[OAI-implementers] Resumption Token Expiring.

Michael Nelson mln@cs.odu.edu
Fri, 6 Dec 2002 16:44:28 -0500 (EST)

On Fri, 6 Dec 2002, Jose Blanco wrote:

> I am trying to avoid using a database to determine if our resumptionToken
> has expired, and I am finding it impossible. A resumption Token may appear
> perfectly valid, but because portion our data may have been updated, it
> really is not valid.  It is very difficult to determine when the data is
> updated, unless this information where kept in a database.  Fortunately the
> updates are infrequent, but none the less this situation can occur.  Can any
> of you share your thoughts on this?

I'm not sure I fully understand what you mean when you say "avoid using a
database"...  are you unable to store any info at your repository?  could
you not store the date of the latest update (t)?

for example, if your expanded your rT to include the time of the latest
update (tL) from when the first "List" verb was recvd, you could check
each time you recv the rT to see if t > tL, and if so, you could
invalidate the rT.

if for some reason you can't locally store t, you could compute each time
by doing a ListIdentifiers verb to yourself using tL as the value for the
"from" argument. if you get "noRecordsMatch", then your rT is still valid,
otherwise it is invalid.  

I hope I've understood your question...



> Thanks,
> Jose
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Michael L. Nelson mln@cs.odu.edu http://www.cs.odu.edu/~mln/
Dept of Computer Science, Old Dominion University, Norfolk VA 23529
+1 757 683 6393 +1 757 683 4900 (f)