HTTP (Hyper Text Transfer Protocol)

Submitted by admin on Fri, 11/13/2009 - 01:28
Phillips first multiplane
  1. introduction
  2. what it is
  3. what it isn't
  4. where it is
  5. history

introduction

 

what it is

 

(from http://www.webopedia.com/TERM/H/HTTP.html)

HTTP
Last modified: Monday, August 05, 2002 
Short for H yper T ext T ransfer P rotocol , the underlying protocol used by the World Wide Web . HTTP defines how messages are formatted and transmitted, and what actions Web servers and browsers should take in response to various commands. For example, when you enter a URL in your browser, this actually sends an HTTP command to the Web server directing it to fetch and transmit the requested Web page .

The other main standard that controls how the World Wide Web works is HTML , which covers how Web pages are formatted and displayed.

HTTP is called a stateless protocol because each command is executed independently, without any knowledge of the commands that came before it. This is the main reason that it is difficult to implement Web sites that react intelligently to user input. This shortcoming of HTTP is being addressed in a number of new technologies, including ActiveX , Java , JavaScript and cookies .

(from Hypertext Transfer Protocol -- HTTP/1.1, RFC 2616 Fielding, et al.)

?

(from http://www.webopedia.com/TERM/M/MIME.html)

MIME
Last modified: Monday, April 08, 2002

Short for Multipurpose Internet Mail Extensions, a specification for formatting non-ASCII messages so that they can be sent over the Internet. Many e-mail clients now support MIME, which enables them to send and receive graphics, audio, and video files via the Internet mail system. In addition, MIME supports messages in character sets other than ASCII.

There are many predefined MIME types, such as GIF graphics files and PostScript files. It is also possible to define your own MIME types.

In addition to e-mail applications, Web browsers also support various MIME types. This enables the browser to display or output files that are not in HTML format.

MIME was defined in 1992 by the Internet Engineering Task Force (IETF). A new version, called S/MIME, supports encrypted messages.

--

(from http://www.iana.org/assignments/media-types/)

[RFC2045,RFC2046] specifies that Content Types, Content Subtypes, Character Sets, Access Types, and conversion values for MIME mail will be assigned and listed by the IANA.

The following is the list of Directories of Content Types and Subtypes.:

  • application
  • audio
  • image
  • message
  • model
  • multipart
  • text
  • video

 

an HTTP header

web browser HTTP headers 

GET /private/ HTTP/1.1
Host: 10.1.8.58
User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.6) Gecko/20040113 MultiZilla/1.6.1.0b
Accept: application/x-shockwave-flash,text/xml,application/xml,application/xhtml+xml,text/html;q=0.9,
text/plain;q=0.8,image/png,image/jpeg,image/gif;q=0.2,*/*;q=0.1
Accept-Language: en-us,en;q=0.5
Accept-Encoding: gzip,deflate
Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7
Keep-Alive: 300
Connection: keep-alive
Authorization: Basic bmljayBoYXJkaW1hbjpsYWdlcjAwMQ==
Cache-Control: max-age=0

web server HTTP headers 

HTTP/1.1 200 OK
Date: Fri, 19 Mar 2004 16:46:46 GMT
Server: Apache/1.3.27 (Unix) mod_jk/1.2.5 mod_oglord/1.0 DAV/1.0.3 PHP/4.2.3
X-Powered-By: PHP/4.2.3
Keep-Alive: timeout=15, max=100
Connection: Keep-Alive
Transfer-Encoding: chunked
Content-Type: text/html

300
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Frameset//EN" "http://www.w3.org/TR/html4/frameset.dtd">
<html>
...
</html>

a MIME type header

A web server supplies resources to web clients, such as HTML files and image files. It gives each file to a client along with extra information contained in HTTP header lines. The information includes the type of file being supplied.

The descriptions for types of file are borrowed from the e-mail world. They are called MIME (Multipurpose Internet Mail Extensions) types and look like this: application/x-shockwave-flash. The official list of MIME types is looked after by the IETF (Internet Engineering Task Force). Every web server has a copy of this list.

Every MIME type has two parts, such as application/x-shockwave-flash. The bit to the left of the slash is the type. There are eight types, including audio, image and video. The bit on the right of the slash is a sub-type. The IETF describe hundreds of subtypes, and any company can make up another one by sticking the prefix "x-" onto it. The Macromedia company has invented the subtype shockwave-flash to describe files that its Flash players can use.

 

 

 

what it isn't

where it is

history

In 1965 Ted Nelson presented a paper at the Association for Computing Machinery in which he coined the term hypertext.