WCF OperationBehavior: ApplyDispatchBehavior not being called

Question

My goal is to create an endpointbehavior for WCF, which adds an extra Ping() operation to an existing contract. The EndpointBehavior works fine, I can actually see the added Ping() operation when I run my service and use the WCF test client. I've implemented this endpointbehavior as follows:

Configuration:

<configuration>
  <system.serviceModel>

    <services>
      <service name="X">
        <endpoint address="mex" kind="mexEndpoint" />
        <endpoint address="" binding="basicHttpBinding" contract="IX" 
             behaviorConfiguration="ping" />
      </service>
    </services>

    <behaviors>
      <endpointBehaviors>
        <behavior name="ping">
          <PingEndpointBehavior />
        </behavior>
      </endpointBehaviors>
    </behaviors>

    <extensions>
      <behaviorExtensions>
        <add name="PingEndpointBehavior" 
          type="Assembly.PingEndpointBehavior, Assembly, .. />
      <behaviorExtensions>
    </extensions>

  </system.serviceModel>
</configuration>

Endpoint behavior:

public class PingEndpointBehavior : BehaviorExtensionElement, IEndpointBehavior
{
    ...

    public void ApplyDispatchBehavior(ServiceEndpoint endpoint, 
      EndpointDispatcher endpointDispatcher)
    {
        var cd = endpoint.Contract;

        var inputMessage = new MessageDescription(...);
        var outputMessage = new MessageDescription(...); 
        // Set input/output messages correctly

        var od = new OperationDescription("Ping", cd);
        od.Messages.Add(inputMessage);
        od.Messages.Add(outputMessage);

        od.Behaviors.Add(new DataContractSerializerOperationBehavior(od));
        od.Behaviors.Add(new PingOperationBehavior());

        endpoint.Contract.Operations.Add(od);
    }

    ...
}

The operation behavior however, is not working. The ApplyDispatchBehavior() method on the operationbehavior never gets called, and therefore, my own PingInvoker is not used. This results in not getting a response when calling the added Ping() operation to a contract.

The reason for this seems to be that the OperationBehavior only gets added after the service has already started, resulting in the ApplyDispactchBehavior not getting called. See code below:

Operation Behavior:

public class PingOperationBehavior : IOperationBehavior
{
    ...

    public void ApplyDispatchBehavior(OperationDescription od, DispatchOperation do)
    {
        do.Invoker = new PingInvoker();    
    }

    ...
}

Invoker:

public class PingInvoker : IOperationInvoker
{
    ...

    public object Invoke(object instance, object[] inputs, out object[] outputs)
    {
        outputs = new object[0];
        return Ping();
    }

    public static DateTime Ping()
    {
        return DateTime.Now;
    }

    ...
}

Anyone have an idea how I can get the OperationBehavior to work properly?

Note:

• Should work for services hosted in IIS (not self-hosted)
• Except for adding the behavior in configuration (and referencing the assembly that contains the behavior), I don't want to have to change anything on the service

Answer 1

I had this same problem with my custom Behavior. I was deriving from WebHttpBehavior (which inherits from IEndpointBehavior), but the ApplyDispatchBehavior was not being called.

The solution to my problem was to add the missing override keyword like: public override void ApplyDispatchBehavior(...