Since it is not possible to catch regular exception from a WCF service in a silverlight application, there is another way to do it by using BehaviorExtensionElement.
1. On Server-side First create a behavior like this:
public class MyFaultBehavior : BehaviorExtensionElement, IEndpointBehavior
{
public void ApplyDispatchBehavior(ServiceEndpoint endpoint, EndpointDispatcher endpointDispatcher)
{
SilverlightFaultMessageInspector inspector = new SilverlightFaultMessageInspector();
endpointDispatcher.DispatchRuntime.MessageInspectors.Add(inspector);
}
public class SilverlightFaultMessageInspector : IDispatchMessageInspector
{
public void BeforeSendReply(ref Message reply, object correlationState)
{
if (reply.IsFault)
{
HttpResponseMessageProperty property = new HttpResponseMessageProperty();
// Here the response code is changed to 200.
property.StatusCode = System.Net.HttpStatusCode.OK;
reply.Properties[HttpResponseMessageProperty.Name] = property;
}
}
public object AfterReceiveRequest(ref Message request, IClientChannel channel, InstanceContext instanceContext)
{
// Do nothing to the incoming message.
return null;
}
}
// The following methods are stubs and not relevant.
public void AddBindingParameters(ServiceEndpoint endpoint, BindingParameterCollection bindingParameters)
{
}
public void ApplyClientBehavior(ServiceEndpoint endpoint, ClientRuntime clientRuntime)
{
}
public void Validate(ServiceEndpoint endpoint)
{
}
public override System.Type BehaviorType
{
get { return typeof(MyFaultBehavior); }
}
protected override object CreateBehavior()
{
return new MyFaultBehavior();
}
}
2. On Server-side Modify you web.config:
<system.serviceModel>
<!--Add a behavior extension within the service model-->
<extensions>
<behaviorExtensions>
<add name="myFault" type="SilverlightWCF.Web.MyFaultBehavior, SilverlightWCF.Web, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null"/>
</behaviorExtensions>
</extensions>
<behaviors>
<!--Add a endpointBehavior below the behaviors-->
<endpointBehaviors>
<behavior name="myFaultBehavior">
<myFault/>
</behavior>
</endpointBehaviors>
<serviceBehaviors>
<behavior name="SilverlightWCF.Web.MyCoolServiceBehavior">
<serviceMetadata httpGetEnabled="true"/>
<!--For debugging, it might be cool to have some more error information.
to get this, set includeExceptionDetailInFaults to true-->
<serviceDebug includeExceptionDetailInFaults="true"/>
</behavior>
</serviceBehaviors>
</behaviors>
...
<serviceHostingEnvironment aspNetCompatibilityEnabled="true"/>
<services>
<service behaviorConfiguration="SilverlightWCF.Web.MyCoolServiceBehavior" name="SilverlightWCF.Web.MyCoolService">
<!--Set the behaviorConfiguration of the endpoint-->
<endpoint address="" binding="customBinding" bindingConfiguration="customBinding0" contract="SilverlightWCF.Web.MyCoolService" behaviorConfiguration="myFaultBehavior"/>
<endpoint address="mex" binding="mexHttpBinding" contract="IMetadataExchange"/>
</service>
</services>
</system.serviceModel>
3. On Server-side Throw you FaultException
[OperationContract]
public void Foo()
{
throw new FaultException("this is my Exception");
}
4. On Client-side Catch the Exception like this:
void serviceClient_FooCompleted(object sender, System.ComponentModel.AsyncCompletedEventArgs e)
{
if (e.Error == null)
{
// In case of success
}
else if (e.Error is FaultException)
{
FaultException fault = e.Error as FaultException;
string text = e.Error.Message;
}
}
via http://www.codeproject.com/KB/silverlight/SilverlightWCFService.aspx
Vincent Leung .NET Tech Clips 