How does XDI relate to RDF?
This is a hard question to answer in a FAQ. A summary answer is that the proposed XDI meta-schema and RDF use slightly different models for graphing data relationships. This might be compared to the difference between Cartesian and radian coordinate systems. Either can identify any set of points in a plane, but each is optimized for certain kinds of geometric shapes (e.g., line figures vs. circles). Following this analogy, RDF is a very robust, application-independent solution for describing any property of any URI-addressable resource, while XDI is optimized for a specific application: describing data sharing and linking relationships between XRI-addressable resources in XML.
