Topic Maps
What every knowledge worker should know
A simple, standard way to link knowledge and information
Introduction
A Topic Map defines three main sorts of information:
- Topics, which are things or concepts that you're interested in
- Associations, which help you relate one topic to another, and therefore help you to navigate around your subject of interest and
- Occurrences, which are information resources that relate to the topics. You can use them to locate books, articles, files, web pages and other relevant resources.
Why use Topic Maps?
Topic Maps are usable today, even though the technology is at the early adopter stage. There are already standards that define the external representation of Topic Maps, ensuring that maps are portable and compatible. The original ISO13250 Topic Map standard was published in 1999; the current version of the XTM specification (and XMl-based way of representing Topic Maps) was published in 2001. Work on a Standard Processing Model is well under way.
There is a wealth of information about Topic Maps on the web, there are several relevant books, and there are editors, libraries and browsers available. Some are commercial products (many offering free evaluation copies) but there are several Open Source projects, which have already produced some excellent software.
Building your own Topic Map
To start, you should define the theme of your map. Ask yourself why you are building it, and how it will be used. What sort of things should it include?
Next, identify the topics. Look at real-word things as well as concepts and categories that are relevant to your theme.
Now you can start to link your topics with associations. This is similar to the design of associations in an object model or a database, but there are a couple of important differences.
The first thing that might surprise you is that associations in a Topic Map are between individual topics; they are like links between objects or rows, rather than associations between classes or tables.
The second thing is that an association can also be regarded as a topic. This introduces a self-referential aspect that is powerful but mind-stretching. (The self-reference can go further - you can even define the topic map as a topic within itself!)
As soon as you have defined your topics, you can start to add occurrences. An occurrence can be a link to an external resource of some kind. It can also be information stored within the Topic Map.
Of course this process is iterative; you can go back and add more topics, associations and occurrences at any time.
There are several approaches that you can take when implementing this process. You can generate the map data manually or automatically. The tools you will need depend on the precise approach that you are taking.
If you're adding content manually, you can do so from your own knowledge or by marking-up existing data. You can add content automatically by using software that analyses free-form text, structured data or marked-up data.
These options allow you to trade off effort against value added. Topic maps are great, but there's still no free lunch!
Using your Topic Map
The simplest option is to browse it (or let others browse it). A number of tools allow you to expose your map as a collection of virtual web pages, dynamically built from the map itself. Since the map can be serialised as an XML document, you can equally well use it to generate static HTML via an XSL-based stylesheet. Topic Maps are an excellent way to define and build rich web sites.
You can also make programmatic use of the knowledge embedded in the map. You might use a Topic Map to help a search engine uncover more relevant material, or filter hits better. You might even use the Map to provide data to an inference engine that could make deductions based on the contents of the Map.
I hope that this introduction is enough to get you thinking, but it is deliberately simple and incomplete. You'll find additional details below.
Conclusion
If you have followed this far, you're smart enough to build your own Topic Maps. Try out this outstanding new technology and start turning information into knowledge that you (and others) can use.
Resources
- The TAO of Topic Maps
- Benefits of using Topic Maps
- Getting started (by Murray Woodman)
- The Topic Map Tutorial at Bond University