How do you know if a software architecture is deficient or at risk relative to its target system qualities?

The answer is to conduct an evaluation of it. A formal software architecture evaluation should be a standard part of the architecture-based software development life cycle. Architecture evaluation is a cost-effective way of mitigating the substantial risks associated with this highly important artifact.

The achievement of a software system's qualities attributes depends much more on the software architecture than on code-related issues such as language choice, fine-grained design, algorithms, data structures, testing, and so forth. Most complex software systems are required to be modifiable and have good performance. They may also need to be secure, interoperable, portable, and reliable. But for any particular system, what precisely do these quality attributes—modifiability, security, performance, reliability—mean? Can a system be analyzed to determine these desired qualities? How soon can such an analysis occur? What happens these quality attributes are in conflict with each other? How can the tradeoffs be examined, analyzed, and captured?

SEI Methods for Architecture Evaluation

The SEI has developed the following methods for evaluating system and software architectures:

• Architecture Tradeoff Analysis Method (ATAM), used to reveal how well the architecture satisfies particular quality attribute requirements and the risks, sensitivities, and tradeoffs involved in satisfying the requirements.
• Cost-Benefit Analysis Method (CBAM), which guides system engineers and other stakeholders to make economic and utility tradeoffs associated with the architectural decisions.
• Active Reviews for Intermediate Designs (ARID), used to evaluate early designs or portions of designs for their viability in satisfying stakeholder concerns.
• The System and Software ATAM is a variant of the SEI Architecture Tradeoff Analysis Method (ATAM) that is designed to evaluate system architectures.

These techniques can be used alone or in combination to obtain early and continuous benefits to any software development project.

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