Various tools are already available for handling RDF and RDF schemas. We list just a few here; a more complete list is available at the W3C’s RDF home page at http://www.w3.org/RDF/.
The Protégé-2000 Ontology Editor supports the creation of RDF schemas and RDF data. It is a system for knowledge-base design and knowledge acquisition using Java. Pro-tégé- 2000 was developed at Stanford University and is available under the open-source Mozilla public license at http://www.smi.stanford.edu/projects/protege/.
Sergey Melnik has implemented a Java-based RDF API that includes an XML and RDF parser, schema-based vali-dation facilities, cryptographic digests of RDF models and statements, UML support on top of RDF, and support for RDF schema handling in Java. The API is available under an open-source license from http://www-db.stanford.edu/~melnik/rdf/api.html.
SiLRI is a lightweight deductive database that can reason using RDF metadata. It is also Java based and available under an open-source license from http://www.aifb.uni-karlsruhe.de/~sde/rdf.
Ramanathan V. Guha implemented an RDF Database (RDFDB), based on the Berkeley DB. It supports a graph-oriented API using a textual query language similar to SQL, and aims to scale to millions of nodes and triples. RDFDB can be downloaded from http://rdfdb.sourceforge.net.
The FRODO RDFSViz provides a visualization service for ontologies represented in RDF Schema. It uses the Java RDF API implementation from Sergey Melnik and the Graphviz graph drawing program (AT&T and Lucent Bell Labs). The FRODO RDFSViz tool is available at http://www.dfki.uni-kl.de/frodo/RDFSViz/.
Current deployments of RDF technology include:
Web service resources: More on emerging standards, products, and activities.