# Domain Service

> A design pattern that places a domain rule spanning several entities in a stateless service named in the domain's language.

Record: `architecture:domain-service`
Kind: pattern
Layer: [Domain Modeling](https://banes-lab.com/records/layer/domain-modeling.md)
Severity: contextual
Scope: domain, behavior, coordination
Canonical: https://banes-lab.com/ontology#architecture-domain-service

Listed in [Architecture principles](https://banes-lab.com/api/records/architecture.md), after [Entity](https://banes-lab.com/records/architecture/entity.md) and before [Runtime Discovery](https://banes-lab.com/records/architecture/runtime-discovery.md).

## Repair

- Refactored by: Extract Domain Service
- Detected by: domain logic in application/transport layers
- Violated by: multi-entity domain rules living in controllers
- Measured by: misplaced domain-rule count
- Enforced by: domain model review

## Requires

- [Domain Model](https://banes-lab.com/records/architecture/domain-model.md)

## Reinforces

- [Single Responsibility Principle (SRP)](https://banes-lab.com/records/architecture/single-responsibility.md)
- [Ubiquitous Language](https://banes-lab.com/records/architecture/ubiquitous-language.md)

## Enables

- [Cross-Entity Domain Logic](https://banes-lab.com/records/lexicon/cross-entity-domain-logic.md)

## Conflicts with

- [Fat Controller](https://banes-lab.com/records/architecture/fat-controller.md)
- [Transaction Script Sprawl](https://banes-lab.com/records/architecture/transaction-script-sprawl.md)

## In tension with

- [Aggregate](https://banes-lab.com/records/architecture/aggregate.md)

## Tensions

- [Domain Service / Aggregate](https://banes-lab.com/records/tension/aggregate-domain-service.md)

## Severity

- [contextual](https://banes-lab.com/records/vocabulary/severity-contextual.md)

## Category

- [Domain Architecture](https://banes-lab.com/records/architecture-category/domain-architecture.md)

## Linked from

- [Anti-patterns](https://banes-lab.com/ontology/principles/architecture-category-anti-patterns.md)
- [Domain Architecture](https://banes-lab.com/ontology/principles/architecture-category-domain-architecture.md)
- [Core Modular Design](https://banes-lab.com/ontology/principles/architecture-category-core-modular-design.md)
- [Schema / Canonical Data / Semantics](https://banes-lab.com/ontology/principles/architecture-category-schema-canonical-data-semantics.md)
- [Domain Architecture](https://banes-lab.com/ontology/lexicon/lexicon-category-domain-architecture.md)
- [Severity levels](https://banes-lab.com/ontology/schema/the-vocabulary-severity.md)
- [The resolutions](https://banes-lab.com/ontology/schema/the-resolutions.md)