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[netCDF #VEW-543105]: Problems accessing OPeNDAP URL on this 4.3 TDS with NCDUMP

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  • Subject: [netCDF #VEW-543105]: Problems accessing OPeNDAP URL on this 4.3 TDS with NCDUMP
  • Date: Wed, 21 Nov 2012 13:58:37 -0700
There are two different problems here.

First, there is clearly a bug in the
netcdf-c dap code; I will work on that.

Second, you are seeing a message from
the server:
> Error { code = 500; message = "Variable name (h) must be
> unique within Group "^;};
What is happening is probably this.
The underlying dataset has two variables with the name 'h'.
One is in a group that is a subgroup of the root group.
Something like this:
group G1 {
  float h;
  group G2 {
    float h;
  }
}
The problem occurs when the server tries to shoe-horn
this into the DAP2 data model (which does not have groups).
The algorithm currently in the Thredds server
just flattens the groups, so it attempts to produce this:
  float h;//from G1
  float h;//from G2
This is clearly illegal and it produces the error you saw.
Fixing this is a problem would require changing the
algorithm to produce something like this:
  float h;
  float G2.h;
Unfortunately, this would break every other client
that relies on the current algorithm.

The only solution is to change the underlying dataset
and rename one of the two 'h' variables.

=Dennis Heimbigner
  Unidata


Ticket Details
===================
Ticket ID: VEW-543105
Department: Support netCDF
Priority: Normal
Status: Closed