Impact Analysis During Object-Oriented Software Maintenance

Object-Oriented (OO) systems are difficult to understand due to the complex nature of the relationships present in such systems. Inheritance, polymorphism, encapsulation, information hiding, aggregation, and association combine to make maintenance of OO systems difficult. Maintenance activities often have unexpected or unseen effects on the system. These effects can ripple through system components complicating maintenance and testing of the system. Tracing the effects of maintenance provides the maintainer with knowledge that assists in debugging and testing modified and affected components. We developed the Comparative Software Maintenance (CSM) methodology to assist in the maintenance of OO systems. Using Java as a test language, CSM locates potential side effects, ripple effects and other effects of maintenance on class structures, methods, and objects. CSM uses a low-level software architecture model to capture the essence of a Java system. CSM performs either predictive, pre-modification impact analysis on a Java system or post-modification impact analysis on two different versions of the same OO system. We present an improved impact analysis procedure that determines impact of changes to the component level. We apply the results of impact analysis to determine component level testing requirements. The CSM methodology is implemented in JFlex, a software tool for OO program maintenance.