[OAI-implementers] Resumption Token usage for recovery question

Alan Kent ajk@mds.rmit.edu.au
Wed, 13 Feb 2002 14:20:31 +1100

On Tue, Feb 12, 2002 at 08:37:10PM -0500, Xiaoming Liu wrote:
> In current implementation, whenever a network failure happends, the
> harvester may restart from the last successful "resumptionToken", if it's
> lucky and the "resumptionToken" is still valid, everything is fine.
> Otherwise it may have to harvest everything again. Of course, the
> harvester may choose to harvest by date/set, it certainly will save the
> finished part.

Are resumptionTokens therefore guaranteed to be different for each
chunk? (I cannot find that in the spec). I thought OAI allowed a
server to reuse the same resumptionToken for an original request
and followup requests. That is, the resumption token could identify
an original request, but not which incomplete-list of records from
that request to return.

If OAI does not guarantee a distinct resumption token per request,
then its not safe to use them more than once. If a unique token is
guaranteed per request, then yes, I guess they could be used to
recover (if you attempt recovery immediately - before the expiry
on the token runs out).

Are resumptionToken's implicitly assumed to be different for each
incomplete-sublist of a complete-list?