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Re: [thredds] over written file has old global attributes

On the sift machine, because we were doing testing, we have "opendap" with & without thredds and "looking" at the file - ncdump & dncdump with "opendap no thredds" both give correct attributes while dcdump with "thredds" gives old attribute information. Jean 

ncdump -h crescent_runup_ha.nc
...
// global attributes:
                :history = "MOST v2.080 11-05-2007  16:09:22" ;
                :title = "Aleutian-Cascadia: Mwt 8.4, 21.00*b65" ;
dncdump -h http://sift.pmel.noaa.gov/thredds/dodsC/data/crescent_runup_ha.nc 
...
// global attributes:
                :history = "MOST v2.080 11-05-2007  11:49:33" ;
                :title = "Aleutian-Cascadia: Mwt 8.5, 29.00*b25" ;

dncdump -h http://sift.pmel.noaa.gov/opendap/crescent_runup_ha.nc
...
// global attributes:
                :history = "MOST v2.080 11-05-2007  16:09:22" ;
                :title = "Aleutian-Cascadia: Mwt 8.4, 21.00*b65" ;
 ___________________________________________________________
  Jean Newman                             Tel: 206-526-6531
  NOAA Center for Tsunami Research
  NOAA/PMEL/OERD2 - UW/JISAO              FAX: 206-526-6485
  7600 Sand Point Way NE, Bldg. 3    jean.c.newman@xxxxxxxx
  Seattle, WA 98115-6349               jcn@xxxxxxxxxxxxxxxx
 _________________________. URL: http://nctr.pmel.noaa.gov/
                         (__________________________________

On Tue, 6 Nov 2007, Jean.C.Newman@xxxxxxxx wrote:


One other thing, the "old attributes" lasts. I made a run yesterday at
11:23 am and it was over written several time the last at 16:09 and today
if I look at that output file via LAS/"dncdump -h" it still shows the "old
stuff" from the 11:23 run. "ncdump -h crescent_runup_ha.nc" has the
correct 16:09 information. Thanks, Jean
 ___________________________________________________________
  Jean Newman                             Tel: 206-526-6531

On Tue, 6 Nov 2007, Jean.C.Newman@xxxxxxxx wrote:


The question:
Is there some way to turn off caching of metadata so the file is checked
every time it's accessed? Jean
 ___________________________________________________________
  Jean Newman                             Tel: 206-526-6531

On Tue, 6 Nov 2007, Jean.C.Newman@xxxxxxxx wrote:


It's not a browser caching problem. I have a very old LAS that accesses
these files. From the LAS, input for a model run is set up then a servlet
is run on 1 of several possible machines that starts a FORTRAN model run
that overwwites files so that the LAS interface has static files/"DODs"
URLs for the output. We are moving to different code but need to keep this
working until the new is up and reliable. The data updates, I can see
that in the plots, but I use global attributes in labeling and I get the
old information sometimes, 2 out of 31 SIM runs. The example I put out on
the sift machine was run on an internal machine and then sftp-ed to sift.
Then I made another run and again sftp-ed it to the sift machine and saw
the same "old attributes" problem, which I really didn't think I would.
If tomcat is restarted then I get the new information so I imagine it is
some caching problem. I did try removing the file before rerunning the
SIM and that did not solve the problem. Is there some way to turn off
caching of metadata so the file is checked every time it's accessed? Jean
 ___________________________________________________________
  Jean Newman                             Tel: 206-526-6531

On Tue, 6 Nov 2007, John Caron wrote:


The other possibility is caching in your browser. It can be tricky to

be absolutely sure you are getting a fresh copy. I like using the "Live
HTTP Headers" plugin for firefox. But perhaps Shift-Refresh might work
also. An independent test is the ToolsUI application, which never caches:




http://www.unidata.ucar.edu/software/netcdf-java/v2.2/webstart-dev/index.html


If you still see the problem, then it is caching on the server. It

occurs to me that "overwriting the file" may be the problem. You should
be writing a new file, and deleting the old. What exactly are you doing?


Roy Mendelssohn wrote:

Hi jean: '

My guess is you are getting the cached information, which hasn't been
updated.  You can set the frequency of update in the catalog xml
file.  Also, usually if you touch the file  (i.e. do something that
causes to Thredds to access the data( that  usually also updates the
info.

-Roy M.


On Nov 5, 2007, at 4:51 PM, Jean.C.Newman@xxxxxxxx wrote:


I have a set of netcdf files that are being accessed via OpenDAP
and are
regularly overwritten. Most of the files, 29 sets of 31, update
correctly
but in 2 file sets the "Global Attributes" don't update to the new
information although the "data" does. "ncdump -h" shows the correct
information, :history = "MOST v2.080 11-05-2007  16:09:22" ;
              :title = "Aleutian-Cascadia: Mwt 8.4, 21.00*b65" ;
  in the headers but when I look at it in a browser,
http://sift.pmel.noaa.gov/thredds/dodsC/data/crescent_runup_ha.nc.html
I see the old file attributes,
history: "MOST v2.080 11-05-2007  11:49:33"
title: "Aleutian-Cascadia: Mwt 8.5, 29.00*b25".
If I restart tomcat then the correct information shows up.
I'm new at thredds so I may very well be doing something stupid but I
could find no information. Below is the change I made to
$tomcat_home/content/thredds/catalog.xml. Any suggestion?
Thank you, Jean
<service name="ncdods" serviceType="OpenDAP" base="/thredds/dodsC/" />
   <datasetScan name="MOST tsunami model data" ID="mostDatasetScan"
        path="sims" location="/home/tg15/data/sims"
serviceName="ncdods">
     <metadata inherited="true">
       <serviceName>ncdods</serviceName>
     </metadata>
     <filter>
       <include wildcard="*.nc"/>
     </filter>
     <sort>
       <lexigraphicByName increasing="true" />
     </sort>
   </datasetScan>
  ___________________________________________________________
   Jean Newman                             Tel: 206-526-6531
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**********************
"The contents of this message do not reflect any position of the U.S.
Government or NOAA."
**********************
Roy Mendelssohn
Supervisory Operations Research Analyst
NOAA/NMFS
Environmental Research Division
Southwest Fisheries Science Center
1352 Lighthouse Avenue
Pacific Grove, CA 93950-2097

e-mail: Roy.Mendelssohn@xxxxxxxx (Note new e-mail address)
voice: (831)-648-9029
fax: (831)-648-8440
www: http://www.pfeg.noaa.gov/

"Old age and treachery will overcome youth and skill."



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