[XML-SIG] Metadata in XBEL

[Ross Burton]

Hi,

I am involved in adding support for XBEL to Galeon, the GNOME Mozilla
Gecko based browser.  Initial export is working, but there are several
issues related to the metadata elements which I would like some
clarification about.

The specification for metadata is vague, <metadata> elements have a
"owner" attribute which should be a URI. But what forms of metadata are
valid? The DTD implies that there can be no children of metadata
elements (the content is EMPTY).

Currently Galeon-specific attributes are exported as follows:

<site ...>
  <info>
    <metadata owner="http://galeon.sourceforge.net/pixmap">
        /home/users/ross/pictures/slashdot.png
    </metadata>
  </info>
</site>

It does seem that the DTD is in error as requiring all metadata to be in
the owner attribute is rather limiting.  But what content is allowed as
children of the metadata element? Just text? Or could the content of a
metadata element be a free-form XML tree?  For example:

<site ...>
  <info>
    <metadata owner="http://galeon.sourceforge.net">
      <pixmap>/home/users/ross/pictures/slashdot.org</pixmap>
      <toolbar>true</toolbar>
    </metadata>
  </info>
</site>

This, although allowing more free-form data, is heavier for the
application. We intent to be "polite" to XBEL data and store any unknown
metadata so that it can be written out again - if only text is allowed
this is trivial, otherwise tree fragments have to be stored.

I hope this can be cleared up,
Regards,
Ross Burton