WCF Async call that return void and is OneWay

Question

I use WCF to async communicate between 2 processes.
till now I implemented the IAsyncResult pattern, and did it by having 3 methods:
BeginOperation - client.BeginOperation, when service receive it queue the job on threadpool with delegate for Operation
Operation - run on service side
EndOperation - this is what client callback.

My question is, I want to send strings from client to service, I want the send to be async, AND I dont want to get response - just want the service to print the string.
Is this enough ? This must be Non-Blocking

    [OperationContract(IsOneWay = true)]
    void PrintString(string message);

OR i need to do as following:

    [OperationContract(IsOneWay = true, AsyncPattern=true)]
    void BeginPrintString(string message, AsyncCallback callback, object state);
    void EndPrintString(IAsyncResult asyncResult);

Answer 1

IsOneWay should be enough, but it still can block your client in specific circumstances, as well as throw errors.

See this and this posts for more details:

General things you should keep in mind about OneWay operations -

O/W operations must return void. O/W operations can still yield exceptions. invoking an operation on the client channel might still throw an exception if it couldn’t transmit the call over to the service. O/W operations can still block. if the service is pumped with messages and a queue had started, calling O/W operation may block your following code.

Answer 2

You can make it more asynchronous by using a separate thread to do your work.

Instead of:

public void MyOneWayServiceOperation() {
   // do stuff
}

do something like:

public void MyOneWayServiceOperation() {
   new Thread(() => {
      // do stuff
   }).Start();
}

The service operation will have been executed on a new thread anyway, so it shouldn't cause any more problems for your code to be on a different new thread.

You can add a Thread.Sleep() call before your work if you want the service operation to have completed before you begin. This allowed me to quit the service from a service operation without having an exception thrown.