Coarser Grain Linked DataI've written before about my thoughts about the Linked Data movement and my concerns with its mandate regarding the kinds of URIs you use in your RDF. I think, though well intentioned, that particular constraint is a bit too tight and doesn't consider the (hidden) expense and distraction of forcing a producer of RDF content to ensure that all his or her URIs have a web presence.
However, i've been thinking about what a RESTful protocol for interacting with an RDF dataset would look like, Maybe requiring HTTP URIs works better at a differernt level of granularity.
The Semantic Web is meant to be an extension of the Web. The architecture of the web is abstracted in the REST style.
The REST interface is designed to be efficient for large-grain hypermedia data.
The RDF document, the concrete syntax representation of an RDF graph, is what is passed around over HTTP. The graph denotes some semantic web knowledge (interpreted via mathematical logic) and we might want to manipulate that knowledge through the request for and dispatching of RDF documents in various formats: N3, Turtle, NT, Trix, Trig, RDF/XML over HTTP.If I wanted to implement a Facebook social network as a semantic web, I would store all the knowledge / information about a person in an RDF graph so it can be managed over the hypermedia protocol of the web. Higher-order RDF vocabularies such as OWL2-RL, RDFS, OWL2-DL, etc. can be used to describe Facebook content as a complex domain. The domain can describe what a Facebook account holder would store about the things he has asserted knows, and likes relationships against for instance. So, I'd definitely want to be able to get useful information from requests and responses over HTTP against Facebook account identifiers. The transitive (Web) closure of such a facebook graph up to a certain recursion depth would be useful to have along a fb:knows predicate. This is an example of a graph link that is useful to a web agent capable of interpreting RDF content: a semantic web agent.
The hypertext analogy of coarse-grained Linked Data would basically be your current experience browsing Facebook content in your browser: you (for the most part) see updates regarding only the people you know alone, not everything that was said by anybody in the complete facebook dataset. However, the RDF people known by those you know, and RDF things described by friends of yours and their friends, are useful and worth an attempt to 'interpret' in order to determine (for instance) how to display them in the browser or other such entailments from description of content.