Biblio Tech
Information Technology for Libraries

Ex-Libris in SFX deal



Search BTR site

Receive update alerts

Main Sections

[Biblio Tech Review]

This month’s stories

[Ultimate Integration]
Ex-Libris SFX]
Endeavor - Elsevier]
Ex-Libris update]
Sirsi China]
Endeavor sales]
Dialog sale]
Libtech 2000]

Ex-Libris gains marketing rights for SFX

March 2000

An interesting technology developed by University of Ghent in Belgium has been bought by Ex-Libris.  Along with other moves by integrated library system vendors - Innovative’s link and the Endeavor/Elsevier merger - this shows how the convergence of the sourcing and managing knowledge technologies are affecting the industry.  Press release from Ex Libris + Peter Evans summarises the key features of SFX and its implications.

Press Release: February 4, 2000 Chicago, Illinois.

Ex Libris announced today that the company has acquired the sole rights to the SFX Reference Linking Software Solution from the University of Gent (Belgium) and will begin its immediate deployment. SFX will play a vital role in Ex Libris' new Internet Strategy.

The wide use of hyperlinks on the World Wide Web has conditioned Internet users to expect similar linking convenience within other computer environments, including digital library collections.   However, when you want to ascertain the availability of items, it is still a case of "hit-and-miss".

As the Web evolves, the creation of services that link related information entities is an area of strongly growing interest, particularly for the research community and for managers of research-related information systems. Publishers, subscription agents, researchers and libraries are looking for ways to create value-added services through linking these entities.

"SFX is a groundbreaking tool for discovery and navigation that will deliver such linking services in the scholarly information environment" said Oren Beit-Arie, Vice President of Research and Development. "SFX enables linking between all parts of an electronic collection: full-text repositories; abstracting, indexing and citation databases; online library catalogs; citations appearing in research articles and other web resources. For instance, SFX allows publishers to provide links back to individual libraries within the online journal pages. These links enable librarians to add customized online services for users based on their local resources and environment. "

Ex Libris, a leading world-wide developer of high performance applications for libraries and information centers, will be working with the developers of SFX - Herbert Van de Sompel and Patrick Hochstenbach - to deploy SFX world-wide. Several renowned research institutions in the US and Europe have already expressed their interest in becoming early adopters.

Ex Libris is establishing an independent Information Services Division of Ex Libris (USA) Inc. that will be responsible for the development, sales and support of the SFX service.

SFX is a system that dynamically interlinks numerous electronic resources and can be used in a wide range of digital libraries. SFX is based on the research work about the reference linking problem undertaken by Herbert Van de Sompel at the University of Gent and the Los Alamos National Laboratory. It has been applied in the complex digital library environments of both institutions. The solution has successfully demonstrated its ability to dynamically create services interlinking:

Abstracting and indexing databases (Inspec, Medline, PubMed, Public Genome database, MathSci, Compendex, LiSa, Current Contents, BIOSIS, Books in Print, EconLit, Ulrich) · Library catalogues · Citation databases (ISI, SLAC/SPIRES) · Citations in research papers (Wiley InterScience, American Physical Society PROLA archive) · e-print archives (Los Alamos xxx  and the experimental UPS Prototype service), · Internet Bookshops

All of the above were running on a wide variety of platforms (SilverPlatter ERL, Ex Libris Aleph 500, Geac Advance, Topic, etc.).

Reference linking via SFX - some details

The Problem

Knowledgeable researchers and librarians are used to navigating manually between resources - there is nothing new here. A catalogue user moves from the catalogue record to the hard copy. Or from the hard copy to the catalogue to check whether a cited journal is held. Or to a secondary source e.g. abstracting source to discover new articles. When the catalogue and many resources are digital, the task is to make the reference linking, back and forth, a simple click rather than copying out and re-keying - the only alternative.

The user of a library now expects resources to be linked - Web style - easy navigation from one resource to another. When all resources are created by a single organisation e.g. within a single web site, then this is relatively simple.  Links are entered and maintained as simple "static" links.  They are "hardwired" by the html tags. Even then, maintenance of a changing site can be a problem. The commonest example of a static resource link is via the 856 tag in an OPAC record to a Web page. 

In a hybrid library however, there are several type of resource and many potentially useful links to be managed.  This is either difficult, (too many potential links, changing too fast), or impossible (how do you add links within someone else's CD database?).

Dynamic linking

Static linking is hardwired and inflexible.  Dynamic linking provides an interface standard between systems so that the link is created by a program from data passed to it. For example the link from products like SilverPlatter's™ WebSPIRS™ back to the OPAC to check whether holdings are available in that library, is achieved by each side knowing that the linking data is the ISSN.

The trick that SFX tries to achieve is to set up a consistent framework for dynamic linking of a whole variety of resources so that the user can be presented with useful links wherever they might be in the searching process. For example a user should be able to link to the OPAC (to check local holdings of a cited title) whilst reading the full text of an article. This requires a program to "read" the journal article to determine what links might be appropriate.  Such processes are not error free and consequently, dynamic linking is never as accurate as static linking - but it is manageable and it saves the time of the reader.


The ideas behind SFX (Special Effects) were developed at the University of Ghent and have achieved reality with the help of Ex Libris who now have the sole rights for the system.

At the heart of the SFX system is a database of anticipated conceptual links (COLLI).  This is a list of available linkable resources e.g. OPAC, Serials Union List, Current Contents, SwetsNet etc. together with the rules for accessing them e.g. data elements that must be passed, date thresholds, and types of relevant material.

Thus when a user asks for links for a record that it is viewing, the SFX system will firstly grab details of the record being viewed, e.g. it is an OPAC record of a serial with ISSN 1234567X,  this data is matched in the SFX-base and relevant, potential link sources, grouped into types, are presented.

OPAC record: University of Ghent

Title American Mathematical society
Holdings: 22(1921) -
ISSN: 0002-9947

Special Effects


The starting point - the user finds a serial title in the OPAC

Links suggested by SFX


Secondary resources

  • Current Contents for 0002-9947 (user can enter year, volume, issue data here)
  • Journal Citation Reports
  • Ulrich's Serials Database

Pressing the special effects button causes SFX to create a bundle of suggested links - sorted by type


  • University of Leuven
  • Antilope: Belgian union catalogue of serials

Primary resources

  • No links to primary resources are available for this record

Clicking on any link causes SFX to read the OPAC record and prepare a link-to request to the target service and the user is transported to it. This is “just in time” dynamic linking

Some resource types are not available - the SFX-base determines this.

The user can then select the link required.  SFX then, and only then, attempts to link to the source via parsing the data in the viewed record or entered by the reader and transferring the user to the requested resource.  This technique is termed "just in time" rather than "just in case". Real sample screens from University of Ghent can be seen in the article:

Limitations and conclusions

The technical limitations of this approach to reference linking - via a resource database and intelligent analysis of what links might be relevant - will diminish as the algorithms at the heart of the system are improved by Ex Libris.  However for the librarian anxious to integrate as many resources as possible into the system, the limitations may well be in the definition of the software that reads the source record for potential links and the ease with which control can be passed to the source software - the "link-to" service. Very few databases allow this. The Ghent experimental system works with 12 resources. A typical university library may have 200 CD titles - both primary and secondary + web and other resources.

For the user the potential problems are only in that they may be presented with potential links that do not work due to circumstances beyond the control of SFX. e.g. a wrong ISSN on an OPAC record.  This is a small price to pay and provided the occurrence is relatively rare, will be acceptable.

Finally, and more difficult is the issue of licensing, authentication and so on for users who wish to link to another resource.  The tangled web of practice in this area is hampered by the lack of standards amongst providers. Until universal authentication and licensing control standards are developed and adopted, barriers to the wider development and deployment of dynamic linking systems such as SFX will remain.

The Future

As far as I know SFX is the only generic dynamic linking system available. It is in its infancy and other vendors may wish to develop their own on similar ideas.  The industry needs such systems that work reliably and with as wide a range of resources as possible.  Standards for "link-to" services and syntax are essential to avoid isolation of the smaller providers' products in "no-link" ghettos.

More information

Information on SFX from EX Libris site

Detailed articles on SFX have been published in D-Lib Magazine: