Measurement and estimation of packet loss characteristics are challenging due to the relatively rare occurrence and typically short duration of packet loss episodes. While active probe tools are commonly used to measure packet loss on end-to-end paths, there has been little analysis of the accuracy of these tools. The objective of our study is to understand how to measure packet loss episodes accurately with end-to-end probes. Studies show that the standard Poisson-modulated end-to-end measurement of packet loss accuracy has to be improved. Thus, we introduce a new algorithm for packet loss measurement that is designed to overcome the deficiencies in standard Poisson-based tools. Specifically, our method entails probe experiments that follow a geometric distribution to enable more accurate measurements than standard Poisson probing and other traditional packet loss measurement tools. We also find the transfer rate. We evaluate the capabilities of our methodology experimentally by developing and implementing a prototype tool, called BADABING. BADABING reports loss characteristics are far more accurately than traditional loss measurement tools.
Existing System:
In the Existing traditional packet loss measurement tools, the accuracy of the packet loss measurement has to be improved.
Several studies include the use of loss measurements to estimate packet loss, such as Poisson modulated tools which can be quite inaccurate.
Proposed System:
The purpose of our study is to understand how to measure end-to-end packet loss characteristics accurately.
The goal of our study is to understand how to accurately measure loss characteristics on end-to-end paths with probes.
Specifically, our method entails probe experiments that follow a geometric approach to improve the accuracy of the packet loss measurement.
System Requirements
Hardware:
PROCESSOR : PENTIUM IV 2.6 GHz
RAM : 512 MB
MONITOR : 15"
HARD DISK : 20 GB
CDDRIVE : 52X
KEYBOARD : STANDARD 102 KEYS
Software:
FRONT END : JAVA, SWING
TOOLS USED : JFRAME BUILDER
OPERATING SYSTEM: WINDOWS XP
JAVA TECHNOLOGY
Java technology is both a programming language and a platform.
The Java Programming Language
The Java programming language is a high-level language that can be characterized by all of the following buzzwords:
Simple
Architecture neutral
Object oriented
Portable
Distributed
High performance
Interpreted
Multithreaded
Robust
Dynamic
Secure
With most programming languages, you either compile or interpret a program so that you can run it on your computer. The Java programming language is unusual in that a program is both compiled and interpreted. With the compiler, first you translate a program into an intermediate language called Java byte codes -the platform-independent codes interpreted by the interpreter on the Java platform. The interpreter parses and runs each Java byte code instruction on the computer. Compilation happens just once; interpretation occurs each time the program is executed. The following figure illustrates how this works.
FIGURE 2- WORKING OF JAVA
You can think of Java bytecodes as the machine code instructions for the Java Virtual Machine (Java VM). Every Java interpreter, whether it's a development tool or a Web browser that can run applets, is an implementation of the Java VM. Java bytecodes help make "write once, run anywhere" possible. You can compile your program into bytecodes on any platform that has a Java compiler. The bytecodes can then be run on any implementation of the Java VM. That means that as long as a computer has a Java VM, the same program written in the Java programming language can run on Windows 2000, a Solaris workstation, or on an iMac.
The Java Platform
A platform is the hardware or software environment in which a program runs. We've already mentioned some of the most popular platforms like Windows 2000, Linux, Solaris, and MacOS. Most platforms can be described as a combination of the operating system and hardware. The Java platform differs from most other platforms in that it's a software-only platform that runs on top of other hardware-based platforms.
The Java platform has two components:
The Java Virtual Machine (Java VM)
The Java Application Programming Interface (Java API)
You've already been introduced to the Java VM. It's the base for the Java platform and is ported onto various hardware-based platforms.
The Java API is a large collection of ready-made software components that provide many useful capabilities, such as graphical user interface (GUI) widgets. The Java API is grouped into libraries of related classes and interfaces; these libraries are known as packages. The next section, What Can Java Technology Do?, highlights what functionality some of the packages in the Java API provide.
The following figure depicts a program that's running on the Java platform. As the figure shows, the Java API and the virtual machine insulate the program from the hardware.
FIGURE 3- THE JAVA PLATFORM
Native code is code that after you compile it, the compiled code runs on a specific hardware platform. As a platform-independent environment, the Java platform can be a bit slower than native code. However, smart compilers, well-tuned interpreters, and just-in-time bytecode compilers can bring performance close to that of native code without threatening portability.
What Can Java Technology Do?
The most common types of programs written in the Java programming language are applets and applications. If you've surfed the Web, you're probably already familiar with applets. An applet is a program that adheres to certain conventions that allow it to run within a Java-enabled browser.
However, the Java programming language is not just for writing cute, entertaining applets for the Web. The general-purpose, high-level Java programming language is also a powerful software platform. Using the generous API, you can write many types of programs.
An application is a standalone program that runs directly on the Java platform. A special kind of application known as a server serves and supports clients on a network. Examples of servers are Web servers, proxy servers, mail servers, and print servers. Another specialized program is a servlet. A servlet can almost be thought of as an applet that runs on the server side. Java Servlets are a popular choice for building interactive web applications, replacing the use of CGI scripts. Servlets are similar to applets in that they are runtime extensions of applications. Instead of working in browsers, though, servlets run within Java Web servers, configuring or tailoring the server.
How does the API support all these kinds of programs? It does so with packages of software components that provide a wide range of functionality. Every full implementation of the Java platform gives you the following features:
The essentials: Objects, strings, threads, numbers, input and output, data structures, system properties, date and time, and so on.
Applets: The set of conventions used by applets.
Networking: URLs, TCP (Transmission Control Protocol), UDP (User Data gram Protocol) sockets, and IP (Internet Protocol) addresses.
Internationalization: Help for writing programs that can be localized for users worldwide. Programs can automatically adapt to specific locales and be displayed in the appropriate language.
Security: Both low level and high level, including electronic signatures, public and private key management, access control, and certificates.
Software components: Known as JavaBeansTM, can plug into existing component architectures.
Object serialization: Allows lightweight persistence and communication via Remote Method Invocation (RMI).
Java Database Connectivity (JDBCTM): Provides uniform access to a wide range of relational databases.
The Java platform also has APIs for 2D and 3D graphics, accessibility, servers, collaboration, telephony, speech, animation, and more. The following figure depicts what is included in the Java 2 SDK.
FIGURE 4 - JAVA 2 SDK
URL
The Web is a loose collection of higher-level protocols and file formats, all unified in a web browser. One of the most important aspects of the Web is that Tim Berners-Lee devised a scaleable way to locate all of the resources of the Net. The Uniform Resource Locator (URL) is used to name anything and everything reliably.
The URL provides a reasonably intelligible form to uniquely identify or address information on the Internet. URLs are ubiquitous; every browser uses them to identify information on the Web. Within Java's network class library, the URL class provides a simple, concise API to access information across the Internet using URLs.
Format
Two examples of URLs are http;//www.osborne.com/ and http:// www.osborne.com:80/index.htm.
A URL specification is based on four components. The first is the protocol to use, separated from the rest of the locator by a colon (:). Common protocols are http, ftp, gopher, and file, although these days almost everything is being done via HTTP. The second component is the host name or IP address of the host to use; this is delimited on the left by double slashes (/ /) and on the right by a slash (/) or optionally a colon (:) and on the right by a slash (/). The fourth part is the actual file path. Most HTTP servers will append a file named index.html or index.htm to URLs that refer directly to a directory resource.
Java's URL class has several constructors, and each can throw a
MalformedURLException. One commonly used form specifies the URL with a string that is identical to what is displayed in a browser:
URL(String urlSpecifier)
The next two forms of the constructor breaks up the URL into its component parts:
URL(String protocolName, String hostName, int port, String path)
URL(String protocolName, String hostName, String path)
Another frequently used constructor uses an existing URL as a reference context and then create a new URL from that context.
URL(URL urlObj, String urlSpecifier)
The following method returns a URLConnection object associated with the invoking URL object. it may throw an IOException.
URLConnection openConnection( )-It returns a URLConnection object associated with the invoking URL object. it may throw an IOException.
ODBC
Microsoft Open Database Connectivity (ODBC) is a standard programming interface for application developers and database systems providers. Before ODBC became a de facto standard for Windows programs to interface with database systems, programmers had to use proprietary languages for each database they wanted to connect to. Now, ODBC has made the choice of the database system almost irrelevant from a coding perspective, which is as it should be. Application developers have much more important things to worry about than the syntax that is needed to port their program from one database to another when business needs suddenly change.
Through the ODBC Administrator in Control Panel, you can specify the particular database that is associated with a data source that an ODBC application program is written to use. Think of an ODBC data source as a door with a name on it. Each door will lead you to a particular database. For example, the data source named Sales Figures might be a SQL Server database, whereas the Accounts Payable data source could refer to an Access database. The physical database referred to by a data source can reside anywhere on the LAN.
The ODBC system files are not installed on your system by Windows 95. Rather, they are installed when you setup a separate database application, such as SQL Server Client or Visual Basic 4.0. When the ODBC icon is installed in Control Panel, it uses a file called ODBCINST.DLL. It is also possible to administer your ODBC data sources through a stand-alone program called ODBCADM.EXE. There is a 16-bit and a 32-bit version of this program, and each maintains a separate list of ODBC data sources.
From a programming perspective, the beauty of ODBC is that the application can be written to use the same set of function calls to interface with any data source, regardless of the database vendor. The source code of the application doesn't change whether it talks to Oracle or SQL Server. We only mention these two as an example. There are ODBC drivers available for several dozen popular database systems. Even Excel spreadsheets and plain text files can be turned into data sources. The operating system uses the Registry information written by ODBC Administrator to determine which low-level ODBC drivers are needed to talk to the data source (such as the interface to Oracle or SQL Server). The loading of the ODBC drivers is transparent to the ODBC application program. In a client/server environment, the ODBC API even handles many of the network issues for the application programmer.
The advantages of this scheme are so numerous that you are probably thinking there must be some catch. The only disadvantage of ODBC is that it isn't as efficient as talking directly to the native database interface. ODBC has had many detractors make the charge that it is too slow. Microsoft has always claimed that the critical factor in performance is the quality of the driver software that is used. In our humble opinion, this is true. The availability of good ODBC drivers has improved a great deal recently. And anyway, the criticism about performance is somewhat analogous to those who said that compilers would never match the speed of pure assembly language. Maybe not, but the compiler (or ODBC) gives you the opportunity to write cleaner programs, which means you finish sooner. Meanwhile, computers get faster every year.
JDBC
In an effort to set an independent database standard API for Java, Sun Microsystems developed Java Database Connectivity, or JDBC. JDBC offers a generic SQL database access mechanism that provides a consistent interface to a variety of RDBMSs. This consistent interface is achieved through the use of "plug-in" database connectivity modules, or drivers. If a database vendor wishes to have JDBC support, he or she must provide the driver for each platform that the database and Java run on.
To gain a wider acceptance of JDBC, Sun based JDBC's framework on ODBC. As you discovered earlier in this chapter, ODBC has widespread support on a variety of platforms. Basing JDBC on ODBC will allow vendors to bring JDBC drivers to market much faster than developing a completely new connectivity solution.
JDBC was announced in March of 1996. It was released for a 90 day public review that ended June 8, 1996. Because of user input, the final JDBC v1.0 specification was released soon after.
The remainder of this section will cover enough information about JDBC for you to know what it is about and how to use it effectively. This is by no means a complete overview of JDBC. That would fill an entire book.
JDBC Goals
Few software packages are designed without goals in mind. JDBC is one that, because of its many goals, drove the development of the API. These goals, in conjunction with early reviewer feedback, have finalized the JDBC class library into a solid framework for building database applications in Java.
The goals that were set for JDBC are important. They will give you some insight as to why certain classes and functionalities behave the way they do. The eight design goals for JDBC are as follows:
SQL Level API
The designers felt that their main goal was to define a SQL interface for Java. Although not the lowest database interface level possible, it is at a low enough level for higher-level tools and APIs to be created. Conversely, it is at a high enough level for application programmers to use it confidently. Attaining this goal allows for future tool vendors to "generate" JDBC code and to hide many of JDBC's complexities from the end user.
SQL Conformance
SQL syntax varies as you move from database vendor to database vendor. In an effort to support a wide variety of vendors, JDBC will allow any query statement to be passed through it to the underlying database driver. This allows the connectivity module to handle non-standard functionality in a manner that is suitable for its users.
JDBC must be implemental on top of common database interfaces
The JDBC SQL API must "sit" on top of other common SQL level APIs. This goal allows JDBC to use existing ODBC level drivers by the use of a software interface. This interface would translate JDBC calls to ODBC and vice versa.
Provide a Java interface that is consistent with the rest of the Java system
Because of Java's acceptance in the user community thus far, the designers feel that they should not stray from the current design of the core Java system.
Keep it simple
This goal probably appears in all software design goal listings. JDBC is no exception. Sun felt that the design of JDBC should be very simple, allowing for only one method of completing a task per mechanism. Allowing duplicate functionality only serves to confuse the users of the API.
Use strong, static typing wherever possible
Strong typing allows for more error checking to be done at compile time; also, less errors appear at runtime.
Keep the common cases simple
Because more often than not, the usual SQL calls used by the programmer are simple SELECT's, INSERT's, DELETE's and UPDATE's, these queries should be simple to perform with JDBC. However, more complex SQL statements should also be possible.
System Architecture:
Sender
Receiver
Queue
Data Flow Diagram
Sender
Receiver
Queue
(For Packets loss)
Packets
Packets after loss
Modules of the Project:
Packet Separation
Designing the Queue
Packet Receiver
User Interface Design
Packet Loss Calculation
Module Description
Packet Separation:
In this module we have to separate the input data into packets. These packets are then sent to the Queue.
Designing the Queue:
The Queue is designed in order to create the packet loss. The queue receives the packets from the Sender, creates the packet loss and then sends the remaining packets to the Receiver.
Packet Receiver:
The Packet Receiver is used to receive the packets from the Queue after the packet loss. Then the receiver displays the received packets from the Queue.
User Interface Design:
In this module we design the user interface for Sender, Queue, Receiver and Result displaying window. These windows are designed in order to display all the processes in this project.
Packet Loss Calculation:
The calculations to find the packet loss are done in this module. Thus we are developing the tool to find the packet loss.
Activity Diagram
File Selection
User
Packet loss estimation
Packets for loss
Packets with loss
Packet Separation
Queue
Use Case Diagram
Choose Text File
Packet Separation
Queue
Packet received with loss
Packet loss calculation
User
Sequence Diagram:
User
Select File
Packet Separation
Queue
Loss estimation
Packet receiver
Selects File
Gives File
Gives Separated packet
Sends packets with loss
Calculates Packet loss
Class Diagram
User
Select File ()
Send File()
Packet Separation
Separation ()
Queue
Queue ()
Receiver
Receive Packets()
Loss calculation ()
Sample Code:
/****************************************************************/
/* PacketSender */
/* */
/****************************************************************/
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.net.*;
import java.io.*;
/**
* Summary description for PacketSender
*
*/
public class PacketSender extends JFrame
{
// Variables declaration
private JLabel jLabel1;
private JLabel jLabel2;
private JLabel jLabel3;
private JTextField jTextField1;
private JTextArea jTextArea1;
private JScrollPane jScrollPane1;
private JButton jButton1;
private JButton jButton2;
private JButton jButton3;
private JPanel contentPane;
public float filelength;
public byte filebyte[]=new byte[10000];
public String filstr[];
public int filint[];
public char filchar[];
public int i;
Socket st;
// End of variables declaration
public PacketSender()
{
super();
initializeComponent();
//
// TODO: Add any constructor code after initializeComponent call
//
this.setVisible(true);
}
/**
* This method is called from within the constructor to initialize the form.
* WARNING: Do NOT modify this code. The content of this method is always regenerated
* by the Windows Form Designer. Otherwise, retrieving design might not work properly.
* Tip: If you must revise this method, please backup this GUI file for JFrameBuilder
* to retrieve your design properly in future, before revising this method.
*/
private void initializeComponent()
{
jLabel1 = new JLabel();
jLabel1.setFont(new Font("Arial",Font.BOLD,14));
jLabel2 = new JLabel();
jLabel2.setFont(new Font("Arial",Font.BOLD,12));
jLabel3 = new JLabel();
jLabel3.setFont(new Font("Arial",Font.BOLD,12));
jTextField1 = new JTextField();
jTextField1.setFont(new Font("Arial",Font.BOLD,12));
jTextArea1 = new JTextArea();
jTextArea1.setFont(new Font("Arial",Font.BOLD,12));
jScrollPane1 = new JScrollPane();
jButton1 = new JButton();
jButton2 = new JButton();
jButton3 = new JButton();
contentPane = (JPanel)this.getContentPane();
//
// jLabel1
//
jLabel1.setText("SENDER");
//
// jLabel2
//
jLabel2.setText("Open the File");
//
// jLabel3
//
jLabel3.setText("Status Information");
//
// jTextField1
//
jTextField1.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e)
{
jTextField1_actionPerformed(e);
}
});
//
// jTextArea1
//
//
// jScrollPane1
//
jScrollPane1.setViewportView(jTextArea1);
//
// jButton1
//
jButton1.setText("Browse");
jButton1.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e)
{
jButton1_actionPerformed(e);
}
});
//
// jButton2
//
jButton2.setText("Send");
jButton2.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e)
{
jButton2_actionPerformed(e);
}
});
//
// jButton3
//
jButton3.setText("Exit");
jButton3.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e)
{
jButton3_actionPerformed(e);
}
});
//
// contentPane
//
contentPane.setLayout(null);
contentPane.setBackground(new Color(119, 119, 119));
addComponent(contentPane, jLabel1, 161,4,132,30);
addComponent(contentPane, jLabel2, 54,46,192,24);
addComponent(contentPane, jLabel3, 119,156,187,24);
addComponent(contentPane, jTextField1, 40,70,270,30);
addComponent(contentPane, jScrollPane1, 55,184,321,147);
addComponent(contentPane, jButton1, 310,70,80,30);
addComponent(contentPane, jButton2, 80,110,90,30);
addComponent(contentPane, jButton3, 190,110,90,30);
//
// PacketSender
//
this.setTitle("PacketSender");
this.setLocation(new Point(135, 133));
this.setSize(new Dimension(437, 400));
this.setDefaultCloseOperation(WindowConstants.DISPOSE_ON_CLOSE);
}
/** Add Component Without a Layout Manager (Absolute Positioning) */
private void addComponent(Container container,Component c,int x,int y,int width,int height)
{
c.setBounds(x,y,width,height);
container.add(c);
}
//
// TODO: Add any appropriate code in the following Event Handling Methods
//
private void jTextField1_actionPerformed(ActionEvent e)
{
System.out.println("\njTextField1_actionPerformed(ActionEvent e) called.");
// TODO: Add any handling code here
}
private void jButton1_actionPerformed(ActionEvent e)
{
System.out.println("\nLoading File");
// TODO: Add any handling code here
try
{
FileDialog fd=new FileDialog(this,"Open",FileDialog.LOAD);
fd.show();
FileInputStream fin=new FileInputStream(fd.getDirectory()+fd.getFile());
jTextField1.setText(fd.getDirectory()+fd.getFile());
File f = new File(fd.getDirectory()+fd.getFile());
fin.read(filebyte);
filelength=f.length();
jTextArea1.setText("\n File Loaded");
jTextArea1.append("\n File Length = "+filelength);
jTextArea1.append("\n File Size = "+filelength/1024+" KB\n ");
filint=new int[(int)filelength];
filchar=new char[(int)filelength];
filstr=new String[(int)filelength];
jTextArea1.append("\n File Content : \n");
for(i=0;i<filelength;i++)
{
filint[i]=(int)filebyte[i];
filchar[i]=(char)filint[i];
filstr[i]=""+filchar[i];
jTextArea1.append(filstr[i]);
}
}
catch (Exception er)
{
System.out.println(er);
}
}
private void jButton2_actionPerformed(ActionEvent e)
{
System.out.println("Sending Packets");
// TODO: Add any handling code here
try
{
st=new Socket("localhost",4500);
DataOutputStream dos=new DataOutputStream(st.getOutputStream());
dos.writeFloat(filelength);
for(i=0;i<filelength;i++)
{
dos.writeUTF(filstr[i]);
}
st.close();
}
catch (Exception ty)
{
}
}
private void jButton3_actionPerformed(ActionEvent e)
{
System.out.println("\nExit");
// TODO: Add any handling code here
System.exit(1);
}
Screen Shots:
SYSTEM TESTING
PROCESS:
The purpose of testing is to discover errors. Testing is the process of trying to discover every conceivable fault or weakness in a work product. It provides a way to check the functionality of components, sub assemblies, assemblies and/or a finished product It is the process of exercising software with the intent of ensuring that the Software system meets its requirements and user expectations and does not fail in an unacceptable manner. There are various types of test. Each test type addresses a specific testing requirement.
TYPES OF TESTS:
UNIT TESTING:
Unit testing involves the design of test cases that validate that the internal program logic is functioning properly, and that program input produce valid outputs. All decision branches and internal code flow should be validated. It is the testing of individual software units of the application .it is done after the completion of an individual unit before integration. This is a structural testing, that relies on knowledge of its construction and is invasive. Unit tests perform basic tests at component level and test a specific business process, application, and/or system configuration. Unit tests ensure that each unique path of a business process performs accurately to the documented specifications and contains clearly defined inputs and expected results.
INTEGRATION TESTING:
Integration tests are designed to test integrated software components to determine if they actually run as one program. Testing is event driven and is more concerned with the basic outcome of screens or fields. Integration tests demonstrate that although the components were individually satisfaction, as shown by successfully unit testing, the combination of components is correct and consistent. Integration testing is specifically aimed at exposing the problems that arise from the combination of components.
FUNCTIONAL TESTING:
Functional tests provide a systematic demonstrations that functions tested are available as specified by the business and technical requirements, system documentation and user manuals.
Functional testing is centered on the following items:
Valid Input : identified classes of valid input must be accepted.
Invalid Input : identified classes of invalid input must be rejected.
Functions : identified functions must be exercised.
Output : identified classes of application outputs must be exercised.
Systems/Procedures : interfacing systems or procedures must be invoked.
Organization and preparation of functional tests is focused on requirements, key functions, or special test cases. In addition, systematic coverage pertaining to identify
Business process flows; data fields, predefined processes, and successive processes must be considered for testing. Before functional testing is complete, additional tests are identified and the effective value of current tests is determined.
SYSTEM TESTING:
System testing ensures that the entire integrated software system meets requirements. It tests a configuration to ensure known and predictable results. An example of system testing is the configuration oriented system integration test. System testing is based on process descriptions and flows, emphasizing pre-driven process links and integration points.
WHITE BOX TESTING:
White Box Testing is a testing in which in which the software tester has knowledge of the inner workings, structure and language of the software, or at least its purpose. It is purpose. It is used to test areas that cannot be reached from a black box level.
BLACK BOX TESTING:
Black Box Testing is testing the software without any knowledge of the inner workings, structure or language of the module being tested . Black box tests, as most other kinds of tests, must be written from a definitive source document, such as specification or requirements document, such as specification or requirements document. It is a testing in which the software under test is treated, as a black box .you cannot "see" into it. The test provides inputs and responds to outputs without considering how the software works.
Unit Testing:
Unit testing is usually conducted as part of a combined code and unit test phase of the software lifecycle, although it is not uncommon for coding and unit testing to be conducted as two distinct phases.
Test strategy and approach
Field testing will be performed manually and functional tests will be written in detail.
Test objectives
All field entries must work properly.
Pages must be activated from the identified link.
The entry screen, messages and responses must not be delayed.
Features to be tested
Verify that the entries are of the correct format
No duplicate entries should be allowed
All links should take the user to the correct page.
Integration Testing:
Software integration testing is the incremental integration testing of two or more integrated software components on a single platform to produce failures caused by interface defects.
The task of the integration test is to check that components or software applications, e.g. components in a software system or - one step up - software applications at the company level - interact without error.
Test Results: All the test cases mentioned above passed successfully. No defects encountered.
Acceptance Testing:
User Acceptance Testing is a critical phase of any project and requires significant participation by the end user. It also ensures that the system meets the functional requirements.
Test Results: All the test cases mentioned above passed successfully. No defects encountered.
IMPLEMENTATION
MAINTENANCE
The term "software maintenance" is used to describe the software engineering activities that occur following delivery of a software product to the customer. The maintenance phase of the software life cycle is the time period in which a software product performs useful work. Maintenance activities involve making enhancement to software products, adapting products to new environments and correcting problems. Software product enhancement may involve providing new functional capabilities, improving user display and modes of interaction, and upgrading external documents. Adaptation of software to a new environment may involve moving the software to a different machine. Problem correction involves modification and revalidation of software to correct errors. The enhancement of this project can be accomplished easily. That is, any new functional capabilities can be added to the project by simply including the new module in the homepage and giving a hyperlink to that module. Adaptation of this project to a new environment is also performed easily.
CORRECTIVE MAINTENANCE
Even with the best quality assurance activities, it is likely that they customer will uncover defects in the software. Corrective maintenance changes the software to correct defects.
ADAPTIVE MAINTENANCE
An activity that modifies the software to properly interface with a changing environment. The system has been modified so that various change include to the new system.
In case of Fund Transfer, adoptive maintenance has been performed, that is in earlier system (character based UNIX system) changes are fixed and if any new changes are to be included, was a difficult task. Now provisions are given so that the user can define various changes. Such as, it is designed to accommodate the new change in future.
ENHANCEMENT MAINTENANCE
As software is used, the customer/user will recognize additional functions that will provide benefit. Perceptive maintenance extends the software beyond its original functional requirements.
Applications:
Simple techniques that allow users to validate the measurement outputs are introduced. We implemented this method in a new tool, BADABING, which we tested in our laboratory. Our tests demonstrate that BADABING, in most cases, accurately estimates loss frequencies and durations over a range of cross traffic conditions
Future Enhance:
We are also considering alternative, parametric methods for inferring loss characteristics from our probe process. Another task is to estimate the variability of the estimates of congestion frequency and duration themselves directly from the measured data, under a minimal set of statistical assumptions on the congestion process.
Conclusion:
The purpose of our study was to understand how to ensure end-to-end packet loss characteristics accurately with probes and in a way that enables us to specify the impact on the bottleneck queue. We began by evaluating the capabilities of simple Poisson-modulated probing in a controlled laboratory environment consisting of commodity end hosts and IP routers. We consider this test bed ideal for loss measurement tool evaluation since it enables repeatability, establishment of ground truth, and a range of traffic conditions under which to subject the tool. Our initial tests indicate that simple Poisson probing is relatively ineffective at measuring loss episode frequency or measuring loss episode duration, especially when subjected to TCP (reactive) cross traffic.
