Hi Patrick,
What is the version of the TDS with which you are trying to synch? The
TDS has supported lastModified for quite some time, so it would have to
be a pretty old version to not support it. But that's the first thing
that comes to mind.
You could also try looking at the HTTP "Last-Modified" response headers
you are getting back. You can do this with the wget "--save-headers"
option. Or, in Firefox, by using a plugin like Live HTTP Headers.
John, any chance the file caching in the TDS could be masking a change
to the last modified timestamp?
Ethan
On 5/12/2012 3:13 PM, John Caron wrote:
> On 5/11/2012 7:33 AM, Patrick Brockmann wrote:
>> Hi all,
>>
>> I would like to synchonize some netcdf files available from
>> a THREDDS Data Server with a local repository.
>>
>> I have used the wget command and HTTPServer access from
>> the TDS but it seems that the server does not provide enough
>> or correct informations to use properly the --timestamp option
>> of wget (very useful to synchronize).
>> Read http://www.gnu.org/software/wget/manual/wget.html#Time_002dStamping
>>
>> The method works for an old OPeNDAP server but not with 2 different
>> Thredds Data Servers
>>
>> Try:
>> $ wget -N http://dods.ipsl.jussieu.fr/brocksce/tmp/tyty.txt
>> If you retry you get the message
>> ----> Server file no newer than local file `tyty.txt' -- not retrieving.
>> if the 2 files (input and local) are not the same from date or size, the
>> download is done again.
>> If you modify the file by adding a character, you get
>> ----> The sizes do not match (local 43) -- retrieving.
>> If you apply a touch -t 201106230000 on the file to see what happens
>> ----> Remote file is newer, retrieving.
>>
>> I would like to get the same feature (synchro on date and size) when I
>> download from a TDS/HTTPServer.
>>
>> Any help welcome on this synchronization.
>>
>> Regards
>> Patrick
>>
>
> Hi Patrick:
>
> When compression is enabled, which it often is on a TDS, the
> Content-Length header is not sent, since the response is variable length.
> Apparently wget needs that to synch (?) Seems like it should just use
> Last-Modified.
>
> I dont see a workaround without turning off compression.
>
> John
>
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--
Ethan Davis UCAR Unidata Program
edavis@xxxxxxxxxxxxxxxx http://www.unidata.ucar.edu
