Java Data Objects

Chapter 17. J2EE Application Servers

Application servers provide a reliable, scalable, and secure environment in which applications execute. In the Java context, an application server is a platform that implements the J2EE (Java 2 Enterprise Edition) contracts to support applications.

Because of security concerns, many web sites do not allow servers directly facing the Internet to handle business transactions directly. Instead, web servers delegate the more important transactions to an application server isolated from the Internet by firewalls and/or additional layers of code. This architecture minimizes the threat of attacks on the core business infrastructure.

Application servers provide functionality defined strictly by the J2EE platform, typically a superset of functionality provided by web servers. In addition to supporting applications written to the Servlet and JSP contracts, application servers support the EJB (Enterprise JavaBeans) architecture, allowing application-server components to be written as distributed objects. Trusted clients and servlets and JSP pages running in the same or different servers can access these objects directly.

An application server that implements the J2EE contracts also provides a number of services required by applications. There are many more services available, but the following are the most important from the JDO developer’s viewpoint:

JDBC

Provides access to datastores via a standard protocol.

JNDI (Java Naming and Directory Interface)

Provides ...