Peer to Peer Application Development Cracking the Code

379 Pages·2001·2.401 MB·English

by  Dreamtech Software Team

4904-9 cover 10/12/01 1:10 PM Page 1
Peer-to-Peer Application Development
Peer-to-Peer
Dreamtech
Create Tomorrow’s Peer-to-Peer Applications Today
Software
In this unique guide, a crack team of software engineers delivers the
India, Inc.,
programming solutions and source code you need to jump-start a Application Development
is a leading state-of-the-art peer-to-peer application project. Using flow charts
provider of corporate and line-by-line analysis of a full-scale P2P file-sharing application,
software solutions.
they show you how to solve for typical P2P programming challenges
Based in New Delhi,
— and create your own state-of-the-art P2P application using Java
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$49.99 US Team A line-by-line look inside a professional-
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Shelving Category £39.99 UK incl.VAT Dreamtech
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Peer-to-Peer
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Peer-to-Peer
Application
Development
Cracking the Code
Dreamtech Software Team
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Peer-to-Peer Application Development: Cracking the Code
Published by
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Credits
Acquisitions Editor Project Coordinator
Chris Webb Dale White
Project Editor Cover Design
Chandani Thapa Anthony Bunyan
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Copy Editor Indexer
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Media Development Specialist Cover
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Media Development Manager
Laura Carpenter VanWinkle
Dreamtech Software India, Inc., Team
[email protected]
www.dreamtechsoftware.com
Dreamtech Software India, Inc., is a leading provider of corporate software solutions. Based in New
Delhi, India, the company is a successful pioneer of innovative solutions in e-learning technologies.
Dreamtech’s developers have over 50 years of combined software-engineering experience in areas such
as Java, wireless applications, XML, voice-based solutions, .NET, COM/COM+ technologies, distributed
computing, DirectX, Windows Media technologies, and security solutions.
About the Authors
Lead Author Team
Vikas Gupta, Co-founder and President. Vikas holds a B.E. in electronics, with a postgraduate
diploma in sales and marketing and in publishing and printing studies. Actively engaged in developing
and designing new technologies in wireless applications, e-learning, and other cutting-edge areas, he is
also the Managing Director of IDG Books India (P) Ltd.
Avnish Dass, Co-founder and CEO. Avnish is a talented and seasoned programmer who has 15 years of
experience in systems and application/database programming. Avnish has developed security systems,
antivirus programs, wireless and communication technologies, and ERP systems.
Harpreet Singh Matharu, Sr. Software Developer. Harpreet holds a B.Tech. in computer science.
Harpreet specializes in COM services and Windows Systems Programming, including Network
Programming and Windows Security Systems.
Ankur Verma, Sr. Software Developer. Ankur has expertise in technologies such as Windows Media,
Direct X (Direct Show), and Windows Shell Programming Services for Windows NT series. Ankur also
provides the commercial COM/DCOM solutions to Dreamtech Software India, Inc.
Yashraj Chauhan, Sr. Software Developer. Yashraj has an advanced diploma in software development
from IBM, with over three years of experience in Java, XML, and C++, and is pursuing his Masters in
computer science.
Other Contributors
Pooja Aggarwal and Manish Aggarwal, Technical writers. They have contributed to developing the
contents of this book.
Gaurav Malhotra, Pankaj Kumar, Manish N. Srivastav, A team of programmers of Dreamtech
Software India, Inc. They contributed to the development of software in this book.
Acknowledgments
We acknowledge the contributions of the following people for their support in making this book possible:
John Kilcullen for sharing his dream and providing the vision for making this project a reality.
Mike Violano and Joe Wikert for believing in us.
M.V. Shastri, Asim Chowdhury, V.K. Rajan, Sanjeev Chatterjee, and Priti for their immense help in
coordinating various activities throughout this project.
To our parents and family and beloved country, India,
for providing an excellent environment
for nurturing and creating world-class IT talent.
Preface
The Internet evolved out of the need to access information from one computer through another or over a
network of computers. In the beginning, the Internet was a modest network of a few computers allowing
access to data through any of its terminals. Gradually, the concept opened endless possibilities, and the
Internet emerged as a super network — a network of networks — spanning the globe and involving
millions of machines over which information could be shared, accessed, or communicated freely by the
user.
Today, with the Internet’s having graduated to the status of a religion that promises to fulfill the needs of
everyone, regardless of caste, creed, or color, and having become potent enough to grant anything
beseeched, you can find yourself quite lost in its world. Consequently, the need for personal attention and
smaller subnetworks has risen once again. A handful of people got wise to this idea and developed
software that allowed users to share data and to communicate with a set of selective people only: friends,
relatives, or colleagues.
This has become among the most sought-after software on the IT market. A big user group is benefiting
from such software, and many companies are venturing into the concept and capitalizing on it.
In this scenario, an application made on the concept of Peer-to-Peer (P2P), written in popular languages
such as Java and C#, with its foundations for database interaction and communication laid in a platform
as ubiquitous as XML and, above all, with open-source code and elaborate code explanations, is what
developers of such software ultimately dream of. This may sound idealistic, but it is exactly such an
application that this book is all about.
What This Book Covers
This book covers the technology of P2P programming. This is the first book to cover the entire code
behind a Napster-style, file-sharing model. It contains unique coverage of Windows Media Technology
development for making your P2P application multimedia aware. The book is loaded with code, keeping
theory to a minimum. The applications, for which the source code is given in the CD accompanying this
book, are 100 percent tested and working at Dreamtech Software Research Lab. The source code
provided in the book is based on commercial applications, which have been developed by the software
company. Each program of the application is explained in detail so that you gain insight into the
implementation of the technology in a real-world situation. At the end of the book, some add-ons to this
application are provided so that you can further explore new developments.
This book deals with the design, implementation, and coding of the latest form of the client/server model,
the P2P model. The book serves to equip you with enough know-how on the subject so as to enable you
to design a P2P model of your own.
The book begins with the history of the P2P model and goes on to explain the various types of P2P
models, with detailed diagrams to elucidate the subject. After equipping you with basic concepts, it goes
on to develop, step by step, a full-fledged application, which has the scope of being extended with
add-ons.
This book is not meant for beginners. It teaches you the basics of specific technologies only. The
Cracking the Code series is meant for software developers/programmers who wish to upgrade their skills
and understand the secrets behind professional-quality applications. This book starts where other tutorial
books end. It enhances your skills and takes them to the next level as you learn a particular technology. A
thorough knowledge of the Java or C# programming languages is the prerequisite for benefiting the most
from this book. Experience in network programming is an added advantage. For developing streaming
viii Preface
applications, knowledge of Visual C++ is a must. At least a nodding acquaintance with the XML markup
language is desirable, although the book includes a section on XML. Instructions for embedding existing
chat-client and audio/video components have been included. You can craft this application in such a way
that you are able to send your files to be printed to any part of the globe. Besides Globalized Printing, you
can make the application run on wireless models, too. The opportunity is open for you to assess your
networking skills and to improve them.
The pivotal feature of the book is that it offers a complete, ready-to-deploy application with source code.
The purpose of this book is to acquaint programmers with the subject thoroughly so that they are in a
position to write their own codes to build P2P applications. Detailed explanations of the steps involved in
writing your own code to build a P2P application in Java as well as in C # have been furnished.
Although the topic is highly technical, every effort has been made to make the presentation lucid,
interesting, and reader friendly.
How This Book Is Organized
Chapter 1 begins with a discussion of various P2P models, goes on to consider design parameters
(including the target audience, the environment, and the possible range this application may be required
to serve), and finally covers the implementation aspects of one of the aforementioned models. The last
chapter is devoted to the add-ons incorporated in the application.
Chapter 2 explains designing the application you intend to develop. Having provided a basic overall view
and the technical background of the application, the process of designing the application is taken up in
this chapter. The chapter begins with a reiteration of design considerations and parameters. The sort of
communication sought and the means to achieve it by way of this P2P application are detailed. The XML
design specifications are given in detail, as the interoperability of the P2P application has been achieved
by using them. The server side is discussed with a description of using the database, the table design, the
XML implementation in SQL Server 2000, and so on. The client side is described with details of the two
modules the client is made up of — the browser and the listener — along with the techniques for
handling XML parsing, managing peers, connecting to the server and other peers, and finally searching.
It is imperative to mention here that the core of this application is discussed in Chapter 2, and it is
exceptionally beneficial and mandatory for product designers and programmers aspiring to develop
similar applications to peruse this chapter thoroughly.
Chapter 3 contains every detail of the server in reference to the P2P application. Various aspects of using
SQL Server 2000, such as table creation with reference to this application and writing queries for
retrieving data from tables, have been discussed in this chapter. This chapter also walks the reader
through XML-related capabilities of SQL Server 2000.
Apart from giving you a comprehensive picture of the entire development cycle of the server for this
application, this chapter presents a few facts about SQL Server 2000. It elaborates on the complete cycle
of database structure tailoring, mounting it, and writing ASPs over it for connected users to be able to
interact with it easily.
A sound command of RDBMS concepts helps you get the maximum benefit from this chapter.
Chapter 4 introduces you to the task of real cracking of code and illustrates all aspects of high-level
programming. In the Java version of the P2P application, all codes carry a detailed explanation wherever
needed so that you can fully appreciate the code.
The code explanation starts with a discussion of classes pertaining to operations on XML involved in the
application.
Preface ix
After discussing the building blocks of our application, we discuss the application itself. This comprises
the listener module and the browser module (client). These two interact with each other to give the final
shape to this P2P application.
Apart from covering the entire application development in Java, this chapter describes the use of some of
the XML parsers offered by IBM through Java. A firm command of Java and a nodding acquaintance
with IBM Xerces XML parser is desirable, as this chapter deals primarily with implementation without
giving any tutorial of either the language or the parser.
If you intend to make your application in C#, skip this chapter and proceed to the next chapter.
Chapter 5 covers the C# version of this P2P application. All codes and documentation processes carry a
detailed commentary whenever needed so as to enable you to gain a sound understanding of the concept
in question. The code in this chapter has been written using Microsoft Visual Studio .NET (Beta 2).
This application constitutes a listener module and a browser module (client), which interact with each
other to effect the completion of this P2P application. While taking you through the development of the
essential modules of this application, this chapter provides you with the opportunity to evaluate your
skills in the C# language and to improve them. It lets you know how COM components are used in C#,
how windows APIs (such as ShellExec()) can be used with interoperable namespaces, and how delegates
can be used judiciously in programs.
A working knowledge of C# and MS XML parser is expected, as this chapter deals primarily with
implementation without giving a tutorial of either the language or the parser. If you envisage your
application in Java, skip this chapter.
Chapter 6 begins with an elaboration of streaming and goes on to discuss the tools, libraries, and
resources required for extending this application to be able to stream audio/video data. The chapter
concludes by explaining, in steps, the development of a streaming add-on for this P2P application.
The understanding of Windows Media technologies you gain through this chapter can be directed toward
developing or extending applications. This knowledge can be used as a bridge to gain access to even
better applications of Windows Media technologies and DirectX.
Because the SDKs involved for developing this add-on are available for VC++ only as of now, you need
to know VC++ to understand or develop this add-on. This chapter makes use of Windows Media Encoder
SDK. Familiarity with Windows Media technologies is expected of you.
Chapter 7 offers you an opportunity to be innovative in extending this so-far-elementary P2P application.
It provides a deeper insight into the flexibility and the prudence of the design of this application that
makes it possible for you to incorporate add-ons to the application even at an advanced stage in its
development cycle. The implementations of the following add-ons have been described and serve as
practical guidelines if you want to explore the possibilities offered by this application:
♦ Chat client
♦ Globalized Printing
♦ P2P wireless search (Java version only)
The fully functional chat client incorporated in this application provides you with an understanding of
fundamental techniques such as socket programming and introduces you to .NET’s powerful resource
designer. Globalized Printing convinces you how easily a new idea can be incorporated into an
application if some care is taken to keep the foundation of the application ubiquitous. This notion is
further substantiated by the incorporation of the P2P wireless search, which is written in Java and
therefore calls for a working knowledge of CLDC (Connected Limited Device Configuration) for a
complete appreciation of this extension.