RE: how can I open netcdf file in applet?

Dear Monica,

I’m not absolutely sure, but I think the problem lies with the security model of Java applets. I don’t think you’re allowed to load any data from a remote server, except for the server that is hosting the applet itself. Try loading a netCDF file from your web server – it will probably work.

Regards,

Jon

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Dr Jon Blower              Tel: +44 118 378 5213 (direct line)
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From: address@hidden [mailto:address@hidden] On Behalf Of ???
Sent: 09 February 2006 07:12
To: address@hidden
Subject: Fw: how can I open netcdf file in applet?

Dear All :

Sorry, I forget add the srouce code and html file.

Hope it will be help to resolve bugs...

Thank you.

Monica

----- Original Message -----

From: 劉育帆

To: address@hidden

Sent: Thursday, February 09, 2006 3:05 PM

Subject: how can I open netcdf file in applet?

Dear All:
I meet some problem and try two ways to resolve it,

but still can't resolve.

I hope someone can give me the correct resolve ways....

Target :

I want use Applet and NetCDF Java Library (Version 2) to do
1. open the remote netcdf file(http://61.60.103.48:81/g2var1level.nc, the remote file also in same folder with applet class.)
2. print size and data of the Variable("lon" & "lat") which in netcdf file.

I can't get the correct result, but get some error message in Java console :

First way :

I use the function in Applet to open the remote file,
(the function can run in application):

String urlfile = "http://61.60.103.48:81/g2var1level.nc";
NetcdfFile ncfile = NetcdfFile.open(urlfile);

and HTML code use :

First way Error message :

IE version 6.0.2900.2180.xpsp_sp2_gdr.050301-1519
Java Plug-in 1.5.0_06
JRE version 1.5.0_06 Java HotSpot(TM) Client VM

   java.security.AccessControlException: access denied (java.io.FilePermission http:\61.60.103.48:81\g2var1level.nc read)
  at java.security.AccessControlContext.checkPermission(Unknown Source)
  at java.security.AccessController.checkPermission(Unknown Source)
  at java.lang.SecurityManager.checkPermission(Unknown Source)
  at java.lang.SecurityManager.checkRead(Unknown Source)
  at java.io.File.exists(Unknown Source)
  at ucar.nc2.N3iosp.open(N3iosp.java:93)
  at ucar.nc2.NetcdfFile.<init>(NetcdfFile.java:780)
  at ucar.nc2.NetcdfFile.open(NetcdfFile.java:339)
  at ucar.nc2.NetcdfFile.open(NetcdfFile.java:221)
  at ucar.nc2.NetcdfFile.open(NetcdfFile.java:167)
  at ucar.nc2.NetcdfFile.open(NetcdfFile.java:151)
  at MyNetcdfApplet.init(MyNetcdfApplet.java:29)
  at sun.applet.AppletPanel.run(Unknown Source)
  at java.lang.Thread.run(Unknown Source)

Second way :

I change my code in Applet to open the remote file,

String urlfile = getParameter("NCFile");
URL url = "" URL(getCodeBase(), urlfile);

NetcdfFile ncfile = new NetcdfFile(url);

and HTML code use :

Second way Error message :

URL http://61.60.103.48:81/g2var1level.nc
java.security.AccessControlException: access denied (java.io.FilePermission http:\61.60.103.48:81\g2var1level.nc read)
at java.security.AccessControlContext.checkPermission(Unknown Source)
at java.security.AccessController.checkPermission(Unknown Source)
at java.lang.SecurityManager.checkPermission(Unknown Source)
at java.lang.SecurityManager.checkRead(Unknown Source)
at java.io.File.exists(Unknown Source)
at ucar.nc2.N3iosp.open(N3iosp.java:93)
at ucar.nc2.NetcdfFile.<init>(NetcdfFile.java:763)
at MyNetcdfApplet.init(MyNetcdfApplet.java:33)
at sun.applet.AppletPanel.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)

And I didn't sign My applet. Could anyone tell me what keypoint I miss?

(May I need sign it? or not add some import jar file?)

How can I do that My applet can read the remote netcdf file?
The netcdf file also be in My applet class folder.

First way or Second way is better?

Thank you very much~

Monica