Evaluating Architectural Options Simon Field Chief Technology Officer

The development lifecycle context First Architecture Review Second Architecture Review

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: ATAM:Method for Architecture Evaluation ATAM:Method for Architecture Evaluation (technical report from Software Engineering Institute, CMU) Evaluating Software Architectures Evaluating Software Architectures by Paul Clements, Rick Kazman and Mark Klein

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

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)

Matrix 1 – Quality Attributes Relates quality attributes to project business requirements

Matrix 2 – Risk Trade-off Examines risk of failure to achieve each business requirement for each solution option

Matrix 3 – Architectural Fit Examines extent to which each solution option satisfies a selected set of key architectural principles Scoring Guide 0=Doesn't meet principle, 3=Falls short of principle, 5= Satisfactory/Compliant, 7=-Good/Very Good, 10=Fully meets principle/goes beyond it

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