The Semantic Web - Social Semantics: The Search for Meaning on the Web - page 77

The entity given in the request may have a preferred media-type, and the response
should have a media-type as well. The media-type, such as 'application/xml' or 'ap-
plication/rdf+xml,' tells the agent how to interpret the entity body of the response.
Media-types are modeled in IRW through the class MediaType . The relationship
between an http:MediaType and an http:Entity is given by the encodes
relationship. Note that each web representation has a single media-type.
AURImayalsohavea redirectsTo property, a sub-property of accesses ,
that we can use to model HTTP redirection. This can be done via a number of
different techniques, ranging from a 'Content-Location' HTTP entity header to a
300-level HTTP status code, and to model these we rely on the HTTP-in-RDF
ontology. 15 Note that, even in the light of the W3C TAG's httpRange-14 decision,
redirection can also be used between information resources that have nothing to do
with the Semantic Web. So, the domain and range say nothing about the type of
resource.
￿ Agent : An OWL Class. A human or a program that establishes connections for
the purpose of sending requests (Fielding et al. 1999). In the W3C AWWW, an
agent is “a person or a piece of software acting on the information space on behalf
of a person, entity, or process” (Jacobs and Walsh 2004).
- rdfs:subClassOf Resource
￿ requests : An OWL Object Property. “The act of issuing a request message
from a client to a server that includes, within the first line of that message,
the method to be applied to the resource, the identifier of the resource, and
the protocol version in use” (Fielding et al. 1999). A request action is a flow
itself characterized by an agent that sends an entity that includes a URI; this is
expressed in IRW by a property chain axiom.
- rdfs:subPropertyOf accesses
- rdfs:domain Agent
- rdfs:range URI
- http:sendsEntity o comp:hasComponent o
http:hasRequestedURI
￿ WebServer : An OWL Class. “An application program that accepts connections
in order to service requests by sending back responses” (Fielding et al. 1999).
Note that “any server may act as an origin server, proxy, gateway, or tunnel,
switching behavior based on the nature of each request” (Fielding et al. 1999).
A web server hosts at least one web representation and resolves at least one
URI.
- rdfs:subClassOf Agent
- hosts min 1 WebRepresentation
- resolves min URI
15 http://www.w3.org/TR/HTTP-in-RDF10/ .