Dereferencing is retrieving representations of a resource by a URI (Uniform Resource Identifier).


  • What is the difference between a URI and a URL?
  • What is the difference between dereferencing and content negotiation?
  • See references below for further reading

“Story Angela is creating an OWL ontology that defines specific characteristics of devices used to access the Web. Some of these characteristics represent physical properties of the device, such as its length, width and weight. As a result, the ontology includes concepts such as unit of measure, and specific instances, such as meter and kilogram. Angela uses URIs to identify these concepts.

Having chosen a URI for the concept of the meter, Angela faces the question of what should be returned if that URI is ever dereferenced. There is general advice that owners of URIs should provide representations [AWWW] and Angela is keen to comply. However, the choices of possible representations appear legion. Given that the URI is being used in the context of an OWL ontology, Angela first considers a repres entation that consists of some RDF triples that allow suitable computer systems to discover more information about the meter. She then worries that these might be less useful to a human user, who might prefer the appropriate Wikipedia entry. Perhaps, she reasons, a better approach would be to create a representation which itself contains a set of URIs to a range of resources that provide related representations. Perhaps content negotiation can help? She could return different representations based on the content type specified in the request.”


RFC 7231 - Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content