API Endpoint Specification

A API Endpoint Specification is a formal specification that defines the interface contract for an API endpoint (used to enable API integration and API documentation).

• AKA: API Description, API Interface Definition, API Contract, API Operation Specification.
• Context:
  • It can (typically) define API Contract through interface description language.
  • It can (typically) specify HTTP Method with REST verbs.
  • It can (typically) document API Parameter using parameter definition.
  • It can (typically) describe Response Format through data schema.
  • It can (typically) list Error Code with error handling instructions.
  • ...
  • It can (often) include API Authentication with security scheme.
  • It can (often) provide API Version through version identifier.
  • It can (often) specify Rate Limit using throttling rule.
  • It can (often) define API Endpoint URL with URL pattern.
  • ...
  • It can range from being a Simple API Specification to being a Complex API Specification, depending on its endpoint complexity.
  • It can range from being a Basic REST Specification to being an Advanced GraphQL Specification, depending on its API paradigm.
  • ...
  • It can integrate with API Documentation Tool for documentation generation.
  • It can support API Testing Tool for contract validation.
  • It can enable API Mock Server for development testing.
  • ...
• Examples:
  • API Specification Formats, such as:
    • OpenAPI Specifications, such as:
      • Swagger 2.0-based API Specification for REST API contract.
      • OpenAPI 3.0-based API Specification for modern API description.
    • Alternative API Specifications, such as:
      • RAML-based API Specification for YAML-based API definition.
      • API Blueprint-based Specification for markdown-based API specification.
  • API Operation Specifications, such as:
    • API Resource Operation Specifications, such as:
      • API CRUD Endpoint Specification for data management operation.
      • API Search Endpoint Specification for resource query operation.
      • API Batch Operation Specification for bulk data processing.
      • API Filter Operation Specification for advanced data querying.
      • API Sort Operation Specification for result ordering.
    • API Business Operation Specifications, such as:
      • API Payment Endpoint Specification for API payment endpoints (for transaction handling).
      • API Authentication Endpoint Specification for API authentication endpoints (for access control).
      • API Order Endpoint Specification for API order endpoints (for e-commerce operation).
      • API Registration Endpoint Specification for API registration endpoints (for account creation).
      • API File Upload Specification for API file upload endpoints (for content management).
  • ...
• Counter-Examples:
  • API Implementation, which implements rather than specifies the interface.
  • API Documentation, which describes usage rather than defines the contract.
  • API Design Document, which explains design decisions rather than interface details.
• See: HTTP Method, API Request Parameter, API Response Format, API Error Code, API Base URL, OpenAPI Document, API Description Document.

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References

2024-12-30

• Perplexity.ai
  • Question: What are API specifications and descriptions? Please explain their key components, differences, and best practices. Include information about formats, structure, and how they relate to documentation processes.
  • Answer: An API specification provides a standardized blueprint of an API's behavior and design before implementation, while an API description formally documents the API's surface and semantics.
    • Specification Components:
      • Core Elements:
        • Defines API endpoints, parameters, and response formats.
        • Details security configurations and authentication methods.
        • Specifies supported data types and request/response models.
        • Can be written in JSON or YAML format.
      • Popular Specifications:
        • OpenAPI (formerly Swagger) - Most widely adopted, backed by Microsoft and Google.
        • RAML - YAML-based specification focusing on clear, consistent documentation.
        • API Blueprint - Markdown-like specification following design-first philosophy.
    • API Description Structure:
      • Key Components:
        • Composed of an entry document (OpenAPI Document).
        • May contain multiple connected parts.
        • Must include at least one paths, components, or webhooks field.
      • Format Requirements:
        • Uses JSON or YAML format.
        • Requires an openapi field specifying the version.
        • Follows JSON Schema Specification Draft 2020-12.
    • Documentation vs Specification:
      • Purpose:
        • Documentation serves as user guide and reference.
        • Specification serves as technical blueprint.
      • Audience:
        • Documentation targets developers and end users.
        • Specification targets API creators and machines.
    • Best Practices:
      • Design Approach:
        • Use design-first methodology.
        • Maintain single source of truth.
        • Validate specifications regularly.
      • Content Structure:
        • Include clear examples and use cases.
        • Document all endpoints and parameters.
        • Specify error codes and handling procedures.
  • Citations:

[1] https://swagger.io/specification/
[2] https://swagger.io/resources/articles/difference-between-api-documentation-specification/
[3] https://blog.dreamfactory.com/5-best-api-documentation-tools
[4] https://document360.com/blog/api-documentation/
[5] https://docs.mulesoft.com/general/api-led-design
[6] https://docs.oracle.com/en-us/iaas/Content/APIGateway/Tasks/apigatewaycreatingapiobject.htm
[7] https://daily.dev/blog/api-documentation-best-practices-11-tips-for-2024
[8] https://www.altexsoft.com/blog/what-is-api-definition-types-specifications-documentation/
[9] https://www.archbee.com/blog/api-documentation-specification-definition-difference
[10] https://www.getambassador.io/blog/openapi-specification-structure-best-practices

2023

• chat
  • Q: What is an API specification, and provide an example?
  • W: An API specification is a set of rules that describe how a software program should interact with a particular application programming interface (API). It defines the types of requests that can be made, the data formats that should be used, and the rules for handling errors and exceptions.

    For example, consider an API that allows a user to retrieve information about a specific product from an online store. The API specification for this API might define the following:

    • The base URL for making requests to the API (e.g., "https://api.onlinestore.com/products")
    • The HTTP methods that can be used to make requests (e.g., GET, POST, PUT, DELETE)
    • The request parameters (and formats) that can be included in a request (e.g., the ID of the product to retrieve)
    • The format of the data that is returned by the API (e.g., JSON)
    • The possible error codes that may be returned, and their meanings (e.g., 400 Bad Request, 401 Unauthorized)
  • With this information, a developer can build a program that can interact with the API in a predictable and consistent way.

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