on (1) I've had a look at the OASIS tests. I think the jaxen tests are actually closer to being something that would work cross-platform. It ought to be possible to generate tests identical to the applicable oasis ones from jaxen-like ones, but I don't think its entirely automatable the other way around?

Yes, I've read a bunch of those papers. It actually turns out only a handful are directly applicable, because of the jaxen usage model: ie we support multiple object models via navigators, and the api doesn't allow for pre-indexing a document.

eg a problem with optimising with navigators is knowing whether you can cache partial results. Tto cache you need to know if you're at the same node: the DOM doesn't support equals() so Jaxen uses == for node tests, and theres bugs in jira from people who wanted support for OM's that don't support that either! Although, I reckon this problem could and should be solved by adding an 'equals(Node blah)' to the navigators.

The pre-indexing thing comes up a lot in the papers (I notice there's a bunch of VLDB papers there, that tends to be their focus). Its important for in-database trees, but is it a win for smaller in-memory documents? I reckon in-database trees are pretty much out of scope for jaxen, especially once vendors start to build xpath2/xquery support into the DB.

There's a lot of good stuff there though. However jaxen's not even trivially optimised right now: it pulls back all nodes when in a boolean context, variables & functions are bound late rather than early, and so on. Here's how I think the road ahead could realistically look (but be warned I have no say in this!)

- 1.1 release. (Now) Bugfixes. Navigator.parseXPath() deprecated. - 1.2 release. Lazy list optimisation, no API changes required. - 2.0 release. Break apis to allow for better performing usage: JAXP 1.3 compliance. Navigator.equals(node) added. Navigator.parseXPath() removed. - 2.1 release. Rewrite of the xpath engine. The paper I'd thought fitted jaxen best was this one: http://www.dbai.tuwien.ac.at/staff/koch/download/icde2003.pdf

On 15 Nov 2004 21:27:22 -0000, ryan...@bloglines.com <ryan...@bloglines.com> wrote: