API Migration

Overview

API Migration is the planned change by which a consumer moves from one API version, operation, provider, or contract to another. It is used to adopt supported behavior while preserving business continuity and data correctness. It differs from API deprecation, which is the provider’s lifecycle signal rather than the consumer’s implementation project.

A typical implementation works as follows: Teams inventory usage, compare contracts, update mappings and credentials, run parallel tests, backfill or transform state, cut over traffic, and verify outcomes. A successful transport result from API Migration should not be interpreted beyond the exact API state documented by the provider.

Common risks include hidden dependencies and incompatible semantics. Important failure modes include hidden dependencies, incompatible semantics, dual-write divergence, missing history, changed identifiers, and rushed cutover. These failures can cause duplicate or lost operations.

Core controls require teams to use a migration plan, contract diff, test data, staged rollout, rollback criteria, reconciliation, and formal completion review. For API Migration, the application should preserve a correlation path from request construction through response, asynchronous completion, and final business state.

Operational evidence should include source and target versions, consumers, mapping changes, test evidence, cutover time, rollback state, and reconciliation result. API Migration should be documented alongside API Deprecation, API Compatibility, and API Contract Diff.

The API Migration owner should publish stable error semantics and guidance on whether correction, retry, status lookup, or escalation is appropriate. Data handled by API Migration should use documented types, units, timestamp rules, nullable fields, and enum behavior to prevent silent interpretation errors.