Names and Addresses: URL, URN, URI, URC
The key to distributed network processing is publishing and locating
named objects. A heirarchy of naming conventions have been proposed as
a standard for the Web.
- A Uniform Resource Locator (URL) provides a non-persistent means to uniquely identify an object
within a namespace. The format is: transport://user:password@host:port/path.
- A Uniform Resource Name (URN) provides persistent names within a namespace.
This would allow a permanent object to be mirrored over several known sites; if one were unavailable,
the object could be found/resolved at another site.
Several proposals for URNs exist; none have been widely adopted, yet.
- Uniform Resource Identifier (URI) is an abstraction that includes both URLs and URNs.
This is the standard addressing mechanism for the Web.
- A Uniform Resource Citation (URC) provides a set of attribute/value pairs used to describe URIs:
authorship, publishers, copyright, etc. No proposed standard has been submitted yet.
URL Specification - RFC1738
URN Draft - PATH proposal
URI Specification - RFC1630
World Wide Web Consortium
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