Backward Compatibility

Kind: constraint

Layer: Contracts Core

Record: architecture:backward-compatibility

Severity: mandatory

Scope: API, schema, protocol

Canonical: Ontology

A rule or precondition that a new version keeps working for consumers written against an older one.

Listed in Architecture principles, after Invariant and before Forward Compatibility.

Requires

• Versioning
• Stable Interfaces

Reinforces

• Consumer Safety

Enables

• Incremental Deployment

Conflicts with

• Breaking Change

In tension with

• Cleanup / Simplification

Tensions

• Backward Compatibility / Cleanup / Simplification

Violated by

• Breaking Change

Refactored by

• Versioning
• Gradual Deprecation
• Extract Adapter

Severity

• mandatory

Category

• Contracts / Interfaces / Compatibility

Reinforced by

• Contract-First Design
• Consumer-Driven Contracts

Enabled by

• Declared Jurisdiction

Linked from

• Never and always
• Contracts / Interfaces / Compatibility
• Taxonomy / Classification / Naming
• Codebase / System Architecture Styles
• Contracts / Interfaces / Compatibility
• Severity levels
• The resolutions