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Introducing topic maps: a powerful, subject-oriented approach to structuring sets of information. (Content Management).

Article Excerpt
Topic maps are a standard way of representing the complex relationships that often exist between the pieces of information that we use in day-to-day business processes. This article begins by discussing what topic maps are, what they can do, and what people are currently using them for. However, my main goal is to introduce the basic concepts of topic maps and their representation in XML.

The Missing Link in Information Management

Almost all XML vocabularies are designed with a single purpose: to describe information in a way that enables automated processing. We use XML to describe document structures so our documents can be rendered as HTML, WML, PDE or some other presentation format. We also use XML so that business systems can interchange data reliably. Both the ability to render content to different output formats and the reliability of data interchange arise from a predefined agreement about how individual pieces of markup describe the information they wrap.

There's no doubt that information markup is of immense use in automated processes, but alone it can't describe the relationship between different resources or between an information resource and the subject or subjects that the information resource describes. In many systems it's these relationships that enable human beings to make sense of and organize the information they need to work with. In some respects, then, these relationships are the missing link between manageable and unmanageable information.

Topic Maps: Subject-Oriented Markup

If the current set of information-oriented vocabularies based on XML isn't sufficient for information management purposes, it would indicate that what's needed is an alternate view of the information. One such alternate view is provided by topic maps.

In a topic map, rather than focus on the information, you focus on what the information is about. The markup you create is subject oriented rather than information oriented. The fundamental unit of a topic map is a topic, an electronically processible stand-in for a thing that doesn't necessarily have to be processible itself. For example, a topic can represent a person, a building, or a concept, but it can also be used to represent processible things such as Web pages, files, or database cells. In the topic map approach the thing a topic represents is called the subject of the topic.

A single document may describe many different subjects and may establish relationships between those subjects. Using topic map constructs, a topic map author can describe the relationships between the subjects described by different topics and also point to resources that provide information related to the topic in some way. In addition to topics, the two other basic topic map constructs that make this possible are associations, which relate topics to each other, and occurrences, which connect topics to resources that contain some information related to the topic. These three basic concepts are shown in Figure 1.

[FIGURE 1 OMITTED]

A Brief History of Topic Maps

The first standard to describe the topic map approach was published by ISO early in 2000 as ISO 13250:2000. In addition to describing the paradigm itself, ISO 13250 describes an interchange syntax making use of SGML Architectural Forms and link structures defined by the HyTime standard (ISO 10744). The interchange syntax described in this first edition of the ISO topic map specification is highly flexible, enabling users to derive their own DTDs for describing their own information structures, and allowing the use of the full range of multimedia linking structures defined by HyTime.

Soon after the publication of ISO 13250, a separate group called TopicMaps. Org was formed to create a topic map interchange standard based on...

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