This the base interface for all callback handlers registered through the client session that establish a server-side control presence for the client.
public interface IServerHandler
Called when the handler has been registered at the server and is now active.
A session can register at most one a single handler of each type. If there is already a handler registered for the topic path the operation will fail, the registered handler will be closed, and the session error handler will be notified. To change the handler, first close the previous handler.
void OnActive(IRegisteredHandler registeredHandler)
Called if the handler is closed. This happens if the call to register the handler fails, or the handler is unregistered.