xds_greeter_client.cc

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/*
 *
 * Copyright 2021 gRPC authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 */
 
#include <iostream>
#include <memory>
#include <string>
 
#include "absl/flags/flag.h"
#include "absl/flags/parse.h"
 
#include <grpcpp/grpcpp.h>
 
#ifdef BAZEL_BUILD
#include "examples/protos/helloworld.grpc.pb.h"
#else
#include "helloworld.grpc.pb.h"
#endif
 
ABSL_FLAG(std::string, target, "xds:///helloworld:50051", "Target string");
ABSL_FLAG(bool, secure, true, "Secure mode");
 
using grpc::Channel;
using grpc::ClientContext;
using grpc::Status;
using helloworld::Greeter;
using helloworld::HelloReply;
using helloworld::HelloRequest;
 
class GreeterClient {
 public:
  GreeterClient(std::shared_ptr<Channel> channel)
      : stub_(Greeter::NewStub(channel)) {}
 
  // Assembles the client's payload, sends it and presents the response back
  // from the server.
  std::string SayHello(const std::string& user) {
    // Data we are sending to the server.
    HelloRequest request;
    request.set_name(user);
 
    // Container for the data we expect from the server.
    HelloReply reply;
 
    // Context for the client. It could be used to convey extra information to
    // the server and/or tweak certain RPC behaviors.
    ClientContext context;
 
    // The actual RPC.
    Status status = stub_->SayHello(&context, request, &reply);
 
    // Act upon its status.
    if (status.ok()) {
      return reply.message();
    } else {
      std::cout << status.error_code() << ": " << status.error_message()
                << std::endl;
      return "RPC failed";
    }
  }
 
 private:
  std::unique_ptr<Greeter::Stub> stub_;
};
 
int main(int argc, char** argv) {
  absl::ParseCommandLine(argc, argv);
  GreeterClient greeter(grpc::CreateChannel(
      absl::GetFlag(FLAGS_target), absl::GetFlag(FLAGS_secure)
                                       ? grpc::experimental::XdsCredentials(
                                             grpc::InsecureChannelCredentials())
                                       : grpc::InsecureChannelCredentials()));
  std::string user("world");
  std::string reply = greeter.SayHello(user);
  std::cout << "Greeter received: " << reply << std::endl;
 
  return 0;
}