Re: [thredds] unable to do ncml aggregation

• To: thredds@xxxxxxxxxxxxxxxx
• Subject: Re: [thredds] unable to do ncml aggregation
• From: Ethan Davis <edavis@xxxxxxxxxxxxxxxx>
• Date: Tue, 08 Jun 2010 11:39:06 -0600

Hi Upendra,

Are the data files accessible from foo.com through OPeNDAP? If so, try
using the OPeNDAP URLs in the NcML rather than the file server URLs.
With OPeNDAP, whether the source data file is compressed or not
shouldn't matter as that is all handled on the server.

When accessed through the file server, the client software is reading
the bytes from the compressed file over HTTP. When the netCDF-Java
library tries to open a non-OPeNDAP HTTP URL, it assumes the resource is
an uncompressed file (for efficiency and other reasons). When it tries
this on a compressed file, it doesn't recognize the first few bytes of
the file as the netCDF header and so fails to open the dataset.

Hope that helps,

Ethan

On 6/7/2010 4:05 PM, Upendra Dadi wrote:
> Hi,
>  I am trying to aggregate some netcdf files thought ncml. I am getting
> an error like this when aggregating:
>       Cant read http://foo.com/thredds/fileServer/examples/test.nc.bz2:
> not a valid NetCDF file.
> 
> But I am able to open the same file on THREDDS server. Any suggestions
> on what might be going wrong?
> 
> By the way, does THREDDS download the entire netcdf file before
> aggregating?  How do I control how long the temporary dataset stays on
> the server?

 On 6/8/2010 11:10 AM, Upendra Dadi wrote:
> Hello,
>  Can someone please help me here with my ncml issue? My THREDDS server
> is unable to read remote compressed netcdf files present in the ncml
> files. However, it is able to recognize remote uncompressed files as
> well as local compressed files. Does ncml working with remote compressed
> files? Is there a TDS setting I should be looking at? Thanks!

• References:
  • [thredds] unable to do ncml aggregation
    • From: Upendra Dadi