Modular design principles for protocols with an application to the transport layer

A method for specifying services, specifying protocols, and constructing protocol specifications by stepwise refinement of service specifications is presented. The method is based on assertional reasoning and a refinement relation between state transition systems. The method is demonstrated on the transport layer, which is used by application protocols such as electronic mail, file transfer, remote login, etc. A succession of specifications is constructed, starting from a very abstract transport service and culminating in specific transport protocols comparable to TCP and ISO TP4. Each specification offers both connection management and connection-specific data transfer. It is shown how any connection-independent data transfer protocol can be transformed to offer connection-specific data transfer service.<
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