.net – WCF: server-side error handling. best practice

netwcf

I write WCF service and want to keep it's activity log: trace, warnings and error messages. The very straight-forward approach is to wrap all contract service code inside try/catch sections and write error messages from catch part rethrowing service contract error exceptions.

I suppose it would be nice if there would be one code-point to catch all uncaught exceptions instead of dozens try/catch sections. It would be also useful to write contract method parameters from that point to provide detailed error information.

Is it possible with WCF?

What is the best practice in organizing error handling inside WCF services?

Thank you in advance!

Best Answer

Have a look at IErrorHandler interface

It allows an implementer to control the fault message returned to the caller and optionally perform custom error processing such as logging

You can implement your service behavior (see IServiceBehavior interface) and add your handler to ChannelDispatcher error handlers.

See WCF Exception Handling with IErrorHandler for more details.

Related Solutions

.Net WFC/Web service exception handling design pattern

I would suggest you to centralize the error handling of your WCF service instead of putting try/catch on every method. To do this you can implement the IErrorHandler interface:

public class ErrorHandler : IErrorHandler
{
    public bool HandleError(Exception error)
    {
        return true;
    }

    public void ProvideFault(Exception error, MessageVersion version, ref Message msg)
    {
        DataAccessFaultContract dafc = new DataAccessFaultContract(error.Message);
        var fe = new FaultException<DataAccessFaultContract>(dafc);
        Message fault = fe.CreateMessageFault();
        string ns = "http://www.example.com/services/FaultContracts/DataAccessFault";
        msg = Message.CreateMessage(version, fault, ns);
    }
}

The ProvideFault method is called whenever one of your OperationContract throws an exception. It will convert the exception into a custom defined FaultContract and send it to the client. This way you no longer need to put try/catch in every method. You can also send a different FaultContract depending on the exception thrown.

On the client side you need to catch FaultException<DataAccessFaultContract> every time you call a method on your web service.

WCF Exception Handling Strategies

You might find the IErrorHandler interface useful here. We've been using this to do pretty much what you mention - centralised exception logging and providing generalised fault reasons without having to litter the code with numerous try/catches to try and deal with the problem locally.

Best Answer

Related Solutions

.Net WFC/Web service exception handling design pattern

WCF Exception Handling Strategies

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