CompuServe Messages

ACTION_READ_RETURN and ACTION_WRITE_RETURN are used by the handler to basically talk to itself 🙂 Seriously, a handler often creates a packet to be returned to it when an async. operation is complete. (A packet can be considered an overgrown message). For instance, when the con-handler reads characters from the console.device, it sets up the packet (message) that will be returned to it with the new characters. The packet type set is ACTION_READ_RETURN. The con-handler has only one message port; all messages come through that. The ACTION_READ_RETURN lets the con-handler know what the incoming message is, so it processes it properly. When you can have more than one message outstanding, you need to develop a means of telling them apart when they come back. andy