OpenURL

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OpenURL is a type of URL that contains resource metadata for use primarily in libraries. The National Information Standards Organization (NISO) has developed OpenURL and its data container (the ContextObject) as international ANSI standard Z39.88. On 22 June 2006, OCLC was named the maintenance agency for the standard.^[1]

The OpenURL standard is designed to support mediated linking from information resources (sources) to library services (targets). A "link resolver", or "link-server", parses the elements of an OpenURL and provides links to appropriate services as identified by a library. A source is generally a bibliographic citation or bibliographic record used to generate an OpenURL. A target is a resource or service that helps satisfy user's information needs. Examples include full-text repositories; abstracting, indexing, and citation databases; online library catalogs; and other Web resources and services.

An OpenURL consists of a base URL, which addresses the user's institutional link-server, and a query string, which contains contextual data, typically in the form of key-value pairs. The contextual data is most often bibliographic data, but in version 1.0 of OpenURL can also include information about the requester, the resource containing the hyperlink, the type of service required, and so forth. For example:

http://resolver.example.edu/cgi?genre=book&isbn=0836218310&title=The+Far+Side+Gallery+3

is a version 0.1 OpenURL describing a book. http://resolver.example.edu/cgi is the base URL of an example link-server. In version 1.0, this same link becomes somewhat longer:

http://resolver.example.edu/cgi?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:book&rft.isbn=0836218310&rft.btitle=The+Far+Side+Gallery+3

The most common application of OpenURL is to provide appropriate copy resolution: an OpenURL link points to the copy of the resource most appropriate to the context of the request. If a different context is expressed in the query, a different copy ends up resolved to; but the change in context is predictable, and does not require the creator of the hyperlink to handcraft different URLs for different contexts. For instance, changing either the base URL or a requester parameter in the query string can mean that the OpenURL resolves to a copy of a resource in a different library. So the same OpenURL, contained for instance in an electronic journal, can be adjusted by either library to provide access to their own copy of the resource, without completely overwriting the journal's hyperlink. The journal provider in turn is no longer required to provide a different version of the journal, with different hyperlinks, for each subscribing library.

OpenURL was originated by Herbert van de Sompel, a librarian at the University of Ghent. His link-server software, SFX, was purchased by the library automation company Ex Libris which popularized OpenURL in the information industry. Many other companies now market link server systems, including Openly Informatics (1Cate — acquired by OCLC in 2006; rebranded as WorldCat Link Manager in 2007), Swets (SwetsWise Linker), Serials Solutions 360 Link (formerly known as Article Linker), Innovative Interfaces, Inc. (WebBridge), EBSCO (LinkSource), Ovid (LinkSolver), SirsiDynix (Resolver), Fretwell-Downing (OL2), TDNet (TOUR), R.R. Bowker (Ulrichs Resource Linker) and Infor (Vlink).

OpenURL is usually implemented by information providers by dynamically inserting an appropriate base URL into web pages sent to an authenticated user. OpenURL COinS is a new specification that allows free services like Wikipedia to provide OpenURLs by cooperating with client side software agents. Federated search software presents OpenURL links in record fields by employing the library's subscriber links to link servers facilitating access to full-text resources from bibliographic record hyperlinks.