The Graphical Depiction of Design Patterns

If design patterns are to fulfill their promise of dramatically improving the quality, timeliness and reusability of software it is essential that techniques be found to document them concisely and accurately. Graphical notations offer a potentially powerful approach, but unfortunately current techniques for depicting object-oriented design patterns rely on notations that were initially developed for capturing analysis information, and are thus unable to describe some important aspects of patterns. This paper introduces some notational concepts which are tailored to the description of the implementation-level mechanisms from which design patterns are constructed, and are therefore better suited to their documentation. The concepts are first illustrated through their use in the depiction of the well known Observer (or Publisher-Subscriber) pattern, and then in their depiction of the essential elements of a new design pattern called Advertisement.