See also: Uri (homonymy)

A URI , English Uniform Resource To identify , is literally uniform identifier of resource , is short a Character string identifying a physical or abstracted Ressource Web, and whose Syntaxe respects a standard Internet installation for the World Wide Web (see RFC 3986). The Norme was previously known under the term UDI .

IETF initially defined it in the RFC 2396 while being based on proposals of Tim Berners-Lee (RFC 1630). Update by the RFC 2732 then revised many times under the title rfc2396bis , the RFC 3986 defines the URI in January 2005.

The Sigle URI is generally used to indicate such a Character string. For example urn: IETF: RFC: 2396 is a URI identifying the RFC 2396.

The URI are the basic technology of the World Wide Web because all the Hyperlien S of the Web are expressed in the form of URI.

Relation with the URL and URN

A URI can be of " type; locator" or " name" or both.

A Uniform Resource Locator (URL) is a URI which, in addition to that it identifies a Ressource Web, provides the means of acting on a resource or to obtain a representation of the resource describing its primary education access mode or " emplacement" network. For example, the URL http://www.wikipedia.org/ is a URI which identifies a resource (Banner page Wikipedia) and implies that a representation of this resource (as the usual code HTML of the Banner page, as encodés characters) can be obtained via HTTP of a network host called www.wikipedia.org.

A Uniform Resource Name (URN) is a URI which identifies a resource by its name in a space of names. A URN can be employed to speak about a resource without that prejudging its site or the manner of referring it. For example, the URN urn: ISBN: 0-395-36341-1 is a URI which, like an International Standard Book Number (ISBN), authorizes somebody to refer to a book, but suggests neither where, nor how to obtain a real copy from it.

The current point of view of the Work group which supervises the URI is that the terms URL and URN are aspects dependant on the context of the URI, and that one seldom needs to make the distinction between the two. In the technical publications, especially the standards set up by IETF and W3C, the term URL was not recognized for a long time, because it was seldom necessary to make a distinction between the URL and the URI. However, in contexts not techniques and in the software of the World Wide Web, the term URL remains omnipresent. Moreover, the term addresses Web , which does not have a formal definition, is often employed in nontechnical publications like synonym of URL or URI, although generally it refers only to the “HTTP” and “https”.

Examples

The following examples illustrate the URI of everyday usage:

• ftp://ftp.is.co.za/rfc/rfc1808.txt : protocol ftp for the service File Transfer Protocol

• gopher://spinaltap.micro.umn.edu/00/Weather/California/Los%20Angeles : protocol gopher for the services Gopher and Gopher +
• http://www.math.uio.no/faq/compression-faq/part1.html : protocol HTTP for the service Hypertext Transfer Protocol
• mailto:mduerst@ifi.unizh.ch : protocol mailto for the email addresses
• news:comp.infosystems.www.servers.unix : protocol news for the newsgroup Usenet
• telnet://melvyl.ucop.edu/ : protocol telnet for the interactive services via telnet

See too

Internal bonds

• URL ~ URN ~ IRI
• IETF ~ World Wide Web ~ Internet

External bonds

• Web Naming and Adressing Overview (URIs, URLs,…) , principal page of W3C on the addresses Web
• RFC 1630, Universal Identifiers Resource in WWW , June 1994
• RFC 2396, Uniform Identifiers Resource (URI): Generic Syntax , August 1998
• RFC 3986, Uniform Resource To identify (URI): Generic Syntax , January 2005

References