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Tuesday, March 13, 2007

An ecology of query languages 

Jon Udell's Interviews with Kingsley Idehen
Kingsley: Well, I don't know, you tell me. The semantic web gets kind of confusing because there's a lot of research content and some of the guys are real deep graph model geeks that put out a lot of content. But a lot of people don't look at it because it's already sort-of complex and people switch off without really getting to the best of what's really going on. A graph model, ideally, will allow you to explore almost all the comprehensible dimensions of the nodes in that network. So you can traverse that network in a myriad of different ways and it will give you much more flexibility than if you're confined to a tree, in effect, the difference between XQuery and SPARQL. I always see the difference between these two things as this. If you visualize nodes on a network, SPARQL is going to get you to the right node. Your journey to what you want is facilitated by SPARQL, and then XQuery can then take you deeper into this one node, which has specific data that the graph traversal is taking you to. You see what I mean here?

Jon: Since I haven't studied SPARQL at all yet, if you could make that a little more concrete with some sort of an example it would help.

Kingsley: Let's take a microformat as an example. HCard, or an hCalendar, is a well-formed format. In a sense, it's XML. You can locate the hCard in question, so if you had a collection of individuals who had full files on the network in the repository, it could be a graph of a social network or a group of people. Now, through that graph you could ultimately locate common interests. And eventually you may want to set up calendars but if the format of the calendar itself is well formed, with XQuery you can search a location, with XPath it's even more specific. Here you simply want to get to a node in the content and to get a value. Because the content is well formed you can traverse within the content, but XQuery doesn't help you find that content as effectively because in effect XQuery is really all about a hierarchical model.

. . .

Jon: You mentioned Spotlight earlier, and a lot of what you were just describing, in terms of having this very heterogeneous data store that can hold lots of different things, have a coherent way of querying across them and managing metadata in various flavors is, obviously, also, extremely interesting on the desktop. Spotlight is a desktop project, WinFS is going to be a desktop product. Although we have tended to think of this class of technology that you have been developing as server technology, we have desktop machines that can run it perfectly capably. That seems like a pretty interesting scenario.

Kingsley: Absolutely, I mean, Virtuoso, runs from my desktop, see, I have a very federated view of networking. If you look at Web2.0 today, we take the view that everything is going to be hosted somewhere. In a sense, we are looking at a centralized model with these new terminals that we call PCs with browsers talking to a centralized server. So we are networking, but networking is about many points that are able to communicate using different protocols. Client/server, peer-to-peer, you name it. My view is that what people really want to be able to do is, in some cases, run software on a desktop. Virtuoso is so small that of course you can run it on a desktop. Well, you know that anyway yourself, because you ran UserLand on the desktop, and in the beginning that was one of the real keys to its success.

Topics: RDF | Data2.0 | XQuery

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