Since each application or individually deployed module class loader universe is isolated, an application or module cannot load classes from another application or module. This prevents two similarly named classes in different applications from interfering with each other.
To circumvent this limitation for libraries, utility classes, or individually deployed modules accessed by more than one application, you can include the relevant path to the required classes in one of these ways:
Packaging the Client JAR for One Application in Another Application
Using the System class loader or Common class loader requires a server restart and makes a library accessible to any other application or module across the domain.
To use the System class loader, do one of the following, then restart the server:
Use the Admin Console. Select the Application Server component, select the JVM Settings tab, select the Path Settings tab, and edit the System Classpath field. For details, click the Help button in the Admin Console.
Edit the system-classpath attribute of the java-config element in the domain.xml file. For details about domain.xml, see the Sun Java System Application Server Platform Edition 9 Administration Reference.
Using the System class loader makes an application or module accessible to any other application or module across the domain.
To use the Common class loader, copy the JAR files into the domain-dir/lib directory or copy the .class files into the domain-dir/lib/classes directory, then restart the server.
Using the Common class loader makes an application or module accessible to any other application or module across the domain.
For example, using the Common class loader is the recommended way of adding JDBC drivers to the Application Server. For a list of the JDBC drivers currently supported by the Application Server, see the Sun Java System Application Server Platform Edition 9 Release Notes. For configurations of supported and other drivers, see Configurations for Specific JDBC Drivers in Sun Java System Application Server Platform Edition 9 Administration Guide.
By packaging the client JAR for one application in a second application, you allow an EJB or web component in the second application to call an EJB component in the first (dependent) application, without making either of them accessible to any other application or module.
As an alternative for a production environment, you can have the Common class loader load the client JAR of the dependent application as described in Using the Common Class Loader. Restart the server to make the dependent application accessible across the domain.
Deploy the dependent application.
Add the dependent application’s client JAR file to the calling application.
For a calling EJB component, add the client JAR file at the same level as the EJB component. Then add a Class-Path entry to the MANIFEST.MF file of the calling EJB component. The Class-Path entry has this syntax:
Class-Path: filepath1.jar filepath2.jar ...
Each filepath is relative to the directory or JAR file containing the MANIFEST.MF file. For details, see the Java EE specification.
For a calling web component, add the client JAR file under the WEB-INF/lib directory.
If you need to package the client JAR with both the EJB and web components, set delegate="true" in the class-loader element of the sun-web.xml file.
This changes the Web class loader so that it follows the standard class loader delegation model and delegates to its parent before attempting to load a class itself.
For most applications, packaging the client JAR file with the calling EJB component is sufficient. You do not need to package the client JAR file with both the EJB and web components unless the web component is directly calling the EJB component in the dependent application.
Deploy the calling application.
The calling EJB or web component must specify in its sun-ejb-jar.xml or sun-web.xml file the JNDI name of the EJB component in the dependent application. Using an ejb-link mapping does not work when the EJB component being called resides in another application.
You do not need to restart the server.