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      1 /*
      2  *
      3  * Copyright 2015 gRPC authors.
      4  *
      5  * Licensed under the Apache License, Version 2.0 (the "License");
      6  * you may not use this file except in compliance with the License.
      7  * You may obtain a copy of the License at
      8  *
      9  *     http://www.apache.org/licenses/LICENSE-2.0
     10  *
     11  * Unless required by applicable law or agreed to in writing, software
     12  * distributed under the License is distributed on an "AS IS" BASIS,
     13  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     14  * See the License for the specific language governing permissions and
     15  * limitations under the License.
     16  *
     17  */
     18 
     19 #include <iostream>
     20 #include <memory>
     21 #include <string>
     22 
     23 #include <grpcpp/grpcpp.h>
     24 
     25 #ifdef BAZEL_BUILD
     26 #include "examples/protos/helloworld.grpc.pb.h"
     27 #else
     28 #include "helloworld.grpc.pb.h"
     29 #endif
     30 
     31 using grpc::Channel;
     32 using grpc::ClientContext;
     33 using grpc::Status;
     34 using helloworld::HelloRequest;
     35 using helloworld::HelloReply;
     36 using helloworld::Greeter;
     37 
     38 class GreeterClient {
     39  public:
     40   GreeterClient(std::shared_ptr<Channel> channel)
     41       : stub_(Greeter::NewStub(channel)) {}
     42 
     43   // Assembles the client's payload, sends it and presents the response back
     44   // from the server.
     45   std::string SayHello(const std::string& user) {
     46     // Data we are sending to the server.
     47     HelloRequest request;
     48     request.set_name(user);
     49 
     50     // Container for the data we expect from the server.
     51     HelloReply reply;
     52 
     53     // Context for the client. It could be used to convey extra information to
     54     // the server and/or tweak certain RPC behaviors.
     55     ClientContext context;
     56 
     57     // The actual RPC.
     58     Status status = stub_->SayHello(&context, request, &reply);
     59 
     60     // Act upon its status.
     61     if (status.ok()) {
     62       return reply.message();
     63     } else {
     64       std::cout << status.error_code() << ": " << status.error_message()
     65                 << std::endl;
     66       return "RPC failed";
     67     }
     68   }
     69 
     70  private:
     71   std::unique_ptr<Greeter::Stub> stub_;
     72 };
     73 
     74 int main(int argc, char** argv) {
     75   // Instantiate the client. It requires a channel, out of which the actual RPCs
     76   // are created. This channel models a connection to an endpoint (in this case,
     77   // localhost at port 50051). We indicate that the channel isn't authenticated
     78   // (use of InsecureChannelCredentials()).
     79   GreeterClient greeter(grpc::CreateChannel(
     80       "localhost:50051", grpc::InsecureChannelCredentials()));
     81   std::string user("world");
     82   std::string reply = greeter.SayHello(user);
     83   std::cout << "Greeter received: " << reply << std::endl;
     84 
     85   return 0;
     86 }
     87