An example of Semantic markup, deconstructed

In our article, we briefly discuss some of the markup as it is being used, and gave an example of some of the markup on Professor Hendler's home page. On this page, and those linked to it, we will describe this example in significantly more detail.

As we've discussed, the Semantic Web is based on machine-readable descriptions of information, linked to ontologies which define the terms. While this markup does not need to discuss a document which is also available in human-readable form, it is often used this way, and thus in this example we relate the semantic markup to the information on a human-readable page. There are also several different languages that have been proposed for doing semantic web markup, in this example we will show you a couple of different ones that are currently in use.

This example is presented in several steps, each will link you to another web page that explains a key concept for semantic web markup. (Links to a number of related pages are included in the description below - you do not need to follow these for the example, they are provided for those looking for more detail on key concepts.)

• Step 1 is an abbreviated version of the real web page. It presents a simpler version of the home page, in the standard HyperText Markup Language (HTML) that drives the current World Wide Web.
  
  
• Step 2 shows how the page is marked up using a language called SHOE (The Simple HTML Ontology Extensions) . SHOE was developed at the University of Maryland by members of Professor Hendler's research group (particularly Sean Luke who designed the original language and is responsible for the original concept and Jeff Heflin who has helped to develop the concept, written a number of tools and demonstrations, and coauthored many research papers about the work.) SHOE was the first ontology-based markup langauge developed for use on the World Wide Web, and was used in a number of research projects and demonstrations.
  
  
• Step 3 shows how the page can be marked up using a language called DAML+OIL. This language gets its strange name because it was created by a Joint Committee of US and European researchers who were working on two different, but similar languages. DAML stands for the DARPA Agent Markup Language, which is a project being funded by the US Defense Advanced Research Projects Agency -- the same organization that funded much of the original work on the Internet (which was then called the ARPAnet). DARPA is developing not only the language, but many tools and applications that promote its use. OIL stands for the Ontology Interchange Language and eas developed by a number of researchers, primarily a group funded by the European Union's Information Society Technologies Program. The joint committee created a new language with the best features of SHOE, DAML, OIL and several other markup approaches. At the time of this writing, DAML+OIL is the most advanced web ontology language, and it is expected to provide the basis for future web standards for ontologies.
  
  
• Step 4 DAML+OIL is very hard for humans to read (since it is built primarily for computers). However, it is important that humans can examine the information in ontologies and marked up pages when they are doing tool development, debugging, ontology research, etc. Tim Berners-Lee and some of his colleagues at the World Wide Web consortium have been working on a new notation called N3, which can be used to read DAML+OIL more easily.

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