Hierarchical coloured Petri nets for the description of services in an intelligent network

The author reports on studies which were performed to find out in which way an IN-service description can be supported by a formal, but nevertheless illustrative specification. The studies were conducted with the aid of the tender specifications drawn up by Deutsche Bundespost Telekom for components of an IN field trial. The service descriptions contained in these documents are based on the three-level description method according to CCITT recommendation I.130. From the requirements set up for the IN service Freephone/Service 130 a description using hierarchical coloured Petri nets was derived, employing the open Petri net method. The study indicates clearly that the description of functional requirements of IN services should be supported methodologically beyond the scope of the CCITT recommendations and be supplemented by a formal executable specification