book

Building Evolutionary Architectures, 2nd Edition

by Neal Ford, Rebecca Parsons, Patrick Kua, Pramod Sadalage

November 2022

Intermediate to advanced

262 pages

7h 38m

English

O'Reilly Media, Inc.

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The Structure of This BookCase Studies and PenultimateWidgetsConventions Used in This BookUsing Code ExamplesO’Reilly Online LearningHow to Contact UsAdditional InformationAcknowledgments
The Challenges of Evolving SoftwareEvolutionary ArchitectureGuided ChangeIncremental ChangeMultiple Architectural DimensionsHow Is Long-Term Planning Possible When Everything Changes All the Time?Once I’ve Built an Architecture, How Can I Prevent It from Degrading Over Time?Why Evolutionary?Summary
What Is a Fitness Function?CategoriesScope: Atomic Versus HolisticCadence: Triggered Versus Continual Versus TemporalCase Study: Triggered or Continuous?Result: Static Versus DynamicInvocation: Automated Versus ManualProactivity: Intentional Versus EmergentCoverage: Domain-Specific Fitness Functions?Who Writes Fitness Functions?Where Is My Fitness Function Testing Framework?Outcomes Versus ImplementationsSummary
Incremental ChangeDeployment PipelinesCase Study: Adding Fitness Functions to PenultimateWidgets’ Invoicing ServiceCase Study: Validating API Consistency in an Automated BuildSummary
Fitness Functions as Architectural GovernanceCode-Based Fitness FunctionsAfferent and Efferent CouplingAbstractness, Instability, and Distance from the Main SequenceDirectionality of ImportsCyclomatic Complexity and “Herding” GovernanceTurnkey ToolsLegality of Open Source LibrariesA11y and Other Supported Architecture CharacteristicsArchUnitLinters for Code GovernanceCase Study: Availability Fitness FunctionCase Study: Load-Testing Along with Canary ReleasesCase Study: What to Port?Fitness Functions You’re Already UsingIntegration ArchitectureCommunication Governance in MicroservicesCase Study: Choosing How to Implement a Fitness FunctionDevOpsEnterprise ArchitectureCase Study: Architectural Restructuring While Deploying 60 Times per DayFidelity Fitness FunctionsFitness Functions as a Checklist, Not a StickDocumenting Fitness FunctionsSummary
Evolvable Architecture StructureConnascenceConnascence Intersection with Bounded ContextArchitectural Quanta and GranularityIndependently DeployableHigh Functional CohesionHigh Static CouplingDynamic Quantum CouplingContractsCase Study: Microservices as an Evolutionary ArchitectureReuse PatternsEffective Reuse = Abstraction + Low VolatilitySidecars and Service Mesh: Orthogonal Operational CouplingData Mesh: Orthogonal Data CouplingSummary

Evolutionary Database DesignEvolving SchemasShared Database IntegrationInappropriate Data EntanglementTwo-Phase Commit TransactionsAge and Quality of DataCase Study: Evolving PenultimateWidgets’ RoutingFrom Native to Fitness FunctionReferential IntegrityData DuplicationReplacing Triggers and Stored ProceduresCase Study: Evolving from Relational to NonrelationalSummary
Principles of Evolutionary ArchitectureLast Responsible MomentArchitect and Develop for EvolvabilityPostel’s LawArchitect for TestabilityConway’s LawMechanicsStep 1: Identify Dimensions Affected by EvolutionStep 2: Define Fitness Function(s) for Each DimensionStep 3: Use Deployment Pipelines to Automate Fitness FunctionsGreenfield ProjectsRetrofitting Existing ArchitecturesAppropriate Coupling and CohesionCOTS ImplicationsMigrating ArchitecturesMigration StepsEvolving Module InteractionsGuidelines for Building Evolutionary ArchitecturesRemove Needless VariabilityMake Decisions ReversiblePrefer Evolvable over PredictableBuild Anticorruption LayersBuild Sacrificial ArchitecturesMitigate External ChangeUpdating Libraries Versus FrameworksVersion Services InternallyCase Study: Evolving PenultimateWidgets’ RatingsFitness Function-Driven ArchitectureSummary
Technical ArchitectureAntipattern: Last 10% Trap and Low Code/No CodeCase Study: Reuse at PenultimateWidgetsAntipattern: Vendor KingPitfall: Leaky AbstractionsPitfall: Resume-Driven DevelopmentIncremental ChangeAntipattern: Inappropriate GovernanceCase Study: “Just Enough” Governance at PenultimateWidgetsPitfall: Lack of Speed to ReleaseBusiness ConcernsPitfall: Product CustomizationAntipattern: Reporting Atop the System of RecordPitfall: Excessively Long Planning HorizonsSummary
Organizational FactorsDon’t Fight Conway’s LawCultureCulture of ExperimentationCFO and BudgetingThe Business CaseHypothesis- and Data-Driven DevelopmentFitness Functions as Experimental MediaBuilding Enterprise Fitness FunctionsCase Study: Zero-Day Security VulnerabilityCarving Out Bounded Contexts Within Existing Integration ArchitectureWhere Do You Start?Low-Hanging FruitHighest Value FirstTestingInfrastructureCase Study: Enterprise Architecture at PenultimateWidgetsFuture State?Fitness Functions Using AIGenerative TestingWhy (or Why Not)?Why Should a Company Decide to Build an Evolutionary Architecture?Why Would a Company Choose Not to Build an Evolutionary Architecture?Summary

Overview

The software development ecosystem is constantly changing, providing a constant stream of new tools, frameworks, techniques, and paradigms. Over the past few years, incremental developments in core engineering practices for software development have created the foundations for rethinking how architecture changes over time, along with ways to protect important architectural characteristics as it evolves. This practical guide ties those parts together with a new way to think about architecture and time.