RESTperiaatteet

RESTperiaatteet, or Representational State Transfer principles, is a set of architectural constraints designed to create scalable and maintainable web services. It was introduced by Roy Fielding in his doctoral dissertation in 2000. REST is not a protocol or standard, but rather a set of guidelines for building web services that are stateless, client-server, and cacheable.

The core principles of REST include:

1. Statelessness: Each request from a client to a server must contain all the information the server needs to fulfill that request. The server does not store any client context between requests.

2. Client-server architecture: The client and server operate independently, allowing each to evolve separately. The client is responsible for the user interface, while the server handles data storage and retrieval.

3. Cacheability: Responses from the server must define themselves as cacheable or non-cacheable to prevent clients from reusing stale or inappropriate data.

4. Uniform interface: REST uses a standard set of methods (GET, POST, PUT, DELETE) to manipulate resources. This uniformity simplifies and decouples the architecture, allowing each part to evolve independently.

5. Layered system: A client cannot ordinarily tell whether it is connected directly to the end server or to an intermediary along the way. Intermediary servers may improve system scalability by enabling load balancing and shared caches.

6. Code on demand (optional): Servers can extend client functionality by transferring executable code, such as applets or scripts, to the client.

RESTful services typically use HTTP as the application protocol and JSON or XML as the data format. They are widely used in web development due to their simplicity, scalability, and flexibility. RESTperiaatteet have become the foundation for many modern web APIs and microservices architectures.