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From Simon Kitching <>
Subject Re: Digester and attribute matching?
Date Mon, 12 Apr 2004 22:09:20 GMT
On Mon, 2004-04-12 at 06:09, robert burrell donkin wrote:
> i've had a longer think about this, and i'm not really sure anymore 
> that there's any XPath engines that this would work for. the other 
> issue is that some XPath expressions really require the whole of the 
> document to work with. (but scott would probably know better than me if 
> this is feasible so if he's lurking, i'd be interested to hear his 
> opinions.)

I'm sure you're right about xpath requiring the whole doc in memory,
which certainly can't be done in Digester1.0. Personally, I'm fond of
the "light" sax-based approach.

> in terms of adding support for attribute matching, i'm a little 
> reluctant to consider modifying the matching string syntax but i 
> suppose that we could add a wrapper rule (even though it's not a very 
> elegant solution).

> the current design for Rules makes it easy to create new rules 
> implementations but is limited by the amount of information available 
> to the implementation. the string syntax passed into the call is the 
> limiting factor.

Yep. I have been thinking about some generic "conditional-support"
though. Perhaps we could say that any text within [] brackets in a
pattern is a condition. This doesn't affect which rules are selected,
but the condition part is then somehow evaluated as a filter on those
rules (maybe just passed literally to the rule so the rule can interpret
it and decide whether to fire or not?). This would be moderately
xpath-like. But I still think this is more a candidate for 2.0 than the
1.x series.

> this has set me wondering whether something like XSLT would be a cool 
> to map XML to objects. rather than templates, rules would be applied to 
> the products of XPath expressions. xml rules could probably be mined 
> but still would be a lot of work.

I've been thinking about xpath-like pattern support too. I've got a
"to-do" list for 2.0 (if there ever is one) and that is on it.

Rather than XPath/XSLT, though, I would look first at STX, which is the
sax-based equivalent of xslt (which as you note is really DOM-based). I
haven't looked in-depth at this, but it seems "copacetic".

There is more info on STX at



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