metalnemesis
May 21st, 2007, 05:45 AM
Hello,
I am having a problem getting extensions to work with the Sun JVM installed from the repositories. Currently, whenever I try to load a class using the javascript Packages object, I get an error like the following:
Packages.org.xmldb.api.DatabaseManager is not a constructor
The extensions I'm trying to use are JAR files distributed with the Exist XML database product that were copied into the jre/lib/ext directory. The JVM extension mechanism simply doesn't seem to work and can't load any classes from any JAR files (including Sun's own extensions) in the extensions directory. This same application works fine with 2000/XP (where I originally wrote it).
According to Sun's documentation, the extensions mechanism is a standard facility within the JVM. There are no documented ways to "turn it off" other than to set the java.ext.dirs system variable to an empty string.
This is what I've tried so far:
1. Launching Firefox from root on the off-chance that it's a permissions issue. Didn't work. Same error.
2. Checked the permissions of the ext directory and each jar file and they are all as expected: root: all access, everyone else: read.
3. From the java console I've verified that the java.ext.dirs system variable points to the jre/lib/ext directory. It does.
4. Tried adding the jars to the classpath. No change.
5. Tried loading a Sun class, sun.net.spi.nameservice.dns.DNSNameService, contained in the dnsns.jar supplied by Sun. Same error,
7. Tried loading a standard java class from rt.jar, java.lang.string("Hello World") and display the java string with alert(). That worked. Hello World pops up in a dialog box. From this I know that LIveConnect is working, that it is able to communicate with the JVM, and that the JVM is responding correctly and returning the correct object.
At this point I'm stumped. This all works smooth as silk on Win2000 and XP. I am using the same extension JAR files as I do on Windows, the same version of the JVM and plugin, 1.5.0.11-b03, the same version of Firefox, 2.0.0.3 (I use Firefox as my default browser on XP as well), and the same javascript code (I'm actually running it directly from a FAT32 partition so I;m literally using the same file that I use on Windows, not a copy). In short, my Windows and Ubuntu setups are identical, yet none of the installed extensions can be loaded when running Ubuntu and everything works fine on Windows.
One other note. In order for this to work properly I have to modify the java.policy file to allow global unrestricted access, so my java.policy file looks like this:
// default permissions granted to all domains
grant {
permission java.security.AllPermission;
};
So the normal restrictions imposed by the standard policy file for javascript do not apply. I obviously do not use this policy file when doing general surfing and use a script to switch the unrestricted and standard policy files back and forth depending on what I'm doing.
I realize that Exist, my custom web app, and the Sun JVM are not official Ubuntu software and therefore, not officially supported. But if anyone else has had problems with extensions that work on Windows but not on Ubuntu and have a fix or workaround, I'd really appreciate your help!
If I can get this app to work, I can FINALLY start using Ubuntu as my everyday desktop and relegate Windows to the "once in a while when I need to" desktop. Thanks in advance for your help!
I am having a problem getting extensions to work with the Sun JVM installed from the repositories. Currently, whenever I try to load a class using the javascript Packages object, I get an error like the following:
Packages.org.xmldb.api.DatabaseManager is not a constructor
The extensions I'm trying to use are JAR files distributed with the Exist XML database product that were copied into the jre/lib/ext directory. The JVM extension mechanism simply doesn't seem to work and can't load any classes from any JAR files (including Sun's own extensions) in the extensions directory. This same application works fine with 2000/XP (where I originally wrote it).
According to Sun's documentation, the extensions mechanism is a standard facility within the JVM. There are no documented ways to "turn it off" other than to set the java.ext.dirs system variable to an empty string.
This is what I've tried so far:
1. Launching Firefox from root on the off-chance that it's a permissions issue. Didn't work. Same error.
2. Checked the permissions of the ext directory and each jar file and they are all as expected: root: all access, everyone else: read.
3. From the java console I've verified that the java.ext.dirs system variable points to the jre/lib/ext directory. It does.
4. Tried adding the jars to the classpath. No change.
5. Tried loading a Sun class, sun.net.spi.nameservice.dns.DNSNameService, contained in the dnsns.jar supplied by Sun. Same error,
7. Tried loading a standard java class from rt.jar, java.lang.string("Hello World") and display the java string with alert(). That worked. Hello World pops up in a dialog box. From this I know that LIveConnect is working, that it is able to communicate with the JVM, and that the JVM is responding correctly and returning the correct object.
At this point I'm stumped. This all works smooth as silk on Win2000 and XP. I am using the same extension JAR files as I do on Windows, the same version of the JVM and plugin, 1.5.0.11-b03, the same version of Firefox, 2.0.0.3 (I use Firefox as my default browser on XP as well), and the same javascript code (I'm actually running it directly from a FAT32 partition so I;m literally using the same file that I use on Windows, not a copy). In short, my Windows and Ubuntu setups are identical, yet none of the installed extensions can be loaded when running Ubuntu and everything works fine on Windows.
One other note. In order for this to work properly I have to modify the java.policy file to allow global unrestricted access, so my java.policy file looks like this:
// default permissions granted to all domains
grant {
permission java.security.AllPermission;
};
So the normal restrictions imposed by the standard policy file for javascript do not apply. I obviously do not use this policy file when doing general surfing and use a script to switch the unrestricted and standard policy files back and forth depending on what I'm doing.
I realize that Exist, my custom web app, and the Sun JVM are not official Ubuntu software and therefore, not officially supported. But if anyone else has had problems with extensions that work on Windows but not on Ubuntu and have a fix or workaround, I'd really appreciate your help!
If I can get this app to work, I can FINALLY start using Ubuntu as my everyday desktop and relegate Windows to the "once in a while when I need to" desktop. Thanks in advance for your help!