After you develop and assemble your application, you can deploy it in your application server. Application deployment involves installing the application files on the application server and configuring the application for the particular operational environment.
The J2EE specification allows you to develop and assemble applications once and then deploy those applications in any J2EE-compliant environment. When you assemble the application, generate a deployment descriptor. A deployment descriptor is an XML file that contains instructions on how to deploy the application, without regard to the operational environment. When you deploy the application, you provide the specific information that is required for the application to run in your environment.
For example, when you develop the application, you can define security roles in the deployment descriptor. When you deploy the application into your application server run time, you map these security roles to specific users or groups that exist in your environment.
The administrative tools that are packaged with WAS allow you to install J2EE applications that are compliant with the J2EE 1.3 specification, the J2EE 1.2 specification, or both.
After you deploy an application, you may decide to change the application. For example, if you want to add a new Web module, assemble the application with the new module. After you assemble the changed application, use the administrative tools to install the changes into the run time. The changed version includes its own deployment descriptor, and may require that you specify additional configuration information. When you deploy the changed version, the administrative tools merge configuration information for both versions.
For information on how to deploy applications, see Install and uninstall applications in the Administration topic.