graphic design

POSA1 is written far better than other related texts, such as GoF. (And be aware of the fact that GoF only contains design level patterns - it does not contain system architecture level patterns.) At the same time, after its nth reprinting and redesigned book cover, the text still contains non-UML diagrams (although there are some UML-like sequence diagrams included), and very few real code examples. The lack of code examples, though, can in some ways be seen as a positive aspect of the text. Compare this text with Applied Java Patterns, for example. AJP has very extensive code examples, but because the code examples for each pattern run for pages (rather than simply providing code snippets), the reader may be inclined to narrow their view of how the pattern is applied. For example, MVC is definitely not a pattern limited to GUI user interfaces! The point on which I think that POSA1 seems to come out ahead is that the stronger-than-ususal pattern descriptions and applicability, with a small amount of code provided where deemed especially relevant to the point being attempted to make, helps one understand the patterns better rather than memorizing language-specific implementations of patterns. This point is why I think the text was chosen to accompany Software Architecture in Practice for the graduate software engineering course in software architecture I just took.

It's a nice reading after the GoF book. The GoF book provides more practical and easy to implement design level patterns, so I suggest you start from it first. After that, if you want to continue your journey in the software patterns, you should read this one. The first 300+ pages, talking about Architectureal Patterns/Design Patterns, are very good. The rest 100 pages are still interesting, but are a little bit light. Overall, it's a worth reading for software architects/developers. I'd like to give it 4.5 stars - well, 5 stars should also be O.K., considering there are so many quick & rush computer books on the market.

This is an unusual book in the pattern genre. It presents a number of patterns, categorized by archtiectural level. That's just the first part of the book, though. The third of the book is about the process of using, relating, collecting, and distributing patterns.

Only chapter 2 really addresses patterns for the strategic, architectural level of a software system. It does a very adequate job, using a variety of notations, examples, and analysis steps. This book is from 1996, so time has changed our view of some patterns. "Reflection," for example, has become pervasive in applications based on plugins and software components. It is also a fundamental API in the major langauges (Java and C#) released since this book was published - perhaps reflection should be downgraded to an "idiom". That's just nitpicking, though, since reflection is even more important now than when the book was written.

For contrast, the authors present additional design patterns (including some from Gamma's book) for use at tactical design levels. They also discuss idioms patterns that typically involve just a few lines of code within on function. The contrast between the three different levels of implementation and design gives a useful discussion. The authors also present a weak chapter on "systems" or "langauges" of patterns The discussion is OK as far as it goes. The weakness is in what it omits. After reading this brief chapter, the programmer has very little practical information about choosing patterns from some library for some task. The poor programmer has no information at all about how to link patterns together, and that's a real stumbling block for beginning pattern users.

The final section of the book is really sociology. It's about the pattern community, what that community is for, and how to be a working member. I find the discussion un-helpful, but I expect opinions to differ.

Even today, this is a good second book (after Gamma's 'Design Patterns') on patterns and pattern usage. It lack the depth and precision of Gamma's book, and tends to add words without adding meaning. On the positive side, it's broader than Gamma's, and addresses a wider range of implementation levels.