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From Michael Homeijer <M.Homei...@devote.nl>
Subject RE: xmldb logicsheet (XMLDBTransformer is a great start)
Date Tue, 12 Feb 2002 11:08:53 GMT
Have a look at the XMLDBtransformer in scratchpad, it could be easier to add
your functionality there.

Additional functionality for the XMLDBTransformer could be:
- resolving nested xml queries and/or structures (ie. get the collection and
then get a document)
- adding stuff dbxml provides at the command line, ie. listing, adding,
removing and querying collections

To do this two changes have to be made to the transformer:
1. implementing it in a way that commands can easily be added to it. (How
about innerclasses that handle a command?)
2. you should be able to use results from a query or a command in the next
query.

HTH,
Michael Homeijer

> -----Original Message-----
> From: Martin Holz [mailto:holz@fiz-chemie.de]
> Sent: dinsdag 12 februari 2002 12:05
> To: cocoon-users@xml.apache.org
> Subject: Re: xmldb logicsheet ?
> 
> 
> Hi,
> 
> Gianugo Rabellino wrote:
> 
> > Guys,
> >
> > please *don't* use the XMLDB generators. They are going to 
> be deprecated
> > RSN, since they are replaced by the much more powerful Source
> > abstraction that allows to use plain XMLDB URIs to retrieve 
> documents
> > and, yes :), XPath-query the collections :)
> >
> > Usage is straightforward: put the correct DB configuration in
> > cocoon.xconf and use xmldb:// URLs wherever you want in the 
> sitemap :)
> >
> > If you are willing to do XPath queries all you need is to use an
> > xpointerish syntax such as:
> >
> > xmldb:xindice://my.host.name/my/collection/#//my/xpath[@query]
> >
> > Please also note that for the brave ones there is also an 
> ongoing XMLDB
> > transformer worth noticing in scratchpad.
> >
> > HTH,
> 
> I see one problem with the source concept, if you are 
> retrieveing lots of 
> resources from the same collection. There are three steps to
> get a resource from xindice;
> 
> 1) register database
> 2) get collection
> 3) get document
> 
> Typical performance numbers are: 
> 1) Need  158.0 ms for Database.
> 2) Need 1962.0 ms for Collection.  
> 3) Need 294.0 ms for Document.
> 
> Time for 1) drops dramatically after the first call.
> Time for 3) is unavoidable. Time for creating a collection 
> drops too, if you 
> call it more than once, but is still high. So you want to 
> keep the collection 
> open, if you need to get documents  from this collection  often.  
> 
> You could configure a generator  to cache a collection.
> That does not work with current implementation,  but it would 
> be straight 
> forward to add.  I can't see, how to add this capability to 
> the source URL.
> 
> 
> Regards 
> 	Martin
> 
> --
> Martin Holz  <holz@fiz-chemie.de>  phone: 0049-30-39977 218 
> FIZ CHEMIE BERLIN
> 
> 
> 
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