# Codebase / System Architecture Styles > Every principle in this category is listed as a record. Page: Ontology · Principles Canonical: https://banes-lab.com/ontology#architecture-category-codebase-system-architecture-styles Listed in [Ontology · Principles](https://banes-lab.com/api/pages/ontology/principles.md), after [Security / Privacy / Compliance / Governance](https://banes-lab.com/ontology/principles/architecture-category-security-privacy-compliance-governance.md) and before [Coordination Surfaces](https://banes-lab.com/ontology/principles/architecture-category-coordination-surfaces.md). Every principle in this category is listed as a record. Each record carries its kind, its severity, the scopes it applies at and the layer it lives in, then the edge relations that join it to other records, the records that point back at it, the contracts that answer to it and the tensions it takes part in. The descriptors say how it is violated, detected, measured, repaired and enforced. Where the record carries one, an exemplar shows the shape before and after the principle is applied. Relations diagram The relations inside this category. ```mermaid flowchart LR n_ports_and_adapters_architecture["Ports and Adapters Architecture"] n_hexagonal_architecture["Hexagonal Architecture"] n_clean_architecture["Clean Architecture"] n_layered_architecture["Layered Architecture"] n_component_based_architecture["Component-Based Architecture"] n_package_by_feature["Package by Feature"] n_microservices["Microservices"] n_monolith_architecture["Monolith Architecture"] n_pipes_and_filters["Pipes and Filters"] n_service_oriented_architecture["Service-Oriented Architecture"] n_space_based_architecture["Space-Based Architecture"] n_hexagonal_architecture --> n_clean_architecture ``` ### Ports and Adapters Architecture - Kind: [style](https://banes-lab.com/records/kind/style.md) - Category: [Codebase / System Architecture Styles](https://banes-lab.com/ontology/principles/architecture-category-codebase-system-architecture-styles.md) - Severity: [recommended](https://banes-lab.com/records/vocabulary/severity-recommended.md) - Scope: application, service, component - Layer: [Structural Core](https://banes-lab.com/records/layer/structural-core.md) Details Definition A convention of placing every external dependency behind a port the application owns, implemented by an adapter outside it. Requires [Ports](https://banes-lab.com/records/lexicon/ports.md), [Adapters](https://banes-lab.com/records/lexicon/adapters.md), [Dependency Inversion Principle (DIP)](https://banes-lab.com/records/architecture/dependency-inversion.md) Reinforces [Replaceability](https://banes-lab.com/records/architecture/replaceability.md), [Testability](https://banes-lab.com/records/architecture/testability.md) Enables [Infrastructure Independence](https://banes-lab.com/records/lexicon/infrastructure-independence.md) In tension with [Boilerplate](https://banes-lab.com/records/lexicon/boilerplate.md) Conflicts with [Framework Leakage](https://banes-lab.com/records/architecture/framework-leakage.md) Tensions [Ports and Adapters Architecture / Boilerplate](https://banes-lab.com/records/tension/boilerplate-ports-and-adapters-architecture.md) Violated by domain/application importing infrastructure Detected by inward/outward dependency violations Measured by adapter coverage, boundary purity Refactored by Introduce Port, Extract Adapter Enforced by layer dependency rules Before ```typescript class FooService { save(foo: Foo) { return sql.query("insert into foo values (?)", foo); } } ``` After ```typescript interface SaveFooPort { save(foo: Foo): Promise; } class FooService { constructor(private readonly port: SaveFooPort) {} save(foo: Foo) { return this.port.save(foo); } } class SqlFooAdapter implements SaveFooPort { save(foo: Foo) { return sqlFooStore.save(foo); } } ``` How it is checked Checked by layer dependency rules Population Every import, package and service boundary the style's dependency rules range over Freshness A verdict stands until an import, a package boundary or a deployment unit changes Refusal The layer or dependency rule fails the build on an edge the style forbids Observation The import graph and the deployment topology, read from source and configuration Evidence None, because the catalog states this check as a class, so a watched run belongs to each system that adopts it Authoritative side The style's declared dependency rules, which every import and deployment edge conforms to Depends on [Ports](https://banes-lab.com/records/lexicon/ports.md), [Adapters](https://banes-lab.com/records/lexicon/adapters.md), [Dependency Inversion Principle (DIP)](https://banes-lab.com/records/architecture/dependency-inversion.md), [Replaceability](https://banes-lab.com/records/architecture/replaceability.md), [Testability](https://banes-lab.com/records/architecture/testability.md), [Infrastructure Independence](https://banes-lab.com/records/lexicon/infrastructure-independence.md) Shape it refuses [Framework Leakage](https://banes-lab.com/records/architecture/framework-leakage.md), [Framework Leakage](https://banes-lab.com/records/architecture/framework-leakage.md) ### Hexagonal Architecture - Kind: [style](https://banes-lab.com/records/kind/style.md) - Category: [Codebase / System Architecture Styles](https://banes-lab.com/ontology/principles/architecture-category-codebase-system-architecture-styles.md) - Severity: [recommended](https://banes-lab.com/records/vocabulary/severity-recommended.md) - Scope: application, service - Layer: [Structural Core](https://banes-lab.com/records/layer/structural-core.md) Details Definition A convention of keeping a domain core free of framework and data types, with every input and output reached through ports. Requires [Ports and Adapters](https://banes-lab.com/records/lexicon/ports-and-adapters.md), [Domain Core](https://banes-lab.com/records/lexicon/domain-core.md) Reinforces [Clean Architecture](https://banes-lab.com/records/architecture/clean-architecture.md), [Testability](https://banes-lab.com/records/architecture/testability.md) Enables [External System Isolation](https://banes-lab.com/records/lexicon/external-system-isolation.md) In tension with [Initial Complexity](https://banes-lab.com/records/lexicon/initial-complexity.md) Conflicts with [Framework-Centric Core](https://banes-lab.com/records/lexicon/framework-centric-core.md) Tensions [Hexagonal Architecture / Initial Complexity](https://banes-lab.com/records/tension/hexagonal-architecture-initial-complexity.md) Distinct from [Clean Architecture](https://banes-lab.com/records/architecture/clean-architecture.md): Hexagonal architecture isolates the core behind ports, while clean architecture arranges concentric layers whose dependencies point inward. Violated by framework/data types in core Detected by dependency direction violations Measured by core purity score Refactored by Move Framework Outward, Add Ports Enforced by architecture tests Before ```typescript app.post("/foo", async request => sqlFooStore.save(await request.json())); ``` After ```typescript class CreateFooUseCase { constructor(private readonly foos: FooRepository, private readonly events: EventPublisher) {} execute(input: CreateFoo) { return createFooCore(input, this.foos, this.events); } } httpAdapter.bind("POST", "/foo", input => useCase.execute(input)); ``` How it is checked Checked by architecture tests Population Every import, package and service boundary the style's dependency rules range over Freshness A verdict stands until an import, a package boundary or a deployment unit changes Refusal The layer or dependency rule fails the build on an edge the style forbids Observation The import graph and the deployment topology, read from source and configuration Evidence None, because the catalog states this check as a class, so a watched run belongs to each system that adopts it Authoritative side The style's declared dependency rules, which every import and deployment edge conforms to Depends on [Ports and Adapters](https://banes-lab.com/records/lexicon/ports-and-adapters.md), [Domain Core](https://banes-lab.com/records/lexicon/domain-core.md), [Clean Architecture](https://banes-lab.com/records/architecture/clean-architecture.md), [Testability](https://banes-lab.com/records/architecture/testability.md), [External System Isolation](https://banes-lab.com/records/lexicon/external-system-isolation.md) Shape it refuses [Framework-Centric Core](https://banes-lab.com/records/lexicon/framework-centric-core.md) ### Clean Architecture - Kind: [style](https://banes-lab.com/records/kind/style.md) - Category: [Codebase / System Architecture Styles](https://banes-lab.com/ontology/principles/architecture-category-codebase-system-architecture-styles.md) - Severity: [recommended](https://banes-lab.com/records/vocabulary/severity-recommended.md) - Scope: application, system - Layer: [Structural Core](https://banes-lab.com/records/layer/structural-core.md) Details Definition A convention of concentric layers in which source dependencies point only inward, towards the use cases and entities. Requires [Dependency Rule](https://banes-lab.com/records/lexicon/dependency-rule.md), [Use Cases](https://banes-lab.com/records/lexicon/use-cases.md), [Boundaries](https://banes-lab.com/records/lexicon/boundaries.md) Reinforces [Dependency Inversion Principle (DIP)](https://banes-lab.com/records/architecture/dependency-inversion.md), [Testability](https://banes-lab.com/records/architecture/testability.md) Enables [Framework Independence](https://banes-lab.com/records/lexicon/framework-independence.md) In tension with [Boilerplate](https://banes-lab.com/records/lexicon/boilerplate.md) Conflicts with [Layer Leakage](https://banes-lab.com/records/lexicon/layer-leakage.md) Referenced by [Dependency Inversion Principle (DIP)](https://banes-lab.com/records/architecture/dependency-inversion.md), [Hexagonal Architecture](https://banes-lab.com/records/architecture/hexagonal-architecture.md) Tensions [Clean Architecture / Boilerplate](https://banes-lab.com/records/tension/boilerplate-clean-architecture.md) Violated by outer layers imported by inner layers Detected by dependency rule violations Measured by inward dependency compliance Refactored by Move Logic Inward, Extract Interface, Add Adapter Enforced by dependency graph rules Before ```typescript class FooController { async create(request: Request) { return orm.foo.create(await request.json()); } } ``` After ```typescript interface CreateFooGateway { save(foo: Foo): Promise; } class CreateFooInteractor { constructor(private readonly gateway: CreateFooGateway) {} execute(input: CreateFooInput) { return this.gateway.save(Foo.create(input)); } } class FooController { constructor(private readonly useCase: CreateFooInteractor) {} } ``` How it is checked Checked by dependency graph rules Population Every import, package and service boundary the style's dependency rules range over Freshness A verdict stands until an import, a package boundary or a deployment unit changes Refusal The layer or dependency rule fails the build on an edge the style forbids Observation The import graph and the deployment topology, read from source and configuration Evidence None, because the catalog states this check as a class, so a watched run belongs to each system that adopts it Authoritative side The style's declared dependency rules, which every import and deployment edge conforms to Depends on [Dependency Rule](https://banes-lab.com/records/lexicon/dependency-rule.md), [Use Cases](https://banes-lab.com/records/lexicon/use-cases.md), [Boundaries](https://banes-lab.com/records/lexicon/boundaries.md), [Dependency Inversion Principle (DIP)](https://banes-lab.com/records/architecture/dependency-inversion.md), [Testability](https://banes-lab.com/records/architecture/testability.md), [Framework Independence](https://banes-lab.com/records/lexicon/framework-independence.md) Shape it refuses [Layer Leakage](https://banes-lab.com/records/lexicon/layer-leakage.md) ### Layered Architecture - Kind: [style](https://banes-lab.com/records/kind/style.md) - Category: [Codebase / System Architecture Styles](https://banes-lab.com/ontology/principles/architecture-category-codebase-system-architecture-styles.md) - Severity: [contextual](https://banes-lab.com/records/vocabulary/severity-contextual.md) - Scope: application, system - Layer: [Structural Core](https://banes-lab.com/records/layer/structural-core.md) Details Definition A convention of stacking presentation, application and persistence layers, each calling only the layer below it. Requires [Layer Separation](https://banes-lab.com/records/lexicon/layer-separation.md) Reinforces [Separation of Concerns](https://banes-lab.com/records/architecture/separation-of-concerns.md) Enables [Structured Code Organization](https://banes-lab.com/records/lexicon/structured-code-organization.md) In tension with [Anemic Layers](https://banes-lab.com/records/lexicon/anemic-layers.md) Conflicts with [Layer Skipping](https://banes-lab.com/records/lexicon/layer-skipping.md) Referenced by [Separation of Concerns](https://banes-lab.com/records/architecture/separation-of-concerns.md) Tensions [Layered Architecture / Anemic Layers](https://banes-lab.com/records/tension/anemic-layers-layered-architecture.md) Violated by presentation accessing persistence directly Detected by forbidden layer imports Measured by layer violation count Refactored by Move Logic, Introduce Service/Repository Boundary Enforced by layer rules Before ```typescript function createFoo(request: Request) { return sql.query("insert into foo values (?)", JSON.parse(request.body)); } ``` After ```typescript class FooController { constructor(private readonly service: FooService) {} } class FooService { constructor(private readonly repository: FooRepository) {} } class SqlFooRepository implements FooRepository { save(foo: Foo) { return fooTable.insert(foo); } } ``` How it is checked Checked by layer rules Population Every import, package and service boundary the style's dependency rules range over Freshness A verdict stands until an import, a package boundary or a deployment unit changes Refusal The layer or dependency rule fails the build on an edge the style forbids Observation The import graph and the deployment topology, read from source and configuration Evidence None, because the catalog states this check as a class, so a watched run belongs to each system that adopts it Authoritative side The style's declared dependency rules, which every import and deployment edge conforms to Depends on [Layer Separation](https://banes-lab.com/records/lexicon/layer-separation.md), [Separation of Concerns](https://banes-lab.com/records/architecture/separation-of-concerns.md), [Structured Code Organization](https://banes-lab.com/records/lexicon/structured-code-organization.md) Shape it refuses [Layer Skipping](https://banes-lab.com/records/lexicon/layer-skipping.md) ### Component-Based Architecture - Kind: [style](https://banes-lab.com/records/kind/style.md) - Category: [Codebase / System Architecture Styles](https://banes-lab.com/ontology/principles/architecture-category-codebase-system-architecture-styles.md) - Severity: [recommended](https://banes-lab.com/records/vocabulary/severity-recommended.md) - Scope: component, system - Layer: [Structural Core](https://banes-lab.com/records/layer/structural-core.md) Details Definition A convention of building a system from components that declare what they export and what they require. Requires [Component Boundaries](https://banes-lab.com/records/lexicon/component-boundaries.md), [Contracts](https://banes-lab.com/records/lexicon/contracts.md) Reinforces [Modularity](https://banes-lab.com/records/architecture/modularity.md), [Composability](https://banes-lab.com/records/architecture/composability.md) Enables [Reuse](https://banes-lab.com/records/lexicon/reuse.md), [Replaceability](https://banes-lab.com/records/architecture/replaceability.md) In tension with [Integration Overhead](https://banes-lab.com/records/lexicon/integration-overhead.md) Conflicts with [Big Ball of Mud](https://banes-lab.com/records/architecture/big-ball-of-mud.md) Tensions [Component-Based Architecture / Integration Overhead](https://banes-lab.com/records/tension/component-based-architecture-integration-overhead.md) Violated by component internals accessed externally Detected by boundary import violations Measured by component cohesion/coupling Refactored by Extract Component, Define Contract Enforced by component ownership rules Before ```typescript const app = { createFoo, createBar, renderFoo, saveBar, publishBaz, }; ``` After ```typescript const fooComponent = defineComponent({ name: "foo", exports: { createFoo, FooView }, requires: { FooStore, EventBus }, }); ``` How it is checked Checked by component ownership rules Population Every import, package and service boundary the style's dependency rules range over Freshness A verdict stands until an import, a package boundary or a deployment unit changes Refusal The layer or dependency rule fails the build on an edge the style forbids Observation The import graph and the deployment topology, read from source and configuration Evidence None, because the catalog states this check as a class, so a watched run belongs to each system that adopts it Authoritative side The style's declared dependency rules, which every import and deployment edge conforms to Depends on [Component Boundaries](https://banes-lab.com/records/lexicon/component-boundaries.md), [Contracts](https://banes-lab.com/records/lexicon/contracts.md), [Modularity](https://banes-lab.com/records/architecture/modularity.md), [Composability](https://banes-lab.com/records/architecture/composability.md), [Reuse](https://banes-lab.com/records/lexicon/reuse.md), [Replaceability](https://banes-lab.com/records/architecture/replaceability.md) Shape it refuses [Big Ball of Mud](https://banes-lab.com/records/architecture/big-ball-of-mud.md) ### Package by Feature - Kind: [principle](https://banes-lab.com/records/kind/principle.md) - Category: [Codebase / System Architecture Styles](https://banes-lab.com/ontology/principles/architecture-category-codebase-system-architecture-styles.md) - Severity: [recommended](https://banes-lab.com/records/vocabulary/severity-recommended.md) - Scope: package, module - Layer: [Structural Core](https://banes-lab.com/records/layer/structural-core.md) Details Definition A design rule that code is grouped by the feature it serves, so one change stays inside one package. Requires [Feature Cohesion](https://banes-lab.com/records/lexicon/feature-cohesion.md) Reinforces [Modularity](https://banes-lab.com/records/architecture/modularity.md), [Bounded Context](https://banes-lab.com/records/architecture/bounded-context.md) Enables [Locality of Change](https://banes-lab.com/records/lexicon/locality-of-change.md) In tension with [Shared Technical Concerns](https://banes-lab.com/records/lexicon/shared-technical-concerns.md) Conflicts with [Package by Technical Layer Only](https://banes-lab.com/records/lexicon/package-by-technical-layer-only.md) Tensions [Package by Feature / Shared Technical Concerns](https://banes-lab.com/records/tension/package-by-feature-shared-technical-concerns.md) Violated by feature logic scattered across technical folders Detected by change sets spanning many layer packages Measured by change locality Refactored by Repackage by Feature, Move Classes Enforced by package conventions Before ```typescript src/controllers/foo.ts src/controllers/bar.ts src/services/foo.ts src/services/bar.ts src/repositories/foo.ts src/repositories/bar.ts ``` After ```typescript src/foo/controller.ts src/foo/service.ts src/foo/repository.ts src/bar/controller.ts src/bar/service.ts src/bar/repository.ts ``` How it is checked Checked by package conventions Population Every import, package and service boundary the style's dependency rules range over Freshness A verdict stands until an import, a package boundary or a deployment unit changes Refusal The layer or dependency rule fails the build on an edge the style forbids Observation The import graph and the deployment topology, read from source and configuration Evidence None, because the catalog states this check as a class, so a watched run belongs to each system that adopts it Authoritative side The style's declared dependency rules, which every import and deployment edge conforms to Depends on [Feature Cohesion](https://banes-lab.com/records/lexicon/feature-cohesion.md), [Modularity](https://banes-lab.com/records/architecture/modularity.md), [Bounded Context](https://banes-lab.com/records/architecture/bounded-context.md), [Locality of Change](https://banes-lab.com/records/lexicon/locality-of-change.md) Shape it refuses [Package by Technical Layer Only](https://banes-lab.com/records/lexicon/package-by-technical-layer-only.md) ### Microservices - Kind: [style](https://banes-lab.com/records/kind/style.md) - Category: [Codebase / System Architecture Styles](https://banes-lab.com/ontology/principles/architecture-category-codebase-system-architecture-styles.md) - Severity: [contextual](https://banes-lab.com/records/vocabulary/severity-contextual.md) - Scope: system, service, deployment - Layer: [Structural Core](https://banes-lab.com/records/layer/structural-core.md) Details Definition A convention of splitting a system into services that each own their data and deploy independently. Requires [Autonomy](https://banes-lab.com/records/architecture/autonomy.md), [Independent Deployment](https://banes-lab.com/records/lexicon/independent-deployment.md) Reinforces [Scalability](https://banes-lab.com/records/architecture/scalability.md), [Bounded Context](https://banes-lab.com/records/architecture/bounded-context.md) Enables [Decentralized Ownership](https://banes-lab.com/records/lexicon/decentralized-ownership.md) In tension with [Operational Complexity](https://banes-lab.com/records/lexicon/operational-complexity.md), [Consistency](https://banes-lab.com/records/architecture/consistency.md) Conflicts with [Distributed Monolith](https://banes-lab.com/records/architecture/distributed-monolith.md) Referenced by [Bounded Context](https://banes-lab.com/records/architecture/bounded-context.md), [Decentralization](https://banes-lab.com/records/architecture/decentralization.md), [Autonomy](https://banes-lab.com/records/architecture/autonomy.md) Tensions [Microservices / Operational Complexity](https://banes-lab.com/records/tension/microservices-operational-complexity.md), [Microservices / Consistency](https://banes-lab.com/records/tension/consistency-microservices.md) Violated by shared databases, synchronous service chains Detected by deployment coupling, cross-service transactions Measured by deploy independence, coupling metrics Refactored by Split Service, [Own Data](https://banes-lab.com/records/lexicon/own-data.md), Add Events Enforced by service ownership, API contracts Before ```typescript class SharedApplication { createFoo(foo: Foo) { return sharedDb.insert("foo", foo); } createBar(bar: Bar) { return sharedDb.insert("bar", bar); } } ``` After ```typescript class FooService { constructor(private readonly fooStore: FooStore, private readonly outbox: Outbox) {} create(foo: Foo) { return transact(() => [this.fooStore.save(foo), this.outbox.append(fooCreated(foo))]); } } class BarService { constructor(private readonly barStore: BarStore) {} } ``` How it is checked Checked by service ownership, API contracts Population Every import, package and service boundary the style's dependency rules range over Freshness A verdict stands until an import, a package boundary or a deployment unit changes Refusal The layer or dependency rule fails the build on an edge the style forbids Observation The import graph and the deployment topology, read from source and configuration Evidence None, because the catalog states this check as a class, so a watched run belongs to each system that adopts it Authoritative side The style's declared dependency rules, which every import and deployment edge conforms to Depends on [Autonomy](https://banes-lab.com/records/architecture/autonomy.md), [Independent Deployment](https://banes-lab.com/records/lexicon/independent-deployment.md), [Scalability](https://banes-lab.com/records/architecture/scalability.md), [Bounded Context](https://banes-lab.com/records/architecture/bounded-context.md), [Decentralized Ownership](https://banes-lab.com/records/lexicon/decentralized-ownership.md) Shape it refuses [Distributed Monolith](https://banes-lab.com/records/architecture/distributed-monolith.md) ### Monolith Architecture - Kind: [style](https://banes-lab.com/records/kind/style.md) - Category: [Codebase / System Architecture Styles](https://banes-lab.com/ontology/principles/architecture-category-codebase-system-architecture-styles.md) - Severity: [contextual](https://banes-lab.com/records/vocabulary/severity-contextual.md) - Scope: application, deployment - Layer: [Structural Core](https://banes-lab.com/records/layer/structural-core.md) Details Definition A convention of deploying a system as one unit, with its modules kept apart by internal boundaries. Requires [Unified Deployment Boundary](https://banes-lab.com/records/lexicon/unified-deployment-boundary.md) Reinforces [Operational Simplicity](https://banes-lab.com/records/lexicon/operational-simplicity.md) Enables [Transactional Simplicity](https://banes-lab.com/records/lexicon/transactional-simplicity.md) In tension with [Team Autonomy](https://banes-lab.com/records/lexicon/team-autonomy.md), [Independent Scaling](https://banes-lab.com/records/lexicon/independent-scaling.md) Conflicts with [Unbounded Big Ball of Mud](https://banes-lab.com/records/lexicon/unbounded-big-ball-of-mud.md) Tensions [Monolith Architecture / Team Autonomy](https://banes-lab.com/records/tension/monolith-architecture-team-autonomy.md), [Monolith Architecture / Independent Scaling](https://banes-lab.com/records/tension/independent-scaling-monolith-architecture.md) Violated by unclear internal boundaries Detected by cyclic packages, high global coupling Measured by module boundary health Refactored by Modularize Internally, Add Boundaries Enforced by modular monolith rules Before ```typescript await http.post("foo-service", foo); await http.post("bar-service", bar); await http.post("baz-service", baz); ``` After ```typescript class ModularMonolith { constructor(readonly foo: FooModule, readonly bar: BarModule, readonly baz: BazModule) {} } await app.foo.create(foo); await app.bar.create(bar); ``` How it is checked Checked by modular monolith rules Population Every import, package and service boundary the style's dependency rules range over Freshness A verdict stands until an import, a package boundary or a deployment unit changes Refusal The layer or dependency rule fails the build on an edge the style forbids Observation The import graph and the deployment topology, read from source and configuration Evidence None, because the catalog states this check as a class, so a watched run belongs to each system that adopts it Authoritative side The style's declared dependency rules, which every import and deployment edge conforms to Depends on [Unified Deployment Boundary](https://banes-lab.com/records/lexicon/unified-deployment-boundary.md), [Operational Simplicity](https://banes-lab.com/records/lexicon/operational-simplicity.md), [Transactional Simplicity](https://banes-lab.com/records/lexicon/transactional-simplicity.md) Shape it refuses [Unbounded Big Ball of Mud](https://banes-lab.com/records/lexicon/unbounded-big-ball-of-mud.md) ### Pipes and Filters - Kind: [style](https://banes-lab.com/records/kind/style.md) - Category: [Codebase / System Architecture Styles](https://banes-lab.com/ontology/principles/architecture-category-codebase-system-architecture-styles.md) - Severity: [recommended](https://banes-lab.com/records/vocabulary/severity-recommended.md) - Scope: application, data processing, composition - Layer: [Structural Core](https://banes-lab.com/records/layer/structural-core.md) Details Definition A convention of processing data through independent stages that share one input and output interface. Requires [Uniform Stage Interface](https://banes-lab.com/records/lexicon/uniform-stage-interface.md) Reinforces [Single Responsibility Principle (SRP)](https://banes-lab.com/records/architecture/single-responsibility.md), [Composability](https://banes-lab.com/records/architecture/composability.md) Enables [Reorderable Stages](https://banes-lab.com/records/lexicon/reorderable-stages.md), [Independent Stage Testing](https://banes-lab.com/records/lexicon/independent-stage-testing.md) In tension with [End-to-End Traceability](https://banes-lab.com/records/lexicon/end-to-end-traceability.md) Conflicts with [Monolithic Transform Function](https://banes-lab.com/records/lexicon/monolithic-transform-function.md) Tensions [Pipes and Filters / End-to-End Traceability](https://banes-lab.com/records/tension/end-to-end-traceability-pipes-and-filters.md) Violated by one function performing every transform step inline Detected by long sequential transform bodies Measured by transform-step count per function Refactored by Extract Filters, Connect via Pipeline Enforced by [design review](https://banes-lab.com/records/architecture/design-review.md) Before ```typescript function processFoo(raw: string) { const parsed = parseFoo(raw); const cleaned = cleanFoo(parsed); return enrichFoo(cleaned); } ``` After ```typescript const filters: FooFilter[] = [parseFoo, cleanFoo, enrichFoo]; const fooPipeline = connect(filters); fooPipeline.run(raw); ``` How it is checked Checked by design review Population Every import, package and service boundary the style's dependency rules range over Freshness A verdict stands until an import, a package boundary or a deployment unit changes Refusal The layer or dependency rule fails the build on an edge the style forbids Observation The import graph and the deployment topology, read from source and configuration Evidence None, because the catalog states this check as a class, so a watched run belongs to each system that adopts it Authoritative side The style's declared dependency rules, which every import and deployment edge conforms to Depends on [Uniform Stage Interface](https://banes-lab.com/records/lexicon/uniform-stage-interface.md), [Single Responsibility Principle (SRP)](https://banes-lab.com/records/architecture/single-responsibility.md), [Composability](https://banes-lab.com/records/architecture/composability.md), [Reorderable Stages](https://banes-lab.com/records/lexicon/reorderable-stages.md), [Independent Stage Testing](https://banes-lab.com/records/lexicon/independent-stage-testing.md) Shape it refuses [Monolithic Transform Function](https://banes-lab.com/records/lexicon/monolithic-transform-function.md) ### Service-Oriented Architecture - Kind: [style](https://banes-lab.com/records/kind/style.md) - Category: [Codebase / System Architecture Styles](https://banes-lab.com/ontology/principles/architecture-category-codebase-system-architecture-styles.md) - Severity: [contextual](https://banes-lab.com/records/vocabulary/severity-contextual.md) - Scope: application, service, integration - Aliases: SOA - Layer: [Structural Core](https://banes-lab.com/records/layer/structural-core.md) Details Definition A convention of exposing each business capability as a service governed by a published contract. Requires [Service Contract](https://banes-lab.com/records/architecture/service-contract.md) Reinforces [Autonomy](https://banes-lab.com/records/architecture/autonomy.md), [Low Coupling](https://banes-lab.com/records/architecture/low-coupling.md) Enables [Contract-Governed Service Reuse](https://banes-lab.com/records/lexicon/contract-governed-service-reuse.md) In tension with [Operational Overhead](https://banes-lab.com/records/lexicon/operational-overhead.md) Conflicts with [Shared Monolithic Application](https://banes-lab.com/records/lexicon/shared-monolithic-application.md) Tensions [Service-Oriented Architecture / Operational Overhead](https://banes-lab.com/records/tension/operational-overhead-service-oriented-architecture.md) Violated by capabilities bundled in one application object Detected by unrelated operations sharing one class/module Measured by capability cohesion per module Refactored by Expose Capabilities as Contracted Services Enforced by [architecture review](https://banes-lab.com/records/architecture/architecture-review.md) Before ```typescript class Application { createFoo() {} createBar() {} createBaz() {} } ``` After ```typescript const fooService = registerService("FooService", { create: createFoo }, { contract: FooServiceContract }); serviceBus.expose(fooService); ``` How it is checked Checked by architecture review Population Every import, package and service boundary the style's dependency rules range over Freshness A verdict stands until an import, a package boundary or a deployment unit changes Refusal The layer or dependency rule fails the build on an edge the style forbids Observation The import graph and the deployment topology, read from source and configuration Evidence None, because the catalog states this check as a class, so a watched run belongs to each system that adopts it Authoritative side The style's declared dependency rules, which every import and deployment edge conforms to Depends on [Service Contract](https://banes-lab.com/records/architecture/service-contract.md), [Autonomy](https://banes-lab.com/records/architecture/autonomy.md), [Low Coupling](https://banes-lab.com/records/architecture/low-coupling.md), [Contract-Governed Service Reuse](https://banes-lab.com/records/lexicon/contract-governed-service-reuse.md) Shape it refuses [Shared Monolithic Application](https://banes-lab.com/records/lexicon/shared-monolithic-application.md) ### Space-Based Architecture - Kind: [style](https://banes-lab.com/records/kind/style.md) - Category: [Codebase / System Architecture Styles](https://banes-lab.com/ontology/principles/architecture-category-codebase-system-architecture-styles.md) - Severity: [contextual](https://banes-lab.com/records/vocabulary/severity-contextual.md) - Scope: application, scalability, distributed state - Layer: [Structural Core](https://banes-lab.com/records/layer/structural-core.md) Details Definition A convention of holding working state in a replicated in-memory space, so no central database limits scaling. Requires [Replicated In-Memory State](https://banes-lab.com/records/lexicon/replicated-in-memory-state.md) Reinforces [Horizontal Scaling](https://banes-lab.com/records/architecture/horizontal-scaling.md), [Elasticity](https://banes-lab.com/records/architecture/elasticity.md) Enables [Database-Bottleneck Removal](https://banes-lab.com/records/lexicon/database-bottleneck-removal.md) In tension with [Consistency](https://banes-lab.com/records/architecture/consistency.md) Conflicts with [Central Database Bottleneck](https://banes-lab.com/records/lexicon/central-database-bottleneck.md) Tensions [Space-Based Architecture / Consistency](https://banes-lab.com/records/tension/consistency-space-based-architecture.md) Violated by all reads/writes funneled through one central database Detected by single datastore as the scaling limit Measured by central-datastore contention rate Refactored by Adopt a Replicated Data Space Enforced by [architecture review](https://banes-lab.com/records/architecture/architecture-review.md) Before ```typescript const foo = await centralDatabase.find(id); ``` After ```typescript const foo = await fooSpace.read(id); fooSpace.on("write", replicateToPeers); ``` How it is checked Checked by architecture review Population Every import, package and service boundary the style's dependency rules range over Freshness A verdict stands until an import, a package boundary or a deployment unit changes Refusal The layer or dependency rule fails the build on an edge the style forbids Observation The import graph and the deployment topology, read from source and configuration Evidence None, because the catalog states this check as a class, so a watched run belongs to each system that adopts it Authoritative side The style's declared dependency rules, which every import and deployment edge conforms to Depends on [Replicated In-Memory State](https://banes-lab.com/records/lexicon/replicated-in-memory-state.md), [Horizontal Scaling](https://banes-lab.com/records/architecture/horizontal-scaling.md), [Elasticity](https://banes-lab.com/records/architecture/elasticity.md), [Database-Bottleneck Removal](https://banes-lab.com/records/lexicon/database-bottleneck-removal.md) Shape it refuses [Central Database Bottleneck](https://banes-lab.com/records/lexicon/central-database-bottleneck.md) ## Links to - [style](https://banes-lab.com/records/kind/style.md) - [recommended](https://banes-lab.com/records/vocabulary/severity-recommended.md) - [Structural Core](https://banes-lab.com/records/layer/structural-core.md) - [Ports](https://banes-lab.com/records/lexicon/ports.md) - [Adapters](https://banes-lab.com/records/lexicon/adapters.md) - [Dependency Inversion Principle](https://banes-lab.com/records/architecture/dependency-inversion.md) - [Replaceability](https://banes-lab.com/records/architecture/replaceability.md) - [Testability](https://banes-lab.com/records/architecture/testability.md) - [Infrastructure Independence](https://banes-lab.com/records/lexicon/infrastructure-independence.md) - [Boilerplate](https://banes-lab.com/records/lexicon/boilerplate.md) - [Framework Leakage](https://banes-lab.com/records/architecture/framework-leakage.md) - [Ports and Adapters Architecture / Boilerplate](https://banes-lab.com/records/tension/boilerplate-ports-and-adapters-architecture.md) - [Ports and Adapters](https://banes-lab.com/records/lexicon/ports-and-adapters.md) - [Domain Core](https://banes-lab.com/records/lexicon/domain-core.md) - [Clean Architecture](https://banes-lab.com/records/architecture/clean-architecture.md) - [External System Isolation](https://banes-lab.com/records/lexicon/external-system-isolation.md) - [Initial Complexity](https://banes-lab.com/records/lexicon/initial-complexity.md) - [Framework-Centric Core](https://banes-lab.com/records/lexicon/framework-centric-core.md) - [Hexagonal Architecture / Initial Complexity](https://banes-lab.com/records/tension/hexagonal-architecture-initial-complexity.md) - [Dependency Rule](https://banes-lab.com/records/lexicon/dependency-rule.md) - [Use Cases](https://banes-lab.com/records/lexicon/use-cases.md) - [Boundaries](https://banes-lab.com/records/lexicon/boundaries.md) - [Framework Independence](https://banes-lab.com/records/lexicon/framework-independence.md) - [Layer Leakage](https://banes-lab.com/records/lexicon/layer-leakage.md) - [Hexagonal Architecture](https://banes-lab.com/records/architecture/hexagonal-architecture.md) - [Clean Architecture / Boilerplate](https://banes-lab.com/records/tension/boilerplate-clean-architecture.md) - [contextual](https://banes-lab.com/records/vocabulary/severity-contextual.md) - [Layer Separation](https://banes-lab.com/records/lexicon/layer-separation.md) - [Separation of Concerns](https://banes-lab.com/records/architecture/separation-of-concerns.md) - [Structured Code Organization](https://banes-lab.com/records/lexicon/structured-code-organization.md) - [Anemic Layers](https://banes-lab.com/records/lexicon/anemic-layers.md) - [Layer Skipping](https://banes-lab.com/records/lexicon/layer-skipping.md) - [Layered Architecture / Anemic Layers](https://banes-lab.com/records/tension/anemic-layers-layered-architecture.md) - [Component Boundaries](https://banes-lab.com/records/lexicon/component-boundaries.md) - [Contracts](https://banes-lab.com/records/lexicon/contracts.md) - [Modularity](https://banes-lab.com/records/architecture/modularity.md) - [Composability](https://banes-lab.com/records/architecture/composability.md) - [Reuse](https://banes-lab.com/records/lexicon/reuse.md) - [Integration Overhead](https://banes-lab.com/records/lexicon/integration-overhead.md) - [Big Ball of Mud](https://banes-lab.com/records/architecture/big-ball-of-mud.md) - [Component-Based Architecture / Integration Overhead](https://banes-lab.com/records/tension/component-based-architecture-integration-overhead.md) - [principle](https://banes-lab.com/records/kind/principle.md) - [Feature Cohesion](https://banes-lab.com/records/lexicon/feature-cohesion.md) - [Bounded Context](https://banes-lab.com/records/architecture/bounded-context.md) - [Locality of Change](https://banes-lab.com/records/lexicon/locality-of-change.md) - [Shared Technical Concerns](https://banes-lab.com/records/lexicon/shared-technical-concerns.md) - [Package by Technical Layer Only](https://banes-lab.com/records/lexicon/package-by-technical-layer-only.md) - [Package by Feature / Shared Technical Concerns](https://banes-lab.com/records/tension/package-by-feature-shared-technical-concerns.md) - [Autonomy](https://banes-lab.com/records/architecture/autonomy.md) - [Independent Deployment](https://banes-lab.com/records/lexicon/independent-deployment.md) - [Scalability](https://banes-lab.com/records/architecture/scalability.md) - [Decentralized Ownership](https://banes-lab.com/records/lexicon/decentralized-ownership.md) - [Operational Complexity](https://banes-lab.com/records/lexicon/operational-complexity.md) - [Consistency](https://banes-lab.com/records/architecture/consistency.md) - [Distributed Monolith](https://banes-lab.com/records/architecture/distributed-monolith.md) - [Decentralization](https://banes-lab.com/records/architecture/decentralization.md) - [Microservices / Operational Complexity](https://banes-lab.com/records/tension/microservices-operational-complexity.md) - [Microservices / Consistency](https://banes-lab.com/records/tension/consistency-microservices.md) - [Own Data](https://banes-lab.com/records/lexicon/own-data.md) - [Unified Deployment Boundary](https://banes-lab.com/records/lexicon/unified-deployment-boundary.md) - [Operational Simplicity](https://banes-lab.com/records/lexicon/operational-simplicity.md) - [Transactional Simplicity](https://banes-lab.com/records/lexicon/transactional-simplicity.md) - [Team Autonomy](https://banes-lab.com/records/lexicon/team-autonomy.md) - [Independent Scaling](https://banes-lab.com/records/lexicon/independent-scaling.md) - [Unbounded Big Ball of Mud](https://banes-lab.com/records/lexicon/unbounded-big-ball-of-mud.md) - [Monolith Architecture / Team Autonomy](https://banes-lab.com/records/tension/monolith-architecture-team-autonomy.md) - [Monolith Architecture / Independent Scaling](https://banes-lab.com/records/tension/independent-scaling-monolith-architecture.md) - [Uniform Stage Interface](https://banes-lab.com/records/lexicon/uniform-stage-interface.md) - [Single Responsibility Principle](https://banes-lab.com/records/architecture/single-responsibility.md) - [Reorderable Stages](https://banes-lab.com/records/lexicon/reorderable-stages.md) - [Independent Stage Testing](https://banes-lab.com/records/lexicon/independent-stage-testing.md) - [End-to-End Traceability](https://banes-lab.com/records/lexicon/end-to-end-traceability.md) - [Monolithic Transform Function](https://banes-lab.com/records/lexicon/monolithic-transform-function.md) - [Pipes and Filters / End-to-End Traceability](https://banes-lab.com/records/tension/end-to-end-traceability-pipes-and-filters.md) - [Design Review](https://banes-lab.com/records/architecture/design-review.md) - [Service Contract](https://banes-lab.com/records/architecture/service-contract.md) - [Low Coupling](https://banes-lab.com/records/architecture/low-coupling.md) - [Contract-Governed Service Reuse](https://banes-lab.com/records/lexicon/contract-governed-service-reuse.md) - [Operational Overhead](https://banes-lab.com/records/lexicon/operational-overhead.md) - [Shared Monolithic Application](https://banes-lab.com/records/lexicon/shared-monolithic-application.md) - [Service-Oriented Architecture / Operational Overhead](https://banes-lab.com/records/tension/operational-overhead-service-oriented-architecture.md) - [Architecture Review](https://banes-lab.com/records/architecture/architecture-review.md) - [Replicated In-Memory State](https://banes-lab.com/records/lexicon/replicated-in-memory-state.md) - [Horizontal Scaling](https://banes-lab.com/records/architecture/horizontal-scaling.md) - [Elasticity](https://banes-lab.com/records/architecture/elasticity.md) - [Database-Bottleneck Removal](https://banes-lab.com/records/lexicon/database-bottleneck-removal.md) - [Central Database Bottleneck](https://banes-lab.com/records/lexicon/central-database-bottleneck.md) - [Space-Based Architecture / Consistency](https://banes-lab.com/records/tension/consistency-space-based-architecture.md) ## Linked from - [The layer topology](https://banes-lab.com/ontology/schema/the-layer-topology.md) - [The membership](https://banes-lab.com/ontology/schema/the-membership.md)