Re: DOM vs JDOM

[Uche Ogbuji <uche.ogbuji@fourthought.com>]

> > > There is nothing that requires a DOM tree to be held in memory other
> > > than the DOM implementation itself.  Lazy DOMs allow you to
> > > incrementally retrieve and traverse DOM trees, I believe the Xerces
> > > project was working on such a beast, and the dbXML DOM is partially a
> > > lazy DOM.
> >
> >Yep.  4Suite's DbDom is also a lazy DOM.  I agree that the claims quoted
> >from the article are disingenuous.
>
> Is it not true, however, that for applications such
> as XSLT, almost all of the DOM would end up loaded in
> memory?
>
> In my understanding, lazy DOMs only save memory if
> many of the nodes are not accessed at all.
>
> Is this the case?

No.  For instance, DbDOM is based on an ODMG object database
implementation.  The storage manager implements a caching scheme which
allows nodes to be aged and rotated out.

Cache management is quite a difficult area, but quite established, so I'd
bet most persistent DOMs have such swapping schemes.

-- 
Uche Ogbuji                               Principal Consultant
uche.ogbuji@fourthought.com               +1 303 583 9900 x 101
Fourthought, Inc.                         http://Fourthought.com
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