Best way to catch a WCF exception in Silverlight?

Question

I have a Silverlight 2 application that is consuming a WCF service. As such, it uses asynchronous callbacks for all the calls to the methods of the service. If the service

Answer 1

Using a custom WCF Proxy generator is a good solution to handle asynchronous exceptions in Silver-light.Click here to download source code.

Answer 2

I found a forum thread that was talking about this, and it mentions that the best practice is to use the Error property. Between this thread and my own experiences, this is what I can conclude:

• In normal .NET code, the generated proxy class handles the exception properly by putting the exception in the Error property instead of throwing it.

• In Silverlight, the generated proxy class sets the Error property, but does not handle the exception completely. The exception is picked up by the debugger, which pops up the exception box with the message "ProtocolException was unhandled by user code". Despite this message, the exception does not seem to actually make it to the Application_UnhandledException function.

I'd expect that this is one of the things they will fix in the final release.

For now, I will use the Error property and just deal with the debugger breaking execution. If it gets too annoying, I can turn off the break on exception for ProtocolException.

Answer 3

I'm not a plumber, so I decided to create my own WCF service class that overrides some of the functionality of the class file "reference.cs" that is automatically generated by Visual Studio, I then added my own try/catch blocks to catch communication errors.

The class I created looks something like this:

public class myWCFService : MyWCFServiceClient
{

    protected override MyController.MyService.IMyWCFService CreateChannel()
    {
        return new MyWCFServiceClientChannel(this);
    }

}

private class MyWCFServiceClientChannel : ChannelBase<MyController.MyService.IMyWCFService>, MyController.MyService.IMyWCFService
{
    /// <summary>
    /// Channel Constructor
    /// </summary>
    /// <param name="client"></param>
    public MyWCFServiceClientChannel(System.ServiceModel.ClientBase<MyController.MyService.IMyWCFService> client) :
    base(client)
    {
    }
    /// <summary>
    /// Begin Call To RegisterUser
    /// </summary>
    /// <param name="memberInformation"></param>
    /// <param name="callback"></param>
    /// <param name="asyncState"></param>
    /// <returns></returns>
    public System.IAsyncResult BeginRegisterUser(MyDataEntities.MembershipInformation memberInformation, System.AsyncCallback callback, object asyncState)
    {               
        object[] _args = new object[1];
        _args[0] = memberInformation;
        System.IAsyncResult _result = base.BeginInvoke("RegisterUser", _args, callback, asyncState);
        return _result;               
    }
    /// <summary>
    /// Result from RegisterUser
    /// </summary>
    /// <param name="result"></param>
    /// <returns></returns>
    public MyDataEntities.MembershipInformation EndRegisterUser(System.IAsyncResult result)
    {
        try
        {
            object[] _args = new object[0];
            MyDataEntities.MembershipInformation _result = ((MyDataEntities.MembershipInformation)(base.EndInvoke("RegisterUser", _args, result)));
            return _result;
        }
         catch (Exception ex)
        {
            MyDataEntities.MembershipInformation _result = new MyDataEntities.MembershipInformation();
            _result.ValidationInformation.HasErrors = true;
            _result.ValidationInformation.Message = ex.Message;
            return _result;
        }
    }
}