This is an excerpt of something I wrote on the #webapps IRC channel:
<arve> hm
<arve> I have some exploratory work here (not going into details)
<arve> let's just say that <param > for feature isn't enough
<arve> but an example is actually Opera's own Unite
<arve> (looking a bit further, though)
<arve> let's say I wanted to spawn two workers, each with their own web
service
<arve> simply speaking, I can't
<arve> currently, all I can do is:
<arve> <feature name="http://xmlns.opera.com/webserver">
<arve> <param name="type" value="service" />
<arve> <param name="servicepath" value="foo" />
<arve> </feature>
The problem is roughly that the param key-value pair is insufficient when
a <feature> needs to both specify and configure multiple resources, such
as one Opera Unite widget configuring two different web services. The
example above could only ever load one single service per widget (and it
would be what's specified in the widget's <content> element, to boot). A
widget which wanted to configure one document per widget would need to
nest the <param>'s in something.
--
Arve Bersvendsen
Opera Software ASA, http://www.opera.com/