A software provider packages an application or module into a archive file. To deploy the application or module, specify the archive file name. The content and structure of the archive file is defined by the specifications of the J2EE platform. Types of J2EE archive files are as follows:
Web Application Archive (WAR): A WAR file consists of Web components such as servlets and JSPs, as well as static HTML pages, JAR files, tag libraries and utility classes. A WAR file name has the .war extension.
EJB JAR: The EJB JAR file contains one or more enterprise beans, the components used for EJB technology. The EJB JAR file also includes any utility classes needed by the enterprise beans. The name of an EJB JAR file has the .jar extension.
J2EE Application Client JAR: This JAR file contains the code for a J2EE application client, which accesses server-side components such as enterprise beans via RMI/IIOP. In the Administration Console, a J2EE application client is referred to as an “application client.” The name of the J2EE application client JAR file has the .jar extension.
Resource Adapter Archive (RAR): A RAR file holds a resource adapter. Defined by the J2EE Connector Architecture specifications, a resource adapter is a portable component that enables enterprise beans, Web components, and application clients to access resources and foreign enterprise systems. A resource adapter is often referred to as a connector. A RAR file name has the .rar extension.
The software provider might assemble an application into a single EAR file or into separate WAR, EJB JAR, and application client JAR files. In the administration tools, the deployment pages and commands are similar for all types of files.