Java Message Service

Chapter 8. J2EE, EJB, and JMS

J2EE Overview

Java 2, Enterprise Edition ( J2EE) is a specification that unites several other Java enterprise technologies, including JMS, into one complete platform. J2EE is built on three main components: Enterprise JavaBeans, Servlets, and JavaServer Pages ( JSP). Many other technologies, such as JMS, JDBC, JavaMail, JTA, CORBA, and JNDI. are also included as services in J2EE. The Java Message Service actually has two roles in J2EE: it is both a service and the basis for a new enterprise bean type.

To get a better understanding of what J2EE is, and why it is important, we need to discuss the three main components and explain how they are drawn together to form the unified J2EE platform. It is important to keep in mind that all the technologies discussed here are paper specifications licensed and implemented by vendors—a central theme in Sun Microsystems’ enterprise technologies.

Enterprise JavaBeans

Enterprise JavaBeans (EJB) 2.0 defines a Java component model for component transaction monitors (CTMs). A CTM is a marriage of two technologies: distributed objects and transaction processing monitors (TPMs). Distributed object technologies such as CORBA, Java RMI-JRMP, and DCOM provide a networking and routing infrastructure that allows applications to access objects hosted on other processes or computers. A TPM, such as CICS or TUXEDO, provides a robust, secure, and scalable environment for running transactional applications. A CTM combines these technologies ...