WaveClientRpc.ProtocolWaveClientRpc.Stub stub =
WaveClientRpc.ProtocolWaveClientRpc.newStub(client);
// Create a controller, set up request, wait for responses.
RpcController controller = client.newRpcController();
ProtocolOpenRequest request =
ProtocolOpenRequest.newBuilder().setParticipantId(USER).setWaveId(WAVE).build();
stub.open(controller, request, new RpcCallback<ProtocolWaveletUpdate>() {
@Override
public void run(ProtocolWaveletUpdate response) {
responses.add(response);