0.35.1: What are deployment descriptors?

A deployment descriptor contains configuration data that the run-time environment uses for an application. A deployment descriptor can include information about the following:

Deployment descriptors are XML files packaged with the application's files in a Java archive file. A J2EE application contains one application-level deployment descriptor file, governing the application as a whole. It also contains several component-level deployment descriptors, one for each module in the application. The values of the application-level deployment descriptor file override any values at the component level.

Deployment descriptors also include information on binding and IBM extensions. Binding information is required by the application server to bind the deployment information specified in the application to a specific instance. For example, it may map a logical name of an external dependency or resource to the actual physical JNDI name of the resource. It also may map security role information to a set of groups/users. IBM extensions are additions to the standard descriptors for J2EE applications, Web applications, and enterprise beans. The extensions enable Enterprise Edition or legacy (older) systems to work in the WebSphere Application Server environment. They are also used to specify application behavior that is vendor specific, undefined in a current specification, or expected to be included in a future specification. Both binding and extension descriptors are stored in XMI files.