Re: sax or dom in XSLT procesing ?

>some of question is if
>xslt processor (i use xalan) build full tree of data before start
>transform ?

Depends on the processor and how you've configured it.

If you're reading from SAX, Xalan normally does build a full DTM model of 
the source document immediately. It can be told to build that model 
incrementally, as the stylesheet/xpath actually calls for nodes; see 
Xalan's documentation for a discussion of the trade-offs in that approach.

If you're reading from DOM, Xalan incrementally builds a DTM "proxy" to 
access your DOM. This is lighter-weight than a complete DTM would be. It 
still doesn't run as quickly as we'd like and burns more memory than we'd 
like, and we're working on improvements to that section of the processor.

See also archives of the Xalan mailing list, searching for the key words 
"streaming", "pruning", and "filtering", to see past design discussion of 
what we're doing now and some of what we're investigating as future 
refinements to the model.


Summary: If you already have a DOM in memory, use a DOMSource to pass that 
to Xalan and let us Do The Right Thing. If you have some other type of 
model in memory, your best bet is currently to serialize it to SAX and 
hand us a SAXSource. If you don't already have a model in memory, your 
best bet is to obtain/generate a SAX stream, wrap that in a SAXSource, and 
let us read that.

______________________________________
Joe Kesselman  / IBM Research


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