An Opportunistic Approach to Retaining Use Cases in Object-Oriented Source Code

Use cases are widely used to express what software systems are supposed to provide in terms of an interaction between the users and the system. Without a particular effort to preserve them, use cases dissolve in source code turning the task of locating their implementation into a major problem of change request realization. While aspect-oriented programming offers one solution to retaining use cases, there are also opportunities in the mainstream object-oriented programming languages that have no reliable support for aspect-oriented programming. This paper brings an approach to retaining use cases in source code by object-oriented means that employs three techniques: traits, the Event pattern (extracted from the Zend's framework EventManager component), and the Front Controller pattern. By these techniques, all possible kinds of use cases with the exception of specialization use cases are addressed: peer use cases, extension use cases, and inclusion use cases. Use cases are not fully modularized as in aspect-oriented software development with use cases, but the approach ensures their parts can be easily traced. The approach has been evaluated with respect to traceability on an online shop application demonstrating how a use case can be added, removed, or altered.