Service Fabric wcf communication between microservices

Question

I'm trying to make a simple communication between two microservices. So far as a receiver

protected override IEnumerable<ServiceInstanceListener> CreateServiceInstanceListeners()
    {

        return new[]
        {
            new ServiceInstanceListener((context) =>
                new WcfCommunicationListener<ITest>(
                    wcfServiceObject: new Test(),
                    serviceContext: context,
                    endpointResourceName: "ProgramTestEndpoint",
                    listenerBinding: WcfUtility.CreateTcpListenerBinding()
                ),
                name: "ProgramTestListener"
            )
        };
    }

    public class Test : ITest
{
    public async Task<int> ReturnsInt()
    {
        return 2;
    }
}

 [ServiceContract]
public interface ITest
{
    [OperationContract]
    Task<int> ReturnsInt();


}

And I did add to service manifest the endpoint.

<Endpoint Name ="ProgramTestEndpoint"/>

The microservice that wants to communicate has this code

 protected override async Task RunAsync(CancellationToken cancellationToken)
    {
        // TODO: Replace the following sample code with your own logic 
        //       or remove this RunAsync override if it's not needed in your service.

        await Task.Delay(5000);

        CloudClient<ITest> transactionCoordinator = new CloudClient<ITest>
       (
           serviceUri: new Uri($"{Context.CodePackageActivationContext.ApplicationName}/MyStateless"),
           partitionKey: new ServicePartitionKey(0),
           clientBinding: WcfUtility.CreateTcpClientBinding(),
           listenerName: "MyStateless"
       );


        int iterations = await transactionCoordinator.InvokeWithRetryAsync(client => client.Channel.ReturnsInt());
        ServiceEventSource.Current.ServiceMessage(this.Context, "Test-{0}", ++iterations);
        while (true)
        {
            cancellationToken.ThrowIfCancellationRequested();

            ServiceEventSource.Current.ServiceMessage(this.Context, "Working-{0}", ++iterations);

            await Task.Delay(TimeSpan.FromSeconds(1), cancellationToken);
        }
    }

This is my first project in service fabric, I'm not sure what I'm doing wrong, but with this code the application can't receive the return value of the ReturnsInt task.

I tried to debug it and it seems like it can't connect to the other microservice, it look like it is stuck in an infinite loop trying to hit the method. — Anđela Krstić, Jul 03 '20 at 21:06
Would it make any difference to use `partitionKey: ServicePartitionKey.Singleton`? — Oliver, Jul 04 '20 at 10:48

score 1 · Accepted Answer · answered Jul 05 '20 at 17:47

When creating a connection to a stateless service, you should use the ServicePartitionKey.Singleton partition key. In some cases you you don't need to specify one at all, for example when using ServiceProxyFactory to create a connection to a stateless service.

Using new ServicePartitionKey(0) was causing the client to try and connect to an endpoint that didn't exist.

Service Fabric wcf communication between microservices

1 Answers1