Async two-way communication with Windows Named Pipes (.Net)

Question

I have a windows service and a GUI that need to communicate with each other. Either can send messages at any time.

I'm looking at using NamedPipes, but it seems that you cant read & write to the stream at the same time (or at least I cant find any examples that cover this case).

Is it possible to do this kind of two-way communication via a single NamedPipe? Or do I need to open two pipes (one from GUI->service and one from service->GUI)?

Answer 1

Using WCF you can use duplex named pipes

// Create a contract that can be used as a callback
public interface IMyCallbackService
{
    [OperationContract(IsOneWay = true)]
    void NotifyClient();
}

// Define your service contract and specify the callback contract
[ServiceContract(CallbackContract = typeof(IMyCallbackService))]
public interface ISimpleService
{
    [OperationContract]
    string ProcessData();
}

Implement the Service

[ServiceBehavior(InstanceContextMode=InstanceContextMode.PerCall)]
public class SimpleService : ISimpleService
{
    public string ProcessData()
    {
        // Get a handle to the call back channel
        var callback = OperationContext.Current.GetCallbackChannel<IMyCallbackService>();

        callback.NotifyClient();
        return DateTime.Now.ToString();
    }
}

Host the Service

class Server
{
    static void Main(string[] args)
    {
        // Create a service host with an named pipe endpoint
        using (var host = new ServiceHost(typeof(SimpleService), new Uri("net.pipe://localhost")))
        {
            host.AddServiceEndpoint(typeof(ISimpleService), new NetNamedPipeBinding(), "SimpleService");
            host.Open();

            Console.WriteLine("Simple Service Running...");
            Console.ReadLine();

            host.Close();
        }
    }
}

Create the client application, in this example the Client class implements the call back contract.

class Client : IMyCallbackService
{
    static void Main(string[] args)
    {
        new Client().Run();
    }

    public void Run()
    {
        // Consume the service
        var factory = new DuplexChannelFactory<ISimpleService>(new InstanceContext(this), new NetNamedPipeBinding(), new EndpointAddress("net.pipe://localhost/SimpleService"));
        var proxy = factory.CreateChannel();

        Console.WriteLine(proxy.ProcessData());
    }

    public void NotifyClient()
    {
        Console.WriteLine("Notification from Server");
    }
}