XDI

XDI (short for "eXtensible Data Interchange") is a semantic data interchange format and protocol under development by the OASIS XDI Technical Committee. The name comes from the addressable graph model XDI uses: every node in the XDI graph is its own RDF graph that is uniquely addressable.

The main features of XDI are: the ability to link and nest RDF graphs to provide context; full addressability of all nodes in the graph at any level of context; representation of XDI operations as graph statements so authorization can be built into the graph; a standard JSON serialization format; and a simple ontology language for defining shared semantics using XDI dictionary services.

The XDI protocol is based on an exchange of XDI messages which themselves are XDI graphs. Since the semantics of each message is fully contained within the XDI graph of that message, the XDI protocol can be bound to multiple transport protocols. The XDI TC is defining bindings to HTTP and HTTPS, however it is also exploring bindings to XMPP and potentially directly to TCP/IP.