A framework for modeling transfer protocols

Abstract

The notion of specification frameworks transposes the framework approach from software development to the level of formal modeling and analysis. A specification framework is devoted to a special application domain. It supplies re-usable specification modules and guides the construction of specifications. Moreover, it provides theorems to be used as building blocks of verifications. By means of a suitable framework, specification and verification tasks can be reduced to the selection, parametrization and combination of framework elements resulting in a substantial support which opens formal analysis even for real-sized problems. The transfer protocol framework addressed here is devoted to the design of data transfer protocols. Specifications of used and provided communication services as well as protocol specifications can be composed from its specification modules. The theorems correspond to the relations between protocol mechanism combinations and those properties of the provided service which are implemented by them. This article centers on the application of this framework which is discussed with the help of the specification of a sliding window protocol. Moreover the structure of its verification is described. The specification and verification technique applied is based on L. Lamport's temporal logic of actions (TLA). We use the variant cTLA which particularly supports the modeling of process systems.