[thredds] WCS problem in THREDDS ESGF-5.0.1

• To: <thredds@xxxxxxxxxxxxxxxx>
• Subject: [thredds] WCS problem in THREDDS ESGF-5.0.1
• From: <joe.singleton@xxxxxxxxxx>
• Date: Thu, 18 Jan 2018 13:23:26 +0000

Hi all,

I am having problems using WCS with an NcML dataset in THREDDS version
ESGF-5.0.1. WCS seems to work fine for datasets corresponding to actual files,
but not when aggregating datasets with NcML. The WCS endpoint returns the
following response:

  <?xml version="1.0" encoding="UTF-8"?>
  <ServiceExceptionReport xmlns="http://www.opengis.net/ogc"; version="1.2.0">
    <ServiceException>Unknown problem</ServiceException>
  </ServiceExceptionReport>

Some errors are logged in threddsServlet.log (full log attached):

  2018-01-18T12:59:54.951 +0000 [    555825][      16] ERROR - 
thredds.server.wcs.WcsHandler - Unknown problem.
  java.io.FileNotFoundException: Not a Grid Dataset test_aggregate_dataset 
err=/var/lib/tomcat/content/thredds/public/testdata/_aggregate_dataset (No such 
file or directory)

My <dataset> element in the root catalog.xml is:

  <dataset name="Aggregation" ID="test_aggregate_dataset">
    <access serviceName="all" urlPath="test_aggregate_dataset"/>
    <netcdf xmlns="http://www.unidata.ucar.edu/namespaces/netcdf/ncml-2.2";
            
location="/var/lib/tomcat/content/thredds/public/testdata/cci/agg.ncml"/>
  </dataset>

and the referenced NcML contains the following:

  <?xml version="1.0" encoding="UTF-8"?>
  <netcdf xmlns="http://www.unidata.ucar.edu/namespaces/netcdf/ncml-2.2";>
    <aggregation dimName="time" type="joinExisting">
      <variableAgg name="time"/>
      <netcdf 
location='/var/lib/tomcat/content/thredds/public/testdata/cci/ESACCI-SOILMOISTURE-L3S-SSMS-ACTIVE-19910805000000-fv02.2.nc'/>
      <netcdf 
location='/var/lib/tomcat/content/thredds/public/testdata/cci/ESACCI-SOILMOISTURE-L3S-SSMS-ACTIVE-19910806000000-fv02.2.nc'/>
      <netcdf 
location='/var/lib/tomcat/content/thredds/public/testdata/cci/ESACCI-SOILMOISTURE-L3S-SSMS-ACTIVE-19910807000000-fv02.2.nc'/>
      <netcdf 
location='/var/lib/tomcat/content/thredds/public/testdata/cci/ESACCI-SOILMOISTURE-L3S-SSMS-ACTIVE-19910808000000-fv02.2.nc'/>
      <netcdf 
location='/var/lib/tomcat/content/thredds/public/testdata/cci/ESACCI-SOILMOISTURE-L3S-SSMS-ACTIVE-19910809000000-fv02.2.nc'/>
    </aggregation>
  </netcdf>

The referenced datasets exist and are readable by the tomcat user, and when
adding a <dataset> element for one of them directly it can be accessed through
WCS with no problem.

Also, the same aggregation works correctly via WMS, so I think the aggregation
setup is fine.

Looking at the output of strace it seems that THREDDS is trying to stat
'/var/lib/tomcat/webapps/thredds/wcs/test_aggregate_dataset', and open
'/var/lib/tomcat/content/thredds/public/testdata/_aggregate_dataset', both of
which do not exist. I suppose this is what causes the exception logged in the
log file.

If anyone can help at all it would be greatly appreciated.

Thanks,
Joe

Attachment: stacktrace.log
Description: stacktrace.log

• Follow-Ups:
  • Re: [thredds] WCS problem in THREDDS ESGF-5.0.1
    • From: Antonio S . Cofiño