An environment to support designers in the modeling, analysis, and simulation of concurrent systems is described. It is shown how a fully nested structure model supports multilevel design and focuses attention on the interfaces between the modules which serve to encapsulate behavior. Using simple examples, it is shown how a formal graph model can be used to model behavior in three domains: control flow, data flow, and interpretation. The effectiveness of the explicit environment model in SARA is discussed and the capability to analyze correctness and evaluate performance of a system model is demonstrated. A description of the integral help designed into SARA shows how the designer can be offered consistent use of any new tool introduced to support the design process.

Some designers of software systems have recognized the need for providing interactive assistance to the users of their systems. A variety of ad hoc approaches have been used to associate assistance with various aspects of these systems. Common problems with such approaches are inconsistent availability of assistance and inaccurate assistance. A technique is presented for integrating assistance information into the design and implementation of a software system. This technique guarantees consistency and accuracy of syntactic assistance and provides a framework for integral semantic assistance information. The technique for developing self-describing systems centers around a specification of the language with which a user interacts with the system. The language is processed to produce a parser as well as on-line assistance information, error messages, and hard copy user manuals. A method for presenting this user assistance is discussed, and examples of an implemented system are provided.