Pradeepkumar.org

Normal Forms (Min terms, Max terms)

2012-02-10T21:06:00.001+05:30

Introduction to Discrete Mathematics

2012-02-10T20:47:00.001+05:30

This Discrete mathematics is part of my Ph.D Course Work attended at VIT. This notes is a photo copy of my friend Dr. Rajasekharababu of VIT. Thanks to his notes and I really loved this notes and cleared this subject with a high grade. I am posting these notes because I feel I may loose this notes if it is being with me in a digital form. Hope Google database protect these notes (images).

Visit of Dr. Richard Stallman

2012-02-07T19:05:00.001+05:30

Dr. Richard Stallman, the man behind the Free Software Foundation has visited IIT Madras on 6th February 2012. He gave a Lecture on “Free Software, Freedom and Education”. A 3 hour non stop talk at this age is really surprising for the listeners.

A Short glimpse here

He was exactly on time (started exactly 1PM IST)
So many colleges/university students and faculty participated. Up to my knowledge atleast 40 buses from various parts of Chennai visited IIT Madras.
3 hours talk with questionnaire session.
Giving Windows or Linux to a school student is equivalent to Whisky or water. He is much concentrating more on Freedom rather than open source. He advised the Government not to spoil the students by giving whisky (Windows).
If anything given free, the value is not been felt. (that’s what happens with GNU/Linux).

Some annoying things happened

the audiences were interacting with other peers during the lecture. Dr. Stallman keep on telling them “Please be Quite, shhhhhhhhhhhh…..”. Atleast he informed this to the audiences four times.
Some of the students slowly moving out of the seminar hall within the first 30 minutes of the talk. After an hour nearly the strength is almost Half. (of course, uninterested ones have moved)

Over all the above, the seminar and the talk was successful. Dr. Richard Stallman should make his visit to India frequently to motivate Indians particularly students.

Long Live GNU/Linux, Long live Freedom.

Workshop on Wearable Computing in VIT University - Chennai Campus

2012-01-30T20:09:00.002+05:30

Pradeep Kumar TS

How to write a Makefile

2012-01-27T22:59:00.000+05:30

Assume there are more number of source files to be compiled using a set of commands everytime is a tedious process. So there is a facility to compile everything at a stretch is by the use of a Makefile.

The makefile can be named as either “Makefile” or “makefile”.

Let me define four files for my simple application, create a new directory and store all the files given below

main.c (which contains the main program)

sum.c (summing function is defined)

hello.c (print hello world)

function.h (function prototypes are declared)

You can download all the files here

//function.h

int sum(int,int);
void print_hello();

//hello.c

#include <stdio.h>
#include "function.h"
void print_hello()
{
printf("Hello World \n");
}

//sum.c

#include "function.h"
int sum(int a, int b)
{
int c;
c=a+b;
return c;
}

//main.c

#include <stdio.h>
#include "function.h"
int main()
{
int a=10,b=20,c;
print_hello();
c=sum(a,b);
printf("The sum of two numbers is %d ",c);
return 0;
}

There are different methods of compiling this file

Method 1: (gcc command based)

gcc main.c sum.c hello.c –o pradeep

once you execute the above command, an executable named pradeep is created and you can see the output by typing ./pradeep

Method 2: using Makefile

The basic makefile is composed of:

This syntax applied to example would look like:

target: dependencies

[tab] system command

all:

gcc main.c sum.c hello.c –o pradeep

to run this make file(the file name should be Makefile or makefile), execute the command

make

Method 3: using Makefile with dependencies

There may be a chance of using different targets in your makefile, this is because if you modify a single file in your project, you don't have to recompile everything, only what you modified.
Here is an example

all: pradeep

hello: main.o sum.o hello.o
gcc main.o sum.o hello.o -o hello

main.o: main.c
gcc –c main.c

sum.o: sum.c
gcc –c sum.c

hello.o: hello.c
gcc –c hello.c

Method 4: using variables

CC=gcc
CFLAGS=-c -Wall

all: hello

hello: main.o sum.o hello.o
$(CC) main.o sum.o hello.o -o hello

main.o: main.c
$(CC) $(CFLAGS) main.c

sum.o: sum.c
$(CC) $(CFLAGS) sum.c

hello.o: hello.c
$(CC) $(CFLAGS) hello.c

Method 5:

With this brief introduction to Makefiles, you can create some very sophisticated mechanism for compiling your projects.

CC=gcc
CFLAGS=-c -Wall
LDFLAGS=
SOURCES=main.c hello.c sum.c
OBJECTS=$(SOURCES:.cpp=.o)
EXECUTABLE=hello

all: $(SOURCES) $(EXECUTABLE)
$(EXECUTABLE): $(OBJECTS)
$(CC) $(LDFLAGS) $(OBJECTS) -o $@

.c.o:
$(CC) $(CFLAGS) $< -o $@

If you understand this last example, you could adapt it to your own personal projects changing only 2 lines, no matter how many additional files you have !!!.

Thanks to:http://mrbook.org/tutorials/make/

The above examples is tested only on linux and Windows also supports make utility (through nmake utility), the readers are advised to work on their own in Windows. the following link will show you the way to nmake utility

http://msdn.microsoft.com/en-us/library/dd9y37ha(VS.71).aspx

Process ID and Parent Process ID in Linux

2012-01-24T11:59:00.001+05:30

When referring to process IDs in a C or C++ program, always use the pid_t typedef, which is defined in <sys/types.h>.A program can obtain the process ID of the process it’s running in with the getpid() system call, and it can obtain the process ID of its parent process with the getppid() system call. For instance, the program in Listing 3.1 prints its process ID and its parent’s process ID.

   1:  // Printing the process ID and parent process ID

   2:  #include <stdio.h>

   3:  #include <unistd.h>

   4:  int main ()

   5:  {

   6:  printf (“The process ID is %d\n”, (int) getpid ());

   7:  printf (“The parent process ID is %d\n”, (int) getppid ());

   8:  return 0;

   9:  }

fork

When a program calls fork, a duplicate process, called the child process, is created. The parent process continues executing the program from the point that fork was called. The child process, too, executes the same program from the same place. So how do the two processes differ? First, the child process is a new process and therefore has a new process ID, distinct from its parent’s process ID.One way for a program to distinguish whether it’s in the parent process or the child process is to call getpid. However, the fork function provides different return values to the parent and child processes—one process “goes in” to the fork call, and two processes “come out,” with different return values.The return value in the parent process is the process ID of the child.The return value in the child process is zero. Because no process ever has a process ID of zero, this makes it easy for the program whether it is now running as the parent or the child process.

The following example show the fork to duplicate a program’s process. Note that the first block of the if statement is executed only in the parent process, while the else clause is executed in the child process.

1: // to create a process using fork()
2: #include <stdio.h>
3: #include <sys/types.h>
4: #include <unistd.h>
5: int main ()
6: {
7: pid_t child_pid;
8: printf (“the main program process ID is %d\n”, (int) getpid ());
9: child_pid = fork ();
10: if (child_pid != 0) {
11: printf (“this is the parent process, with id %d\n”, (int) getpid ());
12: printf (“the child’s process ID is %d\n”, (int) child_pid);
13: }
14: else
15: printf (“this is the child process, with id %d\n”, (int) getpid ());
16: return 0;
17: }

Observation:

The program can be compiled using gcc compiler

$: gcc –o <linkname> <filename.c>

$: ./linkname

Printing the Uptime and Idle Time of processor (Linux)

2012-01-24T11:49:00.001+05:30

/proc/uptime file contains only two values in seconds, one is the Uptime of the processor (the time upto which the processor was on) and another is the idle time of all the processors (cores).

So idle is always higher than the uptime in case of multicore processors.

The following C program shows the uptime and idle time in terms of days hours and minutes. This is a very simple program just tells you how to convert a given time in days, hours, minutes and seconds.

using C FILE concept, the /proc/uptime file is been read using the “r” mode and values are fetched and then converted into days, hours and seconds.

   1:  // printing the uptime and idle time

   2:  #include <stdio.h>

   3:  /* Summarize a duration of time to standard output. TIME is the

   4:  amount of time, in seconds, and LABEL is a short descriptive label. */

   5:  void print_time (char* label, long time)

   6:  {

   7:  /* Conversion constants. */

   8:  const long minute = 60;

   9:  const long hour = minute * 60;

  10:  const long day = hour * 24;

  11:  /* Produce output. */

  12:  printf (“%s: %ld days, %ld:%02ld:%02ld\n”, label, time / day,

  13:  (time % day) / hour, (time % hour) / minute, time % minute);

  14:  }

  15:  int main ()

  16:  {

  17:  FILE* fp;

  18:  double uptime, idle_time;

  19:  /* Read the system uptime and accumulated idle time from /proc/uptime. */

  20:  fp = fopen (“/proc/uptime”, “r”);

  21:  fscanf (fp, “%lf %lf\n”, &uptime, &idle_time);

  22:  fclose (fp);

  23:  /* Summarize it. */

  24:  print_time (“uptime “, (long) uptime);

  25:  print_time (“idle time”, (long) idle_time);

  26:  return 0;

  27:  }

Printing Linux Environment using C Program

2012-01-24T11:45:00.001+05:30

Linux provides each running program with an environment. The environment is a collection of variable/value pairs. Both environment variable names and their values are character strings. By convention, environment variable names are spelled in all capital letters. You’re probably familiar with several common environment variables already.

For instance:

USER contains your username.

HOME contains the path to your home directory.

PATH contains a colon-separated list of directories through which Linux searches for commands you invoke.

DISPLAY contains the name and display number of the X Window server on which windows from graphical X Window programs will appear.

//Printing the Execution Environment
#include <stdio.h>
/* The ENVIRON variable contains the environment. */
extern char** environ;
int main ()
{
char** var;
for (var = environ; *var != NULL; ++var)
printf (“%s\n”, *var);
return 0;
}

Operating Systems (Yesterday, Today and Tomorrow)–PPT

2012-01-20T08:42:00.003+05:30

Lecture 3,4 operating systems

View more presentations from Pradeep Kumar TS

OS Objectives and functions–PPT

2012-01-20T08:42:00.001+05:30

Lecture 2 os objectives and functions

View more presentations from Pradeep Kumar TS

Introduction to Operating systems–PPT

2012-01-20T08:40:00.001+05:30

Lecture 1 introduction to operating systems

View more presentations from Pradeep Kumar TS

Setting Path in Linux

2012-01-17T22:08:00.001+05:30

Setting a path information in windows is always been easier, since there is a GUI facility “Environmental Variables”, but I Linux setting a path is always been tricky and it should be done through CLI (Command Line Interface). Here are the following ways to do:

Method 1:

For each user (Your login id) of Linux has a home folder (/home/username), there will be a file called as .bashrc (Ubuntu and Fedora) or .bash_profile (Fedora), whatever path has to be set, it should be entered in the above file.

For example: if the software is installed in /home/username/software1/, then the PATH has to be set in the .bashrc or .bash_profile file like this

export PATH=$PATH:/home/username/software1/

($PATH is a shell variable refers to the previous set path also to be included in the PATH setting.)

For Java Home

export JAVA_HOME=/home/username/<Java_path>

Method 2:

The above method of path is applicable only for that user. if other users wanted to access the software, then they have to set the paths. Because, for each user of Linux, the .bashrc or .bash_profile file exists.

if the same path is set for all the users, then the super user can set the path information in the following file

/etc/profile.d/your_path_name.sh

Open the file name (of your choice, but the extension is .sh) and has to be stored in /etc/profile.d/

This folder will be read during the booting process, so all the users of that machine will be able to access the software. The following line is copied to the shell file

export PATH=$PATH:/home/username/software1/

export JAVA_HOME=/home/username/<Java_path>

Basic Linux Commands for Beginners

2012-01-09T20:25:00.001+05:30

Using a Linux machine using a shell Prompt is always a challenge these days. Many of us feel it is tougher to use Linux because of its Conventional Shell prompt, but the GUIs are so sophisticated when compared with Other Operating systems like windows, etc.

But still as a developer, one has to be good at Linux both in the GUI and as well as in Shell. For novice users and beginners, the following commands will make understand the importance of Linux and their commands.

Basic Commands

Commands	usage	Explanation
ls	ls	to list the files and folders
ls –l	ls –l	to list the files and folders in long format
chmod	chmod 777 filename	to change the mode of a file
pwd	pwd	display the present working directory
passwd	passwd	Changing the password of the current user
echo	echo “hello”	display the string hello
	echo $PATH	Display the PATH Variable stored
	echo $HOME	display the Home folder of the current user
	echo $SHELL	displays the type of shell used /bin/bash
tar	tar xf filename.tar	to decompress the tar file and extract the folders
	tar xvf filename.tar	to decompress the tar file and extract the folders with verbose mode
	tar zxvf filename.tar.gz	to decompress from gzip and the extract the tar created.
gzip	gzip –d filename.tar.gz gzip –d filename.gz	to decompress the gzip file
bzip2	bzip2 –d filename.tar.bz2 bzip2 –d filename.bz2	to decompress the bzip2 file
rm	rm name	remove a file or directory called name (the directory should be empty to be deleted)
	rm –rf name	Kill off an entire directory and all it’s includes files and subdirectories
cp	cp filename /home/hello	copy the file called filename to the folder /home/hello
mv	mv filename /home/hello	move the file called filename to the directory /home/hello
cat	cat filename	display the file called filename
su	su	login to superuser from current login (you should know the super user password)
exit	exit	exit out of the shell window or Stop being superuser and revert to normal user
dmesg	dmesg	display the boot time messages
ls	ls	list current processes
kill	kill 123	kill a specific process with ID 123
ifconfig	ifconfig	List ip addresses for all devices on the machine
rpm	rpm –ivh filename.rpm	Install the rpm package called name
	rpm –Uvh filename.rpm	Upgrade the rpm package called name
	rpm –e package	Delete the rpm package called package
	rpm –l package	List the files in the package called package
./configure	./configure	Execute the script preparing the installed files for compiling
find	find / –name fname	Starting with the root directory, look for the file called fname
	find / -name ”fname”	Starting with the root directory, look for the file containing the string fname

File Permissions

If the command ls -l is given, a long list of file names is displayed. The first column in this list details the permissions applying to the file. If a permission is missing for a owner,
group of other, it is represented by - eg.

drwxr-x--x
Read = 4
Write = 2
Execute = 1
File permissions are altered by giving the chmod command and the appropriate octal code for each user type. eg chmod 7 6 4 filename will make the file called filename R+W+X for the owner, R+W for the group and R for others.

chmod 7 5 5 Full permission for the owner, read and execute access for the group and others.
chmod +x filename Make the file called filename executable to all users.

Happy New Year 2012

2011-12-31T22:14:00.001+05:30

Wish you all a very Happy New Year 2012.

Here are some new things you can do in this new year, (Apart from your resolutions, consider this too)

Try to learn music or a musical instrument
Learn a new Language
Do a diploma Course
learn simple photography techniques
Start a Blog and post contents on a weekly basis
If you already have a blog, start a Project 365 (It can be a photograph a day, a 'how to' a day, a quote a day or a recipe a day, etc.
Learn a new technology

Pradeep Kumar TS

How to create an Agent in NS2 (Network Simulator 2)

2011-12-29T21:45:00.001+05:30

Adding a new agent in NS2 uses C++ to be coded. Unlike conventional C++, NS2 uses TclCL and OTCL. There are 6 TclCL classes that are needed to develop any module in NS2.

Tcl
TclClass
EmbeddedTcl
TclObject
TclCommand

A new module in NS2 (an agent, a packet, a queue) can be created using the above classes. for creating a simple agent, refer the post given below
http://www.nsnam.com/2011/12/creating-new-agent-in-network-simulator.html

Pradeep Kumar TS

Google+ connected to Blogger

2011-12-22T16:32:00.001+05:30

Once Google+ is in, there is no need of a separate profile page for Blogger. so Google is giving an option to Choose the profile created through Google+ and not from blogger, so that one can have a common profile for entire Google Application.

This is one added advantage of google+. For enabling this, you can go to http://www.blogger.com and login using the google username and password. Google asks you to connect to Google+ like given below, if you want to enable just click “Get Started” and follow the procedures there on.

There are quite number of advantages for doing this.

You can connect to your friend circle very easily
have common profile both blogger and Google
Whatever you post, there is an option for posing it to your Google+ stream, so your friends know what you are doing regularly in your blog.
Since you are an author of a blog, google search results shows your picture. For activating this facility, see this link http://support.google.com/webmasters/bin/answer.py?hl=en&answer=1408986

Enjoy!!!

C Compiler for Windows 7 64 bit Operating Systems

2011-12-18T22:37:00.000+05:30

Turbo C Compiler is the best compiler so far until we are comfortable with Windows XP. After the Launch of Windows 7, the TC editor is not that much user friendly (as maximisation of DOS Window is hectic) and that too Turbo C was not scalable for 64 bit Windows 7.
But there are some c compiler tools that are quite comfortable to use with (32 bit as well 64 bit OS). Have a look at the following Links
There’s a tools Bloodshed Dev-Cpp which works under the gcc and Mingw is suitable for windows 7 64 bit OS. Also, if you have Microsoft visual C++, then it’s a good choice to run under windows 7 64bit.

So here are the various C compilers for 64bit windows 7 OS

Bloodshed Dev-Cpp
Microsoft Visual Studio (64bit) and Visual Studio Express.
Netbeans 6.9 with Mingw and GCC compiler (here you should have the jdk for 64bit OS)
Eclipse with gcc and mingw (again, the jdk as well eclipse should be of 64bit)
C- Free Professional
Code Lite - CodeLite is an open-source, cross platform IDE for the C/C++ programming languages (build and tested on Windows XP SP3, Windows Vista, Windows 7, Ubuntu 10.04, and Mac OSX 10.5.8). CodeLite is distributed under the terms of the GPLv2 license with an exception:
Pelles C - is a complete development kit for Windows and Windows Mobile.

In netbeans and eclipse the C compiler source path has to be set in to the path variable.

Pradeep Kumar TS

Moving from Wordpress to Blogger

2011-12-18T19:01:00.002+05:30

For What Reasons I wanted to Shift to Blogger
Today is the day, I am moving from Wordpress (Self Hosted blog) to Blogger (Custom domain). Though I feel my google pagerank can be affected, but still I would like to move due to the following reasons

Blogger gives me most of the things free.
I have a better control of everything with one account. (Google Account)
SEO is taken care automatically, since blogger is Google's own. (I need to use some plugin like Wordpress SEO, etc)
Better Social Networking (whether its facebook or google+).
Need not bother about the bandwidth of my hosting provider or the total space limitation.
XHTML issues are taken care automatically by Blogger.
Earlier in blogger, there was no Pages concept, now its comes along with blogger.
Google Panda Update (personally I feel that Panda will do a favor to their own product compared with others).
and there are lot more reasons

How I migrate to Blogger

First I created a blogger URL http://pradeepkumarorg.blogspot.com
Next I need to download all my posts from wordpress. Go to Tools-> export and download. There's a wordpress to Blogger conversion utility http://wordpress2blogger.appspot.com/. This link supports only 1MB. But my blog XML file is 4MB and I export the posts year by year (2008, 2009, 2010, 2011).
Login in to blogger and Settings -> Basic and added my new domain name and since I have my hosting using Godaddy, Blogger has a direct DNS Setup to transfer to Blogger http://www.godaddy.com/blog/bloggerdnssetup.aspx
I set it right and here I go with my domain http://www.pradeepkumar.org

Still what to be done

Now there are problems with the 404 Errors. So, if a missing page is visited by a visitor it will point to a old URL which has to be solved. Google gives a Webmaster Script code for that too. Moreover I used the same permalinks in wordpress that was supported by blogger. So i May not have any problem with all the links in my URL.
But there may be some problems in the Label or Categories which will be solved.
Feedburner link has to be updated.

That's it.

HTML List Box processing using Servlets

2011-11-23T04:25:00.000+05:30

For: Intermediate Users (Those who know Java, JDBC)

This example uses two servlets DishServlet and DishSubmitServlet which tells about Dishes with preparation time, method to cook and ingredients needed.

DishServlet just populates the data from the Database table “dishes” and all the dishes in the table will be in a List Box (Select Box).

Once any dish is selected and submitted, another servlet will show the information about dish preparation, time needed and ingredients. Both the Servlets are going to use the Same Table

Here is the Sample Database Table: Name is “dishes”

dish_name	time_to_prepare	method	ingredients
Pongal	20	using cooker and prepare the dishes	rice, water, salt
Idly	10	using cooker and make 10 pieces in a strech	flour,
Poori	15	make dough using wheat, water and salt	wheat, salt, water, oil
Pizza	30	Take the pizza base and make the topping using sauze, cheese and spread the onions	Oven, Pizza Base, Mozarilla Cheese, Sauze, tomato, capsicum, onion, olive

There are four dishes in the above menu and all of them are populated to a Servlet using the following program

Filename: DishServlet.java

import java.io.*;
import java.sql.*;
import javax.servlet.http.*;
import javax.servlet.*;

public class DishServlet extends HttpServlet
{
    public void doPost(HttpServletRequest req, HttpServletResponse res) throws IOException, ServletException
    {
        res.setContentType("text/html");
        ServletOutputStream out = res.getOutputStream();
        out.println("<html><body>");
        out.println("<form method=post action=DishSubmitServlet>");
        out.println("Please select a Dish to be prepared");
        out.println("<select name=dish>");
        try
        {
            Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
        }
        catch (Exception e)
        {
            out.println("Database Driver Problem" +e.getMessage());
        }
        try
        {
            Connection con=DriverManager.getConnection("jdbc:odbc:pradeep");
            Statement stmt = con.createStatement();
            ResultSet rs = stmt.executeQuery("Select * from dishes");
            while(rs.next())
            {
                String s1=rs.getString(2);
                out.println("<option>"+s1+"</option>");
            }
            out.println("</select>");
            out.println("<input type=submit>");
            out.println("</form></body></html>");
        }
        catch (SQLException ee)
        {

           out.println("DSN Issues "+ee.getMessage());
        }
    }
}

FileName: DishSubmitServlet.java

import java.io.*;
import java.sql.*;
import javax.servlet.http.*;
import javax.servlet.*;

public class DishSubmitServlet extends HttpServlet
{
    public void doPost(HttpServletRequest req, HttpServletResponse res) throws IOException, ServletException
    {
        res.setContentType("text/html");
        ServletOutputStream out = res.getOutputStream();
        String dish=req.getParameter("dish");
        out.println("<html><body>");
        out.println("<table border=1><tr>");
        out.println("<th>Dish Name</th>");
        out.println("<th>Preparation Time</th>");
        out.println("<th>Method to Prepare </th>");
        out.println("<th>Ingredients Needed </th></tr><tr>");

        try
        {
            Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
        }
        catch (Exception e)
        {
            out.println("Database Driver Problem" +e.getMessage());
        }
        try
        {
            Connection con=DriverManager.getConnection("jdbc:odbc:pradeep");
            Statement stmt = con.createStatement();
            ResultSet rs = stmt.executeQuery("Select * from dishes where dish_name='"+dish+"'");
            while(rs.next())
            {
                String s2=rs.getString(2);
                String s3=rs.getString(3);
                String s4=rs.getString(4);
                String s5=rs.getString(5);
                out.println("<td>"+s2+"</td>");
                out.println("<td>"+s3+"</td>");
                out.println("<td>"+s4+"</td>");
                out.println("<td>"+s5+"</td>");
            }
            out.println("</tr></table>");
            out.println("</body></html>");
        }
        catch (SQLException ee)
        {
            out.println("DSN Issues "+ee.getMessage());
        }
    }
}

Compile the file and Make an entry in the web.xml file and run the HTML file using the link http://localhost:8080/examples/DishServlet

Select a Dish from the given Menu and click Submit, you can see a table in the next page that shows the dish and its preparation along with ingredients. See the Images

Servlets and JDBC (User authentication)

2011-11-23T04:07:00.000+05:30

For : Beginners and Intermediate (Those who have basic knowledge on JDBC, Java, Servlets)

This tutorial will tell you about the JDBC connection with Servlet and let to update or insert of query the Database table based on the dynamic Queries. Also this Example will show you how to authenticate a user based on the data stored in the Database Table

Step 1: To create a DSN name, and to create a Database using MS Access, see this Post

Following is the table structure: Name of the table is student

regno	password
pradeepkumar	hellohowareyou
amiitesh	welcome

Create a HTML Form that asks for a username and Password

FileName: msindex.html

<html>
<head>
<title> Form Processing </title>
</head>

<body>
<form method="post" action="FormServlet">
Enter your username : <input type="text" name="regno"><br>
Enter your Password : <input type="password" name="password"><br>
<input type="submit">
</form>
</body>
</html>

FileName: FormServlet.java

import java.io.*;
import java.sql.*;
import javax.servlet.*;
import javax.servlet.http.*;

public class FormServlet extends HttpServlet
{
    public void doPost(HttpServletRequest req, HttpServletResponse res) throws IOException, ServletException
    {
        res.setContentType("text/html");
        ServletOutputStream out=res.getOutputStream();
        String s1=req.getParameter("user");
        String s2=req.getParameter("password");
        out.println("<html><body>");
        try
        {
            Class.forName("sun.jdbc.odbc.JdbcOdbcDriver"); //JDBC ODBC Driver
        }
        catch (Exception e)
        {
            out.println("Driver Issues"+e.getMessage());
        }
        try
        {
            Connection con=DriverManager.getConnection("jdbc:odbc:pradeep");
            Statement stmt=con.createStatement();
            ResultSet rs = stmt.executeQuery("select * from student where regno='"+s1+"' and password='"+s2+"'");
            int count=0;
            while(rs.next())
            {
                count++;
            }
            if(count>0)
                out.println("Success"+s1+"You are authenticated");
            else
            {
                out.println("Your password or username is wrong");
                //res.sendRedirect("form.html");
            }
        }
        catch (SQLException ee)
        {
            out.println("DSN Issues"+ee.getMessage());
        }
    }
}

Compile the file and Make an entry in the web.xml file and run the HTML file using the link http://localhost:8080/examples/msindex.html

Provide a name and password (which is there in the student table given above) and click Submit. You can see a page that authenticates you, if your username and password are correct, else it will show you a warning message.

HTML Form Processing using Servlets

2011-11-23T03:46:00.000+05:30

For : Beginners (Those with basic knowledge on Java Programming)

This tutorial will make you understand how to process a HTML Form using Servlets. For this to accomplish, we need two files One HTML file and One Servlet File

Filename: Form.html (Save this file in C:/tomcat/webapps/examples)

<html>
<head>
<title> Form Servlet Demonstration </title>
</head>

<body>
<form method=post action=MSServlet>
Enter your name: <input type="text" name="user"><br>
Enter the Password: <input type="text" name="age"><br>
<input type="submit">
</form>
</body>
</html>

The above form is submitted to the MSServlet file which resides in the server or the MSServlet (Server) will provide a response to the Client (Form)
The name and age is input by the user and upon submitting the form, the output will be welcoming the user using the name entered in the Text box and also the Age.

File Name : MSServlet.java (Save this file in C:/tomcat/webapps/examples/WEB-INF/classes)

import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
public class MSServlet extends HttpServlet
{
    public void doPost(HttpServletRequest req, HttpServletResponse res) throws IOException, ServletException
    {
        res.setContentType("text/html");
        String s1=req.getParameter("user"); //See the name attribute in the Input tag of HTML form
        String s2=req.getParameter("age"); //see the name attribute in the Input Tag of HTML Form
       pw.println("Welcome Mr."+s1);
        pw.println("Your age is."+s2);
    }
}

Compile the file and Make an entry in the web.xml file and run the HTML file using the link http://localhost:8080/examples/form.html

Provide a name and age and click Submit. You can see a page that Welcomes you.

Running Servlets using Tomcat

2011-11-23T03:30:00.000+05:30

For: Beginners (those who are new to Java Programming)

This tutorial will tell you how to Install tomcat and how to run servlet using Tomcat. However, you can use easier tools like Eclipse or Netbeans or IBM RAD to deploy the Servlets.

Installing Tomcat in Windows 7

Download Tomcat 7.0 from http://tomcat.apache.org/download-70.cgi
Just double Click and install (The default location will be in C:/program Files/Tomcat 7.0/). I have selected C:/tomcat (This path will be very easy to remember and no PATH settings issues will be there
Once installed, to run jsp or servlets, there are some set of jar files are given in the library. Set PATH for those jar files.
To set the path, go to Control Panel –> System –> Advanced System Settings –> Environmental Variables –> Edit PATH in the System Variables (Just update the C:\tomcat\lib\servlet-api.jar) for running servlets. Similarly for jsp also.
Once done open the browser, http://localhost:8080/ will take you to the Tomcat Home Page (if successful, then your installation is succeeded)

Simple Servlet

import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;

public class HelloServlet extends HttpServlet
{
    public void init() throws ServletException
    {}
    public void service(HttpServletRequest req, HttpServletResponse res) throws IOException, ServletException
    {
        res.setContentType("text/plain");
        PrintWriter pw = res.getWriter();
        pw.println("<html><body>");
        pw.println("<h1> Hello World, I am a Servlet </h1>");
        pw.println("</body></html>");
    }
    public void destroy()
    {}

}

Name this program as HelloServlet.java (as the class is public)
Save this file in the folder C:/Tomcat/webapps/examples/WEB-INF/classes (In my case)
Compile this program through terminal or using any IDE like Eclipse or NetBeans
Once Compiled, tell about this Servlet in web.xml File which is located in the C:/tomcat/webapps/examples/WEB-INF (the servlets information has to be provided to this file and there is a format for us to specify the name of the servlets)
Here is the syntax to add the entry in the web.xml file

   <servlet>
      <servlet-name>HelloServlet</servlet-name>
      <servlet-class>HelloServlet</servlet-class>
    </servlet>

<servlet-mapping>
        <servlet-name>HelloServlet</servlet-name>
        <url-pattern>/HelloServlet</url-pattern>
    </servlet-mapping>

In the servlet-mapping tag, url-pattern see there is a /HelloServlet (all servlet url mapping should start with a /)

Once done, Save this file and run the servlet in the browser using this link http://localhost:8080/examples/HelloServlet (if the desired output is not there, try restart your apache server)

Installing NS-2.35 in Ubuntu 11.10 and Fedora 16

2011-11-21T22:03:00.000+05:30

NS-23.5 is released this month and here are the simple instructions to install.

Ubuntu 11.10

1. Install ubuntu

2. Download the Ns-2.35 from this website http://isi.edu/nsnam/ns/

3. Assuming that your ns-2.35 source is in the /home/loginname/ , execute the commands one by one

sudo apt-get update

sudo apt-get install automake autoconf libxmu-dev build-essential

tar zxvf ns-allinone-2.35.tar.gz

cd ns-allinone-2.35

./install

4. Once the process is over, it will give the set of paths to be set.

5. Go to terminal and open .bashrc by giving this command

gedit .bashrc

and copy the following lines ( my login name for linux is pradeep, you can change yours accordingly)

export PATH=$PATH:/home/pradeep/ns-allinone-2.35/bin:/home/pradeep/ns-allinone-2.35/tcl8.5.10/unix:/home/pradeep/ns-allinone-2.35/tk8.5.10/unix
export LD_LIBRARY_PATH=/home/pradeep/ns-allinone-2.35/otcl-1.14:/home/pradeep/ns-allinone-2.35/lib

6. run the command "source .bashrc" (without quotes)

and then type ns (a % symbol indicates the successful installation of ns2) or nam (you can see a network animation windows popped out)

Fedora 16

1. Download the DVD Version (http://www.fedoraproject.org) and Install all the pacakges (if you are not sure about what to be installed)

2. Download the Ns-2.35 from this website http://isi.edu/nsnam/ns/

3. Assuming that your ns-2.35 source is in the /home/loginname/ , execute the commands one by one

tar zxvf ns-allinone-2.35.tar.gz

cd ns-allinone-2.35

./install

4. Once the process is over, it will give the set of paths to be set.

5. Go to terminal and open .bash_profile by giving this command

gedit .bash_profile

and copy the following lines ( my login name for linux is pradeep, you can change yours accordingly)

and already a PATH was already defined and put a : at the end of the existing PATH and copy these lines

/home/pradeep/ns-allinone-2.35/bin:/home/pradeep/ns-allinone-2.35/tcl8.5.10/unix:/home/pradeep/ns-allinone-2.35/tk8.5.10/unix

export LD_LIBRARY_PATH=/home/pradeep/ns-allinone-2.35/otcl-1.14:/home/pradeep/ns-allinone-2.35/lib

6. run the command "source .bash_profile" (without quotes)

and then type ns (a % symbol indicates the successful installation of ns2) or nam (you can see a network animation windows popped out)

Get rid of rel=nofollow (to get google backlinks)

2011-11-20T04:53:00.000+05:30

I have been running this website till 2008 and my website has a reasonable ranking (google PR, alexa or yahoo). But my page was indexed in google with more than 900 links, indexed with Bing and as well yahoo. Also i have backlinks with Bing and yahoo.

But there was no backlinks with Google. I thought the backlinks will come in future. I was waiting for more than a year, there was no such improvement (not even a single link).

Browsed through the net i felt there was a small tweaking has to be done with Wordpress (since my blog was hosted with wordpress). The actual problem is by default, wordpress comments are using the rel=nofollow which indicates the Google search engine not to follow the comments which are having rel=nofollow.

So we need to remove it either by adding a small code (modifying a php file inside the wordpress or else go for some plugin that get rids of the rel=nofollow). Google gives its Page Rank (PR) based on Google Backlinks too. So even if you have a good alexa, compete and other rankings, if rel=nofollow is there, then obviously the Google Page Rank will never go up.

There are quite good number of nofollow plugins are available. May be one such good plugin is No Follow Free.

I installed the plugin today and let me to wait for some more days to get Google Backlinks. (Up to my knowledge, Google indexed pages are different from Google Backlinks).

Links for 2011-07-03 [Digg]

2011-07-04T00:00:00-07:00

Pradeepkumar.org
This is about technology blog deals with "how to" for various tools like ns2, embedded systems, linux, etc.It also displays video lectures, lecture notes of various subjects of indian universities

DSC02368 [Flickr]

2011-06-17T09:21:52-07:00

tspradeepkumar posted a photo:

Its at besant Nagar, chennai. Raining outside, but the watch is watching the rain....

DSC02348 [Flickr]

2011-06-17T09:19:35-07:00

tspradeepkumar posted a photo:

rain drops...

Pradeepkumar.org

Normal Forms (Min terms, Max terms)

Introduction to Discrete Mathematics

Visit of Dr. Richard Stallman

Workshop on Wearable Computing in VIT University - Chennai Campus

How to write a Makefile

Process ID and Parent Process ID in Linux

Printing the Uptime and Idle Time of processor (Linux)

Printing Linux Environment using C Program

Operating Systems (Yesterday, Today and Tomorrow)–PPT

OS Objectives and functions–PPT

Introduction to Operating systems–PPT

Setting Path in Linux

Basic Linux Commands for Beginners

Happy New Year 2012

How to create an Agent in NS2 (Network Simulator 2)

Google+ connected to Blogger

Top Google searches 2011 (Google zeitgeist)

C Compiler for Windows 7 64 bit Operating Systems

Moving from Wordpress to Blogger

HTML List Box processing using Servlets

Servlets and JDBC (User authentication)

HTML Form Processing using Servlets

Running Servlets using Tomcat

Installing NS-2.35 in Ubuntu 11.10 and Fedora 16

Get rid of rel=nofollow (to get google backlinks)

Links for 2011-07-03 [Digg]

DSC02368 [Flickr]

DSC02348 [Flickr]