Accession Number : ADA293254

Title :   Foundations of Technology for Constructing Highly Reliable Distributed Realtime Systems.

Descriptive Note : Final rept. 1 Aug 91-30 Sep 94,

Corporate Author : STANFORD UNIV CA DEPT OF ELECTRICAL ENGINEERING

Personal Author(s) : Luckham, David C.

PDF Url : ADA293254

Report Date : 30 SEP 1994

Pagination or Media Count : 12

Abstract : Under grant AFOSR-91-O354 we have investigated event-based specification and constraint language extensions of our Rapide prototyping language. We have also investigated testing methods and tools for detecting constraint violations in simulations of distributed time-sensitive avionics systems and control systems. Rapide models the behavior of a distributed system by generating causal event simulations. A causal event simulation is a timed poset (partially ordered set of events with timing). Dependencies between events as well as their timing are captured in the poset execution model, thus providing a more detailed and precise picture of the behavior of a realtime, distributed system than current simulation technology based upon sequential traces of events. Posets allow more powerful constraint specifications than traces, e.g., asynchronous behavior. This work has developed (i) basic algorithms for implementing poset computations. (ii) a constraint language for specifying behavior in terms of posetS, and (iii) automatable algorithms and tool-set for detecting constraint violations in posets. To establish the feasibility of scaling this simulation technology to practical avionics examples, we have applied the technology to developing high level systems architectures of avionics systems. We have also applied constraint monitoring of the avionics simulations to detect design errors. The avionics systems studied include the IBM ADAGE helicopter avionics system architecture, and a high level architecture of the Boeing DARTS system for building flight simulators.

Descriptors :   *SYSTEMS ENGINEERING, *DISTRIBUTED DATA PROCESSING, *PROGRAMMING LANGUAGES, ALGORITHMS, AVIONICS, COMPUTERIZED SIMULATION, CONTROL SYSTEMS, COMPUTATIONS, MODELS, REAL TIME, COMPUTER ARCHITECTURE, PROTOTYPES, SEQUENCES, RELIABILITY, FEASIBILITY STUDIES, PRECISION, SCALING FACTOR, ASYNCHRONOUS COMPUTERS.

Subject Categories : Computer Programming and Software
      Computer Systems

Distribution Statement : APPROVED FOR PUBLIC RELEASE