Help Section
This help section will guide you when you encounter some problems using the NetLearn system.
1. Make sure that your browser supports java plug-in in order to run the applet properly.
2. Make sure that you have the latest version of JRE installed in
your computer. It is recommended to have JRE version 1.6.0_05
(or higher).
The applet may fail to initialize if you are using an older version of JRE.
To check the JRE version of your computer (for WIndows OS):
Click the "Start" button, select "Run" in the Start Menu, then type in "cmd".
The command prompt will show up, then type in "java -version".
The system should respond by showing the version of JRE which is installed in
your computer. Below is one example of the windows prompts display.
Here some links to download the newest JRE version:
http://www.filehippo.com/download_java_runtime/
http://mindprod.com/jgloss/jre.html
http://java.sun.com/javase/downloads/index.jsp
3. Make sure that your browser allows pop-up windows.
4. Make sure that you select "yes", when the browser asks your permission to accept the NetLearn certificate.
5. If the applet is still failed to initiate, please check the
error message in the java console and refer to the problem/solution section below.
Hint: How to open the java console?
- Point the mouse cursor to the applet area, use right click mouse and
choose the java console from the available options.
- For IE browser. On your browser, click: Tools --> Sun Java Console.
- For Mozilla Firefox browser. On your browser, click: Tools --> Java Console.
- For Netspace browser. On your browser, click: Tools --> Web Development --> Java Console.
Failed to Initiate The Applet
1. Problem: your browser does not allow access to the NetLearn database.
This error message will show when you open the java console windows:
java.security.AccessControlException: access denied (java.net.SocketPermission beuys.informatik.rwth-aachen.de resolve)
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.checkConnect(Unknown Source)
at java.net.InetAddress.getAllByName0(Unknown Source)
...........
...........
Solution:
These steps below will not harm your computer. It permits your browser to access the database server to let
the applet work properly.
If you have the latest version of JRE (1.6.0_05 or higher) and your browser
supports java plug-in, but you still cannot not see the graph (the applet
is not initiated), you have to configure your java policy file.
Please follow these steps:
- Find the location where your JRE is installed, usually it is installed in: "C:\Programme\Java\jre1.6.0_05\" or the similar location like "C:\Program Files\Java\jre1.6.0_05\"
- Go to the folder security inside the java folder "C:\Programme\Java\jre1.6.0_05\lib\security"
- Open the "java.policy" file using wordpad or notepad. Add these two lines:
permission java.net.SocketPermission "beuys.informatik.rwthaachen.de", "resolve"; permission java.net.SocketPermission "137.226.232.6:50003", "connect,resolve"; - The content of the "java.policy" file after the two lines commands addition (pay attention on where you should put the two lines commands addition, please take a look at the example below):
- save your "java.policy" file.
- Make sure that you have closed all your browsers (IE, Firefox, Netscape, etc.) before trying to re-launch the NetLearn system.
- Start your browser again, and run the applet in the NetLearn system. Now you can have access to the database and are able to see the graph inside the applet.
2. Problem: your browser does not have enough space to load the applet.
This error message will show when you open the java console windows:
java.lang.OutOfMemoryError: Java heap space
at expertisefinding.keywordcommunity.KeywordRelatedGraph.buildGraph(KeywordRelatedGraph.java:323)
at expertisefinding.keywordcommunity.KeywordRelatedGraph.
Solution: Please close all the browsers that you have opened. Re-launch the
browser to load the graph.
