[libvirt] xen driver & events

I'm looking into implementing emitting events from the xen driver, and I've run into a bit of a snag that I would like to discuss I've attached an old version of my patch for reference. However - from past discussions, I know that there was a desire to keep the xen driver stateless. However, given the semantics of xenstore watches, and events, I'm not sure I can see a way to preserve this. Lets take the case of creating a new domain: XenStore gives us the functionaliity to put a watch on the special xenstore key @introduceDomain. However, when the watch fires - I see no mechanism of determining which domain has been introduced. The only mechanism I can find is to maintain a list of domains, and keep this up to date with events. So I'm wondering if anyone has any ideas, or if this will introduce unwanted, but necessary state into the driver? Ben