Handle exceptions in web services with Elmah

Question

Is there a way to globally handle exceptions in regular ASP.NET Web Service (asmx) using ELMAH like we do it in ASP.NET web site ?

Answer 1

ASP.NET web services never fire Application_Error event and exceptions cannot be handled globally by ELMAH like in ASP.NET apps. But we can "manually" log exceptions using ELMAH:

  public int WebServiceMethod() {   try {    ...   }   catch (Exception ex) {     Elmah.ErrorLog.GetDefault(       HttpContext.Current).Log(new Elmah.Error(ex, HttpContext.Current));   } }  

Answer 2

You can use a SoapExtension to do this :

using System; using System.Web.Services.Protocols;  namespace MyNamespace {     class ELMAHExtension : SoapExtension     {         public override object GetInitializer(Type serviceType)         { return null; }          public override object GetInitializer(LogicalMethodInfo methodInfo, SoapExtensionAttribute attribute)         { return null; }          public override void Initialize(object initializer)         { }          public override void ProcessMessage(SoapMessage message)         {             if (message.Stage == SoapMessageStage.AfterSerialize &&                 message.Exception != null)             {                 // Log exception here             }         }     } } 

You register this in the web.config with the following lines :

<system.web>   <webServices>     <soapExtensionTypes>       <add type="MyNamespace.ELMAHExtension, MyDLL" priority="1" group="1" />     </soapExtensionTypes>   </webServices> </system.web> 

This will give you access to the HttpContext and SoapMessage objects which should give you all of the details you need about what was being called. I think the exception you retrieve at this stage will always be a SoapException and that the bit you are interested in is probably the inner exception.