RE: Applicability of LDAP Content Sync to loosely coupled replica sets

At 06:36 PM 6/5/2003, Jeff Parham wrote:
>> >Is LDAP Content Sync intended to be applicable in this case?
>> 
>> Likely (but I'd have to think about it more).  I note that since
>> LDAP Sync supports both updates+present and update+delete
>> incremental synchronization mechanisms, if LCUP is applicable
>> then likely so is LDAP Sync.
>
>I'm not sure I agree there.  The key difference between LCUP and LDAP
>Content Sync is the ability to assert the "member objects" without
>forcing a reload.  The implication is that an incremental sync can force
>the client to drop previous knowledge, which seems to be the heart of
>the problematic example I illustrated.  LCUP doesn't have such a
>mechanism; knowledge is lost only on a full reload.

LCUP not only support an incremental sync mechanism (updates+deletes)
to drop previous knowledge, servers are to use those mechanism to ensure
eventual convergence.  If they cannot ensure eventual convergence, they
are to force a reload.

LDAP Sync provides two incremental sync mechanisms (updates+deletes
and update+present), but has the same eventual convergence requirements.

>If it were determined that dropping knowledge on incremental LDAP
>Content Sync was too problematic (I don't know if this is true -- just
>hypothetical) and dropped from the draft, then it seems to me that the
>result would essentially be the same as LCUP.  Is that an overly
>simplified viewpoint?

I think the WG long ago determined that not providing eventual
convergence was problematic.  To provide eventual convergence,
you not only need mechanism(s) to drop that knowledge, you need
guarantees that the mechanism(s) will be used appropriately to
ensure inconsistencies that might occur are transient.

Kurt