OpenAPI Document

Overview

An OpenAPI Document is a machine-readable description of an HTTP API written according to the OpenAPI Specification. It is not the same as general API documentation because tools can parse it to generate clients, validators, tests, mocks, and contract checks.

The main risks include documentation drift, ambiguous nullable fields, missing error cases, incompatible schema changes, and generated clients based on stale documents. It can define servers, paths, operations, parameters, authentication, request bodies, responses, schemas, and reusable components.

In production, teams should define ownership and apply version control, explicit API version, complete error responses, reusable schemas, security definitions, examples, and automated linting. The OpenAPI Document contract should define identifiers, validation, authorization, status semantics, errors, limits, and version behavior at the same boundary.

Useful measures include spec coverage, lint violations, implementation drift, breaking-change count, and generated-client test results. OpenAPI Document is closely connected to Request Schema, Response Schema, and Schema Validation. Observability for OpenAPI Document should record operation, version, principal, request ID, latency, retry count, error code, and final state without exposing secrets.

Data handled by OpenAPI Document should use documented types, units, timestamp rules, nullable fields, and enum behavior to prevent silent interpretation errors. For OpenAPI Document, the application should preserve a correlation path from request construction through response, asynchronous completion, and final business state.

A successful transport result from OpenAPI Document should not be interpreted beyond the exact API state documented by the provider. Changes to OpenAPI Document should be checked against older clients, stored payloads, enum growth, default behavior, and retry assumptions.