Active Review for Intermediate Designs [Clements, 2000]

Introduction A piloted software design review technique A blend of stakeholder-centric, scenario-based, architecture evaluation method (ATAM and ADR) Goal: expose design to allow early feedback Designers want: To know if the design is tenable To unveil the design to the community of software writers

Benefits Provides valuable insight into design’s viability Allow for timely discovery of errors, inconsistencies, or inadequacies

Active Design Reviews (ADR) Effective technique for ensuring quality, detailed designs in software [Parnas, 85] Actively engaging reviewers to utilize the design in a series of exercises Conventional design review: Examine stacks of documentation Checklist to ensure design meets certain standards

ADRs evaluate detailed designs of modules Questions address: Quality and completeness of documentation Sufficiency, fitness, and suitability of the services provided by the design

Architecture Tradeoff Analysis Method (ATAM) A scenario-based design review techniques Scenarios proven to be valuable in the evaluation of system and software designs Relies on the present of the stakeholders Elicits business goals for system and its architecture Uses those goals and stakeholder participation to focus attention to key portions of the architecture

Benefits of ATAM Benefits: Financial gains Forced preparation Captured rationale Early detection of problems Validation of requirements Improved architecture

Phases in ATAM

Example Utility Tree Performance Utility Usability Maintainability Transaction response time (H, M) Performance Throughput 150 transactions/sec Training Utility Usability Normal operations Database vendor releases new version Maintainability

ARID ADR/ATAM hybrid ADR requires active reviewer participation ATAM embraced stakeholder-generated scenarios Three groups of participants: ARID review team (facilitator, scribe, process observer) Lead designer Reviewers (stakeholders)

Overview of ARID Steps

Phase One Phase 1: Pre-meeting (between lead designer and facilitator) Identify reviewers Prepare design presentation Facilitator ask “first order” questions Identify areas to improve presentation Set the pace for the presentation A practice to the designer

Phase One … (2) Prepare seed scenarios Prepare for the review meeting Designer and facilitator prepare sample set of scenarios E.g. a user in a particular context asks for help, and the system provides help for that context. Prepare for the review meeting Produce copies of presentation, seed scenarios, and review agenda

Phase Two Phase 2: Review Meeting Present ARID method (30 mins by facilitator) Present design (no questions nor suggestions allowed except on factual clarification) Scribe jots down every questions Brainstorm and prioritize scenarios Perform review Provides pseudo code to solve problems posed by the scenario Present conclusions

Output of ARID Initial Architecture System overview from a business perspective: Most important functions Any relevant technical, managerial, economic, or political constraint Business goals that relate to the project Major stakeholders Major quality attributes Set of seed of scenarios

Output of ARID … (2) Set of scenarios and their prioritization from the brainstorming The Utility Tree Issues and problems