[Go-essp-tech] Corrected THREDDS group wiki page link

[stephen.pascoe at stfc.ac.uk]

Thanks Martin.  There is a catalog_version attribute already, although I don't think there is any documentation on what it means.

On the hierarchy, I personally believe we could allow any number of intermediate catalogues containing <catalogRef> elements in the spec.  Datanodes currently only produce 2 levels .../thredds/catalog.xml and .../thredds/esgcet/catalog.xml, but there would be no harm in having deeper nesting.  What I think is less flexible is the constraint that "leaf-catalogs" contain a single container <dataset> element and a set of child <dataset> elements representing files and aggregations.  This design is what LAS and other bits of ESGF rely on. General THREDDS allows you to mix catalogRef, container datasets and "real" datasets throughout the hierarchy.

Anyone, please chip in if you dissagree.

Cheers,
Stephen.

---
Stephen Pascoe  +44 (0)1235 445980
Centre of Environmental Data Archival
STFC Rutherford Appleton Laboratory, Harwell Oxford, Didcot OX11 0QX, UK

From: Juckes, Martin (STFC,RAL,RALSP)
Sent: 23 February 2012 12:11
To: Pascoe, Stephen (STFC,RAL,RALSP); go-essp-tech at ucar.edu
Subject: RE: Corrected THREDDS group wiki page link

Hello All,

Sorry I had to leave the telco early - but it was a useful discussion.

After leaving, I had a couple of thoughts:


(1)    There syntax should be versioned , and the version should be indicated in the catalogue somewhere - whatever we agree on, there is bound to be need to change in the future, and changes will be much easier to manage if we have the version in the catalogue. There could be independent syntax versions for the top level catalogue and the "publication unit" catalogue. The cleanest way to do this would be with an xsd document referenced in the schemaLocation attribute. We could set this up initially with a "permissive" xsd schema imposing necessary constraints, but not all the required constraints.

(2)    The decision to stick to a 2-level hierarchy of THREDDS documents (a top-level catalogue with a list of "catalogRef"s and a sub-catalogue for each publication unit) is certainly right for now, but may be too restrictive in the medium term. The specification of "catalogRef" means that very little information is in the top level, and at the next level you have to fetch everything. Having an 3rd level - e.g. for each simulation - would allow more flexibility in recording changes and pointing to documentation.

Cheers,
Martin

From: go-essp-tech-bounces at ucar.edu [mailto:go-essp-tech-bounces at ucar.edu] On Behalf Of stephen.pascoe at stfc.ac.uk
Sent: 21 February 2012 16:14
To: go-essp-tech at ucar.edu
Subject: [Go-essp-tech] Corrected THREDDS group wiki page link


http://esgf.org/wiki/ESGFInterfaceGroups/ThreddsGroup

---
Stephen Pascoe  +44 (0)1235 445980
Centre of Environmental Data Archival
STFC Rutherford Appleton Laboratory, Harwell Oxford, Didcot OX11 0QX, UK



--
Scanned by iCritical.


-- 
Scanned by iCritical.

-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://mailman.ucar.edu/pipermail/go-essp-tech/attachments/20120223/5eed8fe5/attachment-0001.html