SLA4OAI

SLA4OAI (SLA for the OpenAPI Initiative Specification) describes the service level agreement behind an API defined with OpenAPI. It is a specification extension: an OpenAPI description points to an SLA document from its info section with x-sla, and that document sets out the plans the API is offered under.

• Plans - Each plan can carry pricing (cost, currency, billing period), quotas, rates and an availability window. A base plan holds what every plan inherits.
• Quotas and rates - Quotas are limits counted in static time windows, such as a daily quota. Rates are counted in windows relative to use, such as requests per minute. Both are set per path and method.
• Metrics - The document defines what is counted, such as requests, response time or business metrics like the number of resources created.
• Plans or agreements - A plans document describes what is on offer. An agreement document records what a named customer signed up for.

The specification was developed by the SLA4OAI Technical Committee, convened by the ISA Group at the University of Seville, with practitioners and academics taking part. Version 1.0.0 was published as a draft on 2020-11-16 under the Apache 2.0 license, and the repository was last updated in February 2023. The committee’s discussions live in its Technical Committee wiki.

There are three things to know before using it:

• No field for an uptime guarantee. availability is a time slot that says when the service is offered, not how reliably. The draft mentions guarantees, but neither the draft nor the schema defines them, so uptime percentages, service credits and response times have no standard place.
• The root key differs between documents. The specification text uses sla:, while the JSON Schema and the agreement sample use sla4oas:.
• Limits are set per path. A limit that applies to a whole account, which is how most providers document theirs, has no standard place.

APIs.io generates SLA4OAI documents for the providers in its catalog. Promised uptime is quoted from each provider’s SLA page and reported uptime from its status page, carried in an x-apis-io-* extension. Where no service level was found, a synthetic base is built from the provider’s plans and rate limits and labeled as synthetic.

Industry: API Specification