- From: Kendall Clark <kendall@monkeyfist.com>
- Date: Tue, 15 Mar 2005 08:50:49 -0500
- To: "Seaborne, Andy" <andy.seaborne@hp.com>
- Cc: DAWG Mailing List <public-rdf-dawg@w3.org>
On Tue, Mar 15, 2005 at 01:38:44PM +0000, Seaborne, Andy wrote: > It's the confusion mainly. I hadn't read it as RDF dataset manipulation at > all. I'm now unclear as to what state the server is managing. "The server" answers queries against various RDF graphs. We call the graph or graphs against which a query is executed "the RDF dataset". In our applications at the lab, we often, from a remote client, want to create a new graph, which is to be added to "the RDF dataset" -- that is, it can on subsequent requests be one of the graphs subsequent queries are executed against. Likewise, sometimes we want to remove a graph or graphs from "the RDF dataset". For example, we use graphs to track the source of assertions made in those graphs. In a shared knowledge app, for example, often each user has a graph which contains the assertions made by that user (sometimes a graph represents a "speech act by a single speaker" -- that is, http://foo.bar/kendall22.rdf may represent the claims made by speaker S at time T, while http://foo.bar/kendall929.rdf may represent the claims made by speaker S at time T2). But claims can be retracted as well as asserted. In our case this is equivalent to deleting a graph or graphs. We'd like our clients to be able to signal our servers that a graph should be "dropped". (What "dropping a graph" constitutes is in some sense application-specific. There are at least two senses: the strong sense means the "RDF graph resource" is deleted. In a weaker sense, it just means that it's no longer one of the graphs that the server will answer queries against. We can be agnostic as to this distinction, I think, since they both imply that the server will no longer answer queries against a graph after it's been dropped -- or, to be very precise, at least not until or unless it's re-asserted.) > Manipulating a dataset seems to be more for a distributed application > (designed together) or for the publisher than making information available > on the web but I'll wait until I have a better picture of what's going on > before commenting. Hmm, I don't think I agree with this. We have several rather ordinary "semweb" applications where this functionality is useful, including our ontology editor, photo annotation tool, and our portal toolkit (which has been used in spy stuff, but also life sciences and space sciences apps). For us, anyway, dropGraph(http://foo.bar/kendall22.rdf) is equivalent to removing an interesting class of assertions from a knowledge base. Kendall PS--I felt encouraged to add these graph creation & deletion interfaces because (1) WSDL makes that very easy to do; (2) WSDL gives us a way for servers to communicate clearly to requesters about which interface(s) they support; and (3) we had a fruitful conversation in Boston about "the update problem", which I thought suggested that creating and deleting graphs was nicely orthogonal from creating and deleting *triples*, which strikes me as much more difficult.
Received on Tuesday, 15 March 2005 13:54:33 UTC