Persistent uniform resource locator

EN Texto em inglês Ainda não há artigo no teu idioma: trecho em inglês.

A persistent uniform resource locator (PURL) is a uniform resource locator (URL, i.e. a uniform resource identifier, or URI, that is location-based) that is used to redirect to the location of the requested web resource. PURLs redirect HTTP clients using HTTP status codes. Originally, PURLs were recognizable for being hosted at purl.org or other hostnames containing purl. Early on many of those other hosts used descendants of the original OCLC PURL system software. Eventually, however, the PURL concept came to be generic and was used to designate any redirection service (named PURL resolver) that: PURLs are used to curate the URL resolution process, thus solving the problem of transitory URIs in location-based URI schemes like HTTP. Technically the string resolution on PURL is like SEF URL resolution. The remainder of this article is about the OCLC's PURL system, proposed and implemented by OCLC (the Online Computer Library Center). The PURL concept was developed by Stuart Weibel and Erik Jul at OCLC in 1995. The PURL system was implemented using a forked pre-1.0 release of Apache HTTP Server. The software was modernized and extended in 2007 by Zepheira under contract to OCLC and the official website moved to purlz.org (the 'Z' came from the Zepheira name and was used to differentiate the PURL open-source software site from the PURL resolver operated by OCLC).