Re: [Vtd-xml-users] HowTo use Vtd for GML to Java Mapping?

[Tatu S. <cow...@ya...>]

--- Peter Neu <pet...@gm...> wrote:

> Hello,
> 
> someone on a different mailing list suggested vtd is
> a good tool for mapping
> GML to Java Objects. How is this done in detail?
> Are there any tutorials on this? 

Hmmh. This actually sounds like a strange piece of
advice, depending on what "good" means. VTD does offer
high performance for efficient tree-based access to
xml content. But it does not (and is not meant to I
think) offer any support for actual mapping between
xml and Java. That's what data binding (and/or
serialization) toolkits/libs offer. And on top of
that, there isn't any specific support for GML, and
likewise, that sounds like something to be done on
higher level tools.
VTD could of course be used as the underlying parser
component for such tools. I don't know if there are
such tools out there yet.

As to binding data to Java objects, JAXB 2.0 is widely
considered to be a good and reasonably fast library.
As far as I know, it currently supports just SAX and
StAX parsers under the hood. Since much of overhead is
at binding level (constructing java objects,
populating fileds), parser choice may not affect
overall performance that much.

So regarding goodness: if raw performance is the main
goal, using VTD might make sense. If so, you would NOT
want to map things to objects, but rather deal with
raw xml entities directly.
This would be a trade-off, and resulting code could
very well be hard to use or understand, so its
goodness would depend a lot on priorities.

-+ Tatu +-



 
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