Evaluating software architectures - Methods and case studies

Drawing on clearly identified connections between architecture design decisions and resulting software properties, this book describes systematic methods for evaluating software architectures and applies them to real-life cases. It shows you how such evaluation can substantially reduce risk while adding remarkably little expense and time to the development effort (in most cases, no more than a few days). Evaluating Software Architectures introduces the conceptual background for architecture evaluation and provides a step-by-step guide to the process based on numerous evaluations performed in government and industry.

In particular, the book presents three important evaluation methods:

• Architecture Tradeoff Analysis Method (ATAM)
• Software Architecture Analysis Method (SAAM)
• Active Reviews for Intermediate Designs (ARID)

Detailed case studies demonstrate the value and practical application of these methods to real-world systems, and sidebars throughout the book provide interesting background and hands-on tips from the trenches.

All software engineers should know how to carry out software architecture evaluations. Evaluating Software Architectures is the chance to get up to speed quickly by learning from the experience of others.

Table of Contents

Legal

Preface

Reader's Guide

Acknowledgments

1: What is Software Architecture

Architecture as Vehicle for Communication among Stakeholders

Architecture as the Manifestation of the Earliest Design Decisions

Architecture as a Reusable, Transferable Abstraction of a System

Summary

For Further Reading

Discussion questions

2: Evaluating a Software Architecture

Why Evaluate an Architecture?

When can an Architecture be Evaluated?

Who's Involved?

What Result does an Architecture Evaluation Produce?

For what Qualities can we Evaluate an Architecture?

Why are Quality Attributes too Vague for Analysis?

What are the Outputs of an Architecture Evaluation?

What are the Benefits and Costs of Performing an Architecture Evaluation?

For Further Reading

Discussion Questions

Sidebar: What's Architectural?

Sidebar: "Why Should I Believe You?"

3: The ATAM: A Method for Architecture Evaluation

Summary of ATAM Steps

Detailed Description of the ATAM Steps

The Phases of the ATAM

For Further Reading

Discussion Questions

Sidebar: The Two Faces of the ATAM

Sidebar: Scenarios

Sidebar: Stakeholders

Sidebar: Sensitivities and Risks

4: The BCS--The First Case Study in Applying the ATAM

Preparation

Phase 1

Phase 2

Results of The BCS Evaluation

Summary

Discussion Questions

Sidebar: "Issues"

Sidebar: Leading an Evaluation

Sidebar: Making the Most of Evaluators' Efforts

Sidebar: My Experiences with the ATAM

5: Understanding Quality Attributes

Quality Attribute Characterizations

Using Quality Attribute Characterizations in the ATAM

Attribute-Based Architectural Styles (ABASs)

Putting It All Together

For Further Reading

Discussion Questions

6: A Case Study in Applying the ATAM

Background

Phase 0: Partnership and Preparation

Phase 0 - Step 1: Present the ATAM

Phase 0 - Step 2: Describe Candidate System

Phase 0 - Step 3: Make a Go/No-Go Decision

Phase 0 - Step 4: Negotiate the Statement of Work

Phase 0 - Step 5: Form the Core Evaluation Team

Phase 0 - Step 6: Hold evaluation team kick-off meeting

Phase 0 - Step 7: Prepare for Phase 1

Phase 0 - Step 8: Review the architecture

Phase 1: Initial Evaluation

Phase 1 - Step 1: Present the ATAM

Phase 1 - Step 2: Present Business Drivers

Phase 1 - Step 3: Present Architecture

Phase 1 - Step 4: Identify Architectural Approaches

Phase 1 - Step 5: Generate Quality Attribute Utility Tree

Phase 1 - Step 6: Analyze Architectural Approaches

Hiatus between Phase 1 and Phase 2

Phase 2: Complete Evaluation

Step 0: Prepare for Phase 2

Phase 2 - Steps 1-6

Phase 2 - Step 7: Brainstorm and Prioritize Scenarios

Phase 2 - Step 8: Analyze Architectural Approaches

Phase 2 - Step 9: Present Results

Phase 3: Follow Up

Phase 3 - Step 1: Produce the Final Report

Phase 3 - Step 2: Hold the Post-Mortem Meeting

Phase 3 - Step 3: Build Portfolio and Update Artifact Repositories

For Further Reading

Discussion Questions

7: Introducing the SAAM and Using It to Evaluate an Example Architecture

Steps of a SAAM Evaluation

A SAAM Case Study

Summary

For Further Reading

Discussion Questions

Sidebar: "Their own Worst Critics"

8: Active Reviews for Intermediate Designs (ARID)

An Evaluation Method for Partial Architectures

A Case Study in Applying ARID

Summary

For Further Reading

Discussion Questions

Sidebar: "Active Design Reviews".

9: Comparing Software Architecture Evaluation Methods

Questioning Techniques

Measuring Techniques

Automated Tools and Architecture Description Languages

Hybrid Techniques

ATAM

Summary

For Further Reading

Discussion Questions

Sidebar: Danger Signals to Look For

Sidebar: Quality Attribute Workshops

10: Growing an Architecture Evaluation Capability in Your Organization

Building Organizational Buy-in

Growing a Pool of Evaluators

Establishing a Corporate Memory

Summary

Discussion Questions

Sidebar: "Don't Scare Me Off"

11: Conclusions

You are now Ready!

What Methods have you Seen?

Why Evaluate Architectures?

Why does the ATAM Work?

A Parting Message

Good Luck!

Sidebar: "...but it was OK."

Further Reading

References

Index