[THREDDS #QNQ-559947]: Ncml at reinit
- To: address@hidden
- Subject: [THREDDS #QNQ-559947]: Ncml at reinit
- From: "Unidata THREDDS Support" <address@hidden>
- Date: Tue, 06 Nov 2007 19:35:11 -0700
> > Why do you need to reload the catalogs? Sorry if I'm forgetting details
> > we've already discussed.
> > Are you aggregating datasets? Is the problem something that the
> > "recheckEvery" attribute on the "aggregation"
> > element won't handle?
> Because our models have different run frequency, some of them make outputs
> each days, others every 3 hours ...
> Actually, we don't use the scan capabilities because we need to generate the
> intermediary ncml parts of the catalogs for
> use in another project, that's why we will generate only statics catalogs
> (all files explicitly defined / no scan).
> Our needs
> We have differents products (models outputs) we would like to put into
> Thredds' catalogs. For each of these products,
> we want to see (access) them througth differents views :
> - A "run view" presenting each files independently, classed by run time =>
> one run == one dataset
> - A "5D view" presenting all the files as one huge dataset with a newly
> created dimension : the run time (aggregation type joinNew)
> - A "best estimate view" made with aggregation type joinExisting :
> For example, we have some netcdf files containing 24 hour of analysis and
> 48 hour of forecast, and
> we want to aggregate only the 24 first hours (analysis time) of each file
> and the last run file entirely (analysis + forecast).
> We succeed to produce these three views, but for a last one, the "forecast
> offset date", we don't know how to do because
> it seems not possible to extract some specified data from a netcdf file, I
> mean for example taking only the values corresponding
> to a specified time value (make a selection of all variables for time=1,
> time=24, time=48 ... to present the data per forecast hour)
That is right. You can't select one coordinate point from a dataset in an
> I know that there is the datasetFmrc capability which in facts generate the
> needed views but unfortunatly, as I wrote above,
> we need static catalogs with as much metadata as possible, and we are not
> able to extract the forecast time from the file names
> for some of our products. (because their name does not belong to the
> datetime marker or the run or forecast time is placed in the
> directory name ...)
I don't understand your metadata restriction. Metadata can be inherited by
lower level collections. So, you can add metadata to the datasetFmrc and it
will be in all the sub-collections. Is there a lot of metadata unique to the
FMRC sub-collections? That is something we have talked about doing but is not
> > We have seen similar issues having to do with the JVM PermGen memory. Are
> you getting "java.lang.OutOfMemoryError: PermGen
> > space" messages? If so, try increasing the PermGen space with the
> Ok, I will try that.
> For the moment (until ncml parts are not reloaded when using
> thredds/debug/reinit), we will restart Thredds from the Tomcat Manager
> interface. I wonder if someone requesting the server at the same time (when
> restarting) would get an error because Thredds is turned off and then on.
Yes, I believe if someone hits when the TDS is turned off they will get an
> Some of the questions I asked in the mail before are reproduced in that
> mail, espacially the "selection of parts of netcdf files",
> do you have an idea about that ?
> (one solution would be to write all the variables, dimensions and values
> directly into the catalog but
> I think it is a really bad solution because of the files size which can be
> greater than 100Mo)
I don't see a solution for this at the moment. Other than writing new netCDF
files with just the desired data in them. But that kind of defeats the purpose
Ticket ID: QNQ-559947
Department: Support THREDDS
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