Fitness Functions

5 pages

Building Evolutionary Architectures source
*Building Evolutionary Architectures* — Ford, Parsons, Kua
Deployment Pipelines concept
Fitness function automation; stages, fan-in/fan-out; CD vs CDP; cycle time as business metric; zero-downtime deployment (four phases: prepare/drain/apply/start); expand/contract relational schema pattern; trickle-then-batch schemaless migration; canary group evaluation; immutable infrastructure; EDM deployment patterns
Evolutionary Architecture concept
Three pillars; evolvability by style; strangler fig; six Rs; guidelines; antipatterns; DDD brownfield modernisation strategy; "form follows failure"; bad layering (horizontal coupling); component-based decomposition; decision loop speed and thrashing; service extinction; Farley: testability+deployability as operational drivers, TDD as architectural feedback, architectural descriptions as "tourist maps"
Goal-Question-Metric (GQM) concept
GQM framework (Basili & Weiss 1984): goal → questions → metrics → data tree; goal statement structure (purpose/object/issue/viewpoint); metric selection criteria (signal strength, cost, cross-question reuse); 9-step workshop; Foo Service case study (rate-limit incident → heartbeat + fail-fast ADR → 10-minute detection before user impact)
Software Architecture Metrics source
*Software Architecture Metrics* — Ciceri et al.