component module is the
smallest unit of deployment in the J2EE deployment model. A
module is simply a jar file containing all
of the bits and pieces that define a set of components. Each module
contains components of the same type so that they can be easily
delegated to the containers that handle them.
Each component module is packaged as a jar file with a specific layout for the elements that make up the components. Table 2-2 summarizes the different module jar files and deployment descriptors used for the different J2EE component types:
Table 2-2. Component module format summary
Module jar file suffix
Deployment descriptor filename and location
.rar (“resource archive”)
In addition to the deployment descriptor locations specified Table 2-2, each component module jar file also has a specific file layout that’s required for the elements that make up the components. In a war file, for example, all individual class files included in the module must be placed in the WEB-INF/classes directory, all class libraries are placed in the WEB-INF/lib directory, and so on.
Each component module (except for applet jar files) includes a standard J2EE deployment descriptor. These descriptors are key to the assembly and deployment ...