Deployment Descriptor

A deployment descriptor ( loosely translated "Use Description" ) is a configuration file in XML format. In the context of the Java Platform, Enterprise Edition, this configuration file describes the specific deployment process (English deployment ) and to require information such as:

• Name, class and interfaces of an Enterprise JavaBean (EJB )
• Information about whether certain methods may be invoked under certain types of transactions or must
• References to resources that must be provided by the bean container, such as data sources
• References to other EJBs or Web services
• Optionally define the endpoints of Web services, as the EJBs to be offered
• For entity beans with container -managed persistence, the name of their abstract schema and the definition of its persistent fields and relationships between them; also queries can be defined for certain search methods (so-called Finders )

In addition to these standard features EJB container define additional container -specific properties. At the time of installation, these properties can be specified depending on the container in different ways - in Java properties files, XML files, or interactive. The information can be used during deployment or at runtime.

In Java Web applications deployment descriptor web.xml must bear the name and be located in the WEB-INF directory to the root directory of the Web application. In Java EE applications, the deployment descriptor must be named application.xml and located in the META-INF directory of the enterprise archive ( " EAR " ) are located.