Replication for small-bandwidth, mobile systems

[jan@pki-labor.de]

Hello all,

we're challenged with a PKI scenario with multiple CAs (Certification  
Authorities) publishing into multiple directories. Each CA has its own  
distinct namespace (=DIT) and the directories shall be Muli-Master  
replicated. So far, I think this can be handled via syncrepl.

Now I'm looking for a possibility to replicate (push) certain  
directory contents (e.g. revocation list updates from the CAs) to  
mobile systems which are connected via low bandwidth media (some kBPS  
like slow Modems, which also is already in use for other applications)  
and the connections are not always available (e.g. client out of radio  
reachability). As far as I understood several documents on syncrepl,  
it is not really useful on low bandwidth connections. This push  
service should therefore compress data or at least only transfer the  
differences.

Is there a standardized protocol or other mechanism to accomplish that?
If not, is there a way to trigger something when updates are coming in  
via replication? We would then think of using/building a special  
transfer mechanism that does the job.

Thanks in advance for any hint!

Best regards,
Jan