Pattern-Oriented Software Architecture : Patterns for Resource Management

Rating:
Summary: Clear and well-written
Review: Of all the design pattern books I've seen, this may be the best-written. Each pattern is covered in the ways you would probably expect: what it is, when it applies, what good and bad effects are likely to follow.

This goes a few steps beyond, though. Most patterns are shown in class diagrams, as you'd expect. Interaction diagrams are much more common and complete than in most books, and clearly show the dynamics of different roles working with each other. Multiple different interaction diagrams show multiple different ways to implement the pattern or to put it to use. CRC cards are given for lots of the patterns - among other things, this book gives good examples for people who've never seen CRC cards used before.

The exceptional part of this writing is the "implementation" section of each pattern description. It shows the different steps and factors needed for the analysis leading up to pattern use, a welcome change for people new to this level of abstraction.

Finally, just about every pattern is illustrated in Java code. This will be very helpful for readers who need a concretion to bring the abstraction to life. I always have mixed feeling about code samples, though. I've seen too many design pattern beginners mistake the example for the rule. They lose out on the breadth of the pattern and the many valid ways to interpret it into a working system.

The only drawback to this book is its basic level of presentation. Many of the patterns will be familiar to experienced readers, but that always happens with patterns. The descriptions, however, often miss important topics. This book is dedicated to patterns about resource allocation. They are helpful in resource-constrained embedded systems where deadlock is a real threat; the authors barely mention deadlock, if at all. Resource management, including replication and caching, is also important in parallel and distributed systems. Maintaining global consistency a subtle topic with many variations, and gets just a few paragraphs of discussion.

Still the book is a good one over all. The pattern content is good, and the presentation is outstanding.