Will Topic Maps Guide the Future?
Besides Tim Berners-Lee's talk, the other big buzz at XML 2000 was topic maps, which were the focus of a number of presentations during the technical sessions. Moreover, an impressive number of companies on the exhibition floor demonstrated support for topic maps. Part of it too was the announcement of XML Topic Maps (XTM) 1.0. XTM 1.0 is the product of Topicmaps.Org, which has been formed specifically to bring the topic maps paradigm to the Web.
A simple example of a topic map is illustrated in a "gentle" introduction to the subject on Topicmaps.org. A topic map discussing Shakespeare might include some explicit links to URLs for some of the plays, connecting the URLs to "topics" (one topic called Hamlet, another topic called Tempest). Each of these URLs is considered an "occurrence" of each topic. These two occurrences can then be tied together with an "association"; this seemingly simple connection is what begins to give topic maps their power. Taken together, these topics, occurrences, and associations begin to form a topic map.
Since topic maps are intended to exist in separate documents, and since they don't require the source documents to be changed, they allow the information designer to create many views of the same data. Indeed, though this approach is not supported in a particular product yet, a topic map-supported Web site could allow the end-user to design his or her own topic maps of the content.
Bear in mind that while the thinking behind topic maps is mature, the proposed standard itself is relatively new (published in December of 2000), and the commercial technology supporting the standard is still in its early stages. Having said that, though, there are at least two vendors worth looking at:
- Ontopia's core product is the Ontopia Topic Map Engine. It is a generic implementation of the topic map standard, available as a software development kit. The SDK allows developers to access and manipulate the constructs found in topic maps (topics, associations, and occurrences).
- Empolis, a technology subsidiary of Bertelsmann, produces a product called K42. The K42 knowledge server is a software application developed on the basis of topic map technology. Based on open standards such as Java, XML, and XSL, K42 features a query language for accessing the topic maps.
Look for more implementations of topic maps in search and categorization technology. Empolis, for example, has shown an application of its K42 knowledge server working with the Inxight categorization software. The key for topic maps may well be whether a larger standards organization, such as the W3C, ends up hosting the effort. Given the W3C's emphasis on a semantic Web, it seems only logical it would get behind such an approach, or one much like it. But, indeed, whether topic maps become the preferred means of categorizing data for the Web remains to be seen. In the meantime, there is much work to do-technology to explore, data to be tagged, and, most importantly, users' needs to be met.
URLs of Companies Mentioned
Forrester Research www.forrester.com
World Wide Web Consortium www.w3c.org