"WHAT IS AN ENTERPRISE APPLICATION? What is a portal? How do I build all the configuration files that are required for enterprise applications? How do I put all the pieces together?" These may be some of the questions that you are asking yourself. If so, rest assured-WebLogic has gone a long way to make this process easier and more manageable.

This chapter is the starting point for putting it all together. By the end of this chapter, you will have a working enterprise application running in the WebLogic Portal Server. Although this application will be an admittedly simple one, it will feature many of the common components that your Web applications require. This chapter is meant to give you the big picture. Here we explain the architecture of WebLogic Portal applications. We review key portal concepts and the physical implementation of these concepts including directory structures and configuration files used in aWebLogic Portal application. We also discuss the steps to creating a portal application.

WebLogic Portal Architecture

In this section, we discuss several key concepts that will enable you to understand the context in which aWebLogic Portal application will run. Each portal Web application may have one or more components used to implement the functionality for the portal. These components may include portlets, Java classes, Enterprise JavaBeans (EJBs), etc.

An enterprise application is the highest-level component that can be contained within a portal domain. A portal Web application must be deployed within an enterprise application. One or more portal Web applications may be deployed in the context of an enterprise application. In turn, one or more enterprise applications may be deployed in a portal domain.

As we mentioned in the previous chapter, a portlet is the component of a portal Web application that is used to build functionality into your application. In this chapter, we show you how to build your first portlet and deploy it in the sample portal application.

WebLogic Domains

Any discussion of the architecture of aWebLogic Portal must include the concept of domains. A portal domain is one implementation of aWebLogic Domain.

AWebLogic Domain is a grouping of applications, application components, JDBC connection pools, servers, and other objects. What items or objects are placed under the umbrella of a portal domain is a matter to be determined by the portal architect; however, certain items must be considered when designing a domain implementation:

• If an application is deployed within a certain domain, all objects or components used by that application must also be deployed in the same domain.
• If you configure a cluster within a portal domain, all servers in the cluster must be configured as a part of the portal domain.

WebLogic Domain configurations are managed and monitored using aWebLogic Administration Server. You may run your applications on the Administration Server, and for the purposes of the examples in this book that is what we will do. For production environments, however, it is recommended that you run your Administration Server on a separate machine. WebLogic Administration Servers are the central point for managing and monitoring aWebLogic Domain configuration.

The physical implementation of aWebLogic Portal Domain is constructed in the following way.

WebLogic Portal Domain configuration information and other required files are stored in the root directory for the portal domain on the Administration Server.