[thredds] over written file has old global attributes

Tue Nov 6 11:18:21 MST 2007

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
   NOAA Center for Tsunami Research
   NOAA/PMEL/OERD2 - UW/JISAO              FAX: 206-526-6485
   7600 Sand Point Way NE, Bldg. 3    jean.c.newman at noaa.gov
   Seattle, WA 98115-6349               jcn at u.washington.edu
  _________________________. URL: http://nctr.pmel.noaa.gov/
                          (__________________________________

On Tue, 6 Nov 2007, Jean.C.Newman at noaa.gov 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 at noaa.gov 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
>>>> _______________________________________________
>>>> thredds mailing list
>>>> thredds at unidata.ucar.edu
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>>>> www.unidata.ucar.edu/mailing_lists/
>>>
>>> **********************
>>> "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 at noaa.gov (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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