Health Monitoring and WCF

Question

I'd like to use Health Monitoring to log unhandled exceptions that I trap in my own Error Handler:

public class MyErrorHandler : IErrorHandler, IServiceBehavior
{
    #region IServiceBehavior Members
    public void AddBindingParameters(ServiceDescription serviceDescription, System.ServiceModel.ServiceHostBase serviceHostBase, System.Collections.ObjectModel.Collection<serviceendpoint> endpoints, BindingParameterCollection bindingParameters)
    {
    }

    public void ApplyDispatchBehavior(ServiceDescription serviceDescription, System.ServiceModel.ServiceHostBase serviceHostBase)
    {
        IErrorHandler errorHandler = new VirusInfoErrorHandler();

        foreach (ChannelDispatcherBase channelDispatcherBase in serviceHostBase.ChannelDispatchers)
        {
            ChannelDispatcher channelDispatcher = channelDispatcherBase as ChannelDispatcher;

            if (channelDispatcher != null)
            {
                channelDispatcher.ErrorHandlers.Add(errorHandler);
            }
        }
    }

    public void Validate(ServiceDescription serviceDescription, System.ServiceModel.ServiceHostBase serviceHostBase)
    {
    }

    #endregion

    #region IErrorHandler Members

    public bool HandleError(Exception ex)
    {
        MyErrorEvent l_errEvt = new MyErrorEvent("Oh Noes!", this, WebEventCodes.WebExtendedBase + 2, ex);

        // Always throws a "Value does not fall within the expected range" ArgumentException.
        l_errEvt.Raise();                

        return true;
    }

    public void ProvideFault(Exception error, MessageVersion version, ref Message fault)
    {
    }

    #endregion    
}</serviceendpoint>

public MyErrorEvent(string message, object eventSource, int eventCode, Exception exception)
    : base(message, eventSource, WebEventCodes.WebExtendedBase + eventCode, exception)
{
            
}

public override void FormatCustomEventDetails(WebEventFormatter formatter)
{
    if (formatter == null)
    {
        throw new ArgumentNullException("formatter", "Please supply a valid formatter object.");
    }

    try
    {
        base.FormatCustomEventDetails(formatter);

        formatter.AppendLine("this was a bad error");
    }
    catch (Exception ex)
    {

    }
}

I've created a very simple custom WebRequestErrorEvent (see above).

The exception's stack trace is:

at System.Runtime.InteropServices.Marshal.ThrowExceptionForHRInternal(Int32 errorCode, IntPtr errorInfo)
at System.Web.Hosting.IIS7WorkerRequest.GetServerVariableInternal(String name)
at System.Web.HttpRequest.get_UrlInternal()
at System.Web.Management.WebRequestInformation..ctor()
at System.Web.Management.WebRequestErrorEvent.PreProcessEventInit()
at System.Web.Management.WebBaseEvent.RaiseInternal(WebBaseEvent eventRaised, ArrayList firingRuleInfos, Int32 index0, Int32 index1)
at System.Web.Management.WebBaseEvent.Raise(WebBaseEvent eventRaised)
at System.Web.Management.WebBaseEvent.Raise()
at ACME.MyErrorHandler.HandleError(Exception ex) in G:\Code\MySvc\Lib\ACME.ErrorHandler\MyErrorHandler.cs:line 78
at System.ServiceModel.Dispatcher.ErrorBehavior.HandleErrorCommon(Exception error, ErrorHandlerFaultInfo& faultInfo)

Can a WebRequestErrorEvent not be used with WCF?  I can raise WebRequestEvents in non-Exception scenarios (ex: informational) with no problems, but not WebRequestErrorEvents.

Answer 1

Hello, I haven't used WebRequestErrorEvent. What error code do you get in ThrowExceptionForHRInternal? Just a wild guess, try to enable ASP.NET compatibility mode if you haven't, as this class seems to be an ASP.NET class.

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Answer 2

I have enabled ASP.NET Compatibility Mode in both my web.config:

<serviceHostingEnvironment aspNetCompatibilityEnabled="true" />

and the service itself:

[AspNetCompatibilityRequirements(RequirementsMode = AspNetCompatibilityRequirementsMode.Allowed)]
[ServiceBehavior(InstanceContextMode = InstanceContextMode.PerCall, ConcurrencyMode = ConcurrencyMode.Multiple)]

Interestingly, if I create a custom WebRequestEvent and add a parameter to its constructor for an Exception, the result is the same as with my custom WebRequestErrorEvent.

Answer 3

I recommand you to go through this article

http://www.codeproject.com/Articles/65425/4-Steps-to-Enable-Instrumentation-in-WCF