XOM API for Processing XML with Java

[Wolfgang Hoschek <wolfgang.hoschek AT mac.com>]

On Oct 22, 2006, at 3:50 PM, lneves wrote:

> Wolfgang Hoschek wrote:
>
> > But to put the discussion into perspective: Any reasonable higher
> > level protocol defines a generic framing mechanism, thereby omitting
> > the need to think about XML specific framing anyway.
>
> Unfortunately there are some protocols that are not reasonable. XMPP 
> [1] is one them.
> It's basically a stream of XML fragments dumped into a socket and  
> it's up to the
> angle brackets to do the framing. What is your suggestion to deal  
> with something like
> XMPP?


XMPP basically says a (TCP) connection is used to transport a single  
XMPP stream, which is an open-ended XML document: the document has a  
root element that can have arbitrarily many child elements. During  
the life of the stream, the entity that initiated it can send an  
unbounded number of XML elements over the stream. Errors (e.g. not  
wellformed XML) are unrecoverable, implying closing the connection.  
Presumably errors are unrecoverable because XMPP is lacking a  
sensible framing mechanism, as you point out.

If the question is how to read and write an XMPP stream with XOM:

- for writing: use a StreamingSerializer [1].
- for reading: use the XOM NodeFactory of a StreamingPathFilter [2]  
with a "/*/*" path and any XOM Builder. A user defined handler will  
be called for each XMPP stanza and given the corresponding XOM fragment.

[1] http://dsd.lbl.gov/nux/api/nux/xom/io/StreamingSerializer.html
[2] http://dsd.lbl.gov/nux/api/nux/xom/xquery/StreamingPathFilter.html

Wolfgang.