Object-oriented design: a responsibility-driven approach

Reviewer: Ariel Fabius

Responsibility-driven design is an alternative to data-driven abstraction as a design methodology. The authors argue in favor of maximizing encapsulation and assert that in pursuit of that goal the designer should be “viewing the program in terms of the client/server model.” The client asks the server to provide services, which the server provides upon request. The interactions are defined by the terms of a contract, which provides a list of services that may be requested from the server. According to the authors, responsibility-driven design focuses on the contract (by studying the actions the object is responsible for and the information shared by it), thereby gaining independence from close binding to data structure definitions. Classes and subclasses are viewed as clients of themselves and of the superclass. This approach minimizes reliance on class structure, making changes in the structure easier to implement. While the concept seems worthy of consideration, I would have liked to see more examples and a deeper analysis. On the other hand, the author's objections to the data-driven approach are real enough.