A J2EE application in exploded archive format is a J2EE application in which the J2EE application entities, such as EJB and servlets, are stored outside the J2EE server. The following figure shows an overview of a J2EE application in the exploded archive format.

Figure 1-6 Overview of J2EE applications in exploded archive format

To execute a J2EE application in the exploded archive format, you use WTP to generate the programs in a directory and file structure called the application directory that follows certain fixed rules, and then deploy the application as is.

After the J2EE application is deployed in the exploded archive format, WTP monitors the deployed J2EE application on the J2EE server and when the application is updated, such as when a file is updated, reloads the application automatically (reload functionality). Operations such as stopping, deleting, and importing the J2EE application, are not required.

J2EE applications in the exploded archive format can also be shared among multiple clusters. The J2EE application entity exists outside the J2EE servers and is referenced from each cluster, so when programs are revised, the changes can be applied to all the clusters in one update operation.

Note that you cannot make the following changes for J2EE applications in the exploded archive format already deployed on the J2EE server:

• Adding EJB-JAR and WAR files
• Deleting EJB-JAR and WAR files
• Adding JAR^# libraries
• Deleting JAR^# libraries

#

JAR file (.jar) with lower case extension, excluding the files defined below the <module> tag of the DD (application.xml) of a J2EE application. You can commonly use the library JAR from the J2EE components of a J2EE application.

When you perform these changes, you must delete the J2EE application on the J2EE server, and then re-deploy the application.

With the exploded archive format, WTP creates an application directory that includes an EJB-JAR directory and WAR directory. This section describes the configuration of J2EE applications deployed in the exploded archive format.

Note that if you use Eclipse to develop a J2EE application, Eclipse automatically creates the J2EE application directory and subdirectories in the exploded archive format, so you need not be concerned about the configuration. The following figure shows an example of the application directory configuration.

Figure 1-7 Example of the application directory configuration

The following is the configuration of the EJB-JAR and WAR directories included in the application directory:

• EJB-JAR directory
  The EJB-JAR directory includes the following files:
  
  • Enterprise Bean
  • DD (for the EJB-JAR directory)
• WAR directory
  The WAR directory includes the following files:
  
  • JSPs
  • Servlets
  • DD (for the WAR directory)