Exception Logging for WCF Services using ELMAH

The solution from my blog post (referenced in the OP) was based on an existing solution we were/are using to alter HTTP Response Codes during an error state.

So, for us it was a one-line change to pass the Exception to ELMAH. If there's a better solution, I'd love to know about it too.

For Posterity/Reference, and potential improvement - here's the code from the current solution.

HttpErrorHandler and ServiceErrorBehaviourAttribute Classes

using System;using System.ServiceModel;using System.ServiceModel.Dispatcher;using System.ServiceModel.Channels;using System.ServiceModel.Description;using System.Collections.ObjectModel;using System.Net;using System.Web;using Elmah;namespace YourApplication{    /// <summary>    /// Your handler to actually tell ELMAH about the problem.    /// </summary>    public class HttpErrorHandler : IErrorHandler    {        public bool HandleError(Exception error)        {            return false;        }        public void ProvideFault(Exception error, MessageVersion version, ref Message fault)        {            if (error != null ) // Notify ELMAH of the exception.            {                if (System.Web.HttpContext.Current == null)                    return;                Elmah.ErrorSignal.FromCurrentContext().Raise(error);            }        }    }    /// <summary>    /// So we can decorate Services with the [ServiceErrorBehaviour(typeof(HttpErrorHandler))]    /// ...and errors reported to ELMAH    /// </summary>    public class ServiceErrorBehaviourAttribute : Attribute, IServiceBehavior    {        Type errorHandlerType;        public ServiceErrorBehaviourAttribute(Type errorHandlerType)        {            this.errorHandlerType = errorHandlerType;        }        public void Validate(ServiceDescription description, ServiceHostBase serviceHostBase)        {        }        public void AddBindingParameters(ServiceDescription description, ServiceHostBase serviceHostBase, Collection<ServiceEndpoint> endpoints, BindingParameterCollection parameters)        {        }        public void ApplyDispatchBehavior(ServiceDescription description, ServiceHostBase serviceHostBase)        {            IErrorHandler errorHandler;            errorHandler = (IErrorHandler)Activator.CreateInstance(errorHandlerType);            foreach (ChannelDispatcherBase channelDispatcherBase in serviceHostBase.ChannelDispatchers)            {                ChannelDispatcher channelDispatcher = channelDispatcherBase as ChannelDispatcher;                channelDispatcher.ErrorHandlers.Add(errorHandler);            }        }    }}

Usage Example

Decorate your WCF Services with the ServiceErrorBehaviour Attribute:

[ServiceContract(Namespace = "http://example.com/api/v1.0/")][ServiceErrorBehaviour(typeof(HttpErrorHandler))]public class MyServiceService{  // ...}

When creating a BehaviorExtensionElement it is even possible to activate the behavior using config:

public class ErrorBehaviorExtensionElement : BehaviorExtensionElement{    public override Type BehaviorType    {        get { return typeof(ServiceErrorBehaviourAttribute); }    }    protected override object CreateBehavior()    {        return new ServiceErrorBehaviourAttribute(typeof(HttpErrorHandler));    }}

Config:

<system.serviceModel>    <extensions>      <behaviorExtensions>        <add name="elmah" type="Namespace.ErrorBehaviorExtensionElement, YourAssembly, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null"/>      </behaviorExtensions>    </extensions>    <behaviors>      <serviceBehaviors>        <behavior>          <elmah />        </behavior>      </serviceBehaviors>    </behaviors>  </system.serviceModel>

That way it is also possible to use ELMAH in combination with RIA services!

This may well be obvious to some people but I just spent quite a while trying to figure out why my HttpContext.Current was null despite following all of Will Hughes' excellent answer. Embarassingly, I realised that this was because my WCF service is activated by a MSMQ message.

I ended up rewriting the ProvideFault() method:

if (HttpContext.Current == null){    ErrorLog.GetDefault(null).Log(new Error(error));}else{    ErrorSignal.FromCurrentContext().Raise(error);}