RDF and Ontologies

Resource Description Framework (RDF), a part of the XML story, provides interoperability between applications that exchange information. RDF is another Web standard that’s finding use everywhere, including application integration. RDF was developed by the W3C to provide a foundation of metadata interoperability across different resource description communities and is the basis for the W3C movement to ontologies such as the use of Web Ontology Language (OWL).

RDF uses XML to define a foundation for processing metadata and to provide a standard metadata infrastructure for both the Web and the enterprise. The difference between the two is that XML is used to transport data using a common format, while RDF is layered on top of XML defining a broad category of data. When the XML data is declared to be of the RDF format, applications are then able to understand the data without understanding who sent it.

RDF extends the XML model and syntax to be specified for describing either resources or a collection of information. (XML points to a resource in order to scope and uniquely identify a set of properties known as the schema.)

RDF metadata can be applied to many areas, including application integration. One example would be searching for data, and cataloging data and relationships. RDF is also able to support new technology (such as intelligent software agents and exchange of content rating.)

RDF itself does not offer predefined vocabularies for authoring metadata. However, the W3C does expect standard vocabularies to emerge once the infrastructure for metadata interoperability is in place. Anyone, or any industry, can design and implement a new vocabulary. The only requirement is that all resources be included in the metadata instances using the new vocabulary.

RDF benefits application integration in that it supports the concept of a common metadata layer that is sharable throughout an enterprise or between enterprises. Thus, RDF can be used as a common mechanism for describing data within the application integration problem domain.

Web-Based Standards and Ontologies

The use of languages for ontology is beginning to appear, built on reasoning techniques that provide for the development of special-purpose reasoning services. In fact, the W3C is creating a Web standard for ontology language as part of its effort to define semantic standards for the Web. The Semantic Web is the abstract representation of data on the World Wide Web, based on the Resource Description Framework standards (see the “RDF and Ontologies” tidbit) and other standards still to be defined. It is being developed by the W3C, in collaboration with a large number of researchers and industrial partners.