Re-engineering of the Internet Stream Protocol ST2+ with formalized design patterns

Abstract

Presents a case study on the design of communication protocols using formalized design patterns. On principle, the approach adopts the well-known design patterns concept for reusing design solutions. However, a formal description technique (FDT) is applied as the design language, and therefore knowledge about pattern instantiation or its impact an the embedding context can be precisely specified. We consider formalization to be a prerequisite for increased correctness of the resulting products and tool-supported pattern application. The FDT of our choice is SDL (Specification and Description Language). Thus pattern application follows strict rules in terms of the SDL syntax. Additionally, assumptions and effects stated in terms of the SDL semantics help to ensure the intended working of an SDL pattern within the embedding context. An SDL pattern-based re-engineering of the Internet Stream Protocol (ST2+) is presented. In particular, it is demonstrated how SDL pattern-based design can boost the developer's confidence in the resulting product.