The terms REST and RESTful API are related but distinct:
- REST (Representational State Transfer)
- It is an architectural style that defines a set of constraints for designing networked applications.
- REST is not a protocol or a standard but a set of principles that guide API design.
- It emphasizes stateless communication, resource-based interactions, and the use of standard HTTP methods (GET, POST, PUT, DELETE).
- REST-compliant systems should follow constraints like client-server architecture, statelessness, cacheability, uniform interface, layered system, and optional code on demand.
2. RESTful API (RESTful Web Service)
- A RESTful API is an implementation of the REST architecture in a web service.
- It follows REST principles and allows clients to interact with resources using HTTP methods.
- It typically uses JSON or XML for data exchange.
- A properly designed RESTful API should provide meaningful URIs, standard HTTP status codes, and proper request/response formats.
Key Differences
| Feature | REST | RESTful API |
| Definition | Architectural style | Web service following REST principles |
| Standard? | No, just a set of guidelines | Yes, it implements REST principles |
| Communication | Conceptual, defines how APIs should work | Practical, an actual API built using REST |
| Implementation | Cannot be implemented directly | Implemented using HTTP, JSON, XML, etc. |
Example:
A RESTful API for a library system:
- GET /books → Retrieve all books
- POST /books → Add a new book
- GET /books/1 → Retrieve book with ID 1
- PUT /books/1 → Update book with ID 1
- DELETE /books/1 → Delete book with ID 1
In summary, REST is a concept, while a RESTful API is an actual implementation of that concept in web services.