A RESTful API (Representational State Transfer) is a type of architecture and protocol for designing and managing application programming interfaces (APIs) in distributed systems. RESTful API is built upon the fundamental principles of the REST architecture, a method described by Roy Fielding in his 2000 dissertation.
Key characteristics of RESTful API include:
Address-based access
Each resource is represented by a URL (Uniform Resource Locator), allowing systems to communicate through HTTP requests such as GET, POST, PUT, and DELETE.
Stateless access
Every request from the client contains enough information for the server to understand the request without relying on previous state information. The server does not store information about the client's state between requests.
HTTP method usage
RESTful API uses HTTP methods (GET, POST, PUT, DELETE) to define the purpose of each request. For example, use GET to retrieve information, POST to create new data, PUT to update, and DELETE to remove.
Use of media types
Data is transmitted over the network using formats such as JSON, XML, or other custom formats. Each request needs to specify the desired data format.
Resource identification
Resources are identified by unique URLs, allowing clients to access resources using path-based identifiers.
Cacheable
Requests and responses from a RESTful API can be stored in client or proxy server memory to optimize performance.
Layered system
The REST architecture allows the addition of intermediary layers such as load balancers or proxy servers to enhance scalability and manageability.
RESTful APIs are widely used in web and mobile application development, enabling efficient communication and data sharing between applications. Major web services like Facebook, Twitter, and Google also utilize the RESTful architecture to provide APIs for developers.