-------REST API Design Rulebook
URIs
REST API用URI（Uniform Resource Identifiers ）来表示资源。
例如：
http://api.example.restapi.org/france/paris/louvre/leonardo-da-vinci/mona-lisa
下面的URI就可读性很差：
http://api.example.restapi.org/68dd0-a9d3-11e0-9f1c-0800200c9a66
不过，现在流行短网址，我们可以用可读性差点URI表示此类资源。
URI Format
URI 语法：
URI = scheme "://" authority "/" path [ "?" query ] [ "#" fragment ]
Rule: 我们必须用符号“/”来表示URI中资源的层级关系（Forward slash separator (/) must be used to indicate a hierarchicalrelationship ）
例如：http://api.canvas.restapi.org/shapes/polygons/quadrilaterals/squares
Rule: 在URI末尾，不可以出现符号“/”（A trailing forward slash (/) should not be included in URIs ）
例如：http://api.canvas.restapi.org/shapes/ 这种URI不要使用。
Rule: 在URI路径部分，我们可以使用连字符"-"分割单词提高可读性（Hyphens (-) should be used to improve the readability of URIs ）
Rule: 在URI中不要出现下划"_"线字符，要使用连字符"-"（Underscores (_) should not be used in URIs ）
Rule: URI路径的单词要使用小写形式（Lowercase letters should be preferred in URI paths ）
Rule: URI中不要出现文件扩展名(File extensions should not be included in URIs )
例如：http://api.college.restapi.org/students/3248234/transcripts/2005/fall.json
一般我们利用Content-Type 头信息的media type 类型表示消息格式。
Rule: 在API中使用一致的子域名名字（Consistent subdomain names should be used for your APIs）
例如：http://api.soccer.restapi.org ，api作为子域名，soccer.restapi.org是顶级域名。
Rule: Consistent subdomain names should be used for your client developer portal
例如：http://developer.soccer.restapi.org ，子域名developer的定义。
Rule: A singular noun should be used for document names
Rule: A plural noun should be used for collection names
Rule: A plural noun should be used for store names
Rule: A verb or verb phrase should be used for controller names
Like a computer program’s function, a URI identifying a controller resource should be named to indicate its action. For example:
http://api.college.restapi.org/students/morgan/register
http://api.example.restapi.org/lists/4324/dedupe
Rule: Variable path segments may be substituted with identity-based values
Rule: CRUD功能名称不应该出现在URI中（CRUD function names should not be used in URIs ）
HTTP request methods should be used to indicate which CRUD function is performed.
For example, this API interaction design is preferred:
DELETE /users/1234
Rule: URI中的查询部分可以用来过滤资源（The query component of a URI may be used to filter collections or stores ）
Rule: URI中的查询部分应当具有分页功能（The query component of a URI should be used to paginate collection or store results ）
Rule: GET and POST must not be used to tunnel other request methods
Rule: GET must be used to retrieve a representation of a resource
Rule: HEAD should be used to retrieve response headers
Rule: PUT must be used to both insert and update a stored resource
Rule: PUT must be used to update mutable resources
Rule: POST must be used to create a new resource in a collection
Rule: POST must be used to execute controllers
Rule: DELETE must be used to remove a resource from its parent
Rule: OPTIONS should be used to retrieve metadata that describes a resource’s available interactions
Table 3-1. Response status code categories
Category Description
1xx: Informational Communicates transfer protocol-level information.
2xx: Success Indicates that the client’s request was accepted successfully.
3xx: Redirection Indicates that the client must take some additional action in order to complete their request.
4xx: Client Error This category of error status codes points the finger at clients.
5xx: Server Error The server takes responsibility for these error status codes.
Rule: 200 (“OK”) should be used to indicate nonspecific success
Rule: 200 (“OK”) must not be used to communicate errors in the response body
Rule: 201 (“Created”) must be used to indicate successful resource creation
Rule: 202 (“Accepted”) must be used to indicate successful start of an asynchronous action
Rule: 204 (“No Content”) should be used when the response body is intentionally empty
Rule: 301 (“Moved Permanently”) should be used to relocate resources
Rule: 302 (“Found”) should not be used
Rule: 303 (“See Other”) should be used to refer the client to a different URI
Rule: 304 (“Not Modified”) should be used to preserve bandwidth
Rule: 307 (“Temporary Redirect”) should be used to tell clients to resubmit the request to another URI
Rule: 400 (“Bad Request”) may be used to indicate nonspecific failure
Rule: 401 (“Unauthorized”) must be used when there is a problem with the client’s credentials
Rule: 403 (“Forbidden”) should be used to forbid access regardless of authorization state
Rule: 404 (“Not Found”) must be used when a client’s URI cannot be mapped to a resource
Rule: 405 (“Method Not Allowed”) must be used when the HTTP method is not supported
Rule: 406 (“Not Acceptable”) must be used when the requested media type cannot be served
Rule: 409 (“Conflict”) should be used to indicate a violation of resource state
Rule: 412 (“Precondition Failed”) should be used to support conditional operations
Rule: 415 (“Unsupported Media Type”) must be used when the media type of a request’s payload cannot be processed
Rule: 500 (“Internal Server Error”) should be used to indicate API malfunction
Table 3-2. Vocabulary review
TermDescription
DELETEHTTP request method used to remove its parent.
GET HTTPrequest method used to retrieve a representation of a resource’s state.
HEAD HTTP request method used to retrieve the metadata associated with the resource’s state.
OPTIONS HTTP request method used to retrieve metadata that describes a resource’s available interactions.
POST HTTP request method used to create a new resource within a collection or execute a
controller.
PUT HTTP request method used to insert a new resource into a store or update a mutable
resource.
Request-LineRFC 2616 defines its syntax asMethod SP Request-URI SP HTTP-Version CRLF
Request methodIndicates the desired action to be performed on the request message’s identified resource.
Response status code A three-digit numeric value that is communicated by a server to indicate theresult of a client’s request.
Status-Line RFC 2616 defines its syntax as: HTTP-Version SP Status-Code SP Reason-Phrase
CRLF TunnelingAn abuse of HTTP that masks or misrepresents a message’s intent and undermines the
protocol’s transparency.