Models and environments for designing open distributed systems using formal approaches

A discussion is presented of the main formal techniques developed for designing hierarchies of protocols and services in complex distributed systems. The corresponding approaches and tools are based on the use of formal techniques. Emphasis is on a coherent approach which allows simultaneous handling of function-related and time-related requirements. As a consequence, a state-based methodology is presented which includes extended-time Petri nets and the formal description technique Estelle for behavioral and performance descriptions, including logic and projections for verification. It is shown how extended-time Petri net models can be combined with Estelle to describe dynamic structures and dynamic communication in hierarchies of processes. In addition some of the many techniques under development are presented, and a global classification is provided from which the structure of a complete design workstation could be derived