On context-sensitive service-based protocol derivation

An algorithm by Kant, Higashino and Bochmann (see Proc. 12th. IEEE Int. Phoenix Conf. on Computer Commun., p.310, 1993) for automated derivation of protocol specifications from service specifications written in LOTOS, a standard language for specification of distributed systems, is improved by considering also the surrounding context of the server (i.e. service users) and of its individual constituents. Following ideas of Pucko et al. (see Microprocessing & Microprogramming vol.39, p.195, 1993 and vol.40, p.707, 1994), some protocol messages are omitted as the causal dependence is already implemented by the surrounding context. Unlike the algorithms of Pucko, the algorithm is semi-compositional and thereby less complex. Although it does not delete all the redundant protocol messages, it might substantially reduce their number, particularly in the case of a service specification written in the constraint-oriented style