InfoCenter Home > 4.7.2: J2EE application client programming modelThe J2EE application client programming model provides the benefits of the J2EE platform for the Java client application. The J2EE platform offers the ability to seamlessly develop, assemble, deploy and launch a client application. The tooling provided with the WebSphere platform supports the seamless integration of these stages to help the developer create a client application from start to finish. When a client application is developed using and adhering to the J2EE platform, the client application code is portable from one J2EE platform implementation to another. The client application package might require redeployment using each J2EE platform's deployment tool, but the code that comprises the client application will not change. The J2EE application client runtime supplies a container that provides access to system services for the client application code. The client application code must contain a main method. The application client runtime invokes this main method after the environment is initialized and runs until the Java virtual machine is terminated. The J2EE platform allows the J2EE application client to make use of "nicknames" or "short names," defined within the client application deployment descriptor. These deployment descriptors identify EJBs or local resources (JDBC, JMS, JavaMail and URL) for simplified resolution through the use of JNDI. This simplified resolution to the EJB reference and local resource reference also eliminates changes to the client application code when the underlying object or resource either changes or moves to a different server. Should these changes occur, the J2EE application client might require redeployment. The J2EE application client also provides for initialization of the runtime environment for the client application. This initialization is unique for each client application and is defined by the deployment descriptor. In addition, the J2EE application client runtime provides support for security authentication to the EJBs and local resources. The J2EE application client makes use of the RMI-IIOP protocol. The use of this protocol enables the client application to access EJB references and to make use of CORBA services that are provided by the J2EE platform implementation. Use of the RMI-IIOP protocol and the accessibility of CORBA services assist users in developing a client application that requires access to both EJB references and CORBA object references. When users combine the J2EE and CORBA environments or programming models in one client application, they need to understand the differences between the two programming models, and they must use and manage each appropriately. The following table describes the advantages and disadvantages of the J2EE application client.
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