HTTP basic knowledge

HTTP connection Process

Request method

Request Header

HTTP Request Header Headers

• Status code
• Message structure
• Cookie, session and Token
  • Cookies
  • Session
  • Token

Http://www.runoob.com/http/http-messages.html

HTTP connection Process

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Request method

Request Method Type	Description
GET	Requests the specified page information and returns the entity principal.
POST	Submits data to the specified resource for processing requests (such as submitting a form or uploading a file). The data is included in the request body. A POST request may result in the creation of new resources and/or modification of existing resources.
OPTIONS	Allows clients to view server performance.
HEAD	Similar to a GET request, except that there is no specific content in the returned response to get the header
PUT	Supersedes the contents of the specified document from the data that the client sends to the server.
DELETE	Requests that the server delete the specified page.
CONNECT	The http/1.1 protocol is reserved for proxy servers that can change connections to pipelines.
TRACE	echo the requests received by the server, primarily for testing or diagnostics.

Request header HTTP Request Header header Header

Request headers type	explain	Example
Accept	Specify what types of content clients can receive	Accept:text/plain, text/html
Accept-charset	The set of character encodings that the browser can accept	Accept-charset:iso-8859-5
Accept-encoding	Specifies the Web server to which the browser can support return content compression encoding type	Accept-encoding:compress, gzip
Accept-language	Browser-acceptable language	Accept-language:en,zh
Accept-ranges	You can request one or more child range fields for a Web page entity	Accept-ranges:bytes
Authorization	Authorization Certificate for HTTP Authorization	Authorization:basic qwxhzgrpbjpvcgvuihnlc2ftzq==
Cache-control	Specify the caching mechanism that requests and responses follow	Cache-control:no-cache
Connection	Indicates whether a persistent connection is required. (HTTP 1.1 defaults to persistent connection)	Connection:close
Cookies	When an HTTP request is sent, all cookie values stored under that request domain are sent to the Web server.	Cookie: $Version = 1; Skin=new;
Content-length	The requested content length	content-length:348
Content-type	The requested MIME information corresponding to the entity	content-type:application/x-www-form-urlencoded
Date	Date and time the request was sent	Date:tue, 08:12:31 GMT
Expect	The specific server behavior of the request	Expect:100-continue
From	Email from the user who made the request	From: [email protected]
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 succeeds, and the 304 code is returned without modification	If-modified-since:sat, Oct 19:43:31 GMT
If-none-match	If the content does not change the return 304 code, the parameter is the server's previously sent ETag, and the server responded to the ETag comparison to determine whether the change	If-none-match: "737060cd8c284d8af7ad3082f209582d"
If-range	If the entity does not change, the server sends the missing portion of the client, otherwise the entire entity is sent. The parameters are also ETag	If-range: "737060cd8c284d8af7ad3082f209582d"
If-unmodified-since	Request succeeds only if the entity has not been modified since the specified time	If-unmodified-since:sat, Oct 19:43:31 GMT
Max-forwards	Limit the time that information is transmitted through agents and gateways	Max-forwards:10
Pragma	Used to include implementation-specific instructions	Pragma:no-cache
Proxy-authorization	Connect to an authorization certificate for the agent	Proxy-authorization:basic qwxhzgrpbjpvcgvuihnlc2ftzq==
Range	Request only part of an entity, specify a range	range:bytes=500-999
Referer	The address of the previous page, which is immediately followed by the current request page,	Referer:http://www.zcmhi.com/archives/71.html
TE	The client is willing to accept the transfer encoding and notifies the server to accept the trailing header information	te:trailers,deflate;q=0.5
Upgrade	Specify some kind of transport protocol to the server for the server to convert (if supported)	upgrade:http/2.0, shttp/1.3, irc/6.9, rta/x11
User-agent	The content of the user-agent contains the user information that made the request	user-agent:mozilla/5.0 (Linux; X11)
Via	Notifies the intermediary gateway or proxy server address, communication protocol	via:1.0 Fred, 1.1 nowhere.com (apache/1.1)
Warning	About warning messages for message entities	warn:199 Miscellaneous Warning

Status code

Status Code	Status	Description
$	OK	indicates that the request is handled properly by the server
204	No Content	means the request has been processed successfully, but no content is returned, that is, there is no message entity in the returned response message, and the browser page does not update
301	Moved permanently	Permanent Reset To, indicates that the requested resource has been permanently moved to another location, meaning that the resource has been assigned a new URI
302	Found	temporary redirection indicating that the requested resource was temporarily moved to a resource requested by another location is temporarily provisioned to the new URI
.	Bad Request	indicates that the request message has a syntax error or parameter error and the server does not understand that the server should not repeat the request.
401	Unauthorized	indicates that the request sent requires HTTP authentication information or authentication failed. The response that returns 401 must contain a www-authe that applies to the requested resource Nticate header to challenge user information
403	Forbidden	indicates that access to the requested resource was rejected by the server
404	not Found	indicates that the server could not find the resource you requested
$	Internal server Error	indicates The server made an error while executing the request, possibly a bug in the Web app or a temporary failure.
503	Service unavailable	indicates server overload or shutdown maintenance, cannot process please Request

Message structure

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Cookies, session and Tokencookie

Cookies are divided into ' sessions ' and ' persistent 'cookies

• Session Cookie: is a temporary cookie that has no expiration time and is deleted as the user exits the browser. cannot be shared by the browser. (often used to save SessionID)
• Persistent Cookie: A cookie that is stored on a hard disk, usually with an expiration time and, if it expires, the cookie is deleted. Can be shared by the browser

The cookie principle is as follows:

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Advantages:

• Save on the client, without consuming server resources.

Disadvantages:

• Security level is the lowest of the three, easy to be hijacked and exploited
• Restricted by the browser is very large
• Storage is limited in size and quantity
• cannot be used where cookies are disabled

Session

Session: Also known as "conversation control". is the properties and configuration information required to store a specific user session. When a user jumps between the application's Web pages, the variables stored in the session object are not lost, but persist throughout the user's session.

The session principle is as follows:

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Advantages:

• Relative cookies are more secure.
• The storage object can be flexibly controlled.

Disadvantages:

• There is a distributed system session sharing problem. Require Redis and other ways to resolve.
• Because the session is in a cookie, it also inherits the drawbacks of the cookie.

Token

https://my.oschina.net/jamesfancy/blog/1613994 This article explains the token in great detail.

HTTP basic knowledge