Ganymede XML Pull Parser

Hi, folks.  I just became aware of XMLPULL through O'Reilly's XML.com site.

I implemented an XML Pull Parser on top of SAX in Java a couple of
years ago that appears to have many similarities to XMLPULL.  I do use
an XMLItem base class which I subclass for things like XMLCharData,
XMLElement, XMLError, XMLStartDocument, and so forth, rather than
having a single item type with a get_type() method, but it is
otherwise very similar.

Javadocs for my implementation can be found at

http://tools.arlut.utexas.edu/gash2/doc/javadoc/arlut/csd/Util/XMLReader.html

if anyone is interested in looking at it.

The API is broadly similar to XMLPULL, except that I return discrete
XMLItem objects, and provide a peek() method on the parser to support
non-consumptive examination, rather than providing all accessor
methods on the parser.  This is useful in that I can use my XMLItem
class and its subclasses to at any point extract a tree of descendents
if necessary, rather than sticking with a pure node-by-node parse
pull.  In this way, I have the advantage of retrieving a DOM-like
subtree at any time if that is most convenient for my code, without
having to pay a full DOM price for the full document.

In addition, I have a couple of minor convenience niceties which I'll
mention only for personal pride, you have obviously encountered and
made conscious choices about the same matters.

The first is that the Ganymede XMLReader will eat adjacent open and
close tags to provide a single element whose isEmpty() method will
return true.  I see that you provide a similar method, though I
believe code using XMLPULL will still need to eat the succeeding close
tag?

The second is that the Ganymede XMLReader can be configured to
silently consume, rather than report, any all-whitespace text blocks
between elements.

Finally, the Ganymede XMLReader's implementation is sort of nice, as
it is a threading adaptor between SAX and the XMLReader API.. there is
a circular buffer of fixed size in the XMLReader, and a background
thread which runs the SAX parser and accepts SAX events into the
XMLReader.  If the event consumer runs ahead of the SAX parser thread,
the peekNextItem() and getNextItem() methods on XMLReader will block,
and if the SAX parser runs ahead of the XMLItem consumer thread, the
SAX parser will block.  I wonder if you are doing something similar?

Anyway.  I'm quite happy to see others pushing forward with pull
parsers.. it seems crazy to have to use either a low-level SAX type
interface for anything significant, and it seems crazy to have to pay
a full DOM price for large documents.  Best of luck with XMLPULL.

 jon

-- 
-------------------------------------------------------------------------------
Jonathan Abbey 				              [email protected]
Applied Research Laboratories                 The University of Texas at Austin
Ganymede, a GPL'ed metadirectory for UNIX     http://www.arlut.utexas.edu/gash2

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