Hi Shane Below is a posting from David McCusker who is working on the backedn of Chandler. =============================================================== From: Rys (David) McCusker <david@treedragon.com> Subject: Re: repository access protocol Re: [Design] Knowing when you've read Tim Hoffman wrote:
Any hints as to how RDF will bu used in conjunction.
that is one of the things that makes database design hard. Specifically, jumping through that hoop is one of the degrees of difficulty making the problem harder to solve. Additional degrees of difficulty include things like: *make it network protocol centric *make it fast and scale very large *use existing technology *write custom code for optimization *let the application coders see Python interfaces *make the local case faster than their remote case *make a centralized authorization case work *make the decentralized P2P good and attractive but that's just a sample. As you can see, it's hard to do justice to every priority. In many cases, we cannot give full-blown support to every iota of associated features one might think of in conjunction with one of the priority items. So we need some restrictions. In the case of RDF, we want to support it, and yet we do not want to compromise any of the priorities in pursuit of every feature folks associate with RDF usage. so our solution is that and RDF style application can see any of our content as if it was native to RDF. In other words, there is a mapping from our content to RDF. So you can get our content exported to RDF, among other things. Even more than this, some of Chandler application code wants to use RDF centric schema systems, with direct expression of this met information available at runtime. Katie has proposed a good an interesting system we will used to represent RDF meta information through python interfaces, by putting this information into classes, so RDF reflection features are visible as python APIs. However, consider some random feature of another RDF environment or application, call his feature X. we might not support X in Chandler -- at least, there might be no efficient way to do it, and we won't care. this means we do not aim to do every kind of RDF feature well in Chandler. We only aim to let the data we support the view in RDF terms. So there is a mapping in one direction outward to RDF, but there is not always a mapping the other way inward from RDF.
ie will RDF be used to map/find/query things in the repository?
we had not considered to using RDF specific query language so far in discussions. The repository access protocol will support more than one query language, and provide means to ask which one is supported in a given server. So in principle, a RAP server might use RDF in a query language and advertise this in the protocol dynamically. on the topic of query languages, we are not much further along than committing to more than one query language selectable dynamically at runtime.
and would this map to RAP access patterns ?
I imagine it's possible to implement some kind of RDF system which is implemented in terms of RAP, because RDF is notorious for making no guarantees about performance, so one might iterate over every data item in a database in order to satisfy an RDF query.
(probably not using the correct terminology here)
I'm not very particular about fashionable jargon as long as I understand what you mean. I prefer the informal approach to describing things anyway. -- Rys _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ Open Source Applications Foundation "Design" mailing list http://lists.osafoundation.org/mailman/listinfo/design On Fri, 2003-02-21 at 10:30, Shane Hathaway wrote:
On 02/20/2003 09:06 PM, Tim Hoffman wrote:
In case your not aware Chandler OSAfoundation is basing their new PIM on RDF/ZODB/Python etc...
if you haven't already it might be worth having a look at how they see RDF fitting into the picture.
Wow, that's exactly what I was looking for. I guess I'll find out more when they open up their CVS. I hope it's soon. If they've had any difficulty persisting ZODB objects to RDF, I bet I could help them.
Shane
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