This site provides an overview about the Named Graphs work being conducted by some participants of the Semantic Web Interest Group.
Discussion of this approach takes place on www-rdf-interest.
Other interest group participants who wish to do collaborative development (of documents or other things), are encouraged to cc their e-mail to www-archive, and then post a summary to www-rdf-interest.
Named Graphs is the idea that having multiple RDF graphs in a single document/repository and naming them with URIs provides useful additional functionality built on top of the RDF Recommendations.
Named Graphs and corresponding technologies are currently developed by participants of the Semantic Web Interest Group. The intent is to introduce them into the W3C process in an appropriate way once initial versions are finished.
The work is currently presented in two documents:
The abstract syntax of Named Graphs is based on the abstract syntax of RDF. Basically, a Named Graph is a set of triples named by an URI. This URI can then be used outside or within the graph to refer to it. The abstract syntax of Named Graphs is formally defined in Carroll, Bizer, Hayes, Stickler: Named Graphs, Provenance and Trust.
The Named Graphs vocabulary RDFG can be used to describe graphs and relations between graphs. It defines concepts like rdfg:Graph, rdfg:subGraphOf and rdfg:equivalentGraph.
The meaning of a set of named graphs is built on the RDF Semantics. The semantics of Named Graphs are specified in Carroll, Bizer, Hayes, Stickler: Named Graphs, Provenance and Trust.
TriX (Triples in XML) is a serialization for named graphs. TriX aims to provide a highly normalized, consistent XML representation for RDF graphs, allowing the effective use of generic XML tools such as XSLT, XQuery, etc.
TriG is a plain text format for serializing Named Graphs. The TriG syntax offers a compact and readable alternative to the XML-based TriX syntax.
A collection of RDF documents can be seen as a set of Named Graphs. This gives Named Graphs backward compatibility with RDF/XML, but has the disadvantage that retrieval URL, document name and graph name are mixed up.
TriQL is a query language for extracting information from Named Graphs. It is based on RDQL. The basic idea of TriQL is using graph patterns instead of triple pattern for querying sets of named graphs. A graph pattern consists of an optional graph name and a set of triple patterns.
RDFQ is an RDF vocabulary and query model for resource and resource knowledge discovery. The RDFQ vocabulary provides for the definition of templates which can be matched against actual resource descriptions. The results of an RDFQ query is a RDF graph containing (a) the concise bounded descriptions of all resources matched by one or more of the specified target templates, and/or (b) a set of variable binding declarations expressed using the Result Set Vocabulary. Queries can be constrained to Named Graphs matching one or more graph templates.
NG4J is an extension to the Jena Semantic Web toolkit for parsing, manipulating and serializing sets of Named Graphs. NG4J implements the TriX and the TriG syntax and the TriQL query language. A graph set can viewed as a single Jena model, providing provenance-enabled Jena statements. NG4J supports storing sets of Named Graphs in various databases. NG4J is available under BSD license.
This section describes applications and potential application areas of Named Graphs.
The Sematic Web Publishing (SWP) vocabulary can be used within the named graph framework to integrate information about provenance, assertional status, and digital signatures of graphs.
Named Graphs together with the SWP vocabulary can be used as a basis for flexible trust evaluations.
Named Graphs aim at more complex RDF application areas like:
Some basic examples of how to use Named Graphs for this kind of applications is found in