Asynchronously consume synchronous WCF service

Question

I’m currently in the process of migrating a client application over to .NET 4.5 to make use of async/await. The application is a client for a WCF service which currently off

Answer 1

The client side and server side are totally separate from an async standpoint, they do not care about each other at all. You should have your sync function on your sever and only the sync function on your server.

If you want to do it "right", on the client you will not be able to reuse the same interface for your generating your channel factory as the interface that is used to generate the server.

So your server side would look like this

using System.ServiceModel;
using System.Threading;

namespace WcfService
{
    [ServiceContract]
    public interface IService
    {
        [OperationContract]
        string GetTest();
    }

    public class Service1 : IService
    {
        public string GetTest()
        {
            Thread.Sleep(2000);
            return "foo";
        }
    }
}

and your client side would look like this

using System;
using System.Diagnostics;
using System.ServiceModel;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace SandboxForm
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();

            var button = new Button();
            this.Controls.Add(button);

            button.Click += button_Click;
        }

        private async void button_Click(object sender, EventArgs e)
        {
            var factory = new ChannelFactory("SandboxForm.IService"); //Configured in app.config
            IService proxy = factory.CreateChannel();

            string result = await proxy.GetTestAsync();

            MessageBox.Show(result);
        }
    }

    [ServiceContract]
    public interface IService
    {
        [OperationContract(Action = "http://tempuri.org/IService/GetTest", ReplyAction = "http://tempuri.org/IService/GetTestResponse")]
        Task GetTestAsync();
    }
}