[OAI-implementers] ListRecords request w/out an until..

[Sandra McIntyre]

Your question is interesting. I assume this is why our harvester always includes the "until" parameter as well as the "from" date in its ListRecords requests. On the next re-harvest it uses the former "until" date as the new "from" date, and we are assured of getting all records. I thought this was standard, and that accommodating requests that include only a "from" date was not an issue.

Sandra

=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
Sandra McIntyre  |  Program Director
Mountain West Digital Library  |  Utah Academic Library Consortium
http://mwdl.org  |  +1-801-585-0969  |  sandra.mcintyre at utah.edu


On Feb 1, 2011, at 8:07 AM, "Simeon Warner" <simeon.warner at cornell.edu> wrote:

> Hi Ben,
> 
> This is covered in the in section 3.5.1 of the specification:
> 
> http://www.openarchives.org/OAI/2.0/openarchivesprotocol.htm#Idempotency
> 
> I think your solution for the harvester is the correct one. Provided the 
> harvester starts again with from=t0 all changes between t0 and t2 will be 
> harvested, irrespective of whether or not they were included in the original 
> response (modulo understood problems with items that move between sets for set 
> selective requests).
> 
> Cheers,
> Simeon
> 
> On 02/01/2011 09:09 AM, Benjamin Anderson wrote:
>> Hi,
>> 
>> I'm wondering what others are doing when a ListRecords request w/out an
>> until comes in.� Consider this scenario:
>> 
>> t0 - harvest request (with no until) is initiated
>> t1 - record 101 is added to the repo
>> t2 - harvest is finished (it took multiple requests to complete)
>> 
>> Should record 101 be included in the harvest data?� If not, will the
>> client better issue their next harvest with a from=t0 (a from=t2 would
>> be invalid because they'd miss out on record 101).
>> 
>> We have implemented both oai-pmh harvesters and providers, so I have to
>> consider both ends of this.� Here's what I'm thinking...
>> 
>> As a Provider
>> I will simply lock the repo so that the above scenario can't happen.� If
>> someone is already harvesting (there exist unexpired resumptionTokens)
>> then I will not update the repository.
>> 
>> As a Harvester
>> I will always use the until parameter with the value of the time the
>> harvest was initially started.
>> 
>> I think this keeps me clear of any problems.� Anyone else have thoughts
>> or care to share your solutions?
>> 
>> Thanks,
>> Ben Anderson
>> 
>> 
>> 
>> 
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> 
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