The translation of repository data into OAI_DC is horribly lossy and terribly non-standard in almost all important ways (ways that are important to me as someone trying to analyse global OA holdings). However, at the time it seemed better to the community than the alternative.
One can also raise the question why define OAI-PMH in the first place? And more importantly, why still use it? Fifteen years on the Web-native linked data model seems much more appealing and practical, but to be fair it has taken this long for "linked data" to reach that state.
Web Science Institute
University of Southampton
On 20 Mar 2014, at 11:54, John Salter <[log in to unmask]<mailto:[log in to unmask]>> wrote:
I wasnít involved with repositories when these things were being put in place, but have come across similar issues.
In my mind, DC is good, as itís a low barrier, but OAI-PMH is designed to allow other metadata formats to be used when the need arises (e.g. UKETD_DC (EThOS) metadata schema).
If Primo can harvest other metadata formats, you could create one that provides the information that you want Ė but Iím not sure what the capabilities of Primo are.
Iíve had some conversations with Sheffield (who also use Primo) in this area, as they didnít want to present links to content that wasnít open access.
Iím waiting to find out what options there are in Primo for either harvesting specific sets, or using other metadata formats Ė which may well help solve your problems too.
This also provides some good comments on some other issues Ė based on interpretations of the guidelines: http://core-project.kmi.open.ac.uk/node/31
From: Repositories discussion list [mailto:[log in to unmask]] On Behalf Of Chris Keene
Sent: 20 March 2014 11:30
To: [log in to unmask]<mailto:[log in to unmask]>
Subject: DC OAI-PMH
In the early days of repositories I know a lot of work went in to defining standards for making them inter-operable and to expose their data, notable the OAI initiative. I'm hoping some who were involved in (or who followed) those developments could help enlighten me.
For a number of years I've been curious around the reasoning behind adopting Dublin Core via OAI-PMH as the de facto way to harvest and obtain metadata from a repository. (DC isnít the only format, but it is by far the most common used).
To use data exposed by a system - such as a repository - the first thing I would have thought you need to do is interpret the incoming information.
When reading information from an IR, the system/script that is importing it needs to establish a number of things:
- common bibliographic fields; title, authors, date, publisher, vol/issue, issn/isbn, publication title etc.
- link to IR record
- is full text available? if so where, and in what format.
- what type of item is it.
- Description, citation, subjects etc.
While using a common standard (DC) is clearly a good thing. Processing the above can be a challenge, especially as different repository software platforms and versions can present key pieces of information in different ways. This is perhaps made a little harder as there is no field to specify the software/version in the metadata output
I'll give a couple examples:
To extract the vol/issue/publication title involves looking at all the "dc:identifier" fields, identifying which identifier contains a citation, and then deconstruction the citation to extract the data (and parsing citations is no easy process in itself).
To obtain if a record has the full text openly available, ie OA (with an Eprints system): Check to see if there is a dc:format - if it exists there is a file associated with the record.
But to check it is OA, and not locked down (which is quite common) find the dc:identifier which starts with the same domain name as the OAI interface, presume it is a link to the full text, try and access it, if you succeed (http status code 200) then it is OA. Though if you only have the metadata to work with and can't try and retrieve the URL while processing the record, you obviously canít do this.
Dspace provides quite different data via OAI-PMH so this method would not work.
The reason I bring this up now is that I'm currently trying to improve how our repository records are displayed in our discovery system (Primo, from Ex Libris), the metadata is currently so poor we have hidden them.
A key concept of these systems is that they know which items the user has access to (across all the library's collections and subscriptions), and by default only returns those which the user can access. While Primo has quite a complex system for configuring how records are imported, it doesn't extend to the sort of logic described above.
So from my specific use case (and other dabbling in this area) the data provided by OAI-PMH DC seems difficult to work with.
I'd be interesting to learn a bit of the history of the thinking of how this approach cam about, and whether there are better approaches in processing the data than those I have described here.
Regards, and thanks in advance to any insights
For reference here are two examples (you may find using Firefox, view source, works best)
Eprints (record with a file attached, but not OA)
Chris Keene - Technical Development Manager, University of Sussex Library