HTTP header_html/css_WEB-ITnose

HTTP (HyperTextTransferProtocol) is the Hypertext Transfer Protocol, which is currently the common protocol for web page transmission. The HTTP protocol adopts a request/response model. The browser or other client issues a request and the server responds. As far as the entire network resource transmission is concerned, it includes message-header and message-body. First pass message- header, that is, http headerMessage. http header messages are usually divided into 4 parts: general header, request header, response header, entity header. However, in terms of understanding, the boundaries of this division are not very clear. According to the organization form of http header content in Wikipedia, it is roughly divided into two parts: Request and Response.

Requests section

Header explanation example

Responses part

Accept	Specify the content type that the client can receive	Accept: text /plain, text/html
Accept-Charset	The character encoding set that the browser can accept.	Accept-Charset: iso-8859-5
Accept-Encoding	Specifies the content compression encoding type returned by the web server that the browser can support.	Accept-Encoding: compress, gzip
Accept-Language	Browser-accepted language	Accept-Language: en,zh
Accept-Ranges	You can request one or more sub-range fields of the web page entity	Accept-Ranges: bytes
Authorization	Authorization certificate for HTTP authorization	Authorization: Basic QWxhZGRpbjpvcGVuIHNlc2FtZQ==
Cache-Control	Specify the caching mechanism followed by requests and responses	Cache-Control: no-cache
Connection	Indicates whether a persistent connection is required. (HTTP 1.1 uses persistent connections by default)	Connection: close
Cookie	When an HTTP request is sent, the cookie stored under the request domain name will be All cookie values ​​are sent together to the web server.	Cookie: $Version=1; Skin=new;
Content-Length	Requested content length	Content- Length: 348
Content-Type	The requested MIME information corresponding to the entity	Content-Type: application/x-www-form- urlencoded
Date	The date and time the request was sent	Date: Tue, 15 Nov 2010 08:12:31 GMT
Expect	Requested specific server behavior	Expect: 100-continue
From	Email of the user who made the request	From: user@email.com
Host	Specify the domain name and port number of the requested server	Host: www.zcmhi.com
If-Match	Only valid if the request content matches the entity	If-Match: "737060cd8c284d8af7ad3082f209582d"
If-Modified-Since	If the requested part is modified after the specified time, the request is successful. If it is not modified, a 304 code is returned	If-Modified-Since: Sat, 29 Oct 2010 19:43:31 GMT
If-None-Match	If the content has not changed, return 304 code , the parameter is the Etag previously sent by the server, and is compared with the Etag responded by the server to determine whether it has changed	If-None-Match: "737060cd8c284d8af7ad3082f209582d"
If-Range	If the entity has not changed, the server sends the missing part from the client, otherwise the entire entity is sent.Parameters are also Etag	If-Range: "737060cd8c284d8af7ad3082f209582d"
If-Unmodified-Since	Only if the entity has not been modified after the specified time The request is successful	If-Unmodified-Since: Sat, 29 Oct 2010 19:43:31 GMT
Max-Forwards	Restrict information from passing Time spent by proxies and gateways	Max-Forwards: 10 : no-cache
Proxy-Authorization	Authorization certificate to connect to the proxy	Proxy-Authorization: Basic QWxhZGRpbjpvcGVuIHNlc2FtZQ==
Range	Only request a part of the entity, specify the range	Range: bytes=500-999
Referer	The address of the previous web page, followed by the current requested web page, that is, the source	Referer: http://www.zcmhi.com/archives/71.html
TE	The transfer encoding that the client is willing to accept, and notifies the server to accept the tail plus header information	TE: trailers,deflate;q=0.5
Upgrade	Specify a transport protocol to the server for conversion (if supported)	Upgrade: HTTP/2.0, SHTTP/1.3, IRC/6.9, RTA/ x11
User-Agent	The content of User-Agent contains the user information that made the request	User-Agent: Mozilla/5.0 (Linux; X11 )
Via	Notify the intermediate gateway or proxy server address, communication protocol	Via: 1.0 fred, 1.1 nowhere.com (Apache/1.1)
Warning	Warning information about the message entity	Warn: 199 Miscellaneous warning

Header explanation example

Accept-Ranges	Indicates whether the server supports specified range requests and what type of segmented requests	Accept-Ranges: bytes
Age	Estimated time in seconds from origin to proxy cache formation	Age: 12
Allow	A valid request behavior for a certain network resource. If it is not allowed, 405 will be returned	Allow: GET , HEAD
Cache-Control	Tell all caching mechanisms whether they can be cached and what type	Cache-Control: no-cache
Content-Encoding	The returned content compression encoding type supported by the web server.	Content-Encoding: gzip
Content-Language	Language of the response body	Content-Language: en,zh
Content-Length	The length of the response body	Content-Length: 348
Content-Location	Request an alternate address for the resource	Content-Location: /index.htm
Content-MD5	Return the MD5 check value of the resource	Content-MD5: Q2hlY2sgSW50ZWdyaXR5IQ==
Content-Range	In this part of the entire return body Byte position	Content-Range: bytes 21010-47021/47022
Content-Type	Return the MIME type of the content	Content-Type: text/html; charset=utf-8
Date	The time when the original server message was sent	Date: Tue, 15 Nov 2010 08:12:31 GMT
ETag	The current value of the entity tag of the request variable	ETag: "737060cd8c284d8af7ad3082f209582d"
Expires	The date and time the response expires	Expires: Thu, 01 Dec 2010 16:00:00 GMT
Last-Modified	The last modified time of the requested resource	Last-Modified: Tue, 15 Nov 2010 12:45:26 GMT
Location	is used to redirect the recipient to the location of the non-requested URL to complete the request or identify a new resource	Location: http://www.zcmhi.com/archives/94.html
Pragma	Contains implementation-specific instructions that can be applied to any receiver in the response chain	Pragma: no-cache
Proxy-Authenticate	It indicates the authentication scheme and parameters on that URL that can be applied to the proxy	Proxy-Authenticate: Basic
refresh	Apply to redirect or a new resource is created, redirect after 5 seconds (proposed by Netscape, supported by most browsers)	Refresh: 5; url= http://www.zcmhi.com/archives/94.html
Retry-After	If the entity is temporarily unavailable, notify the client to try again after the specified time	Retry-After: 120
Server	web server software name	Server: Apache/1.3.27 (Unix) (Red-Hat/Linux)
Set-Cookie	Set Http Cookie	Set-Cookie: UserID=JohnDoe; Max-Age=3600; Version=1
Trailer	Indicates that the header field exists at the end of the chunked transfer encoding	Trailer: Max-Forwards
Transfer-Encoding	File Transfer-Encoding	Transfer-Encoding:chunked
Vary	Tells the downstream proxy whether to use a cached response or request from the origin server	Vary: *
Via	Informs the proxy where the client response was sent	Via: 1.0 fred, 1.1 nowhere.com (Apache/1.1)
Warning	Warning entity about possible problems	Warning: 199 Miscellaneous warning
WWW-Authenticate	Indicates the authorization scheme that the client requesting entity should use	WWW-Authenticate: Basic