HTTP initial annotation-Yitoem

HTTP preliminary annotation-Yitoem collected resources on the Internet and some books he had read. Yitoem summarized a wave of HTTP and now it is just a superficial understanding, I hope to write more nutritious notes after in-depth understanding.

Main features of HTTP

+ Supports the customer/Server mode.
+ Simple and fast: when a customer requests a service from the server, only the Request Method and path are required. Common Request methods include GET, HEAD, and POST. Each method specifies the type of contact between the customer and the server. Because the HTTP protocol is simple, the program size of the HTTP server is small, so the communication speed is fast.
+ Flexibility: HTTP allows transmission of any type of data objects. The Type being transferred is marked by Content-Type.
+ No connection: No connection means that only one request is allowed for each connection. After the server processes the customer's request and receives the customer's response, the connection is disconnected. This method can save transmission time.
+ Stateless: HTTP is stateless. Stateless means that the Protocol has no memory for transaction processing. The lack of status means that if subsequent processing requires the previous information, it must be re-transmitted, which may increase the amount of data transmitted each connection. On the other hand, when the server does not need previous information, its response is faster.

HTTP status code

+ The request received by 1xx Informational (Information Status Code) is being processed
+ 2xx Success (Success Status Code) request processed properly
+ 3xx Redirection (Redirection Status Code) requires additional operations to complete the request
+ The 4xx Client Error (Client Error Status Code) request contains a syntax Error or cannot be completed, and the server cannot process the request
+ 5xx Server Error (Server Error Status Code) The Server fails to execute a fully valid request.

The details are as follows:

100 -- the customer must continue to send the request
101 -- the client requests the server to convert the HTTP protocol version according to the request
200 OK -- the request is successful.
201 -- prompt to know the URL of the new file
202 -- accept and process, but not complete
203 -- the returned information is uncertain or incomplete
204 No Content -- the request is received, but the returned information is null.
205 -- when the server completes the request, the user agent must reset the file that has been browsed.
206 -- the Partial Content server has completed some users' GET requests.
300 -- the requested resources can be obtained in multiple places
301 Moved Permanently -- Permanent redirection. Indicates that the requested resource has been assigned a new URI. In the future, use the URI currently referred to by the Resource
302 Found-temporary redirection. Indicates that the requested resource has been allocated with a new URI.
303 See Other -- we recommend that you access Other URLs or access methods.
304 Not Modify -- the client has executed GET, but the file has Not changed. Use the cache that has Not expired on the client directly.
305 -- the requested resource must be obtained from the address specified by the server
306 -- code used in HTTP of the previous version, which is not used in the current version
307 Temporary Redirect -- declares Temporary deletion of requested resources
400 Bad Request -- incorrect Request, such as syntax error
401 Unauthorized -- authorization request failed
402 -- retain valid ChargeTo header response
403 Forbidden -- the request is not allowed
404 Not Found -- no file, query, or URl Found
405 -- the method defined in the Request-Line field is not allowed.
406 -- the requested resource is inaccessible due to the user's Accept drag.
407 -- similar to 401, the user must first be authorized on the Proxy Server
408 -- the client did not complete the request within the specified time
409 -- the request cannot be completed due to the current resource status
410 -- this resource is no longer available on the server and there is no further reference address
411 -- the server rejects the User-Defined Content-Length attribute request
412 -- one or more request header fields are incorrect in the current request
413 -- the requested resource is larger than the size allowed by the server
414 -- the requested resource URL is longer than the length allowed by the server
415 -- the requested resource does not support the request project format
416 -- The request contains the Range request header field, which has no range indication value in the current request resource Range.
It does not contain the If-Range request header field.
417 -- the server does not meet the expectation specified by the request's CT header field. If it is a proxy server, it may be
The first-level server cannot meet the request
500 Internal Server Error -- Internal Error occurred on the Server
501 -- the server does not support the requested function
502 Bad Gateway-the server is temporarily unavailable, sometimes to prevent system overload
503 Server Unavailable-Server overload or service suspension
504 -- the gateway is overloaded. The server uses another gateway or service to respond to the user. The waiting time is long.
505 -- the server does not support or reject the HTTP Version specified in the request header