- From: Tom Adams <tom@tucanatech.com>
- Date: Tue, 23 Nov 2004 09:51:15 -0500
- To: DAWG list <public-rdf-dawg@w3.org>
>> Here is a summary of the discussions that we've been having internally >> on permanent model names > > There's that "model" word again... would you please rephrase > in Feb 2004 terminology? Do you mean RDF Graph? > http://www.w3.org/TR/2004/REC-rdf-concepts-20040210/#dfn-rdf-graph No, I mean model, that's what we call them ;) Yes, I mean a set of triples. Models in TKS/Kowari are mutable containers composed of RDF graphs (Simon: Is that a fair assessment?). > or do you mean something mutable? (Graphs are immutable syntactic > things, like numerals and strings). Yes, models in TKS/Kowari are mutable. >> <snip/> >> o Models should to be named in order to be able to reference them in >> queries; >> o Names should be independent of the method of access (i.e. protocol); > > Not if you mean "model" in the sense of "mutable store" ala > "file" or "document". True, when the only handle you have is a URL (to a file say), then that's fine. However, with resolvers, we're able to express a file or data store as an RDF graph (i.e. a TKS/Kowari model) and make it available to the query engine. So, to confuse the point, you could represent a file containing RDF/XML as a file and query it as such, or an MP3 file could fronted by a resolver and queried as a graph (i.e. TKS/Kowari model). > And if you mean something immutable, it seems a lot simpler to use > a hash. > >> o Names should be independent of the hostname of the machine they're >> stored on; > > Yes, but DNS names meet that criterium. (hint: which machine > is www.w3.org? Which continent, for that matter? A: many.) True. >> <snip/> >> For example: >> >> rmi://knuth.bne.tucanatech.com/server1#foo >> beep://knuth.bne.tucanatech.com/server1#foo >> >> This confuses two distinct properties of a model: the model name and >> how to access the model. > > I'm not at all sure that's the case. Let's take the first example. When the model is referenced in a query: select $x $y $z from <rmi://knuth.bne.tucanatech.com/server1#foo> where $x $y $z ; The model "name" is effectively "rmi://knuth.bne.tucanatech.com/server1#foo". What this is currently saying is: o That there exists a model called "foo"; o The model lives in the TKS/Kowari server "server1"; o The TKS/Kowari server is located on the host "knuth.bne.tucanatech.com"; and o You use RMI to get to it. I think that all these except the model name do not need to be in the name. If someone wants to put this information into a name, fine, but currently we're forcing them to, and not allowing any choice. >> TKS/Kowari stores model information in a special place called the >> system model. This model stores information such as the type of a >> model, e.g. a full text model or a native "Tucana" model. As far as >> Tucana is concerned, we want to solve the problems outlined above, but >> also allow for backwards compatibility with existing queries. As we >> want to be able to store model information in RDF, and make statements >> about models, we need to use a resource to reference a model. We're >> considering using URNs to name models. >> >> Our proposed new model naming scheme would use the system model to >> contain information about the models including their name and how to >> access them. So for example we could be storing the following triples: >> >> <urn:slashdot-org:news-rss> <access> <http://slashdot.org/news.rss> >> <urn:slashdot-org:news-rss> <updateEvery> <5 minutes> >> <urn:knuth-com:server1:foo> <access> <rmi://localhost/server1> >> <urn:tucanatech-com:server1:hr> <access> <rmi://localhost/server1> > > Why not > <http://example/someplace#slashdotNews> <access> ... > ? No reason, that's just the scheme someone came up with a while ago. I don't know if it's still valid, but no one has told me otherwise, so I assume it is. >> The first model <urn:slashdot-org:news.rss> is an remote model that >> you >> access using the given URL (http://slashdot.org/news.rss) and you >> update it every 5 minutes. > > Aha... so you _do_ mean something mutable. Sure do! >> <snip/> > Please take a look at > > The Myth of Names and Addresses > http://www.w3.org/DesignIssues/NameMyth > > and see if you still think urn: helps at all. Hmmm not directly, but I see the point. I shall bring it up with the guys next I speak with them. Thanks for the comments!!! Cheers, Tom -- Tom Adams | Tucana Technologies, Inc. Support Engineer | Office: +1 703 871 5312 tom@tucanatech.com | Cell: +1 571 594 0847 http://www.tucanatech.com | Fax: +1 877 290 6687 ------------------------------------------------------
Received on Tuesday, 23 November 2004 14:51:22 UTC