Application assembly and J2EE applications

Application assembly is the process of creating an Enterprise Archive (EAR) file containing all files related to an application, as well as an XML deployment descriptor for the application. This configuration and packaging prepares the application for deployment onto an appserver.

EAR files are comprised of the following archives:

• Enterprise bean (JAR) files (known as EJB modules)
• Webapp (WAR) files (known as Web modules)
• Application client (JAR) files (known as client modules)
• Resource adapter (RAR) files (known as resource adapter modules)

Ensure that modules are contained in an EAR file so that they may be deployed onto the server. The exceptions are WAR modules, which you can deploy individually. Although WAR modules can contain regular JAR files, they cannot contain the other module types described previously.

The assembly process includes the following:

• Selecting all of the files to include in the module
• Creating a deployment descriptor containing instructions for module deployment on the appserver.

  As you configure properties using the Application Assembly Tool (AAT), the tool generates the deployment descriptor for you. While the AAT graphical interface is recommended, you can also edit descriptors directly in your favorite XML editor.

• Packaging modules into a single Enterprise archive (EAR) file, which contains one or more files in a compressed format

For more information on specific J2EE specifications, see AAT: Resources for Learning.