Ethan Davis wrote:
Hi Stéphane,
Stéphane wrote:
Stephane:
Sorry, but I don't have any knowledge about grib generation!
Ethan:
My grib data is stored in a database, in a specific format.
The script extract the data from my database and is able to perform
specific action, like sub grib extraction.
I think the good way is to trigger the script on demand from Thredds.
But I don't see any way to do call external program from Thredds ?
The TDS does not currently have a way to call a script or access a
database for data retrieval. Besides extracting some data by hand and
then configuring the TDS to serve that data, the only things that come
to mind involve writing some Java code. If that is something you are
interested in, take a look at the following two possibilities:
1) The thredds.servlet.DatasetSource interface which provides
implementations with information from the incoming HTTP request and
response objects that can then be used to locate/build and return a
netCDF dataset. The TDS Reference Document discusses the DatasetSource
interface at the following link:
http://www.unidata.ucar.edu/projects/THREDDS/tech/reference/DatasetSource.html
2) The ucar.nc2.iosp.IOServiceProvider interface can be implemented to
read new data formats and represent them through the netCDF-Java API as
a netCDF dataset. The netCDF-Java Tutorial has a section on the I/O
Service Provider interface:
http://www.unidata.ucar.edu/software/netcdf-java/tutorial/index.html
Hope that is helpful.
By using the DataSource and IOSP plugins to TDS we are able to run
external programs to create data files on-demand and serve them via
TDS. If you decide that you want to undertake the job of writing of
some Java code to implement a similar process you might want to take a
look at our code. Creating sub-classes of the Task and Tool classes to
run your particular scripts or external programs might save you some
work.
Some details can be found here:
http://ferret.pmel.noaa.gov/LAS/documentation/the-ferret-thredds-data-server-f-tds.
Slides from a talk about F-TDS are here:
http://go-essp.gfdl.noaa.gov/2008/files/Roland-Schweitzer-GO-ESSP_09_2008.ppt.
There's a better talk (more general and not as focused on server-side
functions) on the OPeNDAP developers wiki, but it seems to be down at
the moment.
Roland
Ethan
On Tue, Jun 2, 2009 at 6:59 PM, Ethan Davis <edavis@xxxxxxxxxxxxxxxx
<mailto:edavis@xxxxxxxxxxxxxxxx>> wrote:
Hi Stéphane,
Where is the GRIB data and what is the script doing to copy/move the
data into your directory?
Ethan
Stéphane wrote:
> Hello,
>
> I access a set of grib data from a script.
> I would like to offer these data through Thredds server.
>
> I success to manualy extract a grib with my script, put it in a
> directory and then access it through Thredds. It works fine !
> But now, I would like that Thredds server automatically call my script
> to extract the data.
>
> Is there any way to do that ?
>
> Thanks a lot,
> Stéphane
|
