Understanding RESTful APIs
A REST (Representational State Transfer) API is an architectural style for an application programming interface (API) that uses HTTP requests to access and use data. Originally defined by Roy Fielding in his 2000 doctoral dissertation, the RESTful-API has become the industry standard for building Web-Services due to its lightweight nature and scalability.
Core Principles and Constraints
To be considered truly RESTful, a system must adhere to several key architectural constraints:
- Statelessness: The Server does not store any client context between requests. Each request from the Client must contain all the information necessary to service the request.
- Client-Server Architecture: The user interface concerns are separated from the data storage concerns, allowing both to evolve independently.
- Cacheability: Responses must explicitly define themselves as cacheable or non-cacheable to improve network efficiency.
- Uniform Interface: By applying a software engineering principle of generality to the component interface, the overall system architecture is simplified. This involves using URIs to identify Resources.
- Layered System: A client cannot ordinarily tell whether it is connected directly to the end server or to an intermediate like a load balancer or Proxy.
Communication and Data Formats
RESTful systems typically communicate over the HTTP protocol using standard verbs. The most common HTTP-Methods include GET for retrieving data, POST for creating data, PUT for updating data, and DELETE for removing data. While REST is not tied to a specific format, JSON (JavaScript Object Notation) is the most widely used format for data exchange, followed by XML.
For further technical documentation, consult the MDN Web Docs or the W3C Data on the Web Best Practices regarding REST.