UML Support for Designing Software Systems as a Composition of Design Patterns

Much of the research work on design patterns has primarily focused on discovering and documenting patterns. Design patterns promise early reuse benefits at the design stage. To reap the benefits of deploying these proven design solutions, we need to develop techniques to construct applications using patterns. These techniques should define a composition mechanism by which patterns can be integrated and deployed in the design of software applications. Versatile design models should be used to model the patterns themselves as well as their composition. In this paper, we describe an approach called Pattern-Oriented Analysis and Design (POAD) that utilizes UML modeling capabilities to compose design patterns at various levels of abstractions. In POAD, the internal details of the pattern structure are hidden at high design levels (pattern views) and are revealed at lower design levels (class views). We define three hierarchical traceable logical views based on UML models for developing pattern-oriented designs; namely the Pattern-Level view, the Pattern Interfaces view, and the Detailed Pattern-Level view. The discussion is illustrated by a case study of building a framework for feedback control systems.