An Event Algebra for Specifying and Scheduling Workflows

Abstract

Heterogeneous systems arise when preexisting or legacy information systems are integrated in such a way as to preserve their autonomy and past applications. Workflows are the semantically appropriate units of activity in such environments. They involve a variety of tasks and are best represented by different extended transaction models or combinations thereof. We present an approach by which workflows can be efficiently scheduled. Our novel contribution is an event algebra in which dependencies characterizing workflows can be declaratively expressed. We show how to symbolically process these dependencies to determine which events can or must occur, and when. Our approach can represent dependencies compactly and reason with them efficiently. 1 Introduction The design and implementation of heterogeneous information systems poses special problems for task scheduling and management. Heterogeneous systems consist of a number of differently constructed applications and databases that must i...