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Overview of the Constrained Expression Design Language

IP.com Disclosure Number: IPCOM000128367D
Original Publication Date: 1986-Dec-31
Included in the Prior Art Database: 2005-Sep-15
Document File: 5 page(s) / 22K

Publishing Venue

Software Patent Institute

Related People

Laura K. Dillon: AUTHOR [+3]

Abstract

This report describes the Constrained Expression Design Language (CEDL), which is currently under development at the University of Cali-fornia, Santa Barbara, and University of Massachusetts, Amherst. CEDL allows a designer to describe communication and synchronization among the tasks of a concurrent system without delving into unrelated details, such as internal task computations and the representation of data. A CEDL design can be analyzed, using the constrained expression formalism and its associated analysis techniques, to validate important behavioral properties, such as mutually exclusive use of shared resources and absence of deadlock and starvation. In this way synchronization errors can be identified and corrected early in the development process. A CEDL design can then be used as the basis for an Ada' implementation.

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THIS DOCUMENT IS AN APPROXIMATE REPRESENTATION OF THE ORIGINAL.

Overview of the Constrained Expression Design Language

Laura K. Dillon Department of Computer Science October Overview of the Constrained Expression Design Language

L. Dillon

October 13, 1986

Abstract

This report describes the Constrained Expression Design Language (CEDL), which is currently under development at the University of Cali-fornia, Santa Barbara, and University of Massachusetts, Amherst. CEDL allows a designer to describe communication and synchronization among the tasks of a concurrent system without delving into unrelated details, such as internal task computations and the representation of data. A CEDL design can be analyzed, using the constrained expression formalism and its associated analysis techniques, to validate important behavioral properties, such as mutually exclusive use of shared resources and absence of deadlock and starvation. In this way synchronization errors can be identified and corrected early in the development process. A CEDL design can then be used as the basis for an Ada' implementation.

1 Introduction

The Constrained Expression Design Language (CEDL) is based on the Ada programming language [1]. It is primarily intended for describing communica-tion and synchronization among the tasks in a concurrent software system. A constrained expression (21 representing all possible behaviors of a concurrent system can be derived from its CEDL design. The constrained expression can then be simplified and analyzed to uncover potential synchronization-related errors early in the development process. In this report we describe a prelimi-nary version of CEDL 2 A constrained expression formulation of CEDL and the constrained expression analysis techniques are described elsewhere (2,4,5. lAda is a registered trademark of the U.S. Department of Defense (Ads Joint Program Office). aCEDL is currently under development at the University of California, Santa Barbara, and the University of Massachusetts, Amherst. The preliminary version of CEDL described in this report is being used for initial experimentation with the constrained expression approach to analysis and for certain prototype tools.

A CEDL design focuses on the expression of communication and synchro-nization in concurrent software systems. Language features that do not pertain to concurrency are thus kept to a minimum. For example, ennumeration types, which are appropriate for the high-Level expression of control flow dependencies, are the only types permitted in CEDL. Similarly, CEDL does not provide prim-itives for describing data encapsulation, exception handling or generic design units. It does not permit nesting of design units, the use of declarations within blocks, or the dynamic creation or termination of tasks. The restriction against nesting, besides simplifying the use of constrained expressions for representing CEDL designs, reflects a belief that nesting

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