RDF for Information Owners

PART IV

The Semantic Web

IN THIS PART

23       RDF for Information Owners

24       The Semantic Web for Information Owners

Chapter 23

RDF for Information Owners

IN THIS CHAPTER

• Basics of the Resource Description Framework

• The RDF Family of Specifications

• The RDF Data Model

• RDF Schema

 Working with the Angle Brackets

The Resource Description Framework (RDF) gives information owners a way of expressing meaning on the Web that machines can understand (and humans will, ultimately, profit from). This chapter explains how RDF expresses machine-understandable meaning using its data model; the next chapter, on the Semantic Web, will show some of the good things that RDF makes happen. So, if you want the business case for RDF applications, skip ahead to Chapter 24, “The Semantic Web for Information Owners.” If mastery of RDF syntax and semantics is what you’re after, read on.

RDF is spelled out in a family of W3C specifications. Like many families, though, the RDF family members are not all quite at the same level of maturity, and not all of them agree with each other all the time. Therefore, to help you avoid the pitfall of spending a lot of time on parts of RDF that are either obsolete or immature, we’ll first go through the specifications, giving extra attention to open issues and resources that will keep your expertise current.

RDF’s data model gives RDF its power to express machine-understandable meaning, and that’s what we’ll look at next. Because the RDF data model is a graph, we’ll study just enough graph theory to deal with that formalism and get through the model. Then, we’ll go through the data model in detail, showing the RDF graph in both pictorial and XML syntax, all in ready-reference form. Then we’ll do the same thing for RDF schema, and you’ll see how RDF schema’s class hierarchy allows the meaning of RDF instances to be constrained and validated.

Finally, we’ll look at some angle bracket–type issues in handling RDF, such as how to embed RDF in Web pages, and so on.

Therefore, by the time you finish this chapter, your expertise will extend beyond the basics of RDF to

   The RDF family of specifications

   Issues with the specs and where to go to resolve them

   The RDF data model (and a little graph theory)

   What RDF schema validates and how it does so

   XML and pictorial RDF syntax