Deborah- > (b) sharing a meaningless internal identifier via OAI PMH as dc:identifier is > bad practice, and should never be a fallback default.
You make a good point: The pid satisfies the requirements for a unique identifier as per OAI-PMH section 2.4, but it doesn't hold up to the use of the resource identifiers very well on its own. It seems like a natural extension to the features requested in: https://jira.duraspace.org/browse/FCREPO-650 https://jira.duraspace.org/browse/FCREPO-655 ... to work towards the OAI-PMH interfaces include a dereferenceable URI. That seems like an appropriate default to me, but it still may not be what you want! > The DC element's dc:identifier field is restricted to being the fedora pid. This is a misunderstanding; at least as of Fedora 3.3 you can add additional dc:identifier's. I'd have to check the code to see whether you can actually eliminate the pid's inclusion, and what the consequences of that would be (I wouldn't recommend it in any case). > Thorny has repeatedly said that we shouldn't be loading up the DC datastream > with metadata because it's bad practice (mostly because of the performance > problems he discusses in that e-mail you cite). Is that not true? If you load inline DC datastreams up with large data, you may incur a performance penalty; especially if you version the DC datastream. So there are three factors there: Is it inline, is it large, is it versioned. These three factors relate to any datastream in Fedora, though, not just the DC datastream. Thorny also said you shouldn't try to include qualified dublin core data, but that is a separate issue. Thanks for hashing this out! These lists are an important source of documentation for me, and it's important to revisit long-standing issues to make sure received wisdom is still aligned with the state of the application. - Ben On 2/25/11, Kaplan, Deborah <[email protected]> wrote: >> Fedora's "internal" >> datastream is not called oai_dc; it's called "DC", and uses an element >> with the namespace prefix "oai_dc" as a container. > > Fair enough; I was sloppy with my terminology and I shouldn't have been. > > That meeting said, it's clear that this is a blocker for any number of > people who are getting set up either with Fedora itself for the first time, > or with Fedora and OAI PMH. The namespace prefix oai_dc *means* something > out in the world, and for that matter so does the identifier "DC" (even if > not as formally). Asking it in Fedora to mean something else confuses new > users, it is one more roadblock between concept and production for tool > which is nontrivial to configure at the best of times. > > Quoting Thorny: "I wish we had called the DC datastream "repoMeta" or > something. It was just intended to be the base metadata needed for the > repository manager to be able to function and was not intended to be exposed > externally." > > People setting up a Fedora instance, or implementing OAI PMH for an existing > Fedora instance, see the apparently meaningful prefix oai_dc, on top of the > apparently meaningful datastream name "DC", and get confused. Yes, I > understand that oai_dc is reserved in such a way that it can't be used > internal to Fedora, it's reserved for an OAI PMH implementation. Yet normal > humans are going to see the namespace oai_dc and react accordingly. At a > minimum, the documentation should be updated to highlight this potential > confusion. > >> It is a default, so it >> seems appropriate for proai to fallback to that in the absence of >> other configuration. > > Except it doesn't, because (a) the message on the mailing lists for the last > year has repeatedly been "don't put any metadata into DC datastream, except > what Fedora requires", and more importantly (b) sharing a meaningless > internal identifier via OAI PMH as dc:identifier is bad practice, and should > never be a fallback default. > >> The "internal" character of the DC datastream isn't that dramatic- >> your objects can certainly have identifiers, titles, and formats that >> you define for them. > > Actually, that's not true. They can't have identifiers you define for them. > The DC element's dc:identifier field is restricted to being the fedora pid. > Unless there is something I am very much missing. > > Thorny has repeatedly said that we shouldn't be loading up the DC datastream > with metadata because it's bad practice (mostly because of the performance > problems he discusses in that e-mail you cite). Is that not true? > > > -Deborah > ------------------------------------------------------------------------------ > Free Software Download: Index, Search & Analyze Logs and other IT data in > Real-Time with Splunk. Collect, index and harness all the fast moving IT > data > generated by your applications, servers and devices whether physical, > virtual > or in the cloud. 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