Magic 8 Ball

Magic 8 ball shows an answer it receives from a server:

Magic 8 ball has the following components:

• magic8ball Qt GRPC client application that includes the qt_add_protobuf() and qt_add_grpc() CMake functions for message and service Qt code generation.
• SimpleGrpcServer application that calls C++ gRPC plugin for generating server code and implementing simple server logic.

Both components use generated messages from the protobuf schema described in the exampleservice.proto file:

syntax = "proto3";

package qtgrpc.examples;

message AnswerRequest {
    string message = 1;
}

message AnswerResponse {
    string message = 1;
}

service ExampleService {
    rpc answerMethod(AnswerRequest) returns (AnswerResponse) {}
}

The client application connects to the localhost with port 50051:

            id: channelOptions
            host: "http://localhost:50051"

And sends a request to the server part:

    function sendRequest()
    {
        grpcClient.answerMethod(_answerReq, setResponse, errorCallback)
    }

Click the Ask question button to send the request to the SimpleGrpcServer application.

The SimpleGrpcServer application chooses a random answer from the list of answers and sends the data to the client's port.

Status ExampleServiceServiceImpl::answerMethod(grpc::ServerContext *,
                                               const AnswerRequest *request,
                                               AnswerResponse *response)
{
    if (request->message() == "sleep")
        QThread::msleep(2000);

    response->set_message(std::string(answers[generateRandomIndex()]));
    return Status();
}

After receiving a response the client application shows the answer.

Example project @ code.qt.io