Re: [xml] sax2 interface and parsing on the fly

On Mon, Apr 12, 2004 at 07:37:27PM +0200, aliban gmx net wrote:
for my sparetime project of the last 0.75 year i was building a XMPP 
lib for usage on different platforms. it is not finished yet but 
nearly done.
For the stream analysation I wrote some kind of stream readed that is 
in fact a sax interface that i randomly fed with new buffer 
containing the new received elements (<message/> <presence/>)
yesterday i downloaded a new build of libxml2 (windows binaries of 
I noticed that my lib did not behave as expected.
in fact the startElement() function is not called anymore.
whatever when i disconnect from xmpp server (the server sends a 
</stream:stream> then!) the function gets called and all the data is 
parsed then...

  You are generalizing on a small test case, the push parsing is
atill done on the fly, the change is that it may buffer data.

Therefor my current code seems not to execute parsing anymore. i 
don't know why but there might be two explainations:

1. you mutated the libxml2 sax2 parser to something like xmlreader 
(and this can not parse xml on the fly anymore)
2. you changed the behaviour of some function that in earlier version 
caused the parser to parse. Probably xmlParseChunk()

It would be great if you can help me and it would be even more great 
if you wont tell me that libxml2 (sax2) will not be able to parse on 
the fly in future anymore.

This is a consequence of a real bug fix:

  when pushing data the push parser has to find if a start element ends.
it was doing so by looking for < and > from the end of the buffer provided.
To garantee synchronous evaluation like you ask for, it would force the push
front-end to scan the buffer *fully* to be sure there is no evaluation
error on the start/end tag parsing boundaries. This is expensive, and
most applications do not need it.
  This is a trade off. Another API could be added for your need forcing
to flush the current available data.
  It is not a matter of parsing on the fly, it is a matter of expectations
put on top of the APIs that I never garanteed before. Adding the extra
flush API is possible, it is not my top priority. It's all about
xmlParseGetLasts() and xmlParseTryOrFinish() in parser.c


Daniel Veillard      | Red Hat Network
veillard redhat com  | libxml GNOME XML XSLT toolkit | Rpmfind RPM search engine

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