Question

Could you please tell me why duplex communication with TcpTransportBindingElement doesn’t work in my Metro application ?

According to this document Metro subset of .Net Framework supports TCP binding.

So I wrote WCF server as console application. Here is source code:

static void Main()
{
    UiWcfSession.OnInitialize += ClientInitialize;

    var baseAddresses = new Uri("net.tcp://localhost:9000/");

    var host = new ServiceHost(typeof(UiWcfSession), baseAddresses);

    var reliableSession = new ReliableSessionBindingElement { Ordered = true, InactivityTimeout = TimeSpan.MaxValue };
    var binding =
        new CustomBinding(reliableSession, new TcpTransportBindingElement()) { ReceiveTimeout = TimeSpan.MaxValue };

    host.AddServiceEndpoint(typeof(IClientFulfillmentPipeService), binding, "");

    var metadataBehavior = new ServiceMetadataBehavior();
    host.Description.Behaviors.Add(metadataBehavior);
    var mexBinding = MetadataExchangeBindings.CreateMexTcpBinding();
    host.AddServiceEndpoint(typeof(IMetadataExchange), mexBinding, "mex");

    host.Open();

    Thread.CurrentThread.Join();
}

private static void ClientInitialize(int uiprocessid, string key)
{
    Debug.WriteLine("ClientInitialize");
}

and here is client code in Metro app:

partial class MainPage
{
    public MainPage()
    {
        InitializeComponent();
    }

    private void onclick(object sender, RoutedEventArgs e)
    {
        try
        {
            var ep = new EndpointAddress("net.tcp://localhost:9000/");
            var binding = new CustomBinding(new TcpTransportBindingElement());
            var ctx = new InstanceContext(new Wrapper());
            var pipeFactory = new DuplexChannelFactory<IClientFulfillmentPipeService>(ctx, binding, ep);
            IClientFulfillmentPipeService commChannel = pipeFactory.CreateChannel();

            // open up the the comm channel with a reasonable timeout...
            ((IChannel)commChannel).Open();

            commChannel.Initialize(1234, "Test");

            ((IChannel)commChannel).Close();
        }
        catch (Exception ex)
        {
            Debug.WriteLine(ex.Message);
        }
    }
}

So it kinda works. But when I walk step by step in the debugger in Metro app it hangs and never returns from the function commChannel.Initialize.

Why is it happening ? What am I missing ?

Answer 1

Turns out I can’t use synchronous client in Metro. I have to use asynchronous calls. That’s why it didn’t work.