Packaging and Deployment

Now that we've looked at the different J2EE services supported by WebLogic and how your application components can take advantage of them, we turn our attention to how the different application components ought to be packaged and deployed. J2EE requires a number of different deployment descriptor files, and WebLogic adds its own set too. In this chapter, you will learn how WebLogic's tools help you to generate and edit the XML deployment descriptors needed for your J2EE modules. We also look at how to package enterprise applications, web applications, EJB modules, and any J2EE connectors your application may require.

Once your applications are packaged appropriately, you need to deploy them. WebLogic supports a two-phase deployment strategy wherein your application is first distributed to the servers. Your application then is checked during a prepare phase on each server, after which it is activated. You will learn about WebLogic's two-phase deployment, and the various staging modes that determine how an application is distributed to the different server instances in your domain. In addition, we look at how WebLogic's support for auto-deployment eases development and deployment during the development stages of your application. We also explore the various deployment tools that enable you to deploy an enterprise application (and its modules) to WebLogic, and how you can specify the order in which the different application modules ought to be deployed.

In order to correctly deploy the different J2EE modules within an enterprise application, you also need a good understanding of WebLogic's classloader hierarchy. We provide you with a firm grasp of WebLogic's classloading features and its impact on class visibility, the deployment of utility classes, and call-by-reference. We also discuss vital considerations for when you need to deploy applications in different situations for example, application deployment in a single-server environment, a multi-server domain, and a clustered environment.

Finally, we illustrate WebLogic's split development directory approach, which eases the development and deployment of enterprise applications on a single WebLogic instance. It comes complete with Ant tasks for building, deploying, and packaging applications.