TEAM Zarate Tarrani Notes From the Field

On Architecture. A new book that adds to the software architecture body of knowledge is Evaluating Software Architectures: Methods and Case Studies by Paul Clements, Rick Kazman and Mark Klein.

The authors provide an in-depth treatment of three methods for evaluating software architectures, all of which were developed at the Software Engineering Institute with involvement by the authors. The methods examined are:

1. ATAM (Architecture Tradeoff Analysis Method)
2. SAAM (Software Architecture Analysis Method)
3. ARID (Active Reviews for Intermediate Designs)

Each of the above address software evaluations in increasing levels of detail, with the book's main emphasis on ATAM.

What makes this book so valuable is the fact that you can learn much about developing software architectures from the criteria with which they are evaluated. For example, the discussion on quality attributes is eye-opening because what architects consider to be well formed quality attributes are usually too vague to properly evaluate, resulting in ill defined architectures in the first place. Knowing how to evaluate the architecture will provide the keys for defining a solid architecture. More important is the way the authors define the outputs of the architecture evaluation, which gives the practicing architect a framework for design that fully meets the evaluation criteria. The net result is that a defined architecture will unambiguously communicate the design to the development team, as well as to the QA team.

I especially like the business oriented approach that addresses the costs and benefits of evaluation, the three approaches from which to choose that best meets technical and business goals, and the case studies that support each of the approaches. Another strong point about this book is architecture is also evaluated with production in mind. Too many books only consider architecture from the development point of view, or in rare cases, from development and QA points of view. The evaluation techniques in this book extend to support and maintenance. The authors make selection of the best technique easy by comparing them in Chapter 9, and provide an approach to implement evaluations in Chapter 10.

If you're an architect I also recommend augmenting the excellent material in this book with Design and Use of Software Architectures by Jan Bosch , which gives an alternate method to ATAM that is more complete in many respects. Even if you espouse Bosch's approach, however, the approach and techniques given in Evaluating Software Architectures: Methods and Case Studies are complementary. I personally recommend both books and assign equal value to them.

Additional Resources:

• SEI's ATAM page
• SEI's SAAM page
• SEI's ARID page
• Jan Bosch's page (see articles and book page for additional documents and information about Design and Use of Software Architectures.)