Deployment Descriptor

A deployment descriptor or DD in short is a configuration file for an artifact that is deployed to some container/engine.

In the Java Platform, Enterprise Edition, a deployment descriptor contains information about a web application or enterprise application and also includes the information about how the application should be deployed. The deployment tool that deploys a module or application with specific container options is also managed by deployment descriptor. It also describes specific configuration requirements that a deployer must resolve. XML is used for the syntax of these deployment descriptor files. In web applications, the deployment descriptor is called web.xml and resides in a WEB-INF subdirectory at the web application root, while in case of  Java EE applications, the deployment descriptor must be named application.xml and must be placed directly in the META-INF directory at the top level of the application .ear file.

Process deployment descriptor of BPEL-Engine ActiveBPEL is also an example of a deployment descriptor.