Question

I have normal WCF service with few methods.

I would like to log some information and perform some actions at the beginning of method and in the end.

By implementing IParameterInspector I can easily do lot of logging. Methods BeforeCall and AfterCall give me almost everything I need.

But it doesn’t work for exceptions. There is IErrorHandler, which allows me to perform some handling if exception happened. Drawback is that I don’t know from which method it was thrown. All because IErrorHandler is attached to service behavior, not to operation itself.

However, I can get method name using code below:

((System.Reflection.RuntimeMethodInfo)(exception.TargetSite)).Name == "MyMethod"

This doesn’t look like good idea for me.

Question: Guys, are there any other WCF extensions I can use to achieve my goal? Would you recommend to use old buddy try-catch, and maybe wrap it into some nice syntax so I can perform actions at the beginning and in the end? What would be the syntax? What do you use for similar purposes?

Thanks ahead.

Answer 1

How about an IOperationInvoker?

public class NHibernateOperationInvoker : IOperationInvoker {
    private readonly IOperationInvoker _invoker;
    private readonly String _operationName;

    public NHibernateOperationInvoker(IOperationInvoker invoker, String operationName) {
        _invoker = invoker;
        _operationName = operationName;
    }

    public Object[] AllocateInputs() {
        return _invoker.AllocateInputs();
    }

    public Object Invoke(Object instance, Object[] inputs, out Object[] outputs) {
        using (var context = NHibernateContext.CreateNew()) {
            try {
                var result = _invoker.Invoke(instance, inputs, out outputs);
                context.Commit();
                return result;
            } catch(Exception ex) {
                Debug.Fail("Operation " + _operationName + " failed with " + ex.Message);
            }
        }
    }

    public IAsyncResult InvokeBegin(Object instance, Object[] inputs, AsyncCallback callback, Object state) {
        throw new NotImplementedException("NHibernateOperationInvoker.InvokeBegin");
    }

    public Object InvokeEnd(Object instance, out Object[] outputs, IAsyncResult result) {
        throw new NotImplementedException("NHibernateOperationInvoker.InvokeEnd");
    }

    public Boolean IsSynchronous {
        get { return true; }
    }
}

This is attached using an IOperationBehavior which does dispatchOperation.Invoker = new NHibernateOperationInvoker(dispatchOperation.Invoker, dispatchOperation.Name);