Uniform Resource Name

From Freepedia

A Uniform Resource Name (URN) is a Uniform Resource Identifier (URI) that uses the urn scheme, and does not connote availability of the identified resource. Both URNs (names) and URLs (locators) are URIs, and some URI may be a name and a locator at the same time.

RFC 2141 says:

Uniform Resource Names (URNs) are intended to serve as persistent, location-independent resource identifiers and are designed to make it easy to map other namespaces (that share the properties of URNs) into URN-space. Therefore, the URN syntax provides a means to encode character data in a form that can be sent in existing protocols, transcribed on most keyboards, etc.

1 Comparison with URLs
2 Examples
3 See also
4 External links

Comparison with URLs

Suppose you own a copy of the book The Last Unicorn.

If you tell someone, "My copy of the book is on the lightstand in my bedroom," that's like a URL — you're telling someone where something is.

But if you tell someone, "I read a neat book; it's called The Last Unicorn," then that's like a URN — you're telling someone the name of something.

A person who knows where a particular copy is can get it for you, or tell someone else where it is. (URL)

A person who knows its name can reason about it, they can tell if they've seen it before, and maybe they can talk about what's inside the story. (URN)

You could tell somebody: "You can find urn:ietf:rfc:3187 (URN) over at http://www.faqs.org/rfcs/rfc3187.html (URL)."

Examples

"urn:isbn:0451450523" - the URN for "The Last Unicorn", identified by its book number.
"urn:ietf:rfc:3187" - the URN for the IETF's RFC 3187.
"urn:oid:2.16.840" - the URN corresponding to the OID for the United States.
"urn:sha1:YNCKHTQCWBTRNJIV4WNAE52SJUQCZO5C" - the URN representing the exact MP3 file of the I have a dream speech by Martin Luther King.
"urn:uuid:6e8bc430-9c3a-11d9-9669-0800200c9a66" - a URN using a version 1 UUID.