状态无关性
Rest 架构中不维持client，resource and request 的状态，我们通常称 Rest 服务是状态无关的。基于此的优势是为设计Rest架构提供了简便；每一个请求可以被完全单独的处理；与HTTP协议的状态无关保持一致。不足之处在于但是如果需要获取或者维持状态，需要消耗额外的资源。
缓存
缓存的设计是为了减少server端的负担，client 不需要每次都向 server 发送请求，client可以使用缓存技术来保存 server response。
HTTP Code:
| S.N. | HTTP Code & Description |
|---|---|
| 1 | 200 OK, shows success. |
| 2 | 201 CREATED, when a resource is successful created using POST or PUT request. Return link to newly created resource using location header. |
| 3 | 204 NO CONTENT, when response body is empty for example, a DELETE request. |
| 4 | 304 NOT MODIFIED, used to reduce network bandwidth usage in case of conditional GET requests. Response body should be empty. Headers should have date, location etc. |
| 5 | 400 BAD REQUEST, states that invalid input is provided e.g. validation error, missing data. |
| 6 | 401 UNAUTHORIZED, states that user is using invalid or wrong authentication token. |
| 7 | 403 FORBIDDEN, states that user is not having access to method being used for example, delete access without admin rights. |
| 8 | 404 NOT FOUND, states that method is not available. |
| 9 | 409 CONFLICT, states conflict situation while executing the method for example, adding duplicate entry. |
| 10 | 500 INTERNAL SERVER ERROR, states that server has thrown some exception while executing the method. |