Re: [thredds] Supported file compression methods

• To: thredds@xxxxxxxxxxxxxxxx
• Subject: Re: [thredds] Supported file compression methods
• From: John Caron <caron@xxxxxxxxxxxxxxxx>
• Date: Fri, 16 Dec 2011 17:43:51 -0700

thanks, glenn.

On 12/14/2011 3:20 AM, Comiskey, Glenn wrote:

Thanks John, you confirmed my understanding. However, have a problem
with several ZIP (.zip) files in a dataset:

[2011-12-14T10:13:55.900+0000] ERROR ucar.nc2.ft.fmrc.FmrcDataset: Cant
open file
java.io.IOException: Cant read C:/<dir1>/<dir2>/<filename>.nc.zip: not a
valid CDM file.
        at ucar.nc2.NetcdfFile.open(NetcdfFile.java:744)

The netCDF-Java version in use is v4.2.25.

The files can readily be opened with ZIP applications and the compressed
NetCDF file (.nc) extracted without issue.

Regards,

Glenn

------------------------------

Message: 3
Date: Tue, 13 Dec 2011 10:09:50 -0700
From: John Caron<caron@xxxxxxxxxxxxxxxx>
To: thredds@xxxxxxxxxxxxxxxx
Subject: Re: [thredds] Supported file compression methods
Message-ID:<4EE786DE.1040500@xxxxxxxxxxxxxxxx>
Content-Type: text/plain; charset="iso-8859-1"; Format="flowed"

On 12/13/2011 2:33 AM, Comiskey, Glenn wrote:

Hi,
Can anyone list what file compression methods THREDDS can support when
accessing data files, i.e. can a data file be stored in a compressed
format, such as bzip2, and yet THREDDS can still access the file and
extract data.
Kind regards,
Glenn Comiskey
Data System Administrator

If the URL ends with a with ".Z", ".zip", ".gzip", ".gz", or ".bz2", the
file is assumed to be/*compressed*/. The netCDF-Java library will
uncompress/unzip and write a new file without the suffix, then read from
the uncompressed file. Generally it prefers to place the uncompressed
file in the same directory as the original file. If it does not have
write permission on that directory, it will use thecache directory
<http://www.unidata.ucar.edu/software/netcdf-java/reference/Caching.html

defined

by*ucar.nc2.util.DiskCache.

*see
http://www.unidata.ucar.edu/software/netcdf-java/reference/faq.html#Read
ing

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• References:
  • Re: [thredds] Supported file compression methods
    • From: Comiskey, Glenn