# The layer topology > The layer topology holds the four core layers, the domains beneath them, the cross-cutting domains and the edges that join them. Page: Ontology · Schema Canonical: https://banes-lab.com/ontology/schema#the-layer-topology The layer topology holds the four core layers, the domains beneath them, the cross-cutting domains and the edges that join them. Every layer is an algorithm contract, and each record names the categories of principle and term that belong to it. Why a layer grouping exists beside the topical one is described in [the canon is grouped twice](https://banes-lab.com/software-architecture/principles/the-canon-is-grouped-twice.md) on the architecture page. Relations diagram The layer topology. ```mermaid flowchart TB n_layer_atomic_boundary["Atomic Boundary"] n_layer_causality_core["Causality Core"] n_layer_computation_core["Computation Core"] n_layer_contracts_core["Contracts Core"] n_layer_correctness_core["Correctness Core"] n_layer_declarative_core["Declarative Core"] n_layer_design_patterns_core["Design Patterns Core"] n_layer_domain_modeling["Domain Modeling"] n_layer_enforcement_core["Enforcement Core"] n_layer_evolution_principles["Evolution Principles"] n_layer_execution_core["Execution Core"] n_layer_extensibility_core["Extensibility Core"] n_layer_human_factors["Human Factors"] n_layer_observability["Observability"] n_layer_performance_core["Performance Core"] n_layer_resource_core["Resource Core"] n_layer_security_core["Security Core"] n_layer_structural_core["Structural Core"] n_layer_resource_core -- observe --> n_layer_computation_core n_layer_computation_core -- feeds --> n_layer_execution_core n_layer_resource_core -- feeds --> n_layer_execution_core n_layer_execution_core -- feeds --> n_layer_structural_core n_layer_structural_core -- feedback --> n_layer_execution_core n_layer_structural_core -- feeds --> n_layer_human_factors n_layer_structural_core -- feeds --> n_layer_evolution_principles n_layer_evolution_principles -- feeds --> n_layer_human_factors n_layer_correctness_core -- cross-cuts --> n_layer_structural_core n_layer_security_core -- cross-cuts --> n_layer_structural_core n_layer_performance_core -- cross-cuts --> n_layer_structural_core n_layer_contracts_core -- cross-cuts --> n_layer_structural_core n_layer_causality_core -- cross-cuts --> n_layer_structural_core n_layer_declarative_core -- cross-cuts --> n_layer_structural_core n_layer_extensibility_core -- cross-cuts --> n_layer_structural_core n_layer_observability -- cross-cuts --> n_layer_structural_core n_layer_enforcement_core -- cross-cuts --> n_layer_structural_core n_layer_atomic_boundary -- cross-cuts --> n_layer_structural_core n_layer_domain_modeling -- cross-cuts --> n_layer_structural_core n_layer_design_patterns_core -- cross-cuts --> n_layer_structural_core ``` ### Atomic Boundary - Contract: [Atomic Boundary](https://banes-lab.com/records/algo/atomic-boundary.md) Details Member categories [Transactions / State / Concurrency](https://banes-lab.com/ontology/principles/arch-category-transactions-state-concurrency.md) Outgoing edges cross-cuts → [Structural Core](https://banes-lab.com/records/layer/structural-core.md) Incoming edges none ### Causality Core - Contract: [Causality Core](https://banes-lab.com/records/algo/causality-core.md) Details Member categories [Causality / Ordering / Distributed Time](https://banes-lab.com/ontology/principles/arch-category-causality-ordering-distributed-time.md) Outgoing edges cross-cuts → [Structural Core](https://banes-lab.com/records/layer/structural-core.md) Incoming edges none ### Computation Core - Contract: [Computation Core](https://banes-lab.com/records/algo/computation-core.md) Details Member categories [Correctness / Determinism / Verification](https://banes-lab.com/ontology/principles/arch-category-correctness-determinism-verification.md) Outgoing edges feeds → [Execution Core](https://banes-lab.com/records/layer/execution-core.md) Incoming edges observe → [Resource Core](https://banes-lab.com/records/layer/resource-core.md) ### Contracts Core - Contract: [Contracts Core](https://banes-lab.com/records/algo/contracts-core.md) Details Member categories [Contracts / Interfaces / Compatibility](https://banes-lab.com/ontology/principles/arch-category-contracts-interfaces-compatibility.md), [Schema / Canonical Data / Semantics](https://banes-lab.com/ontology/principles/arch-category-schema-canonical-data-semantics.md) Outgoing edges cross-cuts → [Structural Core](https://banes-lab.com/records/layer/structural-core.md) Incoming edges none ### Correctness Core - Contract: [Correctness Core](https://banes-lab.com/records/algo/correctness-core.md) Details Member categories [Error Handling / Resilience](https://banes-lab.com/ontology/principles/arch-category-error-handling-resilience.md), [Model Architecture](https://banes-lab.com/ontology/principles/arch-category-model-architecture.md), [Self-Healing / Recovery / Deployment Safety](https://banes-lab.com/ontology/principles/arch-category-self-healing-recovery-deployment-safety.md), [Quality Attributes](https://banes-lab.com/ontology/lexicon/lex-category-quality-attributes.md) Outgoing edges cross-cuts → [Structural Core](https://banes-lab.com/records/layer/structural-core.md) Incoming edges none ### Declarative Core - Contract: [Declarative Core](https://banes-lab.com/records/algo/declarative-core.md) Details Member categories [Metadata / Self-Description / Declarative Systems](https://banes-lab.com/ontology/principles/arch-category-metadata-self-description-declarative-systems.md), [Metaprogramming / Language-Oriented Architecture](https://banes-lab.com/ontology/principles/arch-category-metaprogramming-language-oriented-architecture.md) Outgoing edges cross-cuts → [Structural Core](https://banes-lab.com/records/layer/structural-core.md) Incoming edges none ### Design Patterns Core - Contract: [Design Patterns Core](https://banes-lab.com/records/algo/design-patterns-core.md) Details Member categories [Behavioral Patterns](https://banes-lab.com/ontology/principles/arch-category-behavioral-patterns.md), [Creational Patterns](https://banes-lab.com/ontology/principles/arch-category-creational-patterns.md), [Structural Patterns](https://banes-lab.com/ontology/principles/arch-category-structural-patterns.md) Outgoing edges cross-cuts → [Structural Core](https://banes-lab.com/records/layer/structural-core.md) Incoming edges none ### Domain Modeling - Contract: [Domain Modeling](https://banes-lab.com/records/algo/domain-modeling.md) Details Member categories [Domain Architecture](https://banes-lab.com/ontology/principles/arch-category-domain-architecture.md) Outgoing edges cross-cuts → [Structural Core](https://banes-lab.com/records/layer/structural-core.md) Incoming edges none ### Enforcement Core - Contract: [Enforcement Core](https://banes-lab.com/records/algo/enforcement-core.md) Details Member categories [anti-patterns](https://banes-lab.com/ontology/principles/arch-category-anti-patterns.md) Outgoing edges cross-cuts → [Structural Core](https://banes-lab.com/records/layer/structural-core.md) Incoming edges none ### Evolution Principles - Contract: [Evolution Principles](https://banes-lab.com/records/algo/evolution-principles.md) Details Member categories [Architecture Review / Evolution / Governance Artifacts](https://banes-lab.com/ontology/principles/arch-category-architecture-review-evolution-governance-artifacts.md), [Architecture Review Evolution Governance](https://banes-lab.com/ontology/lexicon/lex-category-architecture-review-evolution-governance.md) Outgoing edges feeds → [Human Factors](https://banes-lab.com/records/layer/human-factors.md) Incoming edges feeds → [Structural Core](https://banes-lab.com/records/layer/structural-core.md) ### Execution Core - Contract: [Execution Core](https://banes-lab.com/records/algo/execution-core.md) Details Member categories [Control / Coordination / Centralization](https://banes-lab.com/ontology/principles/arch-category-control-coordination-centralization.md), [Event / Messaging / Asynchronous Architecture](https://banes-lab.com/ontology/principles/arch-category-event-messaging-asynchronous-architecture.md), [Streaming / Pipeline / Dataflow Processing](https://banes-lab.com/ontology/principles/arch-category-streaming-pipeline-dataflow-processing.md), [Event Messaging Async](https://banes-lab.com/ontology/lexicon/lex-category-event-messaging-async.md) Outgoing edges feeds → [Structural Core](https://banes-lab.com/records/layer/structural-core.md) Incoming edges feeds → [Computation Core](https://banes-lab.com/records/layer/computation-core.md), feeds → [Resource Core](https://banes-lab.com/records/layer/resource-core.md), feedback → [Structural Core](https://banes-lab.com/records/layer/structural-core.md) ### Extensibility Core - Contract: [Extensibility Core](https://banes-lab.com/records/algo/extensibility-core.md) Details Member categories [Plugin / Extensibility / IoC](https://banes-lab.com/ontology/principles/arch-category-plugin-extensibility-ioc.md), [Runtime Discovery / Dynamic Binding](https://banes-lab.com/ontology/principles/arch-category-runtime-discovery-dynamic-binding.md) Outgoing edges cross-cuts → [Structural Core](https://banes-lab.com/records/layer/structural-core.md) Incoming edges none ### Human Factors - Contract: [Human Factors](https://banes-lab.com/records/algo/human-factors.md) Details Member categories none Outgoing edges none Incoming edges feeds → [Structural Core](https://banes-lab.com/records/layer/structural-core.md), feeds → [Evolution Principles](https://banes-lab.com/records/layer/evolution-principles.md) ### Observability - Contract: [Observability](https://banes-lab.com/records/algo/observability.md) Details Member categories [Observability / Auditability / Traceability](https://banes-lab.com/ontology/principles/arch-category-observability-auditability-traceability.md) Outgoing edges cross-cuts → [Structural Core](https://banes-lab.com/records/layer/structural-core.md) Incoming edges none ### Performance Core - Contract: [Performance Core](https://banes-lab.com/records/algo/performance-core.md) Details Member categories [Scalability / Performance / Optimization](https://banes-lab.com/ontology/principles/arch-category-scalability-performance-optimization.md) Outgoing edges cross-cuts → [Structural Core](https://banes-lab.com/records/layer/structural-core.md) Incoming edges none ### Resource Core - Contract: [Resource Core](https://banes-lab.com/records/algo/resource-core.md) Details Member categories [Portability / Infrastructure / Deployment](https://banes-lab.com/ontology/principles/arch-category-portability-infrastructure-deployment.md) Outgoing edges observe → [Computation Core](https://banes-lab.com/records/layer/computation-core.md), feeds → [Execution Core](https://banes-lab.com/records/layer/execution-core.md) Incoming edges none ### Security Core - Contract: [Security Core](https://banes-lab.com/records/algo/security-core.md) Details Member categories [Security / Privacy / Compliance / Governance](https://banes-lab.com/ontology/principles/arch-category-security-privacy-compliance-governance.md), [Security Privacy Compliance](https://banes-lab.com/ontology/lexicon/lex-category-security-privacy-compliance.md) Outgoing edges cross-cuts → [Structural Core](https://banes-lab.com/records/layer/structural-core.md) Incoming edges none ### Structural Core - Contract: [Structural Core](https://banes-lab.com/records/algo/structural-core.md) Details Member categories [Codebase / System Architecture Styles](https://banes-lab.com/ontology/principles/arch-category-codebase-system-architecture-styles.md), [Core Modular Design](https://banes-lab.com/ontology/principles/arch-category-core-modular-design.md), [SOLID / Object-Oriented Design](https://banes-lab.com/ontology/principles/arch-category-solid-object-oriented-design.md), [Taxonomy / Classification / Naming](https://banes-lab.com/ontology/principles/arch-category-taxonomy-classification-naming.md), [Core Vocabulary](https://banes-lab.com/ontology/lexicon/lex-category-core-vocabulary.md) Outgoing edges feedback → [Execution Core](https://banes-lab.com/records/layer/execution-core.md), feeds → [Human Factors](https://banes-lab.com/records/layer/human-factors.md), feeds → [Evolution Principles](https://banes-lab.com/records/layer/evolution-principles.md) Incoming edges feeds → [Execution Core](https://banes-lab.com/records/layer/execution-core.md), cross-cuts → [Correctness Core](https://banes-lab.com/records/layer/correctness-core.md), cross-cuts → [Security Core](https://banes-lab.com/records/layer/security-core.md), cross-cuts → [Performance Core](https://banes-lab.com/records/layer/performance-core.md), cross-cuts → [Contracts Core](https://banes-lab.com/records/layer/contracts-core.md), cross-cuts → [Causality Core](https://banes-lab.com/records/layer/causality-core.md), cross-cuts → [Declarative Core](https://banes-lab.com/records/layer/declarative-core.md), cross-cuts → [Extensibility Core](https://banes-lab.com/records/layer/extensibility-core.md), cross-cuts → [Observability](https://banes-lab.com/records/layer/observability.md), cross-cuts → [Enforcement Core](https://banes-lab.com/records/layer/enforcement-core.md), cross-cuts → [Atomic Boundary](https://banes-lab.com/records/layer/atomic-boundary.md), cross-cuts → [Domain Modeling](https://banes-lab.com/records/layer/domain-modeling.md), cross-cuts → [Design Patterns Core](https://banes-lab.com/records/layer/design-patterns-core.md) ## Links to - [The canon is grouped twice](https://banes-lab.com/software-architecture/principles/the-canon-is-grouped-twice.md) - [Atomic Boundary](https://banes-lab.com/records/algo/atomic-boundary.md) - [Transactions / State / Concurrency](https://banes-lab.com/ontology/principles/arch-category-transactions-state-concurrency.md) - [Structural Core](https://banes-lab.com/records/layer/structural-core.md) - [Causality Core](https://banes-lab.com/records/algo/causality-core.md) - [Causality / Ordering / Distributed Time](https://banes-lab.com/ontology/principles/arch-category-causality-ordering-distributed-time.md) - [Computation Core](https://banes-lab.com/records/algo/computation-core.md) - [Correctness / Determinism / Verification](https://banes-lab.com/ontology/principles/arch-category-correctness-determinism-verification.md) - [Execution Core](https://banes-lab.com/records/layer/execution-core.md) - [Resource Core](https://banes-lab.com/records/layer/resource-core.md) - [Contracts Core](https://banes-lab.com/records/algo/contracts-core.md) - [Contracts / Interfaces / Compatibility](https://banes-lab.com/ontology/principles/arch-category-contracts-interfaces-compatibility.md) - [Schema / Canonical Data / Semantics](https://banes-lab.com/ontology/principles/arch-category-schema-canonical-data-semantics.md) - [Correctness Core](https://banes-lab.com/records/algo/correctness-core.md) - [Error Handling / Resilience](https://banes-lab.com/ontology/principles/arch-category-error-handling-resilience.md) - [Model Architecture](https://banes-lab.com/ontology/principles/arch-category-model-architecture.md) - [Self-Healing / Recovery / Deployment Safety](https://banes-lab.com/ontology/principles/arch-category-self-healing-recovery-deployment-safety.md) - [Quality Attributes](https://banes-lab.com/ontology/lexicon/lex-category-quality-attributes.md) - [Declarative Core](https://banes-lab.com/records/algo/declarative-core.md) - [Metadata / Self-Description / Declarative Systems](https://banes-lab.com/ontology/principles/arch-category-metadata-self-description-declarative-systems.md) - [Metaprogramming / Language-Oriented Architecture](https://banes-lab.com/ontology/principles/arch-category-metaprogramming-language-oriented-architecture.md) - [Design Patterns Core](https://banes-lab.com/records/algo/design-patterns-core.md) - [Behavioral Patterns](https://banes-lab.com/ontology/principles/arch-category-behavioral-patterns.md) - [Creational Patterns](https://banes-lab.com/ontology/principles/arch-category-creational-patterns.md) - [Structural Patterns](https://banes-lab.com/ontology/principles/arch-category-structural-patterns.md) - [Domain Modeling](https://banes-lab.com/records/algo/domain-modeling.md) - [Domain Architecture](https://banes-lab.com/ontology/principles/arch-category-domain-architecture.md) - [Enforcement Core](https://banes-lab.com/records/algo/enforcement-core.md) - [anti-patterns](https://banes-lab.com/ontology/principles/arch-category-anti-patterns.md) - [Evolution Principles](https://banes-lab.com/records/algo/evolution-principles.md) - [Architecture Review / Evolution / Governance Artifacts](https://banes-lab.com/ontology/principles/arch-category-architecture-review-evolution-governance-artifacts.md) - [Architecture Review Evolution Governance](https://banes-lab.com/ontology/lexicon/lex-category-architecture-review-evolution-governance.md) - [Human Factors](https://banes-lab.com/records/layer/human-factors.md) - [Execution Core](https://banes-lab.com/records/algo/execution-core.md) - [Control / Coordination / Centralization](https://banes-lab.com/ontology/principles/arch-category-control-coordination-centralization.md) - [Event / Messaging / Asynchronous Architecture](https://banes-lab.com/ontology/principles/arch-category-event-messaging-asynchronous-architecture.md) - [Streaming / Pipeline / Dataflow Processing](https://banes-lab.com/ontology/principles/arch-category-streaming-pipeline-dataflow-processing.md) - [Event Messaging Async](https://banes-lab.com/ontology/lexicon/lex-category-event-messaging-async.md) - [Computation Core](https://banes-lab.com/records/layer/computation-core.md) - [Extensibility Core](https://banes-lab.com/records/algo/extensibility-core.md) - [Plugin / Extensibility / IoC](https://banes-lab.com/ontology/principles/arch-category-plugin-extensibility-ioc.md) - [Runtime Discovery / Dynamic Binding](https://banes-lab.com/ontology/principles/arch-category-runtime-discovery-dynamic-binding.md) - [Human Factors](https://banes-lab.com/records/algo/human-factors.md) - [Evolution Principles](https://banes-lab.com/records/layer/evolution-principles.md) - [Observability](https://banes-lab.com/records/algo/observability.md) - [Observability / Auditability / Traceability](https://banes-lab.com/ontology/principles/arch-category-observability-auditability-traceability.md) - [Performance Core](https://banes-lab.com/records/algo/performance-core.md) - [Scalability / Performance / Optimization](https://banes-lab.com/ontology/principles/arch-category-scalability-performance-optimization.md) - [Resource Core](https://banes-lab.com/records/algo/resource-core.md) - [Portability / Infrastructure / Deployment](https://banes-lab.com/ontology/principles/arch-category-portability-infrastructure-deployment.md) - [Security Core](https://banes-lab.com/records/algo/security-core.md) - [Security / Privacy / Compliance / Governance](https://banes-lab.com/ontology/principles/arch-category-security-privacy-compliance-governance.md) - [Security Privacy Compliance](https://banes-lab.com/ontology/lexicon/lex-category-security-privacy-compliance.md) - [Structural Core](https://banes-lab.com/records/algo/structural-core.md) - [Codebase / System Architecture Styles](https://banes-lab.com/ontology/principles/arch-category-codebase-system-architecture-styles.md) - [Core Modular Design](https://banes-lab.com/ontology/principles/arch-category-core-modular-design.md) - [SOLID / Object-Oriented Design](https://banes-lab.com/ontology/principles/arch-category-solid-object-oriented-design.md) - [Taxonomy / Classification / Naming](https://banes-lab.com/ontology/principles/arch-category-taxonomy-classification-naming.md) - [Core Vocabulary](https://banes-lab.com/ontology/lexicon/lex-category-core-vocabulary.md) - [Correctness Core](https://banes-lab.com/records/layer/correctness-core.md) - [Security Core](https://banes-lab.com/records/layer/security-core.md) - [Performance Core](https://banes-lab.com/records/layer/performance-core.md) - [Contracts Core](https://banes-lab.com/records/layer/contracts-core.md) - [Causality Core](https://banes-lab.com/records/layer/causality-core.md) - [Declarative Core](https://banes-lab.com/records/layer/declarative-core.md) - [Extensibility Core](https://banes-lab.com/records/layer/extensibility-core.md) - [Observability](https://banes-lab.com/records/layer/observability.md) - [Enforcement Core](https://banes-lab.com/records/layer/enforcement-core.md) - [Atomic Boundary](https://banes-lab.com/records/layer/atomic-boundary.md) - [Domain Modeling](https://banes-lab.com/records/layer/domain-modeling.md) - [Design Patterns Core](https://banes-lab.com/records/layer/design-patterns-core.md) ## Linked from - [The canon is grouped twice](https://banes-lab.com/software-architecture/principles/the-canon-is-grouped-twice.md)