Client update protocol

Hello all,

I recently read over the LCUP document and this text looks very good 
for DIT synchronization.  What I am looking for is some type of "event" 
mechanism to trigger a client to connect/bind and initiate LCUP.  This 
would require the directory server to have knowledge of "who" is 
interested in being notified of DIT updates.  I may have 500,000 
clients for a directory, and I would prefer not to have to have the 
clients poll the server.  If a particular LCUP context is modified, I 
would like some type of async notification sent to interested parties.  
  Most of the work of actually synchronizing the DIT is covered by the 
LCUP document, I just need the clients to be notified "when" to perform 
LCUP. Ideally, the trigger mechanism would be some type of lightweight, 
connectionless notification, similar to an SNMP trap but more specific.

There is activity going on with global, scalable event notification 
architectures that is not specific to any IETF work, and we are looking 
into this.  However, I wanted to make sure I understand the taxonomy of 
any and all work related to solving this type of problem.

If there is work going on in this area in this, or another working 
group, I would appreciate any and all pointers, or other comments.

Thanks in advance,
Randy