Rest之路 - Rest架构中的重要概念(二)

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。

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.