Chapter 10: Web Applications

Overview

Oracle AS 10g (9.0.4) is J2EE 1.3 compatible and supports web applications based on the Servlet 2.3 and Java Server Pages (JSP) 1.2 specifications, which are both backward compatible to previous versions. Web applications can access all the other resources deployed within OC4J, including Enterprise JavaBeans (EJBs), Java Message Service (JMS) connection factories and destinations, JDBC data sources, and JavaMail sessions. The web application itself may include Servlet classes, JSPs, tag libraries for JSPs, Servlet filters, deployment descriptors and other XML configuration files, and any resources or static content (HTML pages, images, and so on) required by the application.

In addition to the functionality required by the J2EE 1.3 specifications, OC4J supports many additional features that can be configured in an orion-web .xml descriptor. Some of the most useful settings include the ability to override settings in web.xml , additional container-managed security, and automatic caching and content expiration. These features are very useful in a production environment; intelligent content-expiration settings can boost an application's performance.

The orion-web.xml descriptor is placed in the same location ( /WEB-INF ) as the standard web.xml deployment descriptor. This server-specific deployment descriptor, which inherits from a global file of the same format, resolves any references declared in the standard deployment descriptor, such as EJBs, JMS destinations, and security roles, and configures the web container for the application.

Before you get into the nuts and bolts of OC4J deployment descriptor files, let's take a quick look at the basic web development process, including common directory structures, build strategies, and deployment options.