# Message Broker

> Descriptive data about topics, queues and routing rules, held by an intermediary service that delivers messages between producers and consumers.

Record: `architecture:message-broker`
Kind: artifact
Layer: [Execution Core](https://banes-lab.com/records/layer/execution-core.md)
Severity: contextual
Scope: integration, messaging
Canonical: https://banes-lab.com/ontology#architecture-message-broker

Listed in [Architecture principles](https://banes-lab.com/api/records/architecture.md), after [Message Queue](https://banes-lab.com/records/architecture/message-queue.md) and before [Event Bus](https://banes-lab.com/records/architecture/event-bus.md).

## Repair

- Refactored by: Add Broker, Route Messages
- Detected by: direct service calls in async workflows
- Violated by: broker bypass for async integration
- Measured by: broker usage coverage
- Enforced by: architecture policy

## Requires

- [Message Queue/Topics](https://banes-lab.com/records/lexicon/message-queue-topics.md)
- [Routing](https://banes-lab.com/records/lexicon/routing.md)

## Reinforces

- [Low Coupling](https://banes-lab.com/records/architecture/low-coupling.md)
- [Scalability](https://banes-lab.com/records/architecture/scalability.md)

## Enables

- [Pub/Sub](https://banes-lab.com/records/lexicon/pub-sub.md)
- [Work Distribution](https://banes-lab.com/records/lexicon/work-distribution.md)

## Conflicts with

- [Point-to-Point Coupling](https://banes-lab.com/records/lexicon/point-to-point-coupling.md)

## In tension with

- [Operational Dependency](https://banes-lab.com/records/lexicon/operational-dependency.md)

## Tensions

- [Message Broker / Operational Dependency](https://banes-lab.com/records/tension/message-broker-operational-dependency.md)

## Severity

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

## Category

- [Event / Messaging / Asynchronous Architecture](https://banes-lab.com/records/architecture-category/event-messaging-asynchronous-architecture.md)

## Linked from

- [Core Modular Design](https://banes-lab.com/ontology/principles/architecture-category-core-modular-design.md)
- [Scalability / Performance / Optimization](https://banes-lab.com/ontology/principles/architecture-category-scalability-performance-optimization.md)
- [Core Vocabulary](https://banes-lab.com/ontology/lexicon/lexicon-category-core-vocabulary.md)
- [Event Messaging Async](https://banes-lab.com/ontology/lexicon/lexicon-category-event-messaging-async.md)
- [Severity levels](https://banes-lab.com/ontology/schema/the-vocabulary-severity.md)
- [The resolutions](https://banes-lab.com/ontology/schema/the-resolutions.md)