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.
you need the C++ gRPC plugin installed. Find details here: Module prerequisites
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 binds on the localhost with port 50051:
QUrl url("http://localhost:50051", QUrl::StrictMode);
m_client->attachChannel(std::make_shared<QGrpcHttp2Channel>(url,
QGrpcInsecureChannelCredentials()
| QGrpcInsecureCallCredentials()));And sends a request to the server part:
void ClientService::sendRequest()
{
// clean error on UI before new request
emit errorRecieved("");
AnswerRequest request;
request.setMessage("sleep");
m_client->answerMethod(request, m_response.get());
}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.