How to implement an async wcf client for a synchronous service - wcf

Question

Is there a way to create an async client for a synchronous WCF service without adding a service reference? This is for a .NET 4 client.

Answer 1

A service reference in Visual Studio is nothing else than a code generator that creates a proxy class with corresponding data elements necessary to call your web service. Of course you can hand build a proxy if you really want to go over tedious and boring work.
Maybe start by decompiling System.ServiceModel.ClientBase using .net reflector?
Do some research on ChannelFactory: http://msdn.microsoft.com/en-us/library/system.servicemodel.channelfactory.aspx
Even when implementing my own client by wrapping a ChannelFactory, I am still using the Add Service reference in another project to create the class definitions and move them into the real project. That's a good compromise.
Here's a simple async service interface:
[ServiceContract(Name = "IService")]
public interface IServiceAsync
{
[OperationContract(AsyncPattern = true)]
IAsyncResult BeginGetStuff(string someData, AsyncCallback callback, object state);
IEnumerable<Stuff> EndGetStuff(IAsyncResult result);
}
The .NET contract might look like this:
[ServiceContract]
public interface IService
{
[OperationContract]
IEnumerable<Stuff> GetStuff(string someData);
}
Then in code, assuming you use HTTP, No security and binary message encoding, something like this (Sorry I haven't compiled any of this, just typed it using some of the code I have written for projects):
//Create a binding for the proxy to use
HttpTransportBindingElement httpTransportBindingElement;
httpTransportBindingElement = new HttpTransportBindingElement();
absoluteServiceUri = new Uri(absoluteServiceUri.OriginalString + BinaryEndpointUri, UriKind.Absolute);
}
//Create the message encoding binding element - we'll specify binary encoding
var binaryMessageEncoding = new BinaryMessageEncodingBindingElement();
//Add the binding elements into a Custom Binding
var customBinding = new CustomBinding(binaryMessageEncoding, httpTransportBindingElement);
// Set send timeout
customBinding.SendTimeout = this.SendTimeout;
var factory = new ChannelFactory<IServiceAsync>(customBinding, new EndpointAddress(absoluteServiceUri, new AddressHeader[0]));
var channel = factory.CreateChannel();
channel.BeginGetStuff(Bla, results => { // Do something }, null);