Bob DuCharme, author and speaker, has provided an excellent example of one of the benefits RDF has over XML. In his example, DuCharme shows how to perform a simple federated query with RDF across two different address books. He writes, "Once, at an XML Summer School session, I was giving a talk about semantic web technology to a group that included several presenters from other sessions. This included Henry Thompson, who I've known since the SGML days. He was still a bit skeptical about RDF, and said that RDF was in the same situation as XML—that if he and I stored similar information using different vocabularies, we'd still have to convert his to use the same vocabulary as mine or vice versa before we could use our data together."
He continues, "I told him he was wrong—that easy aggregation without conversion is where semantic web technology shines the brightest. I've finally put together an example. Let's say that I want to query across his address book and my address book together for the first name, last name, and email address of anyone whose email address ends with '.org'."
Image: Courtesy Bob DuCharme