WCF: Retrieving MethodInfo from OperationContext

Question

Is there an elegant way to get the method that will be executed on a service instance from MessageInspector/AuthorizationPolicy/some other extension point? I could use

OperationContext.Current.IncomingMessageHeaders.Action

but I hope there's some way to do it without manually matching SOAP actions with OperationContracts.

What I'm trying to do is examine the method's attributes before it executes.

Dixie

Answer 1

It took me forever, but I did find a way that's better than finding and slogging through the entire contract:

string action = operationContext.IncomingMessageHeaders.Action;
DispatchOperation operation = 
    operationContext.EndpointDispatcher.DispatchRuntime.Operations.FirstOrDefault(o =>
        o.Action == action);
// Insert your own error-handling here if (operation == null)
Type hostType = operationContext.Host.Description.ServiceType;
MethodInfo method = hostType.GetMethod(operation.Name);

And there you are. You can get the attributes or do whatever else you like.

Note: You might be tempted to try to use the OperationSelector in the DispatchRuntime. The problem I found was that in my case, at the particular stage of processing, the OperationSelector was a null reference. If you have access to this property, it's probably faster and more reliable to use than "scanning" the OperationCollection as above.

Hypothesis

DispatchOperation does not contain a definition for FirstOrDefault? – Delphinus

@Fulvio: Make sure you've added a namespace reference to System.Linq. – Hypothesis

Thanks for that. I managed to get it working, however I need to grab the parameter values from the OperationContext and I'm having a bit of trouble doing that. – Delphinus

This doesn't work if the operation is renamed in the OperationContract. – Respiratory

Answer 2

If OperationContext.CurrentIncomingMessageHeaders.Action is null, you can do this -- it's a bit terser:

string actionName = OperationContext.Current.IncomingMessageProperties["HttpOperationName"] as string;
Type hostType = operationContext.Host.Description.ServiceType;
MethodInfo method = hostType.GetMethod(actionName);

Folsom

Answer 3

Based on @Aaronaught and @TimDog 's answers, and this SO question I came up with a solution that should work for both REST and SOAP.

///<summary>Returns the Method info for the method (OperationContract) that is called in this WCF request.</summary>
System.Reflection.MethodInfo GetActionMethodInfo(System.ServiceModel.OperationContext operationContext ){
    string bindingName = operationContext.EndpointDispatcher.ChannelDispatcher.BindingName;
    string methodName;
    if(bindingName.Contains("WebHttpBinding")){
            //REST request
            methodName = (string) operationContext.IncomingMessageProperties["HttpOperationName"];
    }else{
            //SOAP request
            string action = operationContext.IncomingMessageHeaders.Action;
            methodName = operationContext.EndpointDispatcher.DispatchRuntime.Operations.FirstOrDefault(o =>o.Action == action).Name;
    }
    // Insert your own error-handling here if (operation == null)
    Type hostType = operationContext.Host.Description.ServiceType;
    return hostType.GetMethod(methodName);
}

Tague

Unfortunately, we are going Core and ChannelDispatcher is no longer reachable. Just leaving this comment for the next one who tries to get CoreWCF up and running, you have been warned! – Goddamned

Answer 4

Castle WCF integration facility enables you to do just that (among many useful things) by using DynamicProxy proxies. Take a look here.

There's not much documentation on it, so for docs on how to use it it's best to take a look at its tests.

Teador