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Re: Spreadsheet & Remote Data Servers

Thanks Curtis & Dave,

That's pretty cool! [One of the problems I had was using a different version of
visad.jar on the client].

I can now load  up live temerature data in the spreadsheet and see the various
cells update in real time.
However, when I try to do some cell arithmetic, I get unexpected results.
I've verified this with the attached data file temperature.csv which has data in
the form x-> temperature.

Note that the temperature is in degrees Celsius.

I load the file into cell A1, and also into cell B1.
I map x to x and temperature to y, and see the data as expected.
In cell A2, I enter the formula A1d1-B1d1, and do the mappings, and expect to
see a straight line of temperature = 0 degC, but what I actually get is a
straight line of temperature = -273.15 degC

Any ideas?

James.


Curtis Rueden wrote:

> Hi James,
>
> >Can I get the spreadsheet to load data which is available via a remote
> >data server other than the spreadsheet.
> >This remote data server is the usual VisAD RemoteServerImpl which
> >provides  the data  via RemoteDataReferences.
>
> Yes, you can get the SpreadSheet to recognize data from pretty much
> any RMI server, as long as you follow the simple naming conventions.
>
> For an RMI server at my.ip.com, if you name it "MyServer", and the name
> of the DataReference is "DataRef", then you'd access the data object in
> the SpreadSheet using the string:
>     rmi://my.ip.com/MyServer/DataRef
>
> To help you out, I've written a little example that creates a
> RemoteServer and loads a data object into it.  (The source code is
> at the bottom of this email.)  Start it up by typing:
>     java MiniDataServer ServerName DataName dataFile
>
> where ServerName is the desired name for the RMI server, DataName is
> the desired name for the data reference, and dataFile is the name of
> the data file to load up and serve.  Be sure you start up rmiregistry
> before running MiniDataServer.
>
> Then, load up the SpreadSheet and try:
>     rmi://ip.address/ServerName/DataName
> (where ip.address is your machine's IP address) and you should see
> the data in the SpreadSheet cell.
>
> Please let me know if you have any more trouble with this.
>
> Good luck,
> Curtis
>
> -----------------------------------------
> // MiniDataServer.java
>
> import java.awt.event.*;
> import java.net.*;
> import java.rmi.*;
> import javax.swing.*;
> import visad.*;
> import visad.data.*;
> import visad.java2d.DisplayImplJ2D;
>
> public class MiniDataServer {
>
>   public static void main(String[] args) throws Exception {
>     if (args.length < 3) {
>       System.err.println("Please specify three command line arguments:");
>       System.err.println("  - Server name (e.g., MyServer)");
>       System.err.println("  - Cell name (e.g., A1)");
>       System.err.println("  - Data file (e.g., mydata.nc)");
>       System.exit(-1);
>     }
>     String server = args[0];
>     String cell = args[1];
>     String file = args[2];
>
>     // load data
>     System.out.println("Loading " + file + "...");
>     DefaultFamily loader = new DefaultFamily("loader");
>     Data data = loader.open(file);
>
>     // set up display
>     System.out.println("Setting up display...");
>     ScalarMap[] maps = data.getType().guessMaps(false);
>     DisplayImplJ2D display = new DisplayImplJ2D("MiniDataServer");
>     for (int i=0; i<maps.length; i++) display.addMap(maps[i]);
>     DataReferenceImpl ref = new DataReferenceImpl(cell);
>     ref.setData(data);
>     display.addReference(ref);
>
>     // start up remote server
>     System.out.println("Starting remote server...");
>     RemoteServerImpl rsi = null;
>     try {
>       rsi = new RemoteServerImpl();
>       Naming.rebind("///" + server, rsi);
>     }
>     catch (java.rmi.ConnectException exc) {
>       System.err.println("Please run rmiregistry first.");
>       System.exit(-2);
>     }
>     catch (MalformedURLException exc) {
>       System.err.println("Error binding server; try a different name.");
>       System.exit(-3);
>     }
>     catch (RemoteException exc) {
>       System.err.println("Error binding server:");
>       exc.printStackTrace();
>       System.exit(-4);
>     }
>     rsi.addDataReference(ref);
>
>     // set up GUI
>     System.out.println("Bringing up display...");
>     JFrame frame = new JFrame("Mini data server");
>     JPanel pane = new JPanel();
>     pane.setLayout(new BoxLayout(pane, BoxLayout.X_AXIS));
>     frame.setContentPane(pane);
>     pane.add(display.getComponent());
>     frame.addWindowListener(new WindowAdapter() {
>       public void windowClosing(WindowEvent e) { System.exit(0); }
>     });
>     frame.pack();
>     frame.show();
>   }
>
> }

--
James Kelly
Regional Computing and Distributed Systems        Bureau of Meteorology
PO Box 1289K                                  Melbourne 3001, Australia
Phone: 61-3-9669-4724 Fax: 61-3-9669-4128     Email: J.Kelly@xxxxxxxxxx

Attachment: temperature.csv
Description: application/unknown-content-type-excel.csv