A Formal Model of Web Services Transport Layer

In this paper, we present a formal model of Web services transport layer based on CSP which addresses multiple transport, multiple Message Exchange Patterns (MEPs) and dynamic switching among multiple transport protocols. This approach abstracts message transferred over networks as transport object and splits message transportation process of a transport protocol into two CSP processes: a transport input process which receives incoming messages and a transport output process which sends outgoing messages. Meanwhile, we introduce a transport object collecting process, a business logic process and a transport object dispatching process within Web services transport layer and precisely describe their interactions with multiple transport protocols. Furthermore, we explore state transitions of transport objects within an interaction using state machine and discuss how multiple MEPs and switching among multiple transports are supported. Our analysis and experience give us the confidence to conclude that our formal model can act as a guidance to build next generation transport layer for Web services.