Editing Persistent uniform resource locator (section)

==History==
The PURL concept was developed by Stuart Weibel and Erik Jul at [[OCLC]] in 1995.<ref>{{cite journal |last1=Weibel |first1=Stuart |last2=Jul |first2=Erik |title=PURLs to improve access to the Internet |journal=OCLC Newsletter |date=1995 |issue=November/December |page=19 |url=https://library.oclc.org/digital/collection/p267701coll28/id/1839 |access-date=17 December 2021}}</ref> 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 <code>purlz.org</code> (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).

PURL version numbers may be considered confusing. OCLC released versions 1 and 2 of the Apache-based source tree, initially in 1999 under the OCLC Research Public License 1.0 License and later under the OCLC Research Public License 2.0 License.<ref>[http://opensource.org/licenses/oclc2 OCLC Research Public License 2.0]</ref> Zepheira released PURLz 1.0 in 2007 under the Apache License, Version 2.0.<ref>[http://opensource.org/licenses/apache2.0 Apache License, Version 2.0]</ref> PURLz 2.0 was released in [[Software release life cycle#Beta|Beta testing]] in 2010 but the release was never finalized. The [[Callimachus Project]] implemented PURLs as of its 1.0 release in 2012.

The oldest PURL [[HTTP]] resolver was operated by [[OCLC]] from 1995 to September 2016 and was reached as <code>purl.oclc.org</code> as well as <code>purl.org</code>, <code>purl.net</code>, and <code>purl.com</code>.

Other notable PURL resolvers include the US Government Printing Office (<code>purl.fdlp.gov</code>), which is operated for the [[Federal Depository Library Program]] and has been in operation since 1997.

The PURL concept is used in the <code>w3id.org</code>, that may replace the old PURL-services and PURL-technologies.

On 27 September 2016 OCLC announced a cooperation with [[Internet Archive]] resulting in the transfer of the resolver service and its administration interface to Internet Archive.<ref name="oclc_20160927_oclcpurlia">{{cite press release|title=OCLC and Internet Archive work together to ensure future sustainability of Persistent URLs |url=http://www.oclc.org/news/releases/2016/201623dublin.en.html |date=27 September 2016 |publisher=OCLC |location=Dublin, Ohio |access-date=10 April 2023 |archive-url=https://web.archive.org/web/20230202162123/https://cdm15003.contentdm.oclc.org/digital/collection/p15003coll6/id/649 |archive-date=2 February 2023 |url-status=live |quote=OCLC and Internet Archive today announced the results of a year-long cooperative effort to ensure the future sustainability of purl.org. The organizations have worked together to build a new sustainable service hosted by Internet Archive that will manage persistent URLs and sub-domain redirections for purl.org, purl.com, purl.info and purl.net}}</ref> The service is supported on newly created software, separate from all previous implementations. The transfer re-enabled the ability to manage PURL definitions that had been disabled in the OCLC-hosted service for several months. The service hosted on Internet Archive servers supports access via <code>purl.org</code>, <code>purl.net</code>, <code>purl.info</code>, and <code>purl.com</code>. OCLC now redirects DNS requests for <code>purl.oclc.org</code> to <code>purl.org</code>.