Under certain circumstances it may be desirable to restrict Java Web Start clients to a certain JVM Version. For example, Java 1.7.0_25 is known to break character-based web start-launched applications in BBj 12.x through BBj 13.01.  

This knowledge base article discusses the steps necessary to prevent Web Start clients from upgrading to Java 1.7.0_25 until you are ready to upgrade to the latest BBj version that resolves this problem.

The are two components to restricting Java Web Start clients to a certain version of Java:

• User version restriction within the JNLP to prevent newer JREs from being used on the web start client.

• Prevent Java updates on the Windows client.

JNLP Version Restriction

BBj Jetty-Configured JNLP

Follow these steps to add version restriction to a JNLP configured to run via the BBj Jetty web server:

1. In Enterprise Manager, select the JNLP Configuration module.

2. Under the JNLP configuration, expand the Resource Section and the Default child node.

3. In the Java Version field, enter the Java version to which you wish to restrict your web start clients. You may either restrict your clients
   — to a specific minor JRE version, for example:  1.6.0_45  
   —-OR
   — to a major JRE version with a ‘*’ wildcard, for example:  1.6* (see Figure 1)

4. Click Save.

Figure 1.  Changing the Java Version in the Enterprise Manager JNLP Configuration module

Version Restriction in Apache or IIS-served JNLPs

For Apache or IIS-served JNLP files, simply add the following property to the JNLP file, under the resources section:

<resources>

   <java version=”1.6*”/>

Preventing Automatic Updates on Windows PCs

Oracle includes automatic updates with JRE installations on Windows PCs. These updates might install a JRE version that is higher than the JNLP version designation. Follow these steps to prevent Oracle automatic JRE updates on the client.

Note:  In Windows Active Directory domains, Java updates may be disabled with Group Policy. See Microsoft Group Policy documentation for instructions on how to accomplish this.

Change Automatic Update Settings

1. Change the Java update settings through the Java Control panel
   o Windows XP: Click Start > Settings > Control Panel
   o Windows 7 and Vista: Click Start > Control Panel

2. Type Java in the Search Control Panel located in the upper right corner.

3. Launch the Java Control Panel by double-clicking on the Java icon. The Java Control Panel appears.

4. Click the Update tab to access the settings.

5. To disable Java Update, deselect the Check for Updates Automatically check box (see Figure 2).
   
   Figure 2.  Disabling Java automatic updates in the Windows Java Control Panel