[OAI-implementers] Sets in OAI-PMH and DSpace

Hickey,Thom hickey@oclc.org
Tue, 21 Oct 2003 15:50:18 -0400

I believe what you are proposing is perfectly legal, but there is no
implication in OAI that A:C has anything to do with B:C, and no way to
harvest collection C without specifying a community of A or B.  Of course
the set description could explain all this and a group could come to
agreement as to how the sets were going to be used.


> -----Original Message-----
> From: Tansley, Robert [mailto:robert.tansley@hp.com]
> Sent: Tuesday, October 21, 2003 3:36 PM
> To: Hickey,Thom; oai-implementers@oaisrv.nsdl.cornell.edu
> Subject: RE: [OAI-implementers] Sets in OAI-PMH and DSpace
> > The set structure in OAI is very simple, but also has almost 
> > complete flexibility, so I'm sure you could encode any 
> > relationships that DSpace is aware of in them.  But the 
> > retrieval on sets is quite limited, so it isn't clear what 
> > good it would do.  
> > 
> > I agree with Hussein -- keep them simple.  For DSpace, 
> > possibly a unique ID for each collection.
> My understanding was that sets could be flat or hierarchical; 
> presumably this means a strict hierarchy, i.e. no node could 
> have >1 parent -- is this correct?  If so, DSpace could not 
> expose the case where a Collection appears in two 
> Communities, since the same Collection would have two 
> setSpecs.  However, thinking about it, maybe this is actually 
> OK, since that Collection would effectively be two OAI sets 
> with two separate setSpecs; for selective harvesting 
> purposes, harvesters don't necessarily need to know that the 
> two sets are in fact the same Collection.
> Here's a quick example in case this isn't clear... Collection 
> C is contained in Community A and Community B:
> Community A      Community B
>         \          /
>          \        /
>           \      /
>          Collection C
> The exposed OAI set structure would be:
> setSpec     setName
>  A          Community A
>  A:C        Collection C
>  B          Community B
>  B:C        Collection C
> Is there any reason why the above might be 'illegal' in 
> OAI-PMH?  Might any harvesters get confused?
> P.S. sorry if cross-posting to dspace-tech & oai-implementers 
> caused any duplication weirdness... I for one seemed to get 
> about 6 copies of replies, I don't know whether that was the 
> mailing lists or my client getting confused though!
>  Robert Tansley / Hewlett-Packard Laboratories / (+1) 617 551 7624