# /research/publications/archive/releases/1996-06-21.htm

originally: http://www.oclc.org/research/publications/archive/releases/1996-06-21.htm

# OCLC makes PURL software available free of charge on the World Wide Web

DUBLIN, Ohio, June 21, 1996--OCLC's PURL software, a tool for managing Internet addresses and aliases, may now be licensed free of charge and can be downloaded from http://purl.oclc.org on the World Wide Web.

A PURL is a Persistent Uniform Resource Locator, which provides flexible naming and name resolution services for Internet resources that can help ensure reliable, long-term access to Internet resources with minimal maintenance.

The OCLC PURL software was developed by the OCLC Office of Research to assist Internet users in locating resources. Since the Internet is constantly expanding and changing, Uniform Resource Locators (URLs) sometimes change. Once a URL fails, all instances of that URL become invalid. Even minor changes in URLs prevent users from accessing Internet resources, and managing these changes over time is difficult and time consuming.

Instead of pointing directly to the location of an Internet resource much as a URL does, a PURL points to an intermediate Resolution Service, which uniquely associates the PURL with the actual URL. The PURL then returns the URL to the client, which completes the transaction.

According to Erik Jul, manager, OCLC custom services, a PURL works much the same as an alias in an electronic mail system.

"A PURL allows the user to assign one name to a resource that really means something else," said Mr. Jul. "A PURL provides the means to assign a persistent name for a resource even if the item location changes. So PURLs distributed in Web pages, bibliographic records, electronic journals, and other resources can remain viable over time without requiring updates each time an embedded URL changes."

PURLs can be used anywhere reliable, long-term access to Internet resources is desired. Maintenance is performed by connecting to a PURL Resolver using a Web browser and then using the PURL Resolver's maintenance forms to make the appropriate changes to the desired URL.

"The PURL model lends itself to distribution across the Internet," said Mr. Jul. "OCLC is distributing the PURL source code to promote the rapid, wide distribution of this enabling technology."

For instructions on how to become a registered licensee and to download the PURL Server source code, go to http://purl.oclc.org.