[OAI-implementers] Better resumption mechanism - more importa nt than ever!

Alan Kent ajk@mds.rmit.edu.au
Thu, 7 Mar 2002 10:29:50 +1100

On Wed, Mar 06, 2002 at 11:33:53AM -0800, Walter Underwood wrote:
> If a request has two time bounds, both in the past, then the protocol
> should be idempotent. The protocol would need to outlaw back-dated
> changes (put in this record today and date it yesterday).

Is this true? (If so it will change my *possible* implementation ;-)
I agree that new records being added should never be back dated,
but what if an old record is updated?

For example, if a record is inserted in May then updated in July and I
do a query from Jan to June (ie, including May but not July), then
should I get back the old May copy of the record? Or because the record
has been updated (in July), does that mean it is valid for me no longer
to return the May version of my record and only return the July
version (when appropriate)?

If I don't need to return the May version, the the protocol would not
be idempotent. This was my current understanding from old postings on
the list. If I must/should return the May version of the record still,
then I will need to rethink how I implement my harvester (which might
turn into an aggregator). Currently I keep the most recent record
version and throw away old versions (by doing updates on the old

Doing a search service would also be different because I doubt people
want to do a search and find the old version of the record.