API Design & Contract Requirements
Purpose
To establish APIs as stable, documented products that enable safe integration, support external platforms, and allow independent evolution of services while maintaining consistency and reliability across the platform.
Scope
API specification standards, versioning strategy, contract documentation, consistency conventions, idempotency requirements, and gateway integration patterns.
Requirements
| ID | Name | Description |
|---|---|---|
| REQ-API-1 | API as a Product | APIs MUST be treated as first-class products with clear ownership, defined consumers, and measurable KPIs including reliability, latency, adoption rate, and error rates. |
| REQ-API-2 | Machine-Readable Contracts | All externally or cross-product exposed APIs MUST be documented using standard specifications (e.g., OpenAPI), version-controlled, and kept in sync with implementation. |
| REQ-API-3 | Public Contracts Only | APIs MUST expose only public, stable contracts; internal or implementation-specific endpoints MUST NOT be required for integration or validation by other products. |
| REQ-API-4 | Explicit Versioning | API versioning MUST be explicit and governed, with clear rules for introducing, deprecating, and retiring versions, plus documented migration paths for consumers. |
| REQ-API-5 | Consistent Conventions | APIs MUST follow consistent conventions for resource naming, HTTP methods, status codes, error envelopes, and pagination across the platform. |
| REQ-API-6 | Idempotency | APIs performing non-read operations MUST be designed to be idempotent where practical, enabling safe retries and failure recovery. |
| REQ-API-7 | Contract-Based Integration Testing | External platforms and internal products MUST be able to verify integration solely via public API contracts, without privileged access or custom builds. |
| REQ-API-8 | Gateway Cross-Cutting Concerns | Cross-cutting concerns (authentication, authorization, rate limiting, logging, correlation IDs) MUST be handled through standard gateway or platform mechanisms. |
Reference Template
Illustrative, non-normative — shows the expected shape for the requirements above.
openapi: 3.1.0
info:
title: Orders API
version: 1.2.0 # explicit, governed version (REQ-API-4)
servers:
- url: https://api.example.com/v1 # version carried in the path
paths:
/orders:
post:
summary: Create an order
parameters:
- name: Idempotency-Key # safe retries (REQ-API-6)
in: header
required: true
schema: { type: string, format: uuid }
responses:
'201': { description: Created }
default: # consistent error envelope (REQ-API-5)
description: Error
content:
application/problem+json:
schema: { $ref: '#/components/schemas/Problem' }
get:
summary: List orders
parameters: # consistent pagination (REQ-API-5)
- { name: page, in: query, schema: { type: integer, minimum: 1 } }
- { name: pageSize, in: query, schema: { type: integer, maximum: 100 } }
responses:
'200': { description: OK }