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JSP Client Request in jsp tutorials

  • When a Client browser requests for a web page, it sends lot of information to the web server which cannot be read directly because this information travel as a part of header of HTTP request.

  • HTTP header fields are components of the message header of requests and responses in the Hypertext Transfer Protocol (HTTP). They define the operating parameters of an HTTP transaction.

  • The header fields are transmitted after the request or response line, the first line of a message.

  • Below is the list of important header information which comes from browser side which are frequently used in web programming.

 

Header

Description

Example

Accept

This header specifies the MIME types that the browser or other clients can handle. Valuesof image/png or 

image/jpeg are the two most common possibilities.

Accept: text/plain

Accept-Charset

This header specifies the character sets the browser can use to display the information. For example ISO-8859-1.

Accept-Charset: utf-8

Accept-Encoding

This header specifies the types of encodings that the browser knows how to handle. Values of gzip or 

compress are the two most common possibilities.

Accept-Encoding: gzip, deflate

Accept-Language

This header specifies the client's preferred languages in case the servlet can produce results in more than one language. For example en, en-us, ru, etc.

Accept-Language: en-US

Authorization

This header is used by clients to identify themselves when accessing password-protected Web pages.

Authorization:Basic QWxhZGRpbjpvcGVuIHNlc2FtZQ==

Connection

This header indicates whether the client can handle persistent HTTP connections. Persistent connections permit the client or other browser to retrieve multiple files with a single request. A value ofKeep-Alive means that persistent connections should be used

Connection: keep-alive

Content-Length

This header is applicable only to POST requests and gives the size of the POST data in bytes.

Content-Length: 348

Cookie

This header returns cookies to servers that previously sent them to the browser.

Cookie: $Version=1; Skin=new;

Host

This header specifies the host and port as given in the original URL.

Host: en.samedu.in:80

Host: en.samedu.in

If-Modified-Since

This header indicates that the client wants the page only if it has been changed after the specified date. The server sends a code, 304 which means Not Modified header if no newer result is available.

If-Modified-Since: Sat, 29 Oct 2008 19:43:31 GMT

If-Unmodified-Since

This header is the reverse of If-Modified-Since; it specifies that the operation should succeed only if the document is older than the specified date.

If-Unmodified-Since: Sat, 29 Oct 2008 19:43:31 GMT

Referer

This header indicates the URL of the referring Web page. For example, if you are at Web page 1 and click on a link to Web page 2, the URL of Web page 1 is included in the Referer header when the browser requests Web page 2.

Referer: http://cbtsam.com

User-Agent

This header identifies the browser or other client making the request and can be used to return different content to different types of browsers.

User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:12.0) Gecko/20100101 Firefox/12.0

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