Though users can provide URLs to access electronic publications, seamless linking of referenced articles is not always possible: publications might be hosted on different servers having different access permissions. Following a concrete link in BibSonomy, contributed by a specific user, does not consider the access rights of other users. For instance, she might be using her university's network benefiting from the specific subscription rights the university's library has.
OpenURL aims to solve this 'appropriate copy' problem by providing a link to a copy of a work the user has a valid subscription to or to an open access version. BibSonomy allows to redirect requests to an OpenURL resolver chosen from the user. You can include the address of your resolver in the OpenURL field at your "settings" page.
For instance, the library of the University of Kassel is a member of the OVID LinkSolver having access rights to about 18.000 journals. If you want to include the resolver, the corresponding URL would be http://linksolver.ovid.com/OpenUrl/LinkSolver.
Each publication entry has then a link named "OpenURL". If you click on this link, a request will be sent to the given LinkSolver, added with the metadata of the publication. For instance, if you click on OpenURL of the publication "Fast Random Walk with Restart and its Applications" the following URL is constructed and sent to the linksolver.
First part, link to link resolver:
http://linksolver.ovid.com/OpenUrl/LinkSolver
Second part, metadata:
date=2006&id=doi%3A10.1109%2FICDM.2006.70&isbn=0-7695-2701-9&aulast=Tong&aufirst=Hanghang
&title=ICDM+%2706%3A+Proceedings+of+the+Sixth+International+Conference+on+Data+Mining&atitle=
Fast+Random+Walk+with+Restart+and+Its+Applications
The resolver checks the document, your specific subscriptions and allocates the most appropriate document copy for you, if it can find one.
If you are not sure which OpenURL resolver to enter into your settings page, you can find more information at
Overview 1
Overview 2