ABSTRACT
Different properties of channels such as message loss, duplication, and capacity are specified. A reordering protocol illustrates some of these notions. The Sliding Window Axioms are described, and a surprising application is found. If a register resembles a blackboard, channels and networks are rather like a mail system that distributes letters. The writing on the blackboard can be read several times until it is rewritten, but once the letter is picked up the mailbox is emptied. Two sets of instructions are used here by procedures that access a channel: Send/Receive and To Channel/From Channel. Observe that in a non-lossy channel there cannot be both a non terminating send event and a non terminating receive event. In fact, if there is a non terminating receive event then the channel is attentive and hence every send event is in the range of Gamma and is thus terminating.
