grid data sources


I'm trying to modify IDV to retrieve a catalog of gridded data and then the
gridded data itself from a specific web service.  This catalog and retrieval
would look quite similar to the current IDV Catalog chooser.

My question is: Is there a way to create a GridDataSource without a .nc file?
It appears that once a user chooses a model and time and clicks Add Source, IDV
creates a DataSource of type GridDataSource and retrieves a .nc file from the
ucar server.  This Data Source is then used to display all the available 2D and
3D parameters and forecast times in the Data Selector window, and the same data
source is also used when creating the display.  Is that correct?

The issue is that from the web service I will only be receiving XML.  The XML
document would describe the grid data, including parameters and forecast times.
But the actual .nc file will not be available until the final step of Create
Display, and it seems that IDV needs the .nc file for a grid data source at the
step of Add Source in the Chooser window.

I have no intention of heavily modifying the baseline of IDV, I'm only adding
functionality on top of it.  I'm just interested in knowing if there's something
I'm missing or not understanding about DataSources for gridded data and how they
are used to fill the Data Selector window and then create a display.

On an unrelated note, nice easter eggs.  ;)

And just out of curiousity, does anyone know of any active work on enabling IDV
to read GriB files directly?

Any knowledge on IDV's handling of DataSources for gridded data is much