Persistent URL Home Page: I stumbled across this today. I’m not sure if this is a relic of the Web’s past, or if this is still an active project.
“A PURL is a Persistent Uniform Resource Locator. Functionally, a PURL is a URL. However, instead of pointing directly to the location of an Internet resource, a PURL points to an intermediate resolution service. The PURL resolution service associates the PURL with the actual URL and returns that URL to the client. The client can then complete the URL transaction in the normal fashion. In Web parlance, this is a standard HTTP redirect.”
Essentially, a PURL resolution server registers a persistant URL which you can redirect if you move the resource, kind of like DNS for specific URLs, not just domain names.
The HTML source has this in a comment:
“12/29/97 — Copyright (c) 1996, OCLC Online Computer Library Center, Inc”
One page on this site mentioned that it was a reprint of a 1995 article, so this may best be considered a trip down memory lane.
On a per server basis, you can do this now with Apache URL re-writing or ISAPI filters or — easiest of all — just having your 404 page do a database lookup for the URL requested and then redirect to the new URL.