REST

Representational State Transfer (REST) is an architectural style for designing networked applications. It was introduced by Roy Fielding in his doctoral dissertation in 2000. REST is not a standard or a protocol but rather a set of principles that guide the design of scalable and maintainable web services. RESTful services, following these principles, are often referred to as RESTful APIs (Application Programming Interfaces).

Key principles of REST include:

1. Statelessness:
   • RESTful services are stateless, meaning that each request from a client to a server must contain all the information needed to understand and fulfill that request. The server should not store any information about the client’s state between requests.
2. Client-Server Architecture:
   • REST separates the client and server components, allowing them to evolve independently. Clients are not concerned with the internal workings of the server, and servers are not concerned with the state or user interface of the client. This separation enhances scalability and simplifies development.
3. Uniform Interface:
   • The uniform interface is a key principle of REST, providing a consistent and standard way to interact with resources. It consists of several constraints, including:
     • Resource Identification: Resources (e.g., data entities or services) are identified by URIs (Uniform Resource Identifiers).
     • Resource Manipulation through Representations: Resources can have multiple representations (e.g., JSON, XML), and clients interact with these representations to manipulate resources.
     • Stateless Communication: Each request from a client to a server must contain all the information needed to understand and process the request.
4. Resource-Based:
   • In REST, resources are the key abstraction. Resources are entities or services that can be identified by a URI. Examples of resources include data objects, services, or entities in a system.
5. Stateless Communication:
   • Each request from a client to a server must contain all the information needed to understand and process the request. The server should not store any information about the client’s state between requests. This enhances scalability and simplifies implementation.
6. Representations:
   • Resources can have multiple representations, such as JSON, XML, or HTML. Clients interact with these representations to manipulate resources. For example, a client may request data in JSON format and update it with a new JSON representation.
7. Stateless Communication:
   • RESTful communication is stateless, meaning that each request from a client to a server must contain all the information needed to understand and process the request. The server does not store any client state between requests.
8. Cacheability:
   • Responses from the server can be explicitly marked as cacheable or non-cacheable. Caching improves efficiency and reduces the need for repeated requests to the server.
9. Layered System:
   • REST allows for a layered system architecture, where each layer has a specific role and interacts only with adjacent layers. This separation of concerns promotes modularity and flexibility in system design.

RESTful APIs are widely used in web development, particularly for building scalable and interoperable web services. They are commonly employed in combination with HTTP (Hypertext Transfer Protocol), making use of HTTP methods (GET, POST, PUT, DELETE) for resource manipulation. RESTful APIs have become a standard for building web services due to their simplicity, scalability, and widespread adoption.