Tutorial on Message Sequence Charts

MSC is a trace language which in its graphical form admits a particularly intuitive representation of system runs in distributed systems while focusing on the message interchange between communicating entities and their environment. For the first time the MSC recommendation Z.120 (MSC'92) was approved at the ITU meeting Geneva 1992. A new revised MSC recommendation Z.120 (MSC'96) was approved at the closing session of the last study period in April 1996. Whereas in MSC'92 main emphasis was put on the elaboration of basic concepts and a corresponding formal semantics, in the new MSC version - MSC'96 - structural language constructs, essentially composition and object oriented concepts, play a dominant role. With these new concepts, the power of MSC is enhanced considerably in order to overcome the traditional restriction to the specification of only a few selected system runs. Within the tutorial, the use of MSC is demonstrated by means of the ISDN supplementary service 'Completion of Calls to Busy Subscriber (CCBS)'.