J2EE development is split into the following parts. The J2EE development will usually go through these parts in the order they are specified here.
Ў EJB Module
Ў Web Module
Ў Enterprise Application
An EJB Module DC contains the model classes (i.e. message driven bean, Container-Managed Persistence (CMP) Bean, Bean-Managed Persistence (BMP) Bean, stateful session bean or stateless session bean) for an Enterprise Application DC.
When you create an EJB Module DC, the SAP NetWeaver Developer Studio will automatically create a public part for assembly that contains the classes for the beans and a public part for compilation that contains the bean interfaces. You should not modify automatically generated public parts.
"Public part" does not automatically mean that a jar-file is produced.
Compiled classes that can be used by an EJB Assembly DC.
EJB ModuleDCs are best handled using the J2EE DC Explorer in the J2EE Perspective.
A Web Module DC contains the files that belong to the view (and view-controller) part of an enterprise application project, such as JSPs, Servlets and Proxy classes for beans defined in an EJB project.
Since a Web DC usually depends on the public interfaces of one or more EJBs you simply add the EJB Module DCs to the Web DCs "Used DCs".
A war file.
Web DCs are best handled using the J2EE DC Explorer in the J2EE Perspective.
An Enterprise Application DC combines Web Module DCs and EJB Module DCs into an enterprise application. The product of an Enterprise Application DC is a deployable EAR file (Enterprise Application Archive).
There's not much work to do in an Enterprise Application. Basically you just reference public parts (purpose assembly) of EJB Module DCs and Web Module DCs and edit the deployment descriptor if necessary.
An ear-file containing the WAR-file(s) from the Web Module DCs and the EJB files from the EJB Module DCs.
Enterprise Application DCs are best handled using the J2EE DC Explorer in the J2EE Perspective.