Evaluating Architectural Options

1
Evaluating Architectural Options
Simon Field Chief Technology Officer
2
The development lifecycle context
First Architecture Review
Second Architecture Review
3
Architecture Trade-off Analysis Method

• Developed by
• Software Engineering Institute, Carnegie Mellon
  University
• Sponsored by the US Department of Defense
• Review team develop a utility tree showing
  trade-off among quality attributes for solution
  options
• References
• ATAMMethod for Architecture Evaluation
  (technical report from Software Engineering
  Institute, CMU)
• Evaluating Software Architectures by Paul
  Clements, Rick Kazman and Mark Klein

4
Review Structure

• Completion of Matrix 1
• Review preparation
• The Review workshop
• Describe business problem
• Outline solution options
• Review Matrix 1
• Populate Matrices 2 3
• Throughout build list of issues, mitigations
  etc.
• Write Report
• Duration of workshop varies from ½ day to 2 days
  depending on size and complexity of project

5
Governance

• Reviews mandated in ONSide development method
• Conducted on behalf of the ONS Architecture
  Review Board (ARB)
• Report signed of by ARB
• Accepted in writing by Project Board / Project
  Manager, or contested in an appeal
• Appeal heard by the ONS IM Committee (on behalf
  of the Executive Management Group)

6
Matrix 1 Quality Attributes
Relates quality attributes to project business
requirements
7
Matrix 2 Risk Trade-off
Examines risk of failure to achieve each business
requirement for each solution option
8
Matrix 3 Architectural Fit
Examines extent to which each solution option
satisfies a selected set of key architectural
principles
Scoring Guide 0Doesn't meet principle, 3Falls
short of principle, 5 Satisfactory/Compliant,
7-Good/Very Good, 10Fully meets principle/goes
beyond it
9
Conclusions

• Structured reviews help you
• get the right focus on all requirements
  (including NFRs)
• select the right architecture for each project
• steer projects towards your corporate vision
• reduce project risk and costs
• Make sure you get the governance right
• Involve the right stakeholders
• Link to existing corporate methods and processes