A Protocol Composition Model and Its Applications

Protocol composition is an efficient way to design, specify, verify, implement and test the complex communication protocols. A protocol composition model based on the theory of communicating sequential processes (CSP) is proposed, which presents a protocol as a composition of protocol entities. The model consists of two layers: protocol entity layer and protocol interaction layer. In this model, protocols can be further composed into more complex protocols. In order to describe the protocol interaction, the concepts of entity connectors and their associations are used to replace the concept of channel defined in CSP. The association process is defined to clarify the interaction in protocol composition. Examples illustrate its applications in research of multicast protocol by composing unicast protocols and in describing and analyzing Session Initiate Protocol.