class_pair++) {
+//      method_dict["MethodName"] = name_and_input_module_class_pair->first;
+//      method_dict["InputTypeModuleAndClass"] =
+//          name_and_input_module_class_pair->second;
+//      IndentScope raii_indent(out);
+//      out->Print(method_dict,
+//                 "(\'$PackageQualifiedServiceName$\', \'$MethodName$\'): "
+//                 "$InputTypeModuleAndClass$.SerializeToString,\n");
+//    }
+//    out->Print("}\n");
+//    out->Print("response_deserializers = {\n");
+//    for (StringMap::iterator name_and_output_module_class_pair =
+//             output_message_modules_and_classes.begin();
+//         name_and_output_module_class_pair !=
+//         output_message_modules_and_classes.end();
+//         name_and_output_module_class_pair++) {
+//      method_dict["MethodName"] = name_and_output_module_class_pair->first;
+//      method_dict["OutputTypeModuleAndClass"] =
+//          name_and_output_module_class_pair->second;
+//      IndentScope raii_indent(out);
+//      out->Print(method_dict,
+//                 "(\'$PackageQualifiedServiceName$\', \'$MethodName$\'): "
+//                 "$OutputTypeModuleAndClass$.FromString,\n");
+//    }
+//    out->Print("}\n");
+    out->Print("cardinalities = {\n");
+    for (StringMap::iterator name_and_cardinality =
+             method_cardinalities.begin();
+         name_and_cardinality != method_cardinalities.end();
+         name_and_cardinality++) {
+      method_dict["Method"] = name_and_cardinality->first;
+      method_dict["Cardinality"] = name_and_cardinality->second;
+      IndentScope raii_descriptions_indent(out);
+      out->Print(method_dict,
+                 "\'$Method$\': cardinality.Cardinality.$Cardinality$,\n");
+    }
+    out->Print("}\n");
+    out->Print(
+        "stub_options = beta_implementations.stub_options("
+        "host=host, metadata_transformer=metadata_transformer, "
+        "thread_pool=pool, thread_pool_size=pool_size)\n");
+    out->Print(method_dict,
+               "return beta_implementations.dynamic_stub(channel, "
+               "\'$PackageQualifiedServiceName$\', "
+               "cardinalities, options=stub_options)\n");
+        // "request_serializers=request_serializers, "
+        //"response_deserializers=response_deserializers, "
+  }
+}
+
+void PrivateGenerator::PrintStub(
+    const grpc::string& package_qualified_service_name,
+    const grpc_generator::Service* service, grpc_generator::Printer* out) {
+  StringMap dict;
+  dict["Service"] = service->name();
+  out->Print("\n\n");
+  out->Print(dict, "class $Service$Stub(object):\n");
+  {
+    IndentScope raii_class_indent(out);
+    out->Print("\n");
+    out->Print("def __init__(self, channel):\n");
+    {
+      IndentScope raii_init_indent(out);
+      out->Print("\"\"\"Constructor.\n");
+      out->Print("\n");
+      out->Print("Args:\n");
+      {
+        IndentScope raii_args_indent(out);
+        out->Print("channel: A grpc.Channel.\n");
+      }
+      out->Print("\"\"\"\n");
+      for (int i = 0; i < service->method_count(); ++i) {
+        auto method = service->method(i);
+        grpc::string multi_callable_constructor =
+            grpc::string(method->ClientStreaming() ? "stream" : "unary") +
+            "_" +
+            grpc::string(method->ServerStreaming() ? "stream" : "unary");
+        grpc::string request_module_and_class = method->get_fb_builder();
+        grpc::string response_module_and_class = method->get_fb_builder();
+        StringMap method_dict;
+        method_dict["Method"] = method->name();
+        method_dict["MultiCallableConstructor"] = multi_callable_constructor;
+        out->Print(method_dict,
+                   "self.$Method$ = channel.$MultiCallableConstructor$(\n");
+        {
+          method_dict["PackageQualifiedService"] =
+              package_qualified_service_name;
+          method_dict["RequestModuleAndClass"] = request_module_and_class;
+          method_dict["ResponseModuleAndClass"] = response_module_and_class;
+          IndentScope raii_first_attribute_indent(out);
+          IndentScope raii_second_attribute_indent(out);
+          out->Print(method_dict, "'/$PackageQualifiedService$/$Method$',\n");
+          out->Print(method_dict,"\n");
+          out->Print(
+              method_dict,"\n");
+          out->Print(")\n");
+        }
+      }
+    }
+  }
+}
+
+void PrivateGenerator::PrintServicer(const grpc_generator::Service* service,
+                                     grpc_generator::Printer* out) {
+  StringMap service_dict;
+  service_dict["Service"] = service->name();
+  out->Print("\n\n");
+  out->Print(service_dict, "class $Service$Servicer(object):\n");
+  {
+    IndentScope raii_class_indent(out);
+    for (int i = 0; i < service->method_count(); ++i) {
+      auto method = service->method(i);
+      grpc::string arg_name =
+          method->ClientStreaming() ? "request_iterator" : "request";
+      StringMap method_dict;
+      method_dict["Method"] = method->name();
+      method_dict["ArgName"] = arg_name;
+      out->Print("\n");
+      out->Print(method_dict, "def $Method$(self, $ArgName$, context):\n");
+      {
+        IndentScope raii_method_indent(out);
+        out->Print("context.set_code(grpc.StatusCode.UNIMPLEMENTED)\n");
+        out->Print("context.set_details('Method not implemented!')\n");
+        out->Print("raise NotImplementedError('Method not implemented!')\n");
+      }
+    }
+  }
+}
+
+void PrivateGenerator::PrintAddServicerToServer(
+    const grpc::string& package_qualified_service_name,
+    const grpc_generator::Service* service, grpc_generator::Printer* out) {
+  StringMap service_dict;
+  service_dict["Service"] = service->name();
+  out->Print("\n\n");
+  out->Print(service_dict,
+             "def add_$Service$Servicer_to_server(servicer, server):\n");
+  {
+    IndentScope raii_class_indent(out);
+    out->Print("rpc_method_handlers = {\n");
+    {
+      IndentScope raii_dict_first_indent(out);
+      IndentScope raii_dict_second_indent(out);
+      for (int i = 0; i < service->method_count(); ++i) {
+        auto method = service->method(i);
+        grpc::string method_handler_constructor =
+            grpc::string(method->ClientStreaming() ? "stream" : "unary") +
+            "_" +
+            grpc::string(method->ServerStreaming() ? "stream" : "unary") +
+            "_rpc_method_handler";
+        grpc::string request_module_and_class = method->get_fb_builder();
+        grpc::string response_module_and_class = method->get_fb_builder();
+        StringMap method_dict;
+        method_dict["Method"] = method->name();
+        method_dict["MethodHandlerConstructor"] = method_handler_constructor;
+        method_dict["RequestModuleAndClass"] = request_module_and_class;
+        method_dict["ResponseModuleAndClass"] = response_module_and_class;
+        out->Print(method_dict,
+                   "'$Method$': grpc.$MethodHandlerConstructor$(\n");
+        {
+          IndentScope raii_call_first_indent(out);
+          IndentScope raii_call_second_indent(out);
+          out->Print(method_dict, "servicer.$Method$,\n");
+          out->Print(
+              method_dict,"\n");
+          out->Print(
+              method_dict,
+              "\n");
+        }
+        out->Print("),\n");
+      }
+    }
+    StringMap method_dict;
+    method_dict["PackageQualifiedServiceName"] = package_qualified_service_name;
+    out->Print("}\n");
+    out->Print("generic_handler = grpc.method_handlers_generic_handler(\n");
+    {
+      IndentScope raii_call_first_indent(out);
+      IndentScope raii_call_second_indent(out);
+      out->Print(method_dict,
+                 "'$PackageQualifiedServiceName$', rpc_method_handlers)\n");
+    }
+    out->Print("server.add_generic_rpc_handlers((generic_handler,))\n");
+  }
+}
+
+void PrivateGenerator::PrintBetaPreamble(grpc_generator::Printer* out) {
+  StringMap var;
+  var["Package"] = config.beta_package_root;
+  out->Print(var,
+             "from $Package$ import implementations as beta_implementations\n");
+  out->Print(var, "from $Package$ import interfaces as beta_interfaces\n");
+  out->Print("from grpc.framework.common import cardinality\n");
+  out->Print(
+      "from grpc.framework.interfaces.face import utilities as "
+      "face_utilities\n");
+}
+
+void PrivateGenerator::PrintPreamble(grpc_generator::Printer* out) {
+  StringMap var;
+  var["Package"] = config.grpc_package_root;
+  out->Print(var, "import $Package$\n");
+  out->Print("\n");
+  StringPairSet imports_set;
+  for (int i = 0; i < file->service_count(); ++i) {
+    auto service = file->service(i);
+    for (int j = 0; j < service->method_count(); ++j) {
+      auto method = service.get()->method(j);
+
+      grpc::string input_type_file_name = method->get_fb_builder();
+      grpc::string input_module_name =
+          ModuleName(input_type_file_name, config.import_prefix);
+      grpc::string input_module_alias =
+          ModuleAlias(input_type_file_name, config.import_prefix);
+      imports_set.insert(
+          std::make_tuple(input_module_name, input_module_alias));
+
+      grpc::string output_type_file_name = method->get_fb_builder();
+      grpc::string output_module_name =
+          ModuleName(output_type_file_name, config.import_prefix);
+      grpc::string output_module_alias =
+          ModuleAlias(output_type_file_name, config.import_prefix);
+      imports_set.insert(
+          std::make_tuple(output_module_name, output_module_alias));
+    }
+  }
+
+  for (StringPairSet::iterator it = imports_set.begin();
+       it != imports_set.end(); ++it) {
+    var["ModuleName"] = std::get<0>(*it);
+    var["ModuleAlias"] = std::get<1>(*it);
+    out->Print(var, "import $ModuleName$ as $ModuleAlias$\n");
+  }
+}
+
+void PrivateGenerator::PrintGAServices(grpc_generator::Printer* out) {
+  grpc::string package = file->package();
+  if (!package.empty()) {
+    package = package.append(".");
+  }
+
+  out->Print(file->additional_headers().c_str());
+
+  for (int i = 0; i < file->service_count(); ++i) {
+    auto service = file->service(i);
+
+    grpc::string package_qualified_service_name = package + service->name();
+    PrintStub(package_qualified_service_name, service.get(), out);
+    PrintServicer(service.get(), out);
+    PrintAddServicerToServer(package_qualified_service_name, service.get(),
+                             out);
+  }
+}
+
+void PrivateGenerator::PrintBetaServices(grpc_generator::Printer* out) {
+  grpc::string package = file->package();
+  if (!package.empty()) {
+    package = package.append(".");
+  }
+  for (int i = 0; i < file->service_count(); ++i) {
+    auto service = file->service(i);
+
+    grpc::string package_qualified_service_name = package + service->name();
+    PrintBetaServicer(service.get(), out);
+    PrintBetaStub(service.get(), out);
+    PrintBetaServerFactory(package_qualified_service_name, service.get(), out);
+    PrintBetaStubFactory(package_qualified_service_name, service.get(), out);
+  }
+}
+
+grpc::string PrivateGenerator::GetGrpcServices() {
+  grpc::string output;
+  {
+    // Scope the output stream so it closes and finalizes output to the string.
+    auto out = file->CreatePrinter(&output);
+    out->Print(
+        "# Generated by the gRPC Python protocol compiler plugin. "
+        "DO NOT EDIT!\n");
+    StringMap var;
+    var["Package"] = config.grpc_package_root;
+    out->Print(var, "import $Package$\n");
+    PrintGAServices(out.get());
+    out->Print("try:\n");
+    {
+      IndentScope raii_dict_try_indent(out.get());
+      out->Print(
+          "# THESE ELEMENTS WILL BE DEPRECATED.\n"
+          "# Please use the generated *_pb2_grpc.py files instead.\n");
+      out->Print(var, "import $Package$\n");
+      PrintBetaPreamble(out.get());
+      PrintGAServices(out.get());
+      PrintBetaServices(out.get());
+    }
+    out->Print("except ImportError:\n");
+    {
+      IndentScope raii_dict_except_indent(out.get());
+      out->Print("pass");
+    }
+  }
+  return output;
+}
+
+}  // namespace grpc_python_generator
diff --git a/grpc/src/compiler/python_generator.h b/grpc/src/compiler/python_generator.h
new file mode 100644
index 00000000..8e3af8a2
--- /dev/null
+++ b/grpc/src/compiler/python_generator.h
@@ -0,0 +1,55 @@
+/*
+ *
+ * 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_COMPILER_PYTHON_GENERATOR_H
+#define GRPC_INTERNAL_COMPILER_PYTHON_GENERATOR_H
+
+#include <utility>
+
+#include "src/compiler/schema_interface.h"
+
+namespace grpc_python_generator {
+
+// Data pertaining to configuration of the generator with respect to anything
+// that may be used internally at Google.
+struct GeneratorConfiguration {
+  grpc::string grpc_package_root;
+  // TODO(https://github.com/grpc/grpc/issues/8622): Drop this.
+  grpc::string beta_package_root;
+  // TODO(https://github.com/google/protobuf/issues/888): Drop this.
+  grpc::string import_prefix;
+};
+
+}  // namespace grpc_python_generator
+
+#endif  // GRPC_INTERNAL_COMPILER_PYTHON_GENERATOR_H
diff --git a/grpc/src/compiler/python_private_generator.h b/grpc/src/compiler/python_private_generator.h
new file mode 100644
index 00000000..f070145c
--- /dev/null
+++ b/grpc/src/compiler/python_private_generator.h
@@ -0,0 +1,87 @@
+/*
+ *
+ * Copyright 2015, Google Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+#ifndef GRPC_INTERNAL_COMPILER_PYTHON_PRIVATE_GENERATOR_H
+#define GRPC_INTERNAL_COMPILER_PYTHON_PRIVATE_GENERATOR_H
+
+#include <iostream>
+#include <vector>
+
+#include "src/compiler/python_generator.h"
+#include "src/compiler/schema_interface.h"
+
+namespace grpc_python_generator {
+
+// Tucks all generator state in an anonymous namespace away from
+// PythonGrpcGenerator and the header file, mostly to encourage future changes
+// to not require updates to the grpcio-tools C++ code part. Assumes that it is
+// only ever used from a single thread.
+struct PrivateGenerator {
+  const GeneratorConfiguration& config;
+  const grpc_generator::File* file;
+
+  PrivateGenerator(const GeneratorConfiguration& config,
+                   const grpc_generator::File* file);
+
+  grpc::string GetGrpcServices();
+
+ private:
+  void PrintPreamble(grpc_generator::Printer* out);
+  void PrintBetaPreamble(grpc_generator::Printer* out);
+  void PrintGAServices(grpc_generator::Printer* out);
+  void PrintBetaServices(grpc_generator::Printer* out);
+
+  void PrintAddServicerToServer(
+      const grpc::string& package_qualified_service_name,
+      const grpc_generator::Service* service, grpc_generator::Printer* out);
+  void PrintServicer(const grpc_generator::Service* service,
+                     grpc_generator::Printer* out);
+  void PrintStub(const grpc::string& package_qualified_service_name,
+                 const grpc_generator::Service* service,
+                 grpc_generator::Printer* out);
+
+  void PrintBetaServicer(const grpc_generator::Service* service,
+                         grpc_generator::Printer* out);
+  void PrintBetaServerFactory(
+      const grpc::string& package_qualified_service_name,
+      const grpc_generator::Service* service, grpc_generator::Printer* out);
+  void PrintBetaStub(const grpc_generator::Service* service,
+                     grpc_generator::Printer* out);
+  void PrintBetaStubFactory(const grpc::string& package_qualified_service_name,
+                            const grpc_generator::Service* service,
+                            grpc_generator::Printer* out);
+};
+
+}  // namespace grpc_python_generator
+
+#endif  // GRPC_INTERNAL_COMPILER_PYTHON_PRIVATE_GENERATOR_H
diff --git a/grpc/src/compiler/schema_interface.h b/grpc/src/compiler/schema_interface.h
index 638448d3..52060bc5 100644
--- a/grpc/src/compiler/schema_interface.h
+++ b/grpc/src/compiler/schema_interface.h
@@ -79,6 +79,9 @@ struct Method : public CommentHolder {
 
   virtual grpc::string get_input_type_name() const = 0;
   virtual grpc::string get_output_type_name() const = 0;
+
+  virtual grpc::string get_fb_builder() const = 0;
+
   virtual bool NoStreaming() const = 0;
   virtual bool ClientStreaming() const = 0;
   virtual bool ServerStreaming() const = 0;
diff --git a/grpc/tests/grpctest.py b/grpc/tests/grpctest.py
new file mode 100644
index 00000000..1c5e92f0
--- /dev/null
+++ b/grpc/tests/grpctest.py
@@ -0,0 +1,174 @@
+from __future__ import print_function
+
+import os
+import sys
+import grpc
+import flatbuffers
+
+from concurrent import futures
+
+sys.path.append(os.path.join(os.path.dirname(__file__), '..', '..', 'tests'))
+import MyGame.Example.Monster as Monster
+import MyGame.Example.Stat as Stat
+import MyGame.Example.Vec3 as Vec3
+import MyGame.Example.Test as Test
+import MyGame.Example.monster_test_grpc_fb as monster_grpc_fb
+
+
+test_stat_id = "test_stat_id"
+test_stat_val = 8
+test_stat_count = 1
+
+test_monster_name1 = "test_monster_name1"
+test_monster_name2 = "test_monster_name2"
+test_string = "test_string"
+test_color = 2
+test_X = 3.0
+test_Y = 2.0
+test_Z = 6.0
+test_test1 = 4.0
+test_a = 8
+test_b = 5
+test_hp = 67
+test_inventory = [1, 1, 2, 3, 5, 8]
+test_testtype = 4
+
+test_monsters_name_retrieve = ["big_monster", "small_monster"]
+test_no_of_monsters = 2
+
+
+class MonsterStorage(monster_grpc_fb.MonsterStorageServicer):
+
+    def Store(self, request, context):
+
+        m = Monster.Monster().GetRootAsMonster(request, 0)
+
+        assert m.Name().decode("utf-8") == test_monster_name1
+
+        assert m.Pos().X() == test_X
+        assert m.Pos().Y() == test_Y
+        assert m.Pos().Z() == test_Z
+        assert m.Pos().Test1() == test_test1
+        assert m.Pos().Test2() == test_color
+        test3 = Test.Test()
+        assert m.Pos().Test3(test3).A() == test_a
+        assert m.Pos().Test3(test3).B() == test_b
+
+        assert m.Hp() == test_hp
+
+        assert m.Color() == test_color
+
+        assert m.InventoryLength() == len(test_inventory)
+        for i in range(0, len(test_inventory)):
+            assert m.Inventory(i) == test_inventory[len(test_inventory)-i -1]
+
+        assert m.TestType() == test_testtype
+
+        assert m.Test() is not None
+        table = m.Test()
+
+        m2 = Monster.Monster()
+        m2.Init(table.Bytes, table.Pos)
+        assert m2.Name().decode("utf-8") == test_monster_name2
+
+        m3 = m.Enemy()
+        assert m3.Name().decode("utf-8") == test_monster_name2
+
+        assert m.Testarrayofstring(0).decode("utf-8") == test_string
+
+        b = flatbuffers.Builder(0)
+        i = b.CreateString(test_stat_id)
+        Stat.StatStart(b)
+        Stat.StatAddId(b, i)
+        Stat.StatAddVal(b, test_stat_val)
+        Stat.StatAddCount(b, test_stat_count)
+        b.Finish(Stat.StatEnd(b))
+        return bytes(b.Output())
+
+    def Retrieve(self, request, context):
+
+        s = Stat.Stat().GetRootAsStat(request, 0)
+
+        no_of_monsters = test_no_of_monsters
+        for i in range(0, no_of_monsters):
+            b = flatbuffers.Builder(0)
+            i = b.CreateString(test_monsters_name_retrieve[i])
+            Monster.MonsterStart(b)
+            Monster.MonsterAddName(b, i)
+            b.Finish(Monster.MonsterEnd(b))
+            yield bytes(b.Output())
+
+
+def serve():
+
+    server = grpc.server(futures.ThreadPoolExecutor(max_workers=10))
+    monster_grpc_fb.add_MonsterStorageServicer_to_server(MonsterStorage(), server)
+    server.add_insecure_port('[::]:50051')
+
+    server.start()
+
+    run()
+
+
+def run():
+
+    channel = grpc.insecure_channel('127.0.0.1:50051')
+    stub = monster_grpc_fb.MonsterStorageStub(channel)
+
+    b = flatbuffers.Builder(0)
+    name2 = b.CreateString(test_monster_name2)
+    name1 = b.CreateString(test_monster_name1)
+    Monster.MonsterStart(b)
+    Monster.MonsterAddName(b, name2)
+    monster2 = Monster.MonsterEnd(b)
+    test1 = b.CreateString(test_string)
+
+    Monster.MonsterStartInventoryVector(b, len(test_inventory))
+    for i in range(0, len(test_inventory)):
+        b.PrependByte(test_inventory[i])
+    inv = b.EndVector(len(test_inventory))
+
+    Monster.MonsterStartTest4Vector(b, 2)
+    Test.CreateTest(b, 10, 20)
+    Test.CreateTest(b, 30, 40)
+    test4 = b.EndVector(2)
+
+    Monster.MonsterStartTestarrayofstringVector(b, 1)
+    b.PrependUOffsetTRelative(test1)
+    test_array_of_string = b.EndVector(1)
+
+    Monster.MonsterStart(b)
+
+    Monster.MonsterAddHp(b, test_hp)
+    Monster.MonsterAddName(b, name1)
+    Monster.MonsterAddColor(b, test_color)
+    pos = Vec3.CreateVec3(b, test_X, test_Y, test_Z, test_test1, test_color, test_a, test_b)
+    Monster.MonsterAddPos(b, pos)
+    Monster.MonsterAddInventory(b, inv)
+    Monster.MonsterAddTestType(b, test_testtype)
+    Monster.MonsterAddTest(b, monster2)
+    Monster.MonsterAddTest4(b, test4)
+    Monster.MonsterAddEnemy(b, monster2)
+    Monster.MonsterAddTestarrayofstring(b, test_array_of_string)
+    monster = Monster.MonsterEnd(b)
+
+    b.Finish(monster)
+
+    stat_response = stub.Store(bytes(b.Output()))
+
+    s = Stat.Stat().GetRootAsStat(stat_response, 0)
+
+    assert s.Id().decode("utf-8") == test_stat_id
+    assert s.Val() == test_stat_val
+    assert s.Count() == test_stat_count
+
+    monster_reponses = stub.Retrieve(stat_response)
+    count = 0
+    for monster_reponse in monster_reponses:
+        m = Monster.Monster().GetRootAsMonster(monster_reponse, 0)
+        assert m.Name().decode("utf-8") == test_monsters_name_retrieve[count]
+        count = count + 1
+
+
+if __name__ == '__main__':
+    serve()