3.1 Enterprise Systems

An enterprise Java environment, or WAS environment, is nominally viewed as a three-tier architecture (see Section 2.1.2 on page 25). Clients access the information made available through middle- tier systems, which connect to the back-end enterprise systems, as shown in Figure 3.1.

Figure 3.1. WAS Environment

In an enterprise Java environment, the clients can be both Java based and non-Java based. Clients access the servers over a variety of protocols, including HTTP, IIOP, SSL, and other messaging protocols accessible through JMS. These clients connect to and access a J2EE-based server environment providing a hosting system for the enterprise components. These components constitute a presentation layer in the form of servlets, JSP files, HTML files, or XML documents. Alternatively, the components can abstract out the business logic in the form of enterprise beans. Clients may also submit their requests by using e-mail protocols through the JavaMail framework or connect to naming and directory services by using the Java Naming and Directory Interface (JNDI). In an enterprise environment, middle-tier applications are likely to connect to back-end enterprise information systems (EISs). Examples of back-end EISs include relational database management systems (RDBMSs) and ERP applications.

Before delving into the security implications of this architecturally rich environment, it is important to understand the technologies that comprise a J2EE environment.