Harddisk queueing seems necessary, because it is very important that every message could be restored from disk if the server crashes.
I think it is not this easy than i have thought at beginning as the FileRecorder does store raw MessageUnit but not the MessageUnitWrapper with all java references from the xmlBlaster core.
I have to go and play soccer now, i will think about your issue ... hopefully we find a smart solution.
regards,
Marcel