XSE idea

Here is Daniel clarifies things about XSE:

XSE is not about querying with an specific expression language/format (i.e. XPath or SXPath). XSE is just a mechanism for encapsulating state machines checking for matches against a given expression. What the expression looks like depends on the factory that creates the strategy.
Therefore, the factories I showed (i.e. my RootedPath and RelativePath) are only encapsulating code generation for different FSMs, based on an expression language that fits a need. Therefore, I could even create a factory implementing SXPath and still remain in Xml Streaming Events land.

The XSE idea is to provide a callback metaphor to XML parsing, instead of the pull-model of the XmlReader. In fact, it's a sort of evolution over SAX, in that at the same time it offers both worlds: pull model directly from the XseReader, events-based for your registered handlers.