- From: Danny Ayers <danny.ayers@gmail.com>
- Date: Fri, 24 Mar 2006 14:13:03 +0100
- To: "Semantic Web" <semantic-web@w3.org>
- Cc: public-semweb-ui@w3.org, "Adam Green" <adam@darwinianweb.com>, "Shelley Powers" <shelleyp@burningbird.net>
Grazr [1] is a very nice little in-browser UI for hierarchical navigation of data on the Web. It's not hard to imagine it being a very useful tool for browsing information on the Semantic Web. The UI isn't actually all that far from TimBL's Tabulator [2]. But the question is (as asked by Adam Green in offlist email, paraphrased) : where is the data? Grazr currently works with the OPML and RSS formats. OPML is a format for link/text hierarchies, RSS in this context is a simple structural wrapper around HTML content. Both feature a little bit of metadata. In Grazr, OPML provides the navigable trees, links or RSS 2.0 content form the leaf nodes. (These formats suffer from various technical flaws, and carry considerable political baggage but that's not really relevant here). The way Adam posed the question implied that Grazr might be modified to support SemWeb material. So what data is available online which could be usefully navigated in such a tool? In general I imagine cross-site nav could come from rdf:seeAlso's. Leaf nodes could as now be linked HTML pages or literals intended for human consumption: dc:description and the like. But there must surely be a lot more domain-specific material around which would work here: one that springs to mind is following foaf:knows paths from person to person. (Note TimBL's "Backward and Forward links in RDF just as important" [3]) Elsewhere I've suggested (heh, slightly controversially* [4]) that it would be low-cost for Semantic Web systems to output data in simplistic quasi-XML formats like RSS and OPML, to take advantage of existing tools like Grazr and the numerous feed readers. Mountain and Mohammed, take the SemWeb to where a lot of UI-building is happening. Collateral salvage being that another dev community gets exposed to SemWeb tech. (I believe RSS/Atom aggregators have huge potential as SemWeb UIs, but that's a story for another day ;-) But even if you avoid these particular formats like the plague, their general shape may show a useful way of approaching the problem of the impedance mismatch between RDF data and most user interfaces. OPML and RSS are very limited in what they can express, it's all oriented to human-readable content for a start (rather than data in general). But the constraints of these formats match the constraints of an awful lot of tools out there. So if you figure out suitable ways to squash RDF/OWL data down to these formats (or something similar but better spec'd - the XOXO microformat is nearby [5]), that's 95% of the solution for exploiting any labelled-hierarchy style UI. Feed "grazing" is a nice analogy - maybe the RDF processing/flattening is "chewing the cud". Cheers, Danny. * I was tempted to rattle cages a little harder, it wouldn't take that much effort to set up a fairly generic online bridging service. Read the RDF at a given URI into a model, use SPARQL+XSLT to expose it as OPML & RSS, with any embedded URIs (of other RDF sources) prefixed to make them query parameters, so any GETs (from the OPML/RSS tool) will be filtered through the service. But if I exposed Shelley's carefully crafted RDF as OPML, I'd probably be wise to get a new identity, and I don't want to mint a new URI so soon after giving myself one... [1] http://www.grazr.com/ [2] http://www.w3.org/2005/ajar/Help.html [3] http://dig.csail.mit.edu/breadcrumbs/node/72 [4] http://weblog.burningbird.net/2006/03/18/think-of-the-children/ [5] http://microformats.org/wiki/xoxo -- http://dannyayers.com
Received on Friday, 24 March 2006 13:13:17 UTC