INTRODUCTION

Patterns document common solutions to recurring problems in a specific context. They enable an efficient transfer of experience and skills. However, many pattern descriptions tend to focus on the solution to a problem, and not so much on how the various (and often conflicting) forces involved are balanced. Therefore, patterns need to be described and formalized in ways that enable the reader to determine whether the particular solution presented is useful and applicable to his or her problem in a given context.

A large body of patterns has been documented to date, and the different efforts are not well-connected. The Pattern Almanac (Rising, 2000) alone, a major effort summarizing and linking the patterns published at patterns conferences and in books prior to the year 2000, lists over 1,200 patterns contained in over 800 different publications. Most of those are publications with a single pattern. The number of patterns has only increased since, but estimates are harder to obtain lacking a similar effort to the Pattern Almanac.