Constrained expressions: toward broad applicability of analysis methods for distributed software systems

Abstract

It is extremely difficult to characterize the possible behaviors of a distributed software system through informal reasoning. Developers of distributed systems require tools that support formal reasoning about properties of the behaviors of their systems. These tools should be applicable to designs and other preimplementation descriptions of a system, as well as to completed programs. Furthermore, they should not limit a developer's choice of development languages.In this paper we present a basis for broadly applicable analysis methods for distributed software systems. The constrained expression formalism can be used with a wide variety of distributed system development notations to give a uniform closed-form representation of a system's behavior. A collection of formal analysis techniques can then be applied with this representation to establish properties of the system. Examples of these formal analysis techniques appear elsewhere. Here we illustrate the broad applicability of the constrained expression formalism by showing how constrained expression representations are obtained from descriptions of systems in three different notations: SDYMOL, CSP, and Petri nets. Features of these three notations span most of the significant alternatives for describing distributed software systems. Our examples thus offer persuasive evidence for the broad applicability of the constrained expression approach.

Software process validation

“…Another example of a technique to search for a behavior is found in the Constrained Expressions framework [2,17]. This is a method that, given a model, a current simulation state of that model, and a desired event, can answer the question: "Can this event be produced in the future?".…”

Specification of realtime systems using ASTRAL

“…• Extensions to algebraic based languages like CCS [52] such as [58] and Constrained Expressions [19].…”

Automated Analysis of Concurrent and Real-Time Software

“…Detailed and rigorous presentations of the formalism appear in [12] and in the appendix to [14], while less formal treatments intended to provide a more intuitive understanding of the features of the formalism appear in [7] and [4]. The use of constrained expressions with a variety of development notations is illustrated in [7] and [14].…”

“…Detailed and rigorous presentations of the formalism appear in [12] and in the appendix to [14], while less formal treatments intended to provide a more intuitive understanding of the features of the formalism appear in [7] and [4]. The use of constrained expressions with a variety of development notations is illustrated in [7] and [14]. A detailed discussion of the relation between constrained expressions and a variety of other methods for describing and analyzing concurrent software systems can be found in [7] and [17].…”

“…The constraints (which need not be regular) enforce those aspects of the semantics of the design or programming language, such as the appropriate synchronization of rendezvous between different tasks or the consistent use of data, that are not captured in the system expression. The reasons for this two-step process, which might not seem as straightforward as generating behaviors directly from a single expression, are discussed in [14], while an equivalent and more uniform interpretation process for constrained expressions is presented in [4].…”