OpenFeature Specification (Draft)

This repository describes the requirements and expectations for OpenFeature.

:warning: Ongoing research can be found in the research repo. For definitions of key terminology, see the glossary.

Design Principles

• Compatibility with existing feature flag offerings
• Simple, understandable APIs
• Vendor agnosticism
• Language agnosticism
• Low/no dependency
• Extensibility

SDKs and Client Libraries

The project aims to provide a unified API and SDK for feature flag management in various technology stacks. The flag evaluation logic will not be handled in the OpenFeature SDK itself but provide a mechanism for interfacing with an external evaluation engine in a vendor agnostic way.

The OpenFeature project will include client libraries for common technology stacks including, but not limited to:

• Golang
• Java
• JavaScript/TypeScript (Node.js)

Tooling

This specification complies with RFC 2119 and seeks to conform to the W3C QA Framework Guidelines.

In accordance with this, some basic tooling (donated graciously by Diego Hurtado) has been employed to parse the specification and output a JSON structure of concise requirements, highlighting the particular RFC 2119 verb in question.

To parse the specification, simply type make. Please review the generated JSON files, which will appear as siblings to any of the markdown files in the /specification folder.

Style Guide

• Use code blocks for examples.
  • Code blocks should be pseudocode, not any particular language, but should be vaguely "Java-esque".
• Use conditional requirements for requirements that only apply in particular situations, such as particular languages or runtimes.
• Use "sentence case" enclosed in ticks (`) when identifying entities outside of code blocks (ie: evaluation details instead of EvaluationDetails).
• Do not place line breaks into sentences, keep sentences to a single line for easier review.
• String literals appearing outside of code blocks should be enclosed in both ticks (`) and double-quotes (") (ie: "PARSE_ERROR").
• Use "Title Case" for all titles.
• Use the imperative mood and passive voice.