Experimental Physics and
Industrial Control System

"David Dudley" <[email protected]> · Tue, 15 May 2007 13:18:34 -0500

After putting a bunch more comments in my Applet file, what I find is that the call to JCALibrary.getInstance() completes successfully, but the call to jca.createContext() fails.

My code is:
â-------------------------
			try
			{
				URL codebase=this.getCodeBase();
				String host=codebase.getHost();

				// Get the JCALibrary instance
				jca=JCALibrary.getInstance();

				System.out.println("Instance initialization passed");

				System.setProperty("com.cosylab.epics.caj.CAJContext.addr_list",host);
				System.setProperty("com.cosylab.epics.caj.CAJContext.auto_addr_list","false");

				// Create a thread safe context with default configuration values
				ctxt=jca.createContext(JCALibrary.CHANNEL_ACCESS_JAVA);

				System.out.println("Context creation passed");

				System.setProperty("com.cosylab.epics.caj.CAJContext.addr_list",host);
				System.setProperty("com.cosylab.epics.caj.CAJContext.auto_addr_list","false");

			}
			catch(Exception ex)
			{
				System.err.println("Initialization failed for " + dpm.dataSource+":\n" + ex);
				System.exit(1);
			}
â-------------------------

The console outputs:
Instance initialization passed
Initialization failed for Util1:Tot:KW:
java.security.AccessControlException: access denied (java.util.PropertyPermission com.cosylab.epics.caj.CAJContext.addr_list write)
java.security.AccessControlException: access denied (java.lang.RuntimePermission exitVM.1)
	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.checkExit(Unknown Source)
	at java.lang.Runtime.exit(Unknown Source)
	at java.lang.System.exit(Unknown Source)
	at Applet1.initDPM(Applet1.java:279)
	at Applet1.init(Applet1.java:61)
	at sun.applet.AppletPanel.run(Unknown Source)
	at java.lang.Thread.run(Unknown Source)

Line 279 (the error line) is the line number of the System.exit(1) function call.

ideas??

David Dudley

>>> Kay-Uwe Kasemir <[email protected]> 5/15/2007 12:13 PM >>>

On May 15, 2007, at 12:16 , David Dudley wrote:

> OK, all you JCA and CAJ people, here's a problem for you-
>
> I'm setting up JCA/CAJ to run through an applet.  How do I prevent  
> them
> from *attempting* to find the JCALibrary.properties file?
>
> When an applet tries to find the file, it creates an access security
> exception, since Applets, by nature, can't access the underlying file
> system.
>
> I tried doing System.setProperty commands to set
> 'com.cosylab.epics.caj.CAJContext' to values before the createContext,
> but the moment that createContext is accessed, I get an error.

Interesting.

In jca-2.3.0/src/core/gov/aps/jca/JCALibrary.java
there's this code:

     try {
         InputStream is = JCALibrary.class.getResourceAsStream 
( "JCALibrary.properties" );
         if (is == null)
             throw new RuntimeException("resource not found.");
         _builtinProperties.load( is );
     } catch( Throwable ressourceEx ) {
       System.out.println( "Unable to load default configuration....);
     }

I would think the worst that can happen is a println,
and your System.setProperty calls would actually win.

But maybe that attempt to read a file does worse things
to an applet, something that the catch() doesn't catch?
I'd try to change that code section somewhat to see
what's happening in your case.

-Kay

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System