18. Interactive Tutorial Troubleshooting


db4o interactive tutorial uses Java applets to execute code examples directly in your browser enabling you to see the results immediately during reading.
In order to use the interactive functionality a Java JRE 1.5 or above needs to be installed and enabled in the browser.
Normally this and db4o for java installation is all that is needed to start with the interactive examples. However some system configurations can prevent the examples from running properly.
Use the following check-list to locate and fix the problem:
- JRE1.5 or above should be installed.
- JAVA_HOME environment variable should point to the correct JRE (or JDK).
- The Java control panel should be configured to use the web browser.
- Java security settings have to allow a user to grant permissions to signed content and to grant permission to content from an untrusted authority.
- You should also check that your system firewalls do not block interactive content.


    18.1. Configuring JRE on Windows

    To see whether your browser is configured to use the Java Runtime Environment or not, open the Windows Control Panel and check if the Java icon is present.
    In the Java Control Panel:
    - check that your browser is enabled
    - check that the user is granted permissions to signed content (untrusted authority as well).