Alloy: a language and tool for exploring software designs

Abstract

Alloy is A language and a toolkit for exploring the kinds of structures that arise in many software designs. This article aims to give readers a flavor of Alloy in action, and some examples of its applications to date, thus giving a sense of how it can be used in software design work. Software involves structures of many sorts: architectures, database schemas, network topologies, ontologies, and so on. When designing a software system, you need to be able to express the structures essential to the design and to check that they have the properties you expect. You can express a structure by sketching it on a napkin. That's a good start, but it's limited. Informal representations give inconsistent interpretations, and they cannot be analyzed mechanically. So people have turned to formal notations that define structure and behavior precisely and objectively, and that can exploit the power of computation.