The new DIG interface standard (DIG 2.0)

DIG Interface

The DIG interface (often just known as DIG) provides uniform access to Description Logic Reasoners. The interface defines a simple protocol (based on HTTP PUT/GET) along with an XML Schema that describes a concept language and accompanying operations.

The interface is not intended as a heavyweight specification of a reasoning service. Rather, it provides a minimal set of operations (e.g. satisfiability and subsumption checking and classification reasoning) that have been shown to be useful in applications.

A number of reasoners including CEL, FaCT++, Pellet, and RacerPro provide support for DIG. A number of ontology editors (including OilEd, Protege and SWOOP) can use the DIG interface to communicate with such reasoners. The Jena framework also makes use of DIG for reasoning over OWL ontologies.

The current DIG specification is not without its problems. The expressivity offered by DIG 1.1 is not sufficient to capture general OWL-DL ontologies — in particular datatype support is lacking in DIG 1.1 and there is a poor fit between DIG's notion of relations and OWL properties. In order to address these issues, a working group has been formed to move towards a revised DIG specification. The intention is that this specification will be available early in 2006.