Diploma Thesis from the year 2007 in the subject Computer Science - Software, grade: 1, Dresden Technical University, language: English, abstract: Design patterns have proven to be important building blocks and means of reuse in software design. However, the mere number of available design patterns complicates the decision-making which design pattern to choose and demands tools assisting in this process. We hence propose a knowledge-based formal representation of design patterns, a representation that is accessible by tools. Existing approaches to formalizing design patterns generally cover solely the formal description of the structure of design patterns. However, an important part of a design pattern description is the intent section, because the intent describes what the design pattern does and which design problems a pattern addresses. In this work, we develop a novel approach of formalizing design patterns by their intent. The formal representation is based on OWL, the web ontology language. The developed ontology can serve as support for the decision-making of choosing the right design pattern. We furthermore develop a tool that uses the ontology as a knowledge-base. The tool allows the user to visually describe design problems and gives suggestions of design patterns that solve a given design problem.

Since the seminal book by the Gang of Four, design patterns have proven an important tool in software development. Over time, more and more patterns have been discovered and developed for a plethora of design problems. The sheer amount of patterns available makes it hard to impossible to find patterns useful for solving a specific design problem. Hence, tools supporting searching and finding design patterns appropriate to a certain problem would be very useful. In order to develop such tooling, design patterns need to be described in a formal manner such that querying for them by the problem to be solved becomes feasible. Current approaches to formalising design patterns focus on the solution structure of the pattern rather than on the problem solved by the pattern. In this book, we present a formalisation of the intent of the 23 patterns from the Gang-of-Four book. Based on this formalisation we have developed a Design Pattern Wizard that proposes applicable design patterns based on a description of a design problem. This work is appealing both for the professional software developer, and the student of computer science.