Hi John and Joe, Since I was asked, I am answering, not that I am adding anything useful. Yes, if collections and datasets are completely interchangable in all machine-type ways, that works for me. I think John gives the definitive summary below. Of course, if I have a dataset that temporarily does not have any functioning access methods on a particular server, one may not always feel the need to relabel it a collection... Benno Quoting John Caron and Joe <address@hidden>: > > If this is the case then I would suggest that > > > > a) this distinction be preserved by allowing both tags to be > > used(possibly renamed if it would clarify things); and > > > > b) data providers should be encouraged to mark up their catalogs > > appropriately using the two tags, so that THREDDS client UI's can take > > advantage of this to present catalogs in an intuitive way; but > > > > c) these tags should be completely interchangeable in all other ways > > (i.e. same type in the DTD/Schema, and same API calls, any tag that can > > go in a dataset can also go in a collection), since they are > > semantically equivalent at a machine level. > > > > Does that make any sense? Benno, would that satisfy you? > > > > - Joe (ready for a checkup with my ontologist) > Quoting John: > Actually Im inclined to take it a bit further. > > Currently a collection is just some collection of datasets that share some > common theme. If we allow it also to be a dataset (meaning it has a URL, > can > be selected, etc) then I think it should have the meaning that contained > datasets are subsets or specializations of it. Because if they are not it > seems to me that you might as well just represent the collection-as-dataset > as a contained dataset element. [Maybe in this whole discussion I have been > trying to convince myself of that :^] Does everyone agree with that meaning > of nested datasets inside of collection-as-dataset? > > PS: There are still semantic difference between collections and datasets: A > dataset has one or more access elements, a collection 0 or more. > Collections > contain datasets and nested collections. > OTOH, datasets and collections look so similar already in the XML, its > tempting to combine them (which i was playing with earlier in > http://www.unidata.ucar.edu/projects/THREDDS/xml/InvCatalog.0.6a.dtd) > > >
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