Re: throwing SAX Exceptions from SAX Filters

["Simon St.Laurent" <simonstl@simonstl.com>]

On 12 Jul 2001 12:22:38 -0700, David Brownell wrote:
> "Michael Brennan" <Michael_Brennan@allegis.com>
> 
> > If this would only be used within the context of a SAX filter and nowhere
> > else, I'd say just throw a SAXException. That's what I typically do.
> 
> Actually, I try to avoid throwing a SAXException of any kind directly.
> I prefer to call the ErrorHandler and let that decide what to do.  It's not
> always the case that you want to treat all errors as fatal.

In this case, it probably is the case.  If you can't construct the
regular expressions processor, you're not going to have any meaningful
output.

> In the example of this Fragmentations filter, wouldn't many users just want
> to validate docs and report problems so they can be fixed in a batch?  Many
> application level errors can reasonably be treated as validity errors, though
> sometimes you might want to have more granularity than the three types of
> error which ErrorHandler defines.

That's the next case I need to deal with - things like bad patterns
which might disrupt some rules while leaving others intact.

> > SAXExceptions can conveniently carry another exception, so the application
> > can determine what the real original exception was. I tend to leverage that
> > pretty heavily. In fact, I always through a SAXParseException so that the
> > application can get the Locator info and determine where in the XML source
> > the error occurred. That's pretty useful for debugging.
> 
> Yep, I strongly encourage folk to use the Locator when reporting exceptions.
> Essentially all significant SAX parsers provide one (though strictly speaking,
> it's optional).  Good diagnostics are essential, and the SAXParseException
> can be constructed with both the Locator and any "root cause" Exception.

Most of the exceptions I'm having problems with stem from the rules
file, not the target documents - those I expect will be some kind of
extension to SAX exceptions, and Locators will be a lot more meaningful
there.

> If the SAX2 event handler is detecting a context-specific problem it really
> ought to get associated with every problem report ... :)

Someday!  I just have to get that far....