How does SAX-Validation work?

[Matthias Langbein]

Hi,

I wondered whether anybody knows how XML-Schema-Validation with the
common SAX-Parsers work. Do they require to build a DOM-Tree before
processing and validate, or do they handle validation on the fly?

Thx, Langi

 

[Joseph Kesselman]

I wondered whether anybody knows how XML-Schema-Validation with the
common SAX-Parsers work. Do they require to build a DOM-Tree before
processing and validate, or do they handle validation on the fly?

I would assume SAX parsers validate on the fly, essentially by running a
finite state machine based on the schema. Note that this means you may
get halfway through processing the document before you find out that it
doesn't validate; depending on what you're doing with the document that
may mean you need to think about database-style "commit phases" or
reversable operations. (Of course that issue arises any time you've got
data coming in which may be interrupted partway through, including
normal communications traffic.)