Object-oriented modelling of communication protocols for re-use

The main motivation for the present work stems from the wide gap which exists between the research efforts devoted to developing formal descriptions for communication protocols and the effective development methodologies used in industrial implementations. We apply object-oriented (OO) modelling principles to networking protocols, exploring the potential for producing re-useable software modules by discovering the generic underlying class structures and behaviour. Petri nets (PNs) are used for deriving re-useable model elements and the slightly modified TTCN notation is used for message sequence encoding. This demonstrates a formal, practical approach to the development of a protocol implementation through OO modelling. The paper addresses the problem of inter-layer communication among multiple protocol entities (PEs), assuming the standard ISO/OSI Reference Model. A generalised model called the inter-layer communication (ILC) model is proposed. An example of a PE based on the alternating-bit protocol (ABP) is also discussed