The six principles of REST

????????????-???????????? ????????????????????????: RESTful systems are structured as client-server architectures where the client and server are independent of each other, allowing them to evolve separately. This separation enhances scalability and simplifies the overall architecture.

?????????????? ??????????????????: RESTful APIs should have a uniform interface, which helps to simplify and decouple the architecture. This principle is further broken down into four sub-principles:

1. ???????????????????????????? ???? ??????????????????: Each resource in the system should be uniquely identifiable using a URI (Uniform Resource Identifier). This allows clients to manipulate resources by referring to their URIs.

2. ???????????????????????? ???? ?????????????????? ?????????????? ??????????????????????????????: Clients interact with resources through representations, which can be in various formats like JSON, XML, HTML, etc. These representations should include all the necessary data and metadata for the client to understand and modify the resource.

3. ????????-?????????????????????? ????????????????: Messages sent between clients and servers should include metadata that describes how to process the message. This metadata can include content type, caching directives, authentication information, etc.

4. ???????????????????? ???? ?????? ???????????? ???? ?????????????????????? ?????????? (??????????????): Responses from the server should contain hypermedia links that allow clients to discover and navigate the available actions or resources. This allows for better decoupling between the client and server, as the client does not need to have prior knowledge of all available resources and actions.

??????????????????????????: Each request from a client to the server must contain all the necessary information to understand the request, meaning that the server should not store any client state between requests. This allows for better scalability and reliability since servers don't need to manage session information for each client.

????????????????????????: Responses from the server should explicitly indicate whether they are cacheable or not. Caching can significantly improve the efficiency and performance of the system by reducing the need for round trips between the client and server.

?????????????? ????????????: RESTful systems can be composed of multiple layers, where each layer has a specific role or responsibility. This helps to improve scalability by allowing components to be added, modified, or removed without affecting other parts of the system.

???????? ???? ???????????? (????????????????): This principle is optional in REST and suggests that clients can download and execute code from the server. However, this principle is not commonly used in most RESTful systems, as it can introduce security and reliability concerns.