Java Reference
In-Depth Information
• Web modules, which contain servlet class files, web files, supporting class files,
image and HTML files, and, optionally, a web application deployment descriptor.
Web modules are packaged as JAR files with a
.war
(web archive) extension.
• Application client modules, which contain class files and, optionally, an applica-
tion client deployment descriptor. Application client modules are packaged as JAR
files with a
.jar
extension.
• Resource adapter modules, which contain all Java interfaces, classes, native lib-
raries, and, optionally, a resource adapter deployment descriptor. Together, these
implement the Connector architecture (see “
Java EE Connector Architecture
” on
page
30
) for a particular EIS. Resource adapter modules are packaged as JAR files
with an
.rar
(resource adapter archive) extension.
Development Roles
Reusable modules make it possible to divide the application development and deployment
process into distinct roles so that different people or companies can perform different parts
of the process.
The first two roles, Java EE product provider and tool provider, involve purchasing and
installing the Java EE product and tools. After software is purchased and installed, Java
EE components can be developed by application component providers, assembled by ap-
plication assemblers, and deployed by application deployers. In a large organization, each
of these roles might be executed by different individuals or teams. This division of labor
works because each of the earlier roles outputs a portable file that is the input for a subse-
quent role. For example, in the application component development phase, an enterprise
bean software developer delivers EJB JAR files. In the application assembly role, another
developer may combine these EJB JAR files into a Java EE application and save it in an
EAR file. In the application deployment role, a system administrator at the customer site
uses the EAR file to install the Java EE application into a Java EE server.
The different roles are not always executed by different people. If you work for a small
company, for example, or if you are prototyping a sample application, you might perform
tasks in every phase.
Java EE Product Provider
The Java EE product provider is the company that designs and makes available for pur-
chase the Java EE platform APIs and other features defined in the Java EE specification.
Product providers are typically application server vendors that implement the Java EE
platform according to the Java EE 6 Platform specification.
