Re: [thredds] Running THREDDS on top of old OPeNDAP servers

Hi all,

Simon - this is exciting stuff!!! I was wondering - how are you generating the ISO documents? Are you going to add extra information into the THREDDS "Digital Library Metadata Elements" when referred to making ISO19119 records for thredds services? I'm particularly interested in the automatic extraction of geospatial boundaries. I was hoping to use some standard document to extract this. I thought WCS would be good for this, but it has just hit me (unfortunately, somewhat late in this project) that it only works on a small subset (i.e. only for regularly gridded datasets) :(

Looking at the catalog spec, it looks like the geospatial and temporal extent is something that has to be hand-crafted. But given CDM can read these values (and for more than just regularly gridded datasets), it would seem to make sense if this could be automated somehow? Interestingly, the NetCDF Subsetter's dataset.xml document (e.g. http://opendap-ivec.arcs.org.au/thredds/ncss/grid/TERN_AUSCOVER/MODIS/L2/LPDAAC/aust/MOD13Q1.005/2000.02.18/MOD13Q1.2000.049.aust.005.b01.250m_ndvi.hdf.gz/dataset.xml) will produce the required information, but, this is doesn't follow any kind of metadata standards (as far as I know anyway).

Any suggestionsAs Rich was saying, do you have any "ISO thredds catalogs" on a server, dev or otherwise that we can have a look at?

Cheers,

-Pauline.

Richard Signell wrote:
Simon,

This sounds extremely useful and I'd love to give it a try.

Can you please tell us what the "trivial" changes are to NetCDF-Java?

And do you have a real-life example of the catalog below that works
with publicly available OpenDAP data?

Thanks,
Rich

On Wed, Apr 8, 2009 at 8:28 PM,  <Simon.Pigot@xxxxxxxx> wrote:
Hi Pauline,

The following works ok for us (as an example - non-essential details removed):

<?xml version="1.0" encoding="UTF-8"?>
<catalog name="YOUR SITE OPeNDAP Catalog"
       xmlns="http://www.unidata.ucar.edu/namespaces/thredds/InvCatalog/v1.0";
       xmlns:xlink="http://www.w3.org/1999/xlink";>

 <service name="yoursiteopendap" serviceType="OpenDAP" 
base="http://www.yoursite.com/dods/nph-dods/dods-data/"/>
 <datasetScan name="climatology-netcdf" path="climatology-netcdf" 
location="http://www.yoursite.com/dods/nph-dods/dods-data/climatology-netcdf";>
   <serviceName>yoursiteopendap</serviceName>
   <crawlableDatasetImpl className="thredds.crawlabledataset.CrawlableDatasetDods" 
/>
 </datasetScan>
 <datasetScan name="bluelink" path="bluelink" 
location="http://www.yoursite.com/dods/nph-dods/dods-data/bluelink";>
   <serviceName>yoursiteopendap</serviceName>
   <crawlableDatasetImpl className="thredds.crawlabledataset.CrawlableDatasetDods" 
/>
 </datasetScan>
</catalog>

I'm not sure if its all documented somewhere - I worked it out the slow way by 
poking around in the netcdf java code and hunting through the archives of the 
thredds mailing list. There are also some trivial changes you need to make to 
the code (in netcdf-java) to filter out some unwanted artifacts created when 
the scan picks through the html from the OpenDAP server - otherwise you end up 
with some strange, non-functional things in your catalog. Maybe there is a 
better way to do the above?

By way of introduction, we want this sort of catalog to work as part of a 
thredds metadata harvester I'm adding to GeoNetwork which produces ISO19115 
metadata records and ISO19119 records for thredds services. Its nearly at the 
stage where it is working reliably but there are a few more issues I need to 
solve and I'm still learning about Thredds :-)

Cheers and I hope this helps,
Simon

________________________________________
From: thredds-bounces@xxxxxxxxxxxxxxxx [thredds-bounces@xxxxxxxxxxxxxxxx] On 
Behalf Of Pauline Mak [Pauline.Mak@xxxxxxxxxxx]
Sent: Thursday, 9 April 2009 8:56 AM
To: thredds@xxxxxxxxxxxxxxxx
Subject: [thredds] Running THREDDS on top of old OPeNDAP servers

Hi all,

I'm figuring out ways to serve data using THREDDS on top of old OPeNDAP
servers.  I'm aware that you can configure datasets based on a URL, but
that's for a single file... (correct me if I'm wrong!)  However, are
there ways to apply to an directory?  Sort of like a datasetScan +
filters for a directory URL?  When poking through the THREDDS catalog
XSD, there's a crawlableDatasetImpl element.  Is that the sort of things
I need to look at?

Thanks,

-Pauline.

--
Pauline Mak

ARCS Data Services
Ph: (03) 6226 7518
Email: pauline.mak@xxxxxxxxxxx
Jabber: pauline.mak@xxxxxxxxxxx
http://www.arcs.org.au/

TPAC
Email: pauline.mak@xxxxxxxxxxx
http://www.tpac.org.au/



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--
Pauline Mak

ARCS Data Services
Ph: (03) 6226 7518
Email: pauline.mak@xxxxxxxxxxx
Jabber: pauline.mak@xxxxxxxxxxx
http://www.arcs.org.au/

TPAC
Email: pauline.mak@xxxxxxxxxxx
http://www.tpac.org.au/





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