[Interview not answered questions 1]http request, what information does the request header and the response header have?

Tag: Range tells response res data request Identity Order ICA

Recently in the search for a job, the interviewer asked some questions himself did not answer on, here to do a summary.

　　What information does the HTTP request, the request header and the response header have?

　　The most common way for page and server interaction is to Ajax,ajax simply that the browser sends the request to the service side and then the service side returns the data, as shown in the common request headers and response headers.

　　

See general information First, general information has three fields: request URL, request method, status code, remote address.

　　Look at the request Headers,

Accept: Specifies the type of content that the client can receive, and the order in which the content type represents the order in which the client receives it. In AJAX code, you can use the setRequestHeader function method in the XMLHttpRequest object to dynamically set these header information.

Accept-encoding: Specifies that the Web server that the client browser can support returns the content compression encoding type. Indicates that the server is allowed to compress the output before it is sent to the client to conserve bandwidth. The return compression format that the client browser can support is set here.

Accept-language: Specifies the preferred language for the HTTP client browser to display the return information.

Connection: Indicates whether a persistent connection is required. If the Web server side sees the value here as "keep-alive", or sees the request using an HTTP 1.1 (HTTP 1.1 By default for persistent connection), it can take advantage of the persistent connection, when the page contains multiple elements (such as applets, pictures), Significantly reduce the time it takes to download. To do this, the Web server needs to send a content-length (the length of the message body) header back to the client HTTP header, and the simplest implementation is to write the content to Bytearrayoutputstream first, and then Calculates the size of the content before it is formally written.

Connec-length: The length of the request header.

Connect-type: Displays the content type submitted by this HTTP request. This property is typically only required for post submission.

There are two types of encoding available for the Content-type property values:

(1) "application/x-www-form-urlencoded": the type of encoding used when the form data is submitted to the server, the default value is "application/x-www-form-urlencoded". However, this encoding is inefficient when sending large amounts of text to the server, including text or binary data that contains non-ASCII characters.

(2) "Multipart/form-data": When the file is uploaded, the type of encoding used should be "Multipart/form-data", which can both send text data and support binary data upload.

You can use "application/x-www-form-urlencoded" when committing to data alone, and when you commit a file, you need to use the "multipart/form-data" encoding type.

The charset character encoding of the commit content is also specified in the Content-type property. Typically not set, it simply tells the Web server what character encoding to use for the data submitted by the post.

Cookies: Browser-side cookies.

Hose: Client Address

Origin: Destination Address

Referer: Contains a URL where the user accesses the currently requested page from the page represented by the URL

User-agent: Client Information

X-requested-with: Whether it is a synchronous request, or an Ajax asynchronous request if it is XMLHttpRequest. If NULL is a traditional synchronous request

　　Response Header Response Header

　　Because the returned fields in the instance are not very full, the more comprehensive data is found on the network

Accept-ranges	Indicates whether the server supports the specified range request and what kind of staging request	Accept-ranges:bytes
Age	Estimated time (in seconds, non-negative) from the original server to the proxy cache	Age:12
Allow	A valid request behavior for a network resource is not allowed to return 405	Allow:get, HEAD
Cache-control	Tell if all caching mechanisms can be cached and which type	Cache-control:no-cache
Content-encoding	The type of return content compression encoding supported by the Web server.	Content-encoding:gzip
Content-language	The language of the response body	Content-language:en,zh
Content-length	The length of the response body	content-length:348
Content-location	Alternate alternative address to request resource substitution	Content-location:/index.htm
Content-md5	Returns the MD5 checksum value of a resource	content-md5:q2hly2sgsw50zwdyaxr5iq==
Content-range	The byte position of this section in the entire return body	Content-range:bytes 21010-47021/47022
Content-type	Returns the MIME type of the content	content-type:text/html; Charset=utf-8
Date	Time the original server message was issued	Date:tue, 08:12:31 GMT
ETag	The current value of the entity label of the request variable	ETag: "737060cd8c284d8af7ad3082f209582d"
Expires	Date and time when the response expires	Expires:thu, 16:00:00 GMT
Last-modified	Requested last modified time for resource	Last-modified:tue, 12:45:26 GMT
Location	Used to redirect the receiver to the location of the non-request URL to complete the request or identify the new resource	Location:http://www.zcmhi.com/archives/94.html
Pragma	Includes implementing a specific instruction that can be applied to any receiver on the response chain	Pragma:no-cache
Proxy-authenticate	It indicates the authentication scheme and the parameters on the URL that can be applied to the proxy	Proxy-authenticate:basic
Refresh	Applied to redirect or a new resource was created, redirected after 5 seconds (proposed by Netscape, supported by most browsers)	Refresh:5; Url=http://www.zcmhi.com/archives/94.html
Retry-after	Notifies the client to try again after a specified time if the entity is temporarily undesirable	retry-after:120
Server	Web Server Software Name	server:apache/1.3.27 (Unix) (Red-hat/linux)
Set-cookie	Set HTTP Cookies	Set-cookie:userid=johndoe; max-age=3600; Version=1
Trailer	Indicates that the header domain is present at the end of the chunked transfer code	Trailer:max-forwards
Transfer-encoding	File transfer encoding	Transfer-encoding:chunked
Vary	Tells the downstream agent whether to use the cache response or request from the original server	Vary: *
Via	Tells the proxy client where the response was sent by	via:1.0 Fred, 1.1 nowhere.com (apache/1.1)
Warning	Warning about possible issues with the entity	warning:199 Miscellaneous Warning
Www-authenticate	Indicates the authorization scheme that the client request entity should use	Www-authenticate:basic

[Interview not answered questions 1]http request, what information does the request header and the response header have?