Research And Implementation On Services Extracting Of Legacy Object-Oriented Systems

Migrating legacy object-oriented system functionalities to SOA environment is animportant problem that frequently arises in system maintenance and integration tasks. Aservice is often implemented by complex collaborations of many objects in anobject-oriented system. Such complexity brings impedance mismatch between serviceand object. Moreover, the delocalized nature of object-oriented system, where the codeassociated with a service is distributed across many interrelated objects; make thisproblem even more complex.This paper presents a four-staged approach that extracts services from legacyobject-oriented systems with source code and documents. In the first stage source codeof legacy system is loaded and preprocessed to form different modules according to theexplicit dependencies among classes. While preprocessing, some aspect code andserialized code are also embedded to intercept and log execution traces of system aswell as to store states of involved objects. In the second stage, services, which representsystem-level business functionalities, are modeled with use cases. Useful test cases arein turn generated from these use cases. In the third stage, the modularized andintercepted system is executed driven by generated test cases and the execution logs andobject states are recorded. In the last stage, services are located and extracted byanalyzing the execution logs and restoring the object states. The approach is supportedby an integrated tool and the evaluation on five opensource systems yields encouragingresult and demonstrates the practical applicability of the approach.