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[Fwd: latest Catalog XML]

Woops realized that I simply responded to John.

Peter
-- 
 Peter Cornillon                                                       
  Graduate School of Oceanography  - Telephone: (401) 874-6283         
   University of Rhode Island      -       FAX: (401) 874-6728         
    Narragansett RI 02882  USA     -  Internet: address@hidden
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Hi all,

An interesting discussion. I wrestled a bit with this around the time
of the DODS developers meeting last January. I have attached a table
that I put together to help me keep track of the issues. I think that
you have progressed way beyond this, but thought that you might find
it interesting anyway.

Peter

John Caron wrote:
> 
> heres another strawman, incorporating our latest discussions:
> 
> http://www.unidata.ucar.edu/projects/THREDDS/xml/InvCatalog.0.6d.dtd
> 
> Recent changes:
> 
> 1) Collections as datasets. Ethan and I think the cleanest way to allow
> "collections as datasets" is to allow nested datasets. Collections remain
> just groups of datasets. A Collection as a dataset is done as a dataset with
> nested datasets. Nested dataset elements (Joe's meaning #2) should imply (in
> some way we need to clarify better) nested datasets (Joe's meaning #1 and
> #3).
> 
> 2) allow compound services again. I have talked myself into that these will
> be often useful.
> 
> 3) services are now contained within any collection, rather than having to
> be all in the top catalog element. They are scoped by the collection they
> are in (so we no longer use ID, since those are global). This makes a
> catalogRef have (almost) the same semantics as a collection.
> 
> 4) a catalog now only has exactly one collection element. (i considered
> eliminating catalog but i think its better this way).
> 
> 5) "attribute" changed to "property" (tired of saying "the attribute
> attribute")
> 
> 6) access element can specify an absolute URL with a serverType -or- a
> reletive URL with a serverID.
> 
> Unless I get a barrage of objections, I will document this in more detail
> ASAP. I will be gone for a week starting next Tuesdy, so Ethan will continue
> the conversation as needed. Hopefully, we can converge soon and take a
> break! I think I have incorporated all the good ideas i have heard in this
> discussion. Have I left out something, or do you think any feature is not
> worth the complexity?

-- 
 Peter Cornillon                                                       
  Graduate School of Oceanography  - Telephone: (401) 874-6283         
   University of Rhode Island      -       FAX: (401) 874-6728         
    Narragansett RI 02882  USA     -  Internet: address@hidden
Title: Oceanology International
OPeNDAP Data Objects, Collections and Sets



  • OPeNDAP Data Objects are the data retrieved by any OPeNDAP URL (constrained or unconstrained).

    • a portion of a satellite image
    • a mooring record

  • OPeNDAP Datasets (or OPeNDAP Granules) are OPeNDAP Data Objects accessed by an unconstrained URL.

    • a satellite image
    • a mooring record
    • a NetCDF file that contains all satellite images in a given projection from a specific sensor

  • OPeNDAP Data Collections are collections of OPeNDAP Datasets that are accessible either
    • as a new OPeNDAP Dataset via an OPeNDAP Aggregation Server, or
    • as a list of OPeNDAP Datasets via a File Server.

    • all satellite images in a given projection from a specific sensor
    • a collection of mooring records

    Note that the list of OPeNDAP Datasets accessed via an unconstrained request to an OPeNDAP File Server is also an OPeNDAP Dataset.

  • NVODS Datasets are all of the meteorological or oceanographic data at a site that the data provider considers to be logically connected. Could be an OPeNDAP Dataset, an OPeNDAP Data Collection or a group of OPeNDAP Datasets that are not formally linked from an OPeNDAP perspective.

    • all satellite images in a given projection from a specific sensor for which neither an OPeNDAP File Server nor an OPeNDAP Aggregation Server exist
    • a NetCDF file that contains all satellite images in a given projection

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