| /* |
| * |
| * Copyright 2015 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 <grpcpp/grpcpp.h> |
| #include <grpc/support/log.h> |
| |
| #ifdef BAZEL_BUILD |
| #include "examples/protos/helloworld.grpc.pb.h" |
| #else |
| #include "helloworld.grpc.pb.h" |
| #endif |
| |
| using grpc::Channel; |
| using grpc::ClientAsyncResponseReader; |
| using grpc::ClientContext; |
| using grpc::CompletionQueue; |
| using grpc::Status; |
| using helloworld::HelloRequest; |
| using helloworld::HelloReply; |
| using helloworld::Greeter; |
| |
| class GreeterClient { |
| public: |
| explicit 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 producer-consumer queue we use to communicate asynchronously with the |
| // gRPC runtime. |
| CompletionQueue cq; |
| |
| // Storage for the status of the RPC upon completion. |
| Status status; |
| |
| // stub_->PrepareAsyncSayHello() creates an RPC object, returning |
| // an instance to store in "call" but does not actually start the RPC |
| // Because we are using the asynchronous API, we need to hold on to |
| // the "call" instance in order to get updates on the ongoing RPC. |
| std::unique_ptr<ClientAsyncResponseReader<HelloReply> > rpc( |
| stub_->PrepareAsyncSayHello(&context, request, &cq)); |
| |
| // StartCall initiates the RPC call |
| rpc->StartCall(); |
| |
| // Request that, upon completion of the RPC, "reply" be updated with the |
| // server's response; "status" with the indication of whether the operation |
| // was successful. Tag the request with the integer 1. |
| rpc->Finish(&reply, &status, (void*)1); |
| void* got_tag; |
| bool ok = false; |
| // Block until the next result is available in the completion queue "cq". |
| // The return value of Next should always be checked. This return value |
| // tells us whether there is any kind of event or the cq_ is shutting down. |
| GPR_ASSERT(cq.Next(&got_tag, &ok)); |
| |
| // Verify that the result from "cq" corresponds, by its tag, our previous |
| // request. |
| GPR_ASSERT(got_tag == (void*)1); |
| // ... and that the request was completed successfully. Note that "ok" |
| // corresponds solely to the request for updates introduced by Finish(). |
| GPR_ASSERT(ok); |
| |
| // Act upon the status of the actual RPC. |
| if (status.ok()) { |
| return reply.message(); |
| } else { |
| return "RPC failed"; |
| } |
| } |
| |
| private: |
| // Out of the passed in Channel comes the stub, stored here, our view of the |
| // server's exposed services. |
| std::unique_ptr<Greeter::Stub> stub_; |
| }; |
| |
| int main(int argc, char** argv) { |
| // Instantiate the client. It requires a channel, out of which the actual RPCs |
| // are created. This channel models a connection to an endpoint (in this case, |
| // localhost at port 50051). We indicate that the channel isn't authenticated |
| // (use of InsecureChannelCredentials()). |
| GreeterClient greeter(grpc::CreateChannel( |
| "localhost:50051", grpc::InsecureChannelCredentials())); |
| std::string user("world"); |
| std::string reply = greeter.SayHello(user); // The actual RPC call! |
| std::cout << "Greeter received: " << reply << std::endl; |
| |
| return 0; |
| } |