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Scalable Wireless Ad-hoc Network Simulation Literature Survey

Chapter 2

LITERATURE SURVEY

We have used java programming language for implementing this project. The

description of Java, its features, components and functions are described below.

2.1Why Java platform?

Work on Java originally began with the goal of creating a platform-independent

language and operating system for consumer electronics.

Java facilitates the building of distributed applications by a collection of classes for

use in networked applications. By using Java's URL (Uniform Resource Locator) class, an

application can easily access a remote server. Classes also are provided for establishing

socket-level connections.

Features of the Java Language:

Simple

Object-Oriented

Distributed

Interpreted

Robust

Secure

Architecture-Neutral

Portable

High-Performance

Multithreaded

Dynamic

Dept of CSE, SJCIT 5 2007-2008


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The Java Foundations Classes

Java Foundations Classes (JFC) is a set of APIs for building the GUI-related

components of Java applets and applications. The APIs included with JFC include thefollowing:

The Abstract Windowing Toolkit

Swing

Java 2D

Drag and Drop

Accessibility

Swing components provide a pluggable look and feel, which is easy to substitute

another appearance and behavior for an element. The Swing related classes are contained in

javax.swing and its sub packages, such as javax.swing.tree.

Features of Swing components:

Swing buttons and labels can display images instead of, or in addition to text.

User can easily add or change the borders drawn around most swing components.

Users can easily change the behavior or appearance of a swing component by either

invoking methods on it or creating a subclass of it.

Swing components dont have to be rectangular, buttons, for e.g., can be round.

Assistive technologies such as screen renders can get information from swing

components.

Swing lets to specify which look and feel a programs GUI uses.

Swing components are implemented with no native code and arent restricted to the

least common denominator.

The Swing API is flexible, powerful and immense. It is available in two forms:

1. As a core part of the Java2 platform

2. JFC1.1



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In our project we are making use of the JFCs.

For implementing this project we have mainly used Swing that is nothing but a set

of class that provides more powerful and flexible components. The classes of the Swing

which we have used for this project are described below. The classes of the Swing which we

have used for this project are described below.

JButton:

JButton is a push button used to fire action events when they activated. When we

enter the required parameters into the text field of login window and click on login button an

event is generated, the actionlistener listens to the event generated and performs the action of

logging into the system.

JPanel:

JPanel class is used for creating the panel to login window.

JTextField:

JTextField class is used for entering the input into the username, number of nodes in

the network etc., into the textfield.

JPasswordField:

JPasswordField is used for entering the password into the edit field in the login

window.

JTextArea:

JTextArea class displays multiple lines of text in a single font and style. In this project

this class is used to create the status window which shows the status of the operation being

performed in this project.

JLable:

JLable class is used for naming the windows and textboxes that we created in our

project.



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JScrollPane:

Here we are using the JScrollPane class to view contents of the tables if it exceeds the

default size, the scrollbar shows up so that we can view the contents of the table by scrolling

upwards or downwards.

JTabbedPane:

We have used JTabbedPane class for switching from one text field to another or from

one button to another very quickly.

JOptionPane:

In this application if the username and password are not entered properly, it is wrong

and if the information about the nodes are incorrect then this class creates popup windows as

Invalid name and password .This class is mainly used for creating various window.

JScrollPane:

In this application if we want to calculate the ranks for 12 or more than 12 nodes in

the network then this class will create an automatic vertical scrollbar in the nodes parameter

table for viewing parameters of the nodes together.

JInternalFrame:

In this application this class is used to add the columns named IP

Address,Portnumber,Distance,Energy and Link Quality in the parameter entry

table. It also adds the END and Send To all button to the table also. This class is also

used to create the icons also in the application. It also resize the tables depending upon the

nodes entered by the user.

JTable:

In this application this class is mainly used to create the tables of this application.



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2.2 Need of Our Project:-

The Scalable Wireless Ad-hoc Network Simulation project is mainly intended to

demonstrate the advantages that are obtained by using the XTC Algorithm over the other

multicasting algorithms such as expanded ring search algorithm, Core resolution algorithms

etc.... So the need of this project arises to make adhoc network more scalable, more

convenient to use and for smooth data transfer by reducing the network congestion.

Other prominent feature that this project demonstrates are listed below:-

No existing infrastructure is required

Mobile users can easily communicate

High Bandwidth, quality, reliability and variance

Energy conservation very less

Wonderful Scalability

Quality of Service

Simplicity and ease of implementation

Efficient computing

QoS support

OBJECT ORIENTED PROGRAMMING:

Object-oriented programming is an approach that provides a way of

modularizing programs by creating partitioned memory area for both data and functions

that can be used as templates for creating copies of such modules on demand.

Object-oriented programming is at the core of Java. In fact, all Java

programs are object-oriented-this isnt an option the way that is in C++. The major

objective of object-oriented approach is to eliminate some of the flaws encountered in

the procedural approach. OOP treats data as a critical element in the program

development and does not allow it to flow freely around the system. It ties data more

closely to the functions that operate on it and protects it from unintentional modification



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by other functions. OOP allows us to compose a problem into a number of entities called

Objects and then build data and functions around these entities. The combination of data

and methods make up an object.

According to Grady Booch, a leading exponent of the object-oriented

approach, an object has the following characteristics.

It has state.

It may display a behavior.

It has a unique identity.

THREE OOP PRINCIPLES:

Encapsulation

Inheritance

Polymorphism

Encapsulation:

The Wrapping up of data and methods into a single unit (called Class) is

known as encapsulation.

Inheritance:

Inheritance is the process by which objects of one class acquire the

properties of objects of another class.

Polymorphism:

Polymorphism means the ability to take more than one form. For Example,

an operation may exhibit different behavior in different instances.

ADVANTAGES OF OBJECT- ORIENTATION:



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Realistic Modeling.

Reusability.

Resilience to change.

Realistic Modeling:

Since we live in a world of objects, it logically follows that the object-

oriented approach models the real world more accurately than the conventional,

procedural approach.

Reusability:

In the object-oriented approach, you build classes, which can then be used

by several applications. The benefit of reusability translates to a saving in time and effort,

which in turn results in cost benefits.

Resilience to change:

Through the object-oriented approach, system can be allowed to evolve.

When a change is suggested, the old system need not be completely abandoned and

rebuilt from scratch.

Resilience to change, results in ease of maintenance. For the same reason,

even during construction, paths of the system under development can be refined without

any major change to other parts.

JAVA HISTORY:

James Gosling, Patrick Naughton, Chris Warth, Ed Franck, and Mike

Sheridan conceived JAVA, at Sun Micro Systems, Inc. in 1991. This language was

initially called OAK but was renamed JAVA in 1995. Bill Joy, Arthur Van Hoff,

Jonathan Payne, Franck Yellin, and Tim Lindholm were key contributors to the maturing

of the original prototype.



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The original impetus for Java was not the Internet! Instead, the primary

motivation was the need for a platform-independent language that could be used to create

software to be embedded in various consumer electronic devices, such as microwave

ovens and remote controls. As you can probably guess, many different types of CPUs are

used as controllers. The trouble with C and C++ is that they are designed to compile for a

specific target. Although it is possible to compile a c++ program for just about any type

of CPU, to do so requires a full c++ compiler targeted for that CPU. The problem is that

compilers are expensive and time consuming to create. An Easier and more cost-

efficient solution were needed. In an attempt to find such a solution, Gosling and others

began work on a portable, platform-independent language that could be used to produce

code that would run on a variety of CPUs under different environments. This effort

ultimately led to the creation of JAVA.

JAVA FEATURES:

Sun micro systems officially describes Java with the following attributes:

Compiled and interpreted. Platform - independent and portable.

Object-oriented.

Robust and secure.

Distributed.

Familiar, simple and small.

Multithreaded and Interactive.

High performance.

Dynamic and extensible.

Compiled and Interpreted:

Java combines both this approaches thus making Java a two-stage system.

First, Java compiler translates source code into what is known as byte code Instructions.



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In the second stage, Java interpreter generates machine code that can be directly executed

by the machine that is running the Java program.

Platform-Independent and Portable:

The most significant contribution of Java over other languages is its

portability. Changes and upgrades in operating systems, processors and system resources

will not force any changes in Java programs.

Java ensures portability in two ways. First, a Java compiler generates byte

code instructions that can be implemented on any machine. Secondly, the sizes of the

primitive data types are machine-independent.

Object-oriented:

Java is a true object-oriented language. Almost everything in Java is an

object. All program code data reside within object and classes. Java comes with an

extensive set of classes, arranged in packages, that we can use in our programs by

inheritance. The object model in Java is simple and easy to extend.

Robust and Secure:

Java is a robust language. It provides many safeguards to ensure reliable

code. It has strict compile time and runtime checking for data types. It is designed as a

garbage-collected language relieving the programmers virtually all memory management

problems. Java also incorporates the concept of exception handling, which captures series

errors and eliminates any risk of crashing the system.

Security becomes an important issue for a language that is used for

programming on Internet. Threat of viruses and abuse of resources is everywhere. Java

systems not only verify all memory access but also ensure that no viruses are

communicated with an applet. The absence of pointers in Java ensures that programs

cannot gain access to memory locations without proper authorization.

Distributed:



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Java is designed as a distributed language for creating applications on

networks. It has the ability to share both data and programs. Java applications can open

and access remote objects on Internet as easily as they can do in a local system. This

enables multiple programmers at multiple remote locations to collaborate and work

together on a single project.

Simple, small and familiar:

Java is a small and simple language. Many features of C and C++ that are

either redundant or sources of unreliable code are not part of Java. For example, Java

does not use pointers, preprocessor header files, go to statement and many others. It

also eliminates operator overloading and multiple inheritance.

Familiarity is another striking feature of Java. To make the language look

familiar to the existing programmers, it was modeled on C and C++ languages. Java uses

many constructs of C and C++ and therefore, Java code looks like a C++ code. In fact,

Java is simplified version of C++.

Multithreaded and interactive:Multithreaded means handling multiple tasks simultaneously. Java supports

multithreaded programs. This means that we need not wait for the application to finish

one task before beginning another. This feature greatly improves the interactive

performance of graphical applications. The Java runtime comes with tools that support

multiprocessors synchronization and constructs smoothly running interactive systems.

High performance:

Java performance is impressive for an interpreted language, mainly due to

the use of intermediate byte code. According to sun, Java speed is comparable to the

native C/C++. Java architecture is also designed to reduce overheads during runtime.

Further, the incorporation of multithreaded enhances the overall execution speed of Java

programs.

Dynamic and extensible:



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Java is a dynamic language. Java is capable of dynamically linking in new

class libraries, methods and objects. Java can also determine the type of class through a

query, making it possible to either dynamically link or abort the program, depending on

the response.

Java programs support functions written in other languages such as C and

C++. These functions are known as native methods. This facility enables the

programmers to use the efficient functions available in these languages. Native methods

are linked dynamically at runtime.

JAVA AND INTERNET

Internet helped catapult Java to the forefront of programming, and Java, in

turn has had a profound effect on the Internet. The reason for this is quite simple: Java

expands the universe of objects that can move about freely in cyberspace. In a network

too very broad categories of objects are transmitted between the server and your personal

computer: passive information and dynamic, active programs.

As desirable as dynamic, networked programs are, they also present serious

problems in the area of security and portability. Prior to Java, cyberspace was effectivelyclosed to half the entities that now live there. As you will see, Java address those concerns

and, by doing so, has opened the door to an exciting new form of program: the applet.

JAVAS MAGIC: THE BYTECODE:

The key that allows Java to solve both the security and the portability

problems just described is that the output of a Java compiler is not executable code.

Rather, it is Byte code. Byte code isa highly optimized set of instruction designed to

be executed by the Java runtime system, which is called the Java Virtual Machine

(JVM). That is, in its standard form, the JVM is an interpreter byte code. In fact, most

modern languages are designed to compiled, not interpreted mostly because of

performance concerns. The fact that a Java program is executed by the JVM helps

solve the major problems associated with downloading programs over the Internet.



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Translating a Java program into Byte code makes it much easier to run a

program in a wide variety of environments. The reason is straightforward: only the

JVM need to be implemented for each platform. Once the runtime package exists for a

given system, any Java program can run on it. Remember, although the details of the

Java program were compiled to native code, then different versions of the same

program would have to exist for each type of CPU connected to the Internet. This is,

of course, not a feasible solution. Thus the interpretation of byte code is the easiest

way to create truly portable programs.

The fact that a Java programs is interpreted also helps to make it secure.

Because the execution of every Java program is under the control of the JVM, the

JVM can contain the program and prevent it from generating side effects outside of

the system. As you will see, safety is also enhanced by certain functions that exist in

the Java language.

When a program is interpreted, it generally runs substantially slower

than it would run if compiled to executable code. However, with Java, the differential

between the two is not great. The use of byte code enables the Java, runtime system toexecute programs much faster.

Java was designed for interpretation; there is technically nothing about

Java that prevents on-the-fly compilation of byte code into native code. Along these

lines, Sun supplies its Just in Time (JIT) compiler for byte code, which is included in

the Java 2 release. When the JIT compiler is part of the JVM, it compiles byte code

into executable code in real time, on a piece-by-piece, demand basis. It is important to

understand that it is not possible to compile an entire Java program into executable

code all at once, because Java performs various runtime checks that can be done only

at runtime. Instead, the JIT compiles code, as it is needed, during execution. However,

the Just-In-Time approach still yields a significant performance boost. Even when

dynamic compilation is applied to byte code, the probability and safety features still

apply, because the runtime system still is in charge of the environment. Whether your

java program is actually interpreted in the traditional way or compiled On-The-Fly, its

functionality is the same.



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HOT JAVA:

Hot java is the web browser from Sun Microsystems that enables the

display of interactive content on the Web, using the java language. Its biggest draw is

that it was the first Web browser to provide support for the Java language, thus

making the web more dynamic and interactive.

HARDWARE AND SOFTWARE REQUIREMENTS:

Java is currently supported on Windows 95, Windows NT, Sun Solaris,

Macintosh, and UNIX machines. Though, the programs and examples in this book

were tested under Windows 95, the most popular operating system today, they can

implemented on any of the above systems.

The minimum hardware and software requirements for Windows 2000

version of Java are follows:

IBM - compatible 486 system.

Minimum of 8 MB memory Windows 2000 software

A Windows-compatible and sound card, if necessary.

A Hard drive.

A CD-ROM drive.

A Microsoft-compatible mouse.

JAVA ENVIRONMENT:

Java environment includes a large number of development tools and

hundreds of classes and methods. The development tools are part of the system known

as Java Development Kit (JDK) and the classes and methods are part of the Java

Standard Library (JSL), also known as the Application Programming Interface (API).

JAVA DEVELOPMENT KIT:



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The Java Development Kit comes with a collection of tools that are used

for developing and running Java programs. They include:

Applet viewer (for viewing Java applets)

Javac (Java compiler)

Java (java interpreter)

Javap (java disassembler)

Javah (for C header files)

Javadoc (for creating HTML documents)

Jdb (Java debugger)

JAVA DEVELOPMENT TOOLS

Tools Description

Applet viewer Enables us to run Java applets (without actually

using a Java-compatible browser).

Java Java interpreter, which runs applets and application by

reading and interpreting byte code files.



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Javac The Java compiler, which translates Java source code to

byte code files that the interpreter can understand.

Javadoc Creates HTMLformat documentation from Java source

code files.

Javah Produces header files for use with native methods.

Javap Java disassembler, which enables us to convert byte code

files into a program description.

Jdb Java debugger, which helps us to find errors in our

programs.

The way these tools are applied to build and run application program is

illustrated in the following figure.


Text Editor

Java

Source

JavadocHTML

Header

Files

Javac

Java

ClassJavah

Java Jdb


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Figure: Process of building and running Java application programs

To create a Java program, we need to create a sourcecode file using a text editor. The source code is then compiled usingthe Java compiler javac and executed using the Java interpreter

java. The java debugger jdb is used to find errors, if any, in thesource code.

APPLICATION PROGRAMMING INTERFACE:

The java standard library (or API) includes hundreds of classes and methods

grouped into several functional packages. Most commonly used packages are:

Language Support Package :

A collection of classes and methods required for implementing basic features of

Java.

Utilities Packages :

A collection of classes to provide utility functions such as

date and time functions.Input/Output Packages:

A collection of classes required for input/output manipulation.

Networking Packages:

A collection of classes for communicating with other computers via internet.

AWT Package:

The Abstract Window Tool package contains classes that implements platform-

independent graphical user interface.

Applet Package:

This includes a set of classes that allows us to create Java applets. The use of these

library classes will become evident when start developing java programs.


Java

Program

Output


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JAVA PROGRAMS:

A few type of java applications are listed below:

Applications that do not use Graphical User Interface (GUI):

They are similar to traditional programs written in C and C++.Applications using GUI

These are similar to the applications described above, but they have graphical

user interfaces. These applications are used in the Windows environment.

Applets

These programs run on a web page and require a java-enabled browser like

Internet explorer or Netscape navigator. Applets are the programs that you running

on web page.

ServletsServlets do not have graphical user interfaces. They are widely used to extend

the functionality of web servers.

Packages

Packages are collections of classes that can be shared by applications and applets.



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