# Asynchronous Communication

> A design rule that work the caller does not need at once is sent as a message, so the caller does not wait on it.

Record: `architecture:asynchronous-communication`
Kind: principle
Layer: [Execution Core](https://banes-lab.com/records/layer/execution-core.md)
Severity: contextual
Scope: service, system
Canonical: https://banes-lab.com/ontology#architecture-asynchronous-communication

Listed in [Architecture principles](https://banes-lab.com/api/records/architecture.md), after [Integration Events](https://banes-lab.com/records/architecture/integration-events.md) and before [Eventual Consistency](https://banes-lab.com/records/architecture/eventual-consistency.md).

## Repair

- Refactored by: Introduce Queue/Event, Add Callback/Projection
- Detected by: long blocking chains
- Violated by: synchronous call chain for non-immediate work
- Measured by: sync dependency depth
- Enforced by: [architecture review](https://banes-lab.com/records/architecture/architecture-review.md)

## Requires

- [Message Contract](https://banes-lab.com/records/lexicon/message-contract.md)
- [Retry Safety](https://banes-lab.com/records/lexicon/retry-safety.md)

## Reinforces

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

## Enables

- [Event-Driven Architecture](https://banes-lab.com/records/architecture/event-driven-architecture.md)

## Conflicts with

- [Synchronous Chain Trap](https://banes-lab.com/records/architecture/synchronous-chain-trap.md)

## In tension with

- [Immediate Consistency](https://banes-lab.com/records/lexicon/immediate-consistency.md)

## Tensions

- [Asynchronous Communication / Immediate Consistency](https://banes-lab.com/records/tension/asynchronous-communication-immediate-consistency.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

- [Execution joins the halves](https://banes-lab.com/software-architecture/principles/execution-joins-the-halves.md)
- [The principle architecture](https://banes-lab.com/software-architecture/glossary/the-principle-architecture.md)
- [Anti-patterns](https://banes-lab.com/ontology/principles/architecture-category-anti-patterns.md)
- [Core Modular Design](https://banes-lab.com/ontology/principles/architecture-category-core-modular-design.md)
- [Event / Messaging / Asynchronous Architecture](https://banes-lab.com/ontology/principles/architecture-category-event-messaging-asynchronous-architecture.md)
- [Error Handling / Resilience](https://banes-lab.com/ontology/principles/architecture-category-error-handling-resilience.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)
- [Quality Attributes](https://banes-lab.com/ontology/lexicon/lexicon-category-quality-attributes.md)
- [Severity levels](https://banes-lab.com/ontology/schema/the-vocabulary-severity.md)
- [The resolutions](https://banes-lab.com/ontology/schema/the-resolutions.md)