Difference between revisions of "Troubleshooting/Applet"
(applets blocked per security)
(Jmol Object rather than "applet")
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= Problems running the Jmol
= Problems running the Jmol in a web page =
== The applet does not show up ==
== The applet does not show up ==
Revision as of 19:51, 6 September 2014
- 1 Problems running the Java modality of the Jmol Object in a web page
- 1.1 The applet does not show up
- 1.2 The applet is displayed, but models are not
- 1.3 The applet and model are displayed, but further actions have no effect
- 1.4 The applet is displayed, other problems
- 2 Extracting information from the applet
Problems running the Java modality of the Jmol Object in a web page
The applet does not show up
First of all, wait. Java may take time to load the first time, and the applet must be downloaded. So, please wait for a while.
The applet is blocked by Java security
Applets in the browser may be blocked per Java security policies. In some situations, you just need to give permissions when a dialog requests to do so, but there are diverse setups and may be more difficult to solve.
You can find solutions in Installing and Enabling Java (Proteopedia wiki), which has step by step instructions for both Windows and Mac OS X, and for the 5 most popular web browsers.
As a general advice, if the applets are blocked in your browser you should try updating to the latest Java version from Oracle.
Yellow square with a message
A yellow square is displayed in the place the applet should go, with a message inside.
Read the message. Either you don't have Java installed, or the browser is configured not to use it. Enable Java for the browser or (re)install Java from Oracle's site.
If you are certain that you have Java installed, there is a chance that the problem is related to certain incompatibility between browser (particularly Chrome under Windows) and Jmol versions; the fix is to update the Jmol version used by the page; read more.
Black square with an error
A black square is displayed in the place the applet should go, with a message inside:
Error. Click to get more information. When you click, a dialog opens:
Application error. The application could not execute. Click on 'Details' for more information.
When you click, the Java console opens:
load: class JmolApplet not found. java.lang.ClassNotFoundException: JmolApplet (etc.)
Check if you have forgotten to include a call to
jmolInitialize() in your page's source code.
Instructions for using jmolInitialize() and the Jmol.js library.
Applet disappears in Internet Explorer 9
The applet is displayed, but models are not
First of all, make sure you have set the paths correctly for the model files (paths should be relative to the html page; in special ocasions you may also work with absolute paths).
If models still fail to load, open the Java console (instructions) and look for errors. Most often, the cause is a Java security restriction (keep on reading below).
Java security errors
Java imposes a security policy on applets, designed to avoid web pages to act on your local disk. This implies some restrictions on what files can be opened by the Jmol applet.
The Java security errors related to this will have a format similar to:
FileManager opening file:sample.mol script ERROR: script ERROR: io error reading file:sample.mol: java.security.AccessControlException: access denied (java.io.FilePermission sample.mol read)
The rule of thumb is:
- When the page is run from a local disk, Jmol applet can only open files (load models and scripts) that are in the same folder or below where the applet .jar files are.
- When the page is run from a web server, Jmol applet can only open files that are in the same server.
- However, recent Java versions may block access to files despite been in the same server. Particularly, script files invoked (from controls in the page) after the applet has loaded. If that happens, see the next section, The applet and model are displayed, but further actions have no effect, for a possible fix.
- To overcome any of these limitations, you may use the signed applet, since that will request that the user explicitly gives permission beforehand and then there will be no limits for accessing files.
See also Unsigned vs. Signed Applet & Data Access.
Models do not load in a Mac
Pages run from a local disk in a Mac may fail due to Java security errors when you use Firefox or other Mozilla/Gecko browser. You should use Safari on MacOSX for local pages. On the web, Mozilla browsers do work fine.
Models do not load in Linux
On Debian the Jmol application works fine, but the applet refuses to show the model.
Based on some information about a networking problem of Java.
The applet and model are displayed, but further actions have no effect
- The initial loading of model --and possibly a script-- works.
- Further user-triggered actions, like clicking on buttons, links, menus etc. in the page, do not affect the model.
- Java security error is displayed in the Java console, like this:
FileManager opening http://www.something.com/example.spt ERROR in script: io error reading http://www.something.com/example.spt: java.security.AccessControlException: access denied (java.net.SocketPermission 188.8.131.52:443 connect,resolve) eval ERROR: ----line 1 command 1: script >> "example.spt" <<
The applet is displayed, other problems
Everytime a page gets to the 'jmolApplet()' stage, the httpd logs give lots of errors like:
File does not exist: /var/www/html/jmol-11.8.25/org
Also, Jmol pop-up menu doesn't open and gives more of the same errors in the server log.
It was a problem with the browser (Firefox 3.5.9 on Fedora 11): Firefox was using the OpenJDK runtime environment and the associated IcedTea plugin. Installing Sun's Java and its plugin fixed the problem.
OpenJDK Java must be removed
yum whatprovides java will show you the precise versions to uninstall):
> sudo yum remove java-1.6.0-openjdk-plugin-184.108.40.206-36.b18.fc11.i586 > sudo yum remove java-1.6.0-openjdk-220.127.116.11-36.b18.fc11.i586
Then add the new plugin (the precise file to link may differ):
> cd ~/.mozilla > mkdir plugins > cd plugins > ln -s /usr/java/jdk1.6.0_16/jre/plugin/i386/ns7/libjavaplugin_oji.so
Then open Firefox, select
Tools > Addons, and enable the Java plug-in.
Applet does not respond to controls in page (Mac Safari)
This has been reported in Safari 5.0.1 on Mac OS X 10.6.4.
- The page loads but the applet bails (literally the message bar says the applet bailed)
- The applet loads but clicking on a link that should act on the applet does nthing. Safari may even crash.
The problem was tracked down to the AdBlock extension in Safari. Disabling the extension removes the problem.
Extracting information from the applet
Remember that the unsigned applet cannot read from or write to the local disk. Therefore, file operations are excluded; output cannot go to disk, only to the Script Console and/or the Java Console.
Copying code from the script console
Recent versions of Java (at least 1.6.0_25 and later) prevent text output to Jmol Script Console to be copied and then pasted outside Java.
Possible workarounds for this:
- Some output from Jmol is also displayed in the Java Console. From there, you can copy and then paste outside.
- Select the text in the Script Console and, rather than copying it, drag and drop to a text editor.
See also Copying_and_pasting_scripts.