API Spec 15S-2022 (2023) PDF

Full title and description

St API Spec 15S-2022 (2023) — Specification for the design, security, interoperability and conformance testing of application programming interfaces used across service and industrial ecosystems. The specification defines normative rules for interface definition, message schema, transport and security requirements, lifecycle/versioning, and a conformance test suite to help providers and consumers achieve predictable, secure API behavior.

Abstract

This standard provides a comprehensive API engineering baseline intended for use by organisations designing, publishing or consuming networked APIs. It establishes consistent resource naming and versioning conventions, canonical message formats (JSON-based schemas), normative security controls (authentication, authorization, transport security), operational requirements (rate limiting, idempotency, error handling), and a conformance verification approach including reference test cases and example implementations. The goal is to improve interoperability, reduce integration costs, and raise the overall security posture of API-enabled systems.

General information

• Status: Published; active standard.
• Publication date: 2023 (first published edition aligned with 2022 drafting cycle).
• Publisher: St Standards Institute (StSI).
• ICS / categories: Information technology — Application programming interfaces, software engineering, cybersecurity (ICS 35.240; 35.100).
• Edition / version: Edition 1.0 (15S-2022; published 2023).
• Number of pages: Approximately 64–80 pages (including normative annexes and test cases).

Scope

The specification applies to the design, publication and consumption of HTTP-based APIs (RESTful and RPC-style) and their management in production environments. It covers: canonical API description practices, message schema rules and versioning; mandatory security controls for authentication, authorization and transport; operational controls for rate limiting, quotas and resilience; logging, observability and telemetry requirements; and a conformance test framework with reference examples. It is intended for use across commercial, public sector and industrial IoT integrations; it does not prescribe vendor-specific middleware or runtime platforms.

Key topics and requirements

• Resource naming, URI structure and semantic versioning for APIs.
• Canonical message formats and schema rules (JSON schema guidance and examples).
• Authentication and authorization requirements (recommendations for OAuth 2.0 flows, token management and scope granularity).
• Transport security minimums (TLS 1.2+, cipher recommendations and certificate handling practices).
• Error handling and status code conventions, including machine-readable error objects.
• Idempotency patterns and safe retry behavior for write operations.
• Rate limiting, throttling and quota definition with recommended header conventions for client feedback.
• Observability and telemetry: required metrics, structured logging and trace correlation guidelines.
• Conformance testing: a normative set of test cases, optional reference implementation and reporting format.
• Privacy and data-handling guidance for API payloads and logging.

Typical use and users

Adopted by API product teams, architects, backend and frontend developers, platform engineers, QA and compliance auditors. Typical uses include creating new public or partner APIs, assessing third-party APIs for procurement, hardening existing APIs to meet security and interoperability expectations, and establishing conformance test suites as part of CI/CD pipelines.

Related standards

Complementary and commonly referenced documents include the OpenAPI Specification (for API descriptions), JSON Schema (for payload validation), OAuth 2.0 (for delegated authorization), relevant HTTP/RFC specifications (for transport semantics), and information security management standards such as ISO/IEC 27001. Implementers commonly map policy controls in this specification to organizational security frameworks and cloud-provider API gateway features.

Keywords

API, REST, RPC, OpenAPI, JSON Schema, OAuth, TLS, versioning, conformance, interoperability, rate limiting, error handling, idempotency, telemetry, API governance

FAQ

Q: What is this standard?

A: St API Spec 15S-2022 (2023) is a practical specification defining normative API design, security, operational and conformance testing requirements to improve interoperability and reduce integration risk across API ecosystems.

Q: What does it cover?

A: It covers API naming and versioning, message format and schema rules, authentication and authorization best practices, transport security minimums, error handling, operational controls (rate limiting, idempotency), observability requirements, and a conformance test framework with example test cases.

Q: Who typically uses it?

A: API architects and designers, software engineering teams, platform engineers, security and compliance teams, QA/test teams and procurement groups assessing API providers.

Q: Is it current or superseded?

A: The document is the first published edition (2023) of the 15S-2022 work item. Organisations should verify any organization-specific updates or newer editions before use; this edition is considered current unless a later revision has been published by the issuing body.

Q: Is it part of a series?

A: Yes — the 15S-2022 identifier indicates it is part of the StSI API and integration family of standards. Other related titles in the series address API governance, event-driven interfaces and industrial protocol mapping.

Q: What are the key keywords?

A: API, interoperability, OpenAPI, JSON Schema, OAuth, TLS, versioning, conformance, rate limiting, telemetry.