A story about RDF and XML
1.XML Documents represent the XML Infoset; RDF graphs represent what those Infosets are trying to tell us about objects, their inter-relationships and properties.
2.RDF gives us a model for namespace mixing and data merging:
There is no algorithm for merging two XML Infosets, to enable us to pool knowledge acquired from diverse sources. The RDF information model, by constrast, was designed with data aggregation (rather than structured documents) in mind. Merging RDF data is trivial: add the triples extracted from two RDF/XML documents, and store them in a new one.
3.RDF views of the Infoset are explicit about the information we can throw away:
Transforming Infosets into their RDF graph allows us to throw away irrelevant information, such as the aspects of the Infoset concerned with preserving a representation of document ordering. When we define transformations from an XML Infoset into RDF, we show XML processors which parts of the Infoset can be discarded without losing the essence of the message encoded in that XML.