The Semantic Web
According to the W3C Linked Data page, the Semantic Web refers to a technology stack to support the “Web of data”. Semantic Web technologies enable people to create data stores on the Web, build vocabularies, and write rules for handling data. Linked data are empowered by technologies such as RDF, SPARQL, OWL, and SKOS.
- RDF. Resource Description Framework is a standard data model for representing the metadata of resources in the Web; it represents all resources – even those that cannot be directly retrieved. RDF especially helps to process, mix, expose, and share such metadata. In terms of the relational model, an RDF statement specifies a relationship between two resources and it is similar to a triple relation with subject, predicate, and object.
- OWL. Ontology Web Language is based on the basic elements of RDF, but uses a wider vocabulary to describe properties and classes.
- SKOS. Simple Knowledge Organization System is also based on RDF and specifically designed to express hierarchical information. If needed, it is also extendable into OWL.
- SPARQL. Simple Protocol and RDF Query Language is an RDF-based query language used to retrieve and manipulate public and private metadata stored in RDF format.
A commonly used instance of the semantic web is the DBPedia project, which was created to extract structured content from Wikipedia.
Our latest release KNIME Analytics Platform 3.2 includes a great feature: semantic web integration! A full node category is dedicated to querying and manipulating semantic web resources. The new semantic web nodes treat the web of data exactly like a database, with connector nodes, query nodes, and manipulation nodes. Additional nodes are provided to read and write files in various formats.