Chapter 7 Creating Enterprise JavaBeans Components

Deploying the component classes

If you are creating components from scratch in Jaguar Manager, you must follow the steps in this section to deploy the component class and other classes that it depends on. If you deploy from PowerJ, PowerJ performs these steps for you. If you are using another EJB development tool that can export EJB JAR files, import the EJB JAR file as described in the EAServer System Administration Guide. If you import an EJB-JAR file that calls EAServer components that are not implemented in the same JAR file, you must list the stub classes for the called components in the custom class list as described below.

EAServer supports hot refresh of components by using a Java class loader. This feature speeds the development process by allowing you to deploy new class versions without restarting the server. Repeat the steps below to deploy new versions of your implementation.

In a production environment, you may wish to disable refresh to improve performance. See "Disabling component Refresh" for details.

Deploying EJB component classes

Deploy the component class files, stub and skeleton files, and other classes required by the implementation to EAServer. For example, you may need to copy stubs for user defined types and utility classes that are in your component's package.

If deploying class files, place each class in their respective java/classes package subdirectories. If deploying a JAR file, place it in the java/classes subdirectory.

The preferred code base is java/classes For security reasons, it is preferable to deploy Java components to the java/classes subdirectory or some other directory that is not accessible to HTTP downloads. Deploying to this directory also allows your component to be refreshed, and allows you to deploy classes in JAR files without reconfiguring the server's CLASSPATH environment variable. If you deploy to another location, make sure it is listed in the server's CLASSPATH environment variable.
Use Jaguar Manager to configure the component's custom class list, specifying the classes that must be loaded when your component is loaded or reloaded, as described in "The custom class list".
Use Jaguar Manager to refresh the component by highlighting its icon and choosing File | Refresh. You can also refresh the component by refreshing the package, application, or server where it is installed.

The custom class list To support component refresh, you must specify the custom class list to be loaded when a component is refreshed. The custom class list is configured on the Java Classes tab in the Component Properties window. See Chapter 28, "Configuring Custom Java Class Lists" for more information.

You can also configure a custom class list that is shared by all components in the package, or by all components and Web applications in a server or J2EE application, as described in Chapter 28, "Configuring Custom Java Class Lists"

The custom class list for an EJB component must contain these classes:

Stubs for all components that your component calls. If the called component's classes are loaded in a JAR file, list the JAR file name in the custom class list.
Other classes that your component loads and passes as parameters or return values for intercomponent calls, or passes to clients as method return values and output parameter values.
Classes that extend javax.naming.InitialContext or other javax.naming classes and that are called by your component.

Troubleshooting ClassCastException errors When calling javax.naming.InitialContext.lookup, if you see NamingContext exceptions with root-cause exception ClassCastException, check for the following errors:

You are casting to an incorrect type (check the class name of the object returned by lookup).
Your component has refresh enabled, and the custom class list does not contain some required classes.
Your component has refresh enabled, and calls a component that has refresh disabled or vice-versa.

Disabling component Refresh In a production server, you may wish to disable refresh for Java components to decrease memory use and increase performance. When refresh is enabled, duplicate copies of common Java classes can be loaded for components. When refresh is disabled, you must restart the server in order for it to load a new version of your component class. You can also reduce duplicate in-memory classes by configuring the custom class list at the package, server, or application level as described in Chapter 28, "Configuring Custom Java Class Lists"

Refresh property and intercomponent calls If your component calls another Java component, both must have refresh enabled or both must have refresh disabled.

Disabling refresh

Make sure the code bases for all classes used by your component are in the server's CLASSPATH environment variable. JAR files referenced in the custom class list must be added to the server CLASSPATH setting, or expanded into the java/classes EAServer subdirectory.
Display the Component Properties dialog box, and click on the All Properties tab.
Set the com.sybase.jaguar.component.refresh to false (the default is true).
Restart the server for the changes to take effect.