Issues and Tools for Protocol Specification

A system is said to be distributed when it includes several geographically distinct components cooperating in order to achieve a common distributed task. The development of informatic networks and telematic services, as well as the access to public data transmission networks raised the question of building distributed applications. However it should be understood that distributed processing is not only the result of the combination of local data-processing and transmission facilities. • With the introduction of dedicated processors (eg. I/O processors...), then of multiple-processor systems and finally of local area networks, distributed processing has been introduced inside data-processing systems themselves. • Simultaneously distributed processing was appearing within intimity of the telecommunication networks themselves, first with packet and circuit networks, second in Common Signalling Systems [CCITT 80] where a separate computer deals with all signalling information. d i s t r i b u t e d task. t h e set of r u l e s which d e f i n e s t h e dialogue p a r t a m o n g t h e c o o p e r a t i n g e n t i t i e s is called a protocol. When looking into a complex d i s t r i b u t e d s y s t e m e x e c u t i n g an application d i s t r i b u t e d among s e v e r a l m u l t i p r o c e s s o r d a t a-p r o c e s s i n g s y s t e m s c o m m u n i c a t i n g t h r o u g h a p a c k e t