Regarding the approach of aggregating national aggregations:
With the current ubiquitous harvesting protocol (OAI-PMH) I think that this approach, although logical, is just not viable. It is non-trivial to maintain even a single layer of aggregation with this protocol as the state of the resources being aggregated is not reliably conveyed and the fidelity of the aggregation starts to drift over time. This is why - as I have found in cases that I have examined - aggregators which rely on OAI-PMH tend to periodically re-harvest all of their data.
This work-around, which does not scale indefinitely but which is currently just about viable, is quite problematic once a second 'layer' of harvest/aggregation is added. Maintaining state from source, to national aggregation, to global aggregation requires a more sophisticated protocol.
This is the kind of problem which has led Herbert Van de Sompel (and others) to begin work on a better protocol, ResourceSync. However, it will be some time before this is a wide-spread as OAI-PMH, assuming it even gets wide-spread adoption.
So, in this respect, I tend to agree with Thomas.
Paul
On 28 Oct 2013, at 01:23, Thomas Krichel <[log in to unmask]> wrote:
> Elly Dijk writes
>
>> In the Netherlands the scholarly portal NARCIS
>> (http://www.narcis.nl/) harvests the repositories with OA
>> publications of the Dutch universities and other scholarly
>> institutions. I am interested in the harvesting of international
>> subject repositories and the collecting of relevant articles of
>> publishers.
>
> Start with RePEc, we are very harvest friendly.
>
>> The advantage of a UK only aggregate is that if every country has a
>> 'national aggregation point' like NARCIS in the end one can 'connect
>> (aggregate)' all those national aggregation points. It is a start to
>> harvest the national repositories.
>
> It's a pipe dream. It's not going to happen in the U.S anytime
> soon. And that's the biggest part of the cake gone.
>
> --
>
> Cheers,
>
> Thomas Krichel http://openlib.org/home/krichel
> skype:thomaskrichel
-------------------------------------------
Paul Walk
http://www.paulwalk.net
-------------------------------------------
|