Grpc.Core.RpcException method is unimplemented with C# client and Java Server

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I am having trouble finding the source of this error. I implemented a simple service using protobuf:

syntax = "proto3";

package tourism;

service RemoteService {
  rpc Login(LoginUserDTO) returns (Response) {}
}

message AgencyDTO{
  int32 id=1;
  string name=2;
  string email=3;
  string password=4;
}

message LoginUserDTO{
  string password=1;
  string email=2;
}

message SearchAttractionsDTO{
  string name=1;
  int32 start_hour=2;
  int32 start_minute=3;
  int32 stop_hour=4;
  int32 stop_minute=5;
  AgencyDTO loggedUser=6;
}

message AttractionDTO{
  int32 id=1;
  string name=2;
  string agency=3;
  int32 hour=4;
  int32 minute=5;
  int32 seats=6;
  int32 price=7;
}

message ReservationDTO{
  int32 id=1;
  string first_name=2;
  string last_name=3;
  string phone=4;
  int32 seats=5;
  AttractionDTO attraction=6;
  AgencyDTO agency=7;
}

message Response{
  enum ResponseType{
    OK=0;
    NOT_LOGGED_ID=1;
    SERVER_ERROR=2;
    VALIDATOR_ERROR=3;
  }
  ResponseType type=1;
  AgencyDTO user=2;
  string message=3;
}

When using a java client everything works fine, the server receives the request and responds appropriately. When using C# with the same .proto file for generating sources at the client.Login() I get the following errror: Grpc.Core.RpcException Status(StatusCode=Unimplemented, Detail="Method tourism.RemoteService/Login is unimplemented"). The server receives the request but does not have time to respond and throws:

INFO: Request from ex@ex.com
May 22, 2017 12:28:58 AM io.grpc.internal.SerializingExecutor run
SEVERE: Exception while executing runnable io.grpc.internal.ServerImpl$JumpToApplicationThreadServerStreamListener$2@4be43082
java.lang.IllegalStateException: call is closed
    at com.google.common.base.Preconditions.checkState(Preconditions.java:174)
    at io.grpc.internal.ServerCallImpl.sendHeaders(ServerCallImpl.java:103)
    at io.grpc.stub.ServerCalls$ServerCallStreamObserverImpl.onNext(ServerCalls.java:282)
    at ServiceImp.login(ServiceImp.java:20)
    at tourism.RemoteServiceGrpc$MethodHandlers.invoke(RemoteServiceGrpc.java:187)
    at io.grpc.stub.ServerCalls$1$1.onHalfClose(ServerCalls.java:148)
    at io.grpc.internal.ServerCallImpl$ServerStreamListenerImpl.halfClosed(ServerCallImpl.java:262)
    at io.grpc.internal.ServerImpl$JumpToApplicationThreadServerStreamListener$2.runInContext(ServerImpl.java:572)
    at io.grpc.internal.ContextRunnable.run(ContextRunnable.java:52)
    at io.grpc.internal.SerializingExecutor.run(SerializingExecutor.java:117)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at java.lang.Thread.run(Thread.java:745)

Java server:

import io.grpc.Server;
import io.grpc.ServerBuilder;
import io.grpc.stub.StreamObserver;
import tourism.RemoteServiceGrpc;
import tourism.Service;

import java.io.IOException;
import java.util.logging.Level;
import java.util.logging.Logger;

/**
 * Created by Andu on 21/05/2017.
 */
public class ServerGrpc {
    Logger logger= Logger.getLogger(ServerGrpc.class.getName());
    private final Server server;
    private final int port;

    public ServerGrpc(int p){
        port=p;
        server= ServerBuilder.forPort(port).addService(new ServiceImp()).build();
    }

    public void start() throws IOException {
        server.start();
        logger.info("Server started, listening on " + port);
        Runtime.getRuntime().addShutdownHook(new Thread() {
            @Override
            public void run() {
                // Use stderr here since the logger may has been reset by its JVM shutdown hook.
                System.err.println("*** shutting down gRPC server since JVM is shutting down");
                ServerGrpc.this.stop();
                System.err.println("*** server shut down");
            }
        });
    }

    public void stop() {
        if (server != null) {
            server.shutdown();
        }
    }

    void blockUntilShutdown() throws InterruptedException {
        if (server != null) {
            server.awaitTermination();
        }
    }

    private class ServiceImp extends RemoteServiceGrpc.RemoteServiceImplBase {
        Logger log=Logger.getLogger(ServiceImp.class.getName());

        @Override
        public void login(Service.LoginUserDTO request, StreamObserver<Service.Response> responseStreamObserver){
            super.login(request,responseStreamObserver);
            log.log(Level.INFO,"Request from "+request.getEmail());
            Service.Response response= Service.Response.newBuilder().setMessage("Hello "+request.getEmail()+", I know your password: "+request.getPassword()).build();
            responseStreamObserver.onNext(response);
            responseStreamObserver.onCompleted();
        }
    }

}

C# Client:

namespace testGrpc2
{
    class MainClass
    {
        public static void Main(string[] args)
        {
            var channel = new Channel("127.0.0.1:61666",ChannelCredentials.Insecure);
            var client = new RemoteService.RemoteServiceClient(channel);
            Response response=client.Login(new LoginUserDTO{Email="ex@ex.com",Password="notmypassword"});
            Console.WriteLine(response);
            Console.ReadKey();
        }
    }
} 
5 Answers

For me it was that I forget adding endpoint of gRpc service in startup class.

    public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
    {
        if (env.IsDevelopment())
        {
            app.UseDeveloperExceptionPage();
        }

        app.UseRouting();

        app.UseEndpoints(endpoints =>
        {
            endpoints.MapGrpcService<GreeterService>();

            //Add your endpoint here like this
            endpoints.MapGrpcService<YourProtoService>();
        });
    

For me, using the C# client, the problem was that I wasn't overriding the generated service method.

Thanks to Alexandru - this helped solve my problem with Akka gRPC client and Python grPC server. In my case, I had same packages and preamble in .proto file but had eliminated message classes and gRPC functions not needed for this specific use case in the Python gRPC server. When I made the .proto files identical, everything worked and I no longer received UNIMPLEMENTED errors. This is needed for languages beyond the C#/Java example cited. Thanks again.

My server and client were both java, and the problem was removed after closing and opening the project in IntelliJ!!

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