MIT Athena Computing Environment - What Runs Where Web browser Java plugin issues
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What Runs Where
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| What's new? Tips for Using Athena Software Academic Computing locker configuration Web browser Java plugin issues Note on changing window managers |
| # Web browser Java plugin issues In order to use the Java plugin in Firefox, you need to select Edit -> Preferences -> Content, and select Enable Java (for Mozilla this is in Edit -> Preferences -> Advanced; in Netscape select also the Enable Java plugin button). We've had problems with Java plugins in the past. A Java plugin is necessary for applets that require more advanced Java features than are supported by the base Java level incorporated in the browser. We have seen situations where the browser will sometimes recognize the plugin but not at other times, for no evident reason (you can check the plugins by selecting Help -> About Plug-ins in the main Mozilla or Netscape window, or by typing in a URL about:plugins in Firefox). For a plugin to be active, it should appear in the listing of plugins, and the enabled column on the right should say Yes for all features). We've also seen some applets that work with certain plugin versions but break with other ones. Java3d is now supported in the Athena release, and you should be able to view Java3d applets in Firefox and Mozilla without any special configuration setup. ## Firefox/Mozilla plugin use: As of this writing (Athena release 9.4), Firefox is set to use Java and a Java plugin that is part of the Athena release, version 1.5.0_16-b02. However, you can reconfigure it to use a different version from one of the Java lockers by setting the MOZ_PLUGIN_PATH_OVERRIDE environment variable as shown below. The path to the right plugin in each locker in Java versions prior to 1.5 usually follows the form:
    /afs/athena.mit.edu/software/<Java version locker>/distrib/${ATHENA_SYS}/jre/plugin/${ATHENA_SYS}/ns610 (Sun)
    /afs/athena.mit.edu/software/<Java version locker>/distrib/${ATHENA_SYS}/jre/plugin/${ATHENA_SYS}/ns610-gcc32 (Linux)
For example, the following command typed at the Athena prompt would set it to 1.4.2_05 for Linux:
    setenv MOZ_PLUGIN_PATH_OVERRIDE /afs/athena.mit.edu/software/java_v1.4.2_05/distrib/i386_rhel3/jre/plugin/i386_rhel3/ns610-gcc32
Note that ${ATHENA_SYS} refers to the sysname of the Athena release at the time the locker was created; you may need to look in the directory tree to see what it actually is; in older lockers, for Linux, this may be i386_rh9 or i386_rhel3; in recent lockers it will be i386_rhel4. A similar situation applies for Suns. There is an exception: For the Linux 1.4.1-01 plugin the correct path is:
    /afs/athena.mit.edu/software/java_v1.4.1-01/distrib/i386_rhel3/jre/plugin/i386_rhel3/mozilla
For Java 1.5 and later, use path:
    /afs/athena.mit.edu/software/<Java version locker>/distrib/${ATHENA_SYS}/jre/plugin/${ATHENA_SYS}/ns7 (Sun and Linux)
Values of <Java version locker> that should work are: java_v1.4.0_01, java_v1.4.1_01, java_v1.4.2_03, java_v1.4.2_05, java_v1.5.0_18, java_v1.6.0_07, java_v1.6.0_13 (Sun) java_v1.4.1-01 (with variant path noted above), java_v1.4.2_03, java_v1.4.2_05, java_v1.5.0_18, java_v1.6.0_07, java_v1.6.0_13 (Linux) If you put a setenv MOZ_PLUGIN_PATH_OVERRIDE command in your ~/.environment file, this will be set automatically every time you log in. If you need different plugins on Sun and Linux, you can do a conditional test and set it differently depending on platform; an example is below:
     if ($HOSTTYPE == linux) then
      setenv MOZ_PLUGIN_PATH_OVERRIDE /afs/athena.mit.edu/software/java_v1.4.2_03/distrib/i386_rhel3/jre/plugin/i386_rhel3/ns610-gcc32
    else
      setenv MOZ_PLUGIN_PATH_OVERRIDE /afs/athena.mit.edu/software/java_v1.4.0_05/distrib/sun4x_59/jre/plugin/sun4x_59/ns610
    endif
Please note that setting MOZ_PLUGIN_PATH_OVERRIDE may cause Firefox or Mozilla to lose access to other plugins whose locations are set by a related environment variable, MOZ_PLUGIN_PATH, in the Firefox/Mozilla launch script. If this happens and you also need to use those other plugins, you will need to figure out the paths to their locations, and add those paths to MOZ_PLUGIN_PATH_OVERRIDE in a colon-separated list from the path to the Java plugin. Note 8/21/07: there is a known problem with java_v1.6.0 and later Java plugins on Suns- due to a bad interaction with AFS, applets may take a long time to start (up to 5 min.). The only currently known workaround is to use the plugin in a pre-1.6.0 version. Setting correct tags for embedded applets that need to run in multiple browsers is tricky; see this Sun page for advice. Finally, please note that an alternative to viewing applets in a Web browser is to use the appletviewer supplied with the JDK. In this case, you normally load the Web page embedding the applet as a file; also note that the tags enclosing the applet need to be different from the ones used for Web browsers. Users still having problems with our configurations can send questions or comments to the 3partysw@mit.edu mailing list.

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