Summary

This chapter focused entirely on the development of distributed applications on the Linux platform using Java technology. Due to the portable nature of Java technology across different platforms and due to the availability of high-grade commercial development and deployment tools from industry-leading vendors on the Linux platform, Linux is certainly worth considering as an operating system both for development and deployment.

The chapter began with an introduction of distributed technologies supported by Java and the difference between the distributed applications and desktop applications, particularly with respect to data marshalling between client and server applications. Then the discussion focused on the Java serialization concepts, the need to transport serialized objects across the network, the java.io.Serializable interface, and a few example programs demonstrating these concepts.

The next topic of discussion in this chapter was developing socket-based applications, using both TCP and UDP sockets. TCP sockets implement the connection-based protocol, while the UDP sockets implement connectionless protocol, each of these being useful in different scenarios; however, the TCP protocol is the most widely implemented standard for a vast majority of today’s networking applications. The chapter presents working example programs to demonstrate these concepts.

Next, developing RMI-based applications was discussed. RMI forms the basis of enterprise Java architecture and makes use of Java serialization concepts to perform data marshalling and unmarshalling between clients and servers. Implementing a client and server demo using Java RMI classes and implementing security policy for successful deployment of RMI-based applications were discussed in this section.

The next topic discussed in this chapter was CORBA-based application development. The concepts of CORBA framework were discussed to a great depth. Implementing CORBA-based client and server applications was demonstrated in two ways; using the Java 2 SDK and the associated tools, and also using Borland JBuilder8 IDE for development and Visibroker architecture for deployment. Implementing POA policies for better management of servant objects was also discussed.

The last topic of the chapter looked briefly at the Java Messaging Service (JMS) API in which the concepts of asynchronous message-based distributed applications were examined and a simple but clear example presented involving the point-to-point mode of communication. At this point, the readers should be aware that while the CORBA framework supports both synchronous and asynchronous mode communication between a client and server, the Java Messaging Service provides a powerful peer-to-peer asynchronous mode communication.

Chapter 8 will examine some more advanced topics, such as development of Enterprise applications using multiple tools such as Enterprise JavaBeans, Java Server Pages, and the open source Jakarta Struts package.