standard attributes

[Ian Lister]

I defined a handful of standard attributes yesterday and put them up at
http://staff.dstc.com/ilister/attributes.html.

The only thing that's really causing me angst at the moment is the lack of
ability to nest tables of attributes again...  consider for example etrap,
which can send information about both the network host the notification is
about and the monitoring host that is sending the notification. In this
case it would be nice to have a notification like:

Trap: {
  Hostname: printer1.example.com
}
Agent: {
  Hostname: snmp.example.com
  Process-Id: 9432
}
...

That way you can subscribe to all notifications about a specific host (or
hosts in your domain) with "*.Hostname == 'host.example.com'" or similar.

Note that there's nothing to stop you sending a notification equivalent to
the above as:

Trap.Hostname: printer1.example.com
Agent.Hostname: snmp.example.com
Agent.Process-Id: 9432

..but you can't subscribe to a specific host (without enumerating every
possible prefix).

Similarly, presence requests list the requestor as `Requestor' to make the
role clear even though the same information could go just as well in a
(less meaningful but more general) `User' field.

I guess this is what more structured data representations like XML are
good for, but it seems to me that it's still well within the scope of
what Elvin should be...

Ian