J2EE
Digital Bridge J2EE Compliance
- Digital Bridge uses the Tomcat Servlet Container. Apache Tomcat is the Servlet container that is used in the official Reference Implementation for the Java Servlet and JavaServer Pages technologies. [Source: http://tomcat.apache.org].
- The core of the Digital Bridge reference architecture consists of the Model-View-Controller and Command patterns as implemented in the Open Source Struts Framework. Struts is incorporated into the major commercial application servers such as IBM WebSphere and BEA WebLogic. Struts supports upcoming standards-based technology such as JavaServer Faces.
- Digital Bridge has ensured compatibility by making sure that the applications it has developed run under WebSphere. However, since Digital Bridge adheres to J2EE standards the applications would also operate under other application servers, for example the Open Source JBoss Application Server.
Background
(source: http://java.sun.com/j2ee/tutorial/1_3-fcs/doc/Overview2.html#83323)
Multi-tiered distributed application model
The J2EE platform uses a multi-tiered distributed application model. Application logic is divided into components according to function, and the various application components that make up a J2EE application are installed on different machines depending on the tier in the multi-tiered J2EE environment to which the application component belongs. Figure 1-1 shows two multi-tiered J2EE applications divided into the tiers described in the following list.
- Client-tier components run on the client machine.
- Web-tier components run on the J2EE server.
- Business-tier components run on the J2EE server.
- Enterprise information system (EIS)-tier software runs on the EIS server.
Figure 1-1
J2EE Server and Containers
Figure 1-2
Containers are the interface between a component and the low-level platform-specific functionality that supports the component. Before a Web, enterprise bean, or application client component can be executed, it must be assembled into a J2EE application and deployed into its container.
The assembly process involves specifying container settings for each component in the J2EE application and for the J2EE application itself. Container settings customize the underlying support provided by the J2EE server, which includes services such as security, transaction management, Java Naming and Directory Interface
(JNDI) lookups, and remote connectivity:
J2EE server
The runtime portion of a J2EE product. A J2EE server provides EJB and Web containers.
Enterprise JavaBeans (EJB) container
Manages the execution of enterprise beans for J2EE applications. Enterprise beans and their container run on the J2EE server.
Web container
Manages the execution of JSP page and servlet components for J2EE applications. Web components and their container run on the J2EE server.
Application client container
Manages the execution of application client components. Application clients and their container run on the client.
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