Reengineering Large-Scale Polylingual Systems

Building systems from existing applications written in two or more languages is common practice. Such systems are polylingual. Polylingual systems are relatively easy to build when the number of APIs needed to achieve language interoperability is small. However, when the number of distinct APIs become large, maintaining and evolving them becomes a notoriously difficult task. We present a practical and effective process to reengineer large-scale polylingual systems. We offer a programming model that is based on the uniform abstraction of polylingual systems as graphs and the use of path expressions for traversing and manipulating data. This model enables us to achieve multiple benefits, including coding simplicity and uniformity (where neither was present before) that facilitate further reverse engineering. By performing control and data flow analyses of polylingual systems we infer the schemas used by all participating programs and the actions performed by each program on others. Finally, we describe a tool called FORTRESS that automates our reverse engineering process. The contribution of this paper is a process that allows programmers to reverse engineer foreign type systems and their instances semiautomatically at the highest level of design. We know of no other approach with comparable benefits.