Book Image

Learning Network Programming with Java

Book Image

Learning Network Programming with Java

Overview of this book

Network-aware applications are becoming more prevalent and play an ever-increasing role in the world today. Connecting and using an Internet-based service is a frequent requirement for many applications. Java provides numerous classes that have evolved over the years to meet evolving network needs. These range from low-level socket and IP-based approaches to those encapsulated in software services. This book explores how Java supports networks, starting with the basics and then advancing to more complex topics. An overview of each relevant network technology is presented followed by detailed examples of how to use Java to support these technologies. We start with the basics of networking and then explore how Java supports the development of client/server and peer-to-peer applications. The NIO packages are examined as well as multitasking and how network applications can address practical issues such as security. A discussion on networking concepts will put many network issues into perspective and let you focus on the appropriate technology for the problem at hand. The examples used will provide a good starting point to develop similar capabilities for many of your network needs
Table of Contents (16 chapters)
Learning Network Programming with Java
Credits
About the Author
About the Reviewer
www.PacktPub.com
Preface
Index

Distributed hash tables


A Distributed Hash Table (DHT) uses a key/value pair to locate resources in a network. This mapping function is spread across peers making it distributed. This architecture allows P2P networks to scale easily to a large number of nodes and to handle peers joining and leaving a network randomly. A DHT is the basis to support core P2P services. Many applications use DHT, including BitTorrent, Freenet, and YaCy.

The following figure illustrates mapping a key to a value. The key is frequently a string containing the identity of a resource, such as the name of a book; and the value is a number generated to represent the resource. The number can be used to locate the resource in a network and can correspond to the identifier of a node.

P2P networks have been in use for a while. The evolution of these networks is reflected in how resources are mapped as typified by Napster, Gnutella, and Freenet: