Question

My WCF service uses callbacks. To be able to call all clients, I’m using something like this:

[ServiceBehavior (InstanceContextMode = InstanceContextMode.PerSession)]
class Svc
{
    // stores all connections
    private static List<Svc> Connections = new List<Svc> ();

    // callback for this instance
    private ICallback Cb;

    public Svc ()
    {
        Cb = OperationContext.Current.GetCallbackChannel<ICallback> ();
        Connections.Add (this);
    }

    // ... lots of other code that uses or updates the list of connections
}

Is this the right way to do it?

I’m asking because I’m fighting with an apparent design problem in the above approach. I tried to move a lot of common code, including the static List<Svc> to a common base class that can be used by all my WCF services. But when deriving, this list is shared among all subclasses.

I then tried to avoid this undesirable sharing by making the base class generic (Svc<T>, meaning each subclass gets its own static members) but this leads to other annoyances and is not a clean design.

Answer 1

Yes, this is the right approach of storing references to your clients to send callbacks to all of them. I don’t store the CallbackChannel objects but the OperationContext instances in my service.

To your other question: You could extract the code to administrate the list of connected clients to a separate class and use an instance of that class in your service.