Patterns have found a place in the toolbox of modern software developers. From their origins in building architecture to their recognition in frameworks, they have proven to be an effective means of capturing design knowledge. They provide a vocabulary for communicating and a platform for reasoning about design. In one sense they are nothing new, but in another there is still a great deal that many in software development can learn. Many developers find themselves constrained by a view of patterns that is anchored in the seminal but early work of the Gang of Four. There are many valuable perspectives on patterns, as well as many patterns. Appreciation and immersion in such perspectives is likely to improve not only understanding of patterns, but also architectural knowledge and design instinct.

This session takes both a broad and detailed look at patterns, embracing a perspective that spans over a decade of the POSA series. Concrete examples of individual patterns, pattern compounds, pattern complements, pattern stories and pattern languages are given, drawn from the various POSA volumes and beyond. This view is complemented with discussion of the concepts and theory behind patterns, a view that has evolved and matured over two decades of pattern usage in software.