Subject: RE: Is State-based LDUP needed?

From: "Timothy Hahn" <[email-masked]>
Date: Tue, 29 Jan 2002 08:49:07 -0500

Hi all,

Steven Legg wrote:

I think it boils down to two questions.

Q1: Do we insist that replication primitives are always sent in
CSN order per replica ID ?

Q2: Do we insist that superseded primitives are propagated anyway ?

My opinion on these two questions are:

Q1: I vote "yes" to this one.

Q2: I could go either way on this.  It would seem we would be "more 
correct, more of the time" if we insisted that superseded primitives are 
propagated - at the expense of a little more information being sent during 
replication sessions.  However, it would appear that LDUP will work either 
way (after all, "eventual consistency" is what is required).  Thus, I 
would allow this as an implementation choice - i.e. superseded primitives 
MAY (or MAY NOT) be propagated.  I also think that it is in the best 
interests of all involved if the update reconciliation procedures draft 
(or the update replication protocol draft) points out the issues involved 
if superseded primitives are NOT sent.  (It seems a shame that this 
analysis would only be documented in the mailing list archives).

Regards,
Tim Hahn

Internet: [email-masked]
Internal: Timothy Hahn/Endicott/IBM@IBMUS or IBMUSM00(HAHNT)
phone: 607.752.6388     tie-line: 8/852.6388
fax: 607.752.3681

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From: "Steven Legg" <[email-masked]>
Date: Wed, 30 Jan 2002 09:28:22 +1100

Tim,

> Q2: I could go either way on this.  It would seem we would be "more
correct,
> more of the time" if we insisted that superseded primitives are
propagated -
> at the expense of a little more information being sent during replication
> sessions.  However, it would appear that LDUP will work either way (after
> all, "eventual consistency" is what is required).  Thus, I would allow
this
> as an implementation choice - i.e. superseded primitives MAY (or MAY NOT)
be
> propagated.  I also think that it is in the best interests of all involved
if
> the update reconciliation procedures draft (or the update replication
> protocol draft) points out the issues involved if superseded primitives
are
> NOT sent.  (It seems a shame that this analysis would only be documented
in
> the mailing list archives).

I can expand the section in URP on superseded primitives to point out the
issues if the consensus on Q2 is "no". If the consensus is "yes" then I
will instead be taking out all the provisions for state-based
implementations.

Regards,
Steven