The catalogue of design patterns from [Gamm94] contains about twenty design patterns and their mutual relationships. In this paper, we organize these relationships into different categories and revise the design patterns and their relationships. We are then able to arrange the design patterns in different layers. The results simplify the understanding of the overall structure of the catalogue, thereby making it easier to classify other design patterns, and to apply these design patterns to software development.

A design pattern is a particular prose form of recording design information such that designs which have worked well in the past can be applied again in similar situations in the future. The availability of a collection of design patterns can help both the experienced and the novice designer recognize situations in which design reuse could or should occur. We have found that design patterns: 1) provide an effective "shorthand" for communicating complex concepts effectively between designers, 2) can be used to record and encourage the reuse of "best practices", 3) capture the essential parts of a design in compact form, e.g. for documentation of existing software architectures. Since the patterns community is one that shares information in an open forum and builds on the experiences of others, we chose to submit a joint paper on our industrial experiences with patterns. We focus on the lessons learned in our respective industrial settings as a first step towards answering the questions...