Michael said---- The tricky bit will be to avoid making it all too complex... Bill responds --- Indeed. Perhaps we can come up with a simple (extensible) data structure that contains the relevant information, and a way to have the sender specify when it is gathered/stored and when it is sent. Basic senders will simply tell the receiver to gather the data every N seconds and send it every N seconds (plus when there are problems, as defined by the specification). More sophisticated senders could drive more complex relationships, asking the receiver to tabulate/send the data on demand in semi-real time. This would allow a sophisticated sender to send a varying data patterns and get the feedback they require, yet not require too much shared state between the sender and receiver. As long as the receiver is a simple state machine, I think we would be OK. bvs