Tech talk!

Problem - GWT logging not working

2011-10-15T15:21:00.000-07:00

When you inherit certain modules in .gwt.xml file, it disables GWT logging. This happened to me when I tried inheriting Requestfactory. Some modules inherit com.google.gwt.logging.LoggingDisabled internally and thus affect your logging.

To fix this you should explicitly enable logging after you have inherited all your modules. At the end of your list of inherits add the following to your .gwt.xml file-

<set-property name="gwt.logging.enabled" value="TRUE"/>

Executing Postgres crosstab query as a prepared statement

2011-10-15T15:07:00.000-07:00

I was executing a crosstab query as a prepared statement in Java(in a GWT app) and getting the following error -

PSQLException -Can't use query methods that take a query string on a PreparedStatement.

With some helpful folks from stackflow, I was able to resolve the error with the following code -

String query = "SELECT * FROM crosstab(
                      'SELECT rowid, a_name, value 
                       FROM test WHERE a_name = ''att2'' 
                                    OR a_name = ''att3''
                      ORDER BY 1,2'

) AS ct(row_name text, cat_1 text, cat_2 text, cat_3 text);";

PreparedStatement stat = conn.prepareStatement(query);
ResultSet rs = stat.getResultSet();
//Note that, it is executeQuery() and not executeQuery(query)
stat.executeQuery();
rs = stat.getResultSet();
while (rs.next()) {
//TODO
}

Thanks!

PostgreSQL crosstab query - Rotate a table about a pivot

2011-10-15T14:49:00.000-07:00

An interesting feature of relational databases(postgres in this case) is the ability to rotate the table about a pivot. So if you have data like this-
id | rowid | key | value
---+------+----+-------
1 | test1 | key1      | val1
2 | test1 | key2      | val2
3 | test1 | key3      | val3
4 | test1 | key4      | val4
5 | test2 | key1      | val5
6 | test2 | key2      | val6
7 | test2 | key3      | val7
8 | test2 | key4      | val8

And want to have a result set like this -

rowid | key1 | key2 | key3 | key4
------+------+-----+-----+------
test1 | val1 | val2 | val3 | val4
test2 | val5 | val6 | val7 | val8

It can be achieved by a "crosstab" query in a postgres database -

SELECT * FROM crosstab(
     'SELECT rowid, key, value
           FROM test WHERE key= ''key1'' OR key = ''key2''
                       OR key = ''key3'' OR key = ''key4''
           ORDER BY 1,2'
     ) AS ct(rowid text, key1 text, key2 text,
                         key3 text, key4 text);

Virtualbox-Windows 8 developer preview installation error

2011-09-15T22:19:00.000-07:00

Downloaded the Windows 8 developers preview yesterday but only to find I could not get it installed on a Oracle Virtualbox. I tried both 32-bit and 64 bit version on a Win 7 64 bit machine(HP EliteBook 8440p). The 32-bit got stuck at the following screen. I need to look for help on this error 0x81B8C63B

EDIT: From "Smiley"'s comments below, after I turned the Virtualization option ON from the BIOS menu at startup, I was able to install windows 8. Thanks.
Surprisingly, I have a Ubuntu virtual machine and it runs fine without turning on the Vitualization option.

Wxpython snippet - A date time control

2011-03-17T13:06:00.000-07:00

Make sure you have installed wxwidgets.

# Create date control
self.dateCtrl = wx.DatePickerCtrl(panel, -1, pos=(130, 70))

#create time control
self.timeCtrl = wx.lib.masked.timectrl.TimeCtrl(panel,display_seconds=False,
fmt24hr=False, id=-1, name='timeCtrl',
style=0,useFixedWidthFont=True,
value=datetime.now().strftime('%X'), pos = (250,70))

To get values -

self.timeCtrl.GetValue()

self.dateCtrl.GetValue())

C++ - Virtual functions

2011-03-07T23:20:00.000-08:00

I came across an interesting question in an interview today. It was about virtual functions. I wanted to improve my understanding of virtual functions, so here are some interesting findings, some new and some already known to me.

Destructors are called in the order - derived to base(if base destructor is virtual)
A virtual function is member function of a class , whose functionality can be overridden by its derived class.
The virtual function call is resolved at run time. Unlike non-virtual member functions which are resolved at compile time.(static binding/dynamic binding)
If a same 'name' function is implemented in both base class and derived class, the base class function would be called.
A class with one or more pure virtual functions becomes an abstract base class. This means that it has to be inherited.
An interface class has no members variables, and all of the functions are pure virtual.

Yii web service and php soap client

2011-02-04T15:11:00.000-08:00

A web service is a method of communication between two machines. The web methods are exposed for world wide access. Yii has support for implementing web services. It uses SOAP as its foundation layer.

To create a web service-

1. Create a web app using Yii console application.
2. Inside the controllers folder, create a file lets say 'ServiceController.php'.
3. Add the following code, which implements two functions. One adds a session variable and the other returns it back.
<?php
class ServiceController extends CController
{
   public function actions()
    {
       return array(
        'wreader' => array(
          'class' => 'CWebServiceAction',
        ),
      );
    }

    /**
     * @param string username
     * @return float
     * @soap
     */
     public function getauth($uname)
     {

            $session = Yii::app()->session;
            $session['u_id'] = 1111;
            return 1;
     }

     /**
     * @param string username
     * @return float
     * @soap
     */
     public function getemp($uname)
     {
        $session = Yii::app()->session;
        return isset($session['u_id'])?$session['u_id']:999;
     }
}

* Remember to mark the web methods with the tag @soap in its doc comment. Yii relies on doc comment to specify the data type of the web method's input parameters and return value.

Create a php file and enter the following code which consumes the web service.
<?php
$client=new SoapClient('http://127.0.0.1/s/index.php/service/wreader');
echo "\n".$client->getauth('harpreet');
echo "\n".$client->getemp('harpreet');

?>

Execute the php script in a terminal to check out your web service.

Open to suggests/improvements.

Read from Magtek card swipe reader in HID mode using libusb-win

2011-02-04T14:26:00.000-08:00

This post deals with reading card swipe information from a Magtek USB Swipe Reader when set in HID mode. I used Visual Studio C++ Express Edition for a windows development environment. I installed libusb-win32 from http://www.libusb.org/wiki/libusb-win32
Create a C++ project in Visual studio, include the usb.h file and link the project with libusb.lib. Both of these are included in the libusb package.

The following can be used to read the card information-

// magtekusbhidcardswipe.cpp : Defines the entry point for the console application.
//
#include
#include

#include "stdafx.h"
#include "usb.h"

int _tmain(int argc, _TCHAR* argv[])
{
    struct usb_bus *busses;
    struct usb_bus *bus;
    struct usb_device *dev;
    int c, i, res;
    char data[337];
    char idata[10];

    usb_init();
    usb_find_busses();
    usb_find_devices();
    busses = usb_get_busses();
    for (bus = busses; bus; bus = bus->next) {

        for (dev = bus->devices; dev; dev = dev->next) {
        if(dev->descriptor.idProduct == 2 && dev->descriptor.idVendor == 0x801) {
        printf("Product id: %04hx" ,dev->descriptor.idProduct);
        printf("Vendor id: %04hx \n" ,dev->descriptor.idVendor);

        usb_dev_handle *l_Handle = usb_open( dev);
        if( NULL == l_Handle ){
            printf( "usb_open(): no handle to device\n" );
        }
        res = usb_claim_interface(l_Handle, 0);
        if(res < -EBUSY) {
            printf("Device interface not available to be claimed! \n");
            exit(0);
        }
        if(res < -ENOMEM) {
            printf("Insufficient Memory! \n");
            exit(0);
        }
        printf( "\nPlease swipe your card\n",res );

        res = usb_interrupt_read(l_Handle, 0x81, data, 337, -1);
        printf( "\nusb_interrupt_read %d \n",res );

        c=-1;
                //I am interested in only 10 characters in this range
        for(i=1;i<10;i++) {
            idata[++c] = data[i];
        }
        c=atoi(idata);
        printf( "\nMy data : %d\n",c);

        usb_release_interface(l_Handle, 0);
        usb_close(l_Handle);
        }
       }
    }
    getchar();
    return 0;
}

Suggestions/improvements are welcome as always.

Iphone 4 does not mount on Ubuntu after iOS 4.2 upgrade - DBus Error

2011-02-01T20:52:00.000-08:00

After I upgraded my iphone to iOS 4.2, I was not longer able to mount it on Ubuntu 10.10. Whenever I got plugged it in, I would get an error message -
DBus error org.freedesktop.DBus.Error.NoReply: Message did not receive a reply (timeout by message bus)

I looked it up and found a workaround, seems like I need to update to a newer version of libimobiledevice.

Here is how I did it-

Unplug the iPhone and execute the following in the terminal window.

sudo add-apt-repository ppa:pmcenery/ppa
sudo apt-get update
sudo apt-get upgrade

sudo apt-get install libimobiledevice-utils

After the above install, plug in the iphone and execute -

idevicepair unpair
idevicepair pair
idevicepair validate

That was it and we are back with Iphone on Ubuntu.

C++ - prime numbers

2011-01-17T13:12:00.000-08:00

I was reading about algorithms the other day and came to know of a faster algorithm to find prime numbers. It is called the Sieve of Eratosthenes. When I compared the execution times of this algorithm to the one I coded, the times were remarkably faster. A very simple and impressive algorithm to find prime numbers less than a number n.

#include <iostream>
#include <ctime>
using namespace std;

//interesting method of finding primes
// saw this one in one of the algorithm books
void sieve_of_eratosthenes(int n) {

int a[n+1];
for(int i =0 ; i<=n;i++) {
a[i] = 1;
}
for(int i = 2; i<=n/2;i++)
for(int j = 2 ; j <=n/i ; i++)
a[i*j] = 0;
for(int i = 2; i <= n; i++)
if(a[i]) {
cout<< i <<" is prime" << endl;
}
}

// the one I coded
void sieve_of_harpreet(int n) {

bool p;
for(int i=2;i < n;i++) {
p=true;
for(int j = 2 ;j*j < i; j++) { // optimized by checking only until sqrt of the number
if(i%j == 0) {
p = false;
break;
}
}
if(p) {
cout<< i <<" is prime" << endl;
}
}
}

int main() {
unsigned int start = clock();
sieve_of_harpreet(30000000);
std::cout << "Time taken: " << clock()-start << endl;

start = clock();
sieve_of_eratosthenes(30000000);
std::cout << "Time taken: " << clock()-start << endl;

return 0;
}

How to unlock Iphone 4 iOS 4.1 at baseband 2.10.04?

2010-12-15T20:49:00.000-08:00

I have an iPhone 4 with iOS 4.1 at baseband 2.10.04. I want to use the iPhone on a different network as I am traveling out of country? Can anyone point me in the right direction?
I will write a how-to tutorial once I can do it on my iPhone 4.

Bouncing Orbs

2010-11-19T11:54:00.000-08:00

I recently finished a major milestone for a C++/SDL game development course. It is my first mini-game/animation. It was an awesome programming experience. It was amazing to learn things like parallax scrolling, creating explosions, save/restore of animation state in Xml(expat). Thank you Dr. Malloy.

Python - Writing a traceroute using sockets

2010-11-02T09:41:00.000-07:00

I recently learned, how to write a traceroute using socket programming in python. I am sharing it below. I don't take any credit for the code. I may have picked bits and pieces from various different resources on the Internet, as a part of my learning process. It's not very elegant but demonstrates the purpose. Perhaps, some day I can improve it and add few enhancements to it.

#!/usr/bin/python
import sys
import socket

def traceroute(dest_name):
    dest_addr = socket.gethostbyname(dest_name)
    port = 33434
    max_hops = 30
    print dest_name
    icmp = socket.getprotobyname('icmp')
    udp = socket.getprotobyname('udp')
    ttl = 1
    while True:
        print ttl,
        recv_socket = socket.socket(socket.AF_INET, socket.SOCK_RAW, icmp)
        send_socket = socket.socket(socket.AF_INET, socket.SOCK_DGRAM, udp)
        send_socket.setsockopt(socket.SOL_IP, socket.IP_TTL, ttl)
        recv_socket.bind(("", port))
        send_socket.sendto("", (dest_name, port))
        curr_addr = None
        curr_name = None
        try:
            _, curr_addr = recv_socket.recvfrom(512)
            curr_addr = curr_addr[0]

            try:
                curr_name = socket.gethostbyaddr(curr_addr)[0]
            except socket.error:
                curr_name = curr_addr
        except socket.error:
            pass
        finally:
            send_socket.close()
            recv_socket.close()

        if curr_addr is not None:
            curr_host = "%s (%s)" % (curr_name, curr_addr)
        else:
            curr_host = "*"
        print "%d\t%s" % (ttl, curr_host)

        ttl += 1
        if curr_addr == dest_addr or ttl > max_hops:
            break

if __name__ == "__main__":
    traceroute(sys.argv[1])

Can be executed as -

>sudo ./traceroute.py xharpreetx.com

C++ - Maps and Vectors

2010-10-07T00:57:00.000-07:00

I have been learning something really exciting this semester. It is a grad course called Object oriented software development using C++. Apart from learning the pillars of object orientation i.e. encapsulation, inheritance and polymorphism, I have got a chance to delve into game programming. It is a challenging domain and I will post some of my animation/game videos sometime soon.
The other day, I was writing some code to familiarize myself with vectors and maps. Here it goes -
#include <iostream>
#include <map>
#include <vector>
using std::string;
using std::cout;
using std::endl;
using std::vector;

//Todo: check how to use overloading for 'print' function
void print(std::map<string,int> &m) {
std::map<string,int>::const_iterator it;
for(it=m.begin();it!=m.end();++it) {
    std::cout << (it)->first << " = " << (it)->second << std::endl;
}
}
//Todo: check how to use overloading for 'print' function
void print(vector<int> v) {
vector<int>::const_iterator it;
for(it=v.begin();it!=v.end();++it) {
    std::cout<< (*it) << std::endl;
}
}

void initializevec(vector<int> &vec) {
for (unsigned int i = 0 ; i < 20; ++i) {
    vec.push_back(i);
    //demonstrates how capacity grows as size of vector increases
    cout << "size = " << vec.size() << " capacity = " << vec.capacity() << endl;
}
}

int main() {
cout<< " MAP " << endl;
std::map<string,int> mymap;
mymap["b"] = 1;
mymap["a"] = 2;
mymap["c"] = 5;
mymap["d"] = 3;

print(mymap);
cout << "size = " << mymap.size() << endl;

std::map<string,int>::iterator it = mymap.find("c");
cout<< "Deleting 'c' ... " <
mymap.erase(it);
print(mymap);
cout << "size = " << mymap.size() << endl;
std::cout << std::endl;

cout<< " VECTOR " << endl;
vector<int> vec;
initializevec(vec);

vec.push_back(13);
print(vec);

return 0;
}
Compile using -
g++ -W -Wall -Weffc++ -ggdb -O0 filename.cpp

It demonstrates some basic operations of maps and vectors. It was nice to understand how vectors increase their 'capacity' to accommodate new elements.

Yii - data grid view with some customization of cell content format

2010-09-17T07:53:00.000-07:00

Lets start by creating a simple table

CREATE TABLE IF NOT EXISTS `users` (
`id` int(10) unsigned NOT NULL AUTO_INCREMENT,
`username` varchar(20) NOT NULL,
`password` varchar(128) NOT NULL,
`activationKey` varchar(128) NOT NULL DEFAULT '',
`createtime` int(10) NOT NULL DEFAULT '0',
`lastvisit` int(10) NOT NULL DEFAULT '0',
`superuser` int(1) NOT NULL DEFAULT '0',
`status` int(1) NOT NULL DEFAULT '0',
PRIMARY KEY (`id`),
UNIQUE KEY `username` (`username`),
KEY `status` (`status`),
KEY `superuser` (`superuser`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 AUTO_INCREMENT=1 ;

Configure the database connection as shown in one of the earlier posts.

Generate the corresponding model for the table in your database by executing the following commands
>protected\yiic shell

>> model *

Now, I want to create a data grid view to show the details of the table.

To show a link to the new "users" page(with a data grid) on navigation bar, open the file ..\mytestapp\protected\views\layouts\main.php

and add the following entry, in the "mainmenu" div.

widget('zii.widgets.CMenu',array(
            'items'=>array(
array('label'=>'Home', 'url'=>array('/site/index')),
array('label'=>'Users', 'url'=>array('/site/users')), //####### new entry
array('label'=>'About', 'url'=>array('/site/page', 'view'=>'about')),
array('label'=>'Contact', 'url'=>array('/site/contact')),
array('label'=>'Login', 'url'=>array('/site/login'), 'visible'=>Yii::app()->user->isGuest),
array('label'=>'Logout ('.Yii::app()->user->name.')', 'url'=>array('/site/logout'), 'visible'=>!Yii::app()->user->isGuest)
),
)); ?>

The site controller needs information about where to render the new "users" page.
This can be done by adding the following method in the ..\mytestapp\protected\controllers\SiteController.php file

public function actionUsers()
    {
    $dataProvider=new CActiveDataProvider('Users');
    $this->render('users',array('dataProvider'=>$dataProvider,
                ));
    }

As you would notice that these methods should begin with "action" prefix.

Create a new file "users.php" at this location
..\mytestapp\protected\views\site\users.php

The contents of this file would look something like this-

$this->pageTitle=Yii::app()->name . ' - Users';
$this->breadcrumbs=array(
    'Users',
);

?><h1>Users

beginWidget('CActiveForm', array(
    'id'=>'members-form',
    'enableAjaxValidation'=>true,
)); ?>

widget('zii.widgets.grid.CGridView', array(
    'dataProvider'=>$dataProvider,
    'columns'=>array(
   array(
    'name'=>'id',
    'value'=>'CHtml::encode($data->id)'
   ),
   array(
    'name'=>'username',
    'value'=>'CHtml::encode($data->username)'
   ),
   array(
    'name'=>'createtime',
    'value'=>'CHtml::encode(date(\'Y-m-d\', $data->createtime))' //this will format the unix timestamp to a custom date format
   ),
   array(
     'name'=>'lastvisit',
     'value'=>'CHtml::encode(date(\'Y-m-d\', $data->lastvisit))'      // format the cell with date format
   ),
   array(
   'name'=>'status',
     'value'=>'CHtml::encode($data->status==1 ? \'Active\': \'Inactive\' )'
// to render the gridview cell with a particular value
    ),
    ),
)); ?>
endWidget(); ?>

The page should be hosted at
http://localhost/mytestapp/index.php/site/users
or
http://localhost/mytestapp/index.php/?r=site/users

depending on the url manager setting in the config file.

Setup and debug an Yii app in Netbeans IDE

2010-09-09T10:57:00.000-07:00

After using Eclipse for a while I switched to Netbeans IDE for Yii development. It seems faster and easier to setup. Following is my experience of setting up the development environment.

Create a project stub using the following command -
>> yii-1.1.3.r2247\framework\yiic webapp mytestapp

Open Netbeans IDE and proceed with the following steps -

1. Click on File-> New Project
This will open up a dialog box. Select "PHP" under "Categories" and under "Projects" select "PHP Applications with Existing Sources".

Click Next.
2. In the "Sources Folder", input the path of "mytestapp" folder on your machine.
Assign a project name. "mytestapp" for my case.
Select a PHP version.

Click Next
3. The options in this form should be set up automatically like below.

    Click Finish

    This should set up your Yii project in Netbeans IDE.

4. Go to "Debug" menu on the top bar on Netbeans IDE. Select "Debug Project(mytestapp)" and you should be able to debug your project.

5. "Continue(F5)" option in Debug can be used to resume a stopped debug session.

Yii - Authentication from mysql database using a md5 password

2010-08-24T14:37:00.000-07:00

Before proceeding make sure the database has been connected to Yii application. (see previous post)
For this example, the passwords are stored in the database as md5 hash.
You may be required to change the password encoding scheme.

Edit the authenticate method in ../my_app/protected/components/UserIdentity.php to look like this -

public function authenticate()
    {
        //$users=array(
            // username => password
            //'demo'=>'demo',
            //'admin'=>'admin',
        //);

        $user = myUsersTable::model()->findByAttributes( array( 'my_userid_column_name' => $this->username));
        if ($user===null) { // No user was found!
            $this->errorCode=self::ERROR_USERNAME_INVALID;
        }
        // $user->Password refers to the "password" column name from the database
        else if($user->Password !== md5("my_salt1".$this->password))
        {
            $this->errorCode=self::ERROR_PASSWORD_INVALID;
        }
        else { // User/pass match
            $this->errorCode=self::ERROR_NONE;
        }
        return !$this->errorCode;
    }

Enter the username/password pair on the login page and you should be good to go.

A UNIX survival guide for students

2010-08-06T10:27:00.000-07:00

1. Basic UNIX commands
    > ls
        List the contents in current directory.
    > ls -alF
        List the contents in long format in the current directory.

    > cd directoryname
        Change current directory to another directory.

    > mkdir directoryname
        Create a directory.

    > cp file1.txt file2.txt
        Make a copy of file1.txt.

    > mv /home/harpreet/file1.txt /tmp/file2.txt
        Move the file to different location or can be used for renaming a file.

    > rm filename.txt
        Delete a file.

    > rm -R directoryname
        Delete the contents of a directory.

    > head -20 filename.txt
        Get 20 lines from the top of the file.

    > tail -30 filename.txt
        Get 30 lines from the bottom of the file.

2. vi filename.txt
    Edit a file.
    a. Esc dd
        Deletes the current line
    b. Esc u
        Undo the last action
    c. Esc :0       (zero)
        Move cursor to first line of file
    d. Esc $
        Move to end of current line
    e. Esc Shift+g
        Move to end of file
    f. Esc yy
        Copy the current line
        Esc y3y
        Copy the next three lines
    g. Esc p
        Paste the copied line(s)
    h. Esc :35
        Moves the cursor to line number 35
    i. Esc /wordtofind
        Find the word within the file. Press 'n' to move to the next occurrence.

3. > grep 'wordtofind' filename.txt
        Finds the line containing a string from the file
       grep -i 'wordtofind' filename.txt
        Case-insensitive find.

4. > find /tmp/directoryname -name test.txt
        Find a file with name 'test.txt' in the given path.

5. > find . -type f -exec grep -i Row2 {} \; -print
        Find the word 'row2' from all the files in current path.
        Also, shows the line containing an occurrence of the word.

6. > scp harpreet@hostname.edu:/tmp/file.txt .
        Copy a file located on another server to the current directory on the present server.

    > scp file.txt harpreet@hostname.edu:.
        Copy a file from current server to another server into your home directory.

    > scp file.txt harpreet@hostname.edu:/home/directory/file.txt
        Copy a file from one machine to another.

7. > tar cvzf new_tar_file.tar.gz file1.txt file2.txt
        Create a tar file new_tar_file.tar.gz containing file1.txt and file2.txt

    > tar xvzf abc.tar.gz
        Untar the contents of a file abc.tar.gz to the current directory

8. awk - Let us create a file 'test.txt' with these contents
       Row1-column1 Row1-column2 Row1-column3 Row1-column4
   Row2-column1 Row2-column2-HARPREET Row2-column3 Row2-column4
   Row3-column1 Row3-column2 Row3-column3 Row3-column4-SINGH

    Observe the output for various commands
    > awk '{print $2}' test.txt
      Row1-column2
    Row2-column2-HARPREET
    Row3-column2
        The above command prints the second column

    String matching using awk :
    > awk '{if ( $4 ~ /SINGH/ ) { print $2 $3}}' test.txt
    Row3-column2Row3-column3
        The above command matches the string 'SINGH' and prints column 2 and 3.

Corrections/improvements/questions are welcome :)

Compiling Ganglia - Errors and problems

2010-07-30T20:52:00.000-07:00

Some errors and problems:

My install directory was /opt/ganglia.

Error -
checking for gcc... no
checking for cc... no
checking for cl.exe... no
configure: error: no acceptable C compiler found in $PATH
See `config.log' for more details.

Solution -
Add gcc bin path to PATH environment variable

Error -
checking for pcre.h... no
checking for pcre_compile in -lpcre... no
libpcre not found, specify --with-libpcre=no to build without PCRE support

Solution -
PCRE is not installed.
# wget ftp://ftp.sunfreeware.com/pub/freeware/SOURCES/pcre-8.10.tar.gz
# /usr/local/bin/tar -xzf pcre-8.10.tar.gz
# cd pcre-8.10
# ./configure --prefix=/opt/ganglia
# make && make install

Make sure you add, -I/opt/ganglia/include to CFLAGS environment variable
and -L/opt/ganglia/lib to LDFLAGS after this.

Problem -
Graphs not shown in ganglia or images not shown on ganglia front end.

Reason -
php-gd may not have been installed.
You can do so by ( as root) -

# yum install php-gd

Another reason could be front-end can't find RRD path. Make sure it is set in conf.php

Error -

checking for apr-1-config... no
configure: error: apr-1-config binary not found in path

Reason -
APR is not installed or path of apr-1-config is not available through the PATH environment variable.

Error -
libgcc_s.so.1: open failed: No such file or directory

Solution-
Execute the following:
# ldd gmond
...
libgcc_s.so.1 => (file not found)
...

So gmond can link to libgcc

Add the following to you LDFLAGS
# setenv LDFLAGS $LDFLAGS:-R/yourgccpath/gcc-4.0.3/lib

-R records the runtime search path.

Install again
# ./configure --prefix=/opt/ganglia --sysconfdir=/opt/ganglia/etc
# make && make install

Error -
After installation, while executing gmond
apr_pollset_create failed: Invalid argument

Solution -
In your config file gmond.conf, if there is no udp_recv_channel or tcp_accept_channel
defined, gmond fails to run with this error.
Set "deaf = yes " under "globals"

Error -
/usr/bin/ld: cannot find -lpython2.3
collect2: ld returned 1 exit status
make[4]: *** [modpython.la] Error 1

Solution -
I dont remember exactly how i resolved it.
Most likely it was the linker not being able to find python.
Probably by setting library flags this error was resolved.

Error -
false cru libgetopthelper.a getopt1.o getopt.o getopt_init.o
make[2]: *** [libgetopthelper.a] Error 1

Solution -
Add /usr/ccs/bin to PATH environment variable.

In case of dependency not found errors, you could configure options, like --with-libapr, --with-libconfuse to point to dependency paths.

Error -
Some gm_protocol_xdr.c related warnings and finally build fails with this error

ld: fatal: relocations remain against allocatable but non-writable sections
collect2: ld returned 1 exit status

Solution -
Uninstall the dependency 'confuse' and install it by setting CFLAGS="-O3 -fPIC"
> cd ../confuse-2.7/
> make uninstall
> make clean
> env CFLAGS="-O3 -fPIC" ./configure --prefix=/opt/ganglia
> make && make install

Do a configure, make and make install and you should be good.

jQuery - Start date/end date datepicker calendar and datatable

2010-07-30T20:34:00.000-07:00

This post is basically a snippet of code to address the following -
1. Attach jQuery (datepicker) calendar to start date and end date inputs.
2. Create a jQuery datatable
3. On page submit, hide submit button and show a loading image instead.

After you have downloaded jQuery and extracted it to appropriate folders,
create a php file with these contents -

<?php

class InitPage {
    public $jscript = "
    <script type=\"text/javascript\" src=\"js/jquery-1.4.2.min.js\"></script>
    <script type=\"text/javascript\" src=\"ui/jquery.ui.core.js\"></script>
    <script type=\"text/javascript\" src=\"ui/jquery.ui.widget.js\"></script>
    <script type=\"text/javascript\" src=\"ui/jquery.ui.datepicker.js\"></script>
    <script type=\"text/javascript\" src=\"js/jquery.dataTables.js\"></script>
    <script type=\"text/javascript\" src=\"js/myjscript.js\"></script>";

    public $css =
        " <link type=\"text/css\" href=\"themes/redmond/jquery.ui.all.css\" rel=\"stylesheet\" />";
    public $header = "<html><head><title>Random Information</title>";
    public $body = "</head><body ><h1 >Random Information</h1>";
    public $footer =
        "<div id=\"footer\"><p><a href=\"http://rowsandcolumns.blogspot.com\">
        http://rowsandcolumns.blogspot.com</a></div></body> </html>";
    public function print_page($v_header,$v_jscript,$contents,$v_footer="") {
        if(!$v_header) {
            $v_header = $this->header.$this->jscript.$this->css.$this->body;
        }
        if(!$v_footer) {
            $v_footer = $this->footer;
        }
        echo $v_header.$contents.$v_footer;
    }
    function is_date( $str )
    {
    $stamp = strtotime( $str );
    if (!is_numeric($stamp)) {
        return FALSE;
    }
    $month = date( 'm', $stamp );
    $day   = date( 'd', $stamp );
    $year = date( 'Y', $stamp );
    if (checkdate($month, $day, $year)) {
        return TRUE;
    }
    return FALSE;
    }
}

$table_contents = "";

if(isset($_POST) && !empty($_POST)) { //On submit enter here
$bp = new InitPage();
// Get dates and validate if
//start date and end date are in proper format
    if (isset($_POST["start-date"]) &&
                $bp->is_date($_POST["start-date"]) &&
                    isset($_POST["end-date"]) &&
                        $bp->is_date($_POST["end-date"])
        ){

    list($start_date_m, $start_date_d, $start_date_Y)= explode("/",$_POST["start-date"]);
    list($end_date_m, $end_date_d, $end_date_Y)= explode("/",$_POST["end-date"]);

    $start_date = date("Y-m-d H:i:s", mktime(8, 0, 0, $start_date_m, $start_date_d, $start_date_Y));

    $end_date = date("Y-m-d H:i:s", mktime(8, 0, 0, $end_date_m, $end_date_d, $end_date_Y));
    if($end_date <= $start_date) {
        $table_contents.= "<font size=\"2\" color=\"red\">Start date should be
                            less than end date!</font>";
        $bp->print_page("","",$table_contents,"");
        die;
    }
    //Time to hide submit button and show loading image
    sleep(3);
    $table_contents = "<br/><br/><div style=\"width:500;\" >
    <table border=\"1\" width=\"500\" id=\"reading\">
    <thead>
        <tr>
            <th>Serial #</th>
            <th>Name</th>
            <th>Count</th>
        </tr>
    </thead>
    <tbody>
    <tr><td> 1 </td> <td> Managers </td> <td> 10 </td></tr>
    <tr><td> 2 </td> <td> Engineers </td> <td> 50 </td></tr>
    <tr><td> 3 </td> <td> Interns </td> <td> 5 </td></tr>
    <tr><td> 4 </td> <td> Executives </td> <td> 3 </td></tr>
    <tr><td> 5 </td> <td> Facilities </td> <td> 2 </td></tr>
    </tbody>
    <tfoot>
    <tr>
            <th>Serial #</th>
            <th>Name</th>
            <th>Count</th>
    </tr>
    </tfoot>
    </table></div><br/>    ";
    }
    else {
        $table_contents.= "<font size=\"2\" color=\"red\">Start date/End date
                            is not valid!</font>";
    }
    $bp->print_page("","",$table_contents,"");
    die;
}
else { // On first page load
$bp = new InitPage();
$select_cb = "<form action=\"index.php\" method=\"post\">Please select start and
        end date...<br/>
        <br/><label for=\"start-date\">Start date:</label>
        <input type=\"text\" name=\"start-date\" id=\"start-date\"/><br/><br/>
        <label for=\"end-date\">End date: </label>
        <input type=\"text\" name=\"end-date\" id=\"end-date\"/>

        <p><input type=\"submit\" id=\"submit_button\" name=\"submit_button\"
                value=\"Submit\"></p>
        <span id=\"spanloader\" style=\"display: none;\"><img src=\"images/loading1.gif\"
            alt=\"Please wait...\"> Please wait...</span>
        </form> ";
$bp->print_page("","",$select_cb,"");
}
?>

Create javascript file (js/myscript.js) with these contents:

//attach datepicker to start date
$(function() {
    $("#start-date").datepicker();
});
//attach datepicker to end date
$(function() {
    $("#end-date").datepicker();
});

$().ready(function() {
    $('#submit_button').show();

//hide the submit button after click and show loading image
        $('[id$=submit_button]').click(function() {
                $('#spanloader').show();
                $('#submit_button').hide();
            });
});

//set datatable
$(document).ready(function() {
    $('#reading').dataTable({
    "bJQueryUI": true,
    "sPaginationType": "full_numbers"});
} );

This should get you started with a data table and start date end date datepicker using jquery.

Ganglia - Basic installation and configuration guide

2010-07-27T20:38:00.048-07:00

After playing around, with both Zabbix and Ganglia, I decided to go ahead with Ganglia. The installation is tricky but once it is installed, configuring and adding hosts is easy. Here I will discuss, installation and configuration of Ganglia. Both the client and server daemon will be installed on the same machine.

Ganglia is a monitoring system for high-performance computing systems. Ganglia comprises of two daemons. The daemon gmond, acts like a client and sends machine information( as xml fomat), to daemon gmetad which stores these statistics in a round robin database.

A PHP-based web frontend is used to dispay the graphs in near real time.
Before starting Ganglia a few dependencies are required to be installed.

# tcsh

# setenv INSTALL_DIR /opt/rrdtool-1.4.4

# setenv BUILD_DIR /opt/build/rrdbuild

# cd $BUILD_DIR   

# wget http://oss.oetiker.ch/rrdtool/pub/rrdtool-1.4.4.tar.gz 

 # gunzip -c rrdtool-1.4.4.tar.gz | tar xf – # cd rrdtool-1.4.4

# ./configure --prefix=$INSTALL_DIR && make && make install

This would have installed round robin database. It is required only on the head node. The head node (server) would be the one where you want to install gmetad daemon.
Another dependency required for Ganglia is libconfuse.

# cd /opt/build
# wget http://bzero.se/confuse/confuse-2.6.tar.gz
# /bin/tar -xzf confuse-2.6.tar.gz
# cd confuse-2.6
# ./configure --prefix=/opt/ganglia
# env CFLAGS="-O3 -fPIC" ./configure --prefix=/opt/ganglia
# make
# make install

Now we download Ganglia source package and begin installation.

# cd /opt/build/ 

# wget http://sourceforge.net/projects/ganglia/files/ganglia%20monitoring%20core/3.1.7/ganglia-3.1.7.tar.gz/download 

# tar -xzf ganglia-3.1.7.tar.gz 

# cd ganglia-3.1.7   

# setenv CFLAGS "-I/opt/ganglia/include/ -I/opt/rrdtool-1.4.4/include"  

# setenv LDFLAGS "-L/opt/ganglia/lib/ -L/opt/rrdtool-1.4.4/lib"  

# ./configure --prefix=/opt/ganglia --with-gmetad --sysconfdir=/etc/ganglia  

# make  

# make install

Make sure the permissions are appropriate on path /opt/ganglia/rrds. This is the path where I have my round robin database.

# cd /opt/ganglia/sbin/

# ./gmond --default-config > gmond.conf

# ./gmetad --default-config > gmetad.conf

Setup config files for gmetad and gmond.conf
# vi gmond.conf

Set up your udp_send_channel to look like this:

udp_send_channel {
host = masterhostname
port = 8650
ttl = 1
}
# vi gmetad.conf

Modify directives as:

data_source "MyCluster" localhost

rrd_rootdir "/opt/ganglia/rrds" 

# cp gmond.conf /etc/ganglia/.

# cp gmetad.conf /etc/ganglia/.

# cd $BUILD_DIR
# cp gmond/gmond.init /etc/rc.d/init.d/gmond

# vi /etc/rc.d/init.d/gmond

Set this variable as
GMOND=/opt/ganglia/sbin/gmond

Optional (this would enable running the daemons as an automated service) :

# chkconfig --add gmond

# chkconfig --list gmond
gmond     0:off   1:off   2:on    3:on    4:on    5:on    6:off

# /etc/rc.d/init.d/gmond start
Starting GANGLIA gmond:                              [  OK  ]
# cd /opt/build/ganglia-3.1.7/gmetad
# cp gmetad.init /etc/rc.d/init.d/gmetad
# vi /etc/rc.d/init.d/gmetad


GMETAD=/opt/ganglia/sbin/gmetad


# chkconfig --add gmetad

# chkconfig --list gmetad
gmetad    0:off   1:off   2:on    3:on    4:on    5:on    6:off


# /etc/rc.d/init.d/gmetad start
Starting GANGLIA gmetad: [ OK ]

Edit httpd.conf

Add the following lines if they are not a part of your config file.

LoadModule php5_module modules/libphp5.so

 

Edit  DirectoryIndex  like

DirectoryIndex index.html index.html.var index.php
Addtype application/x-httpd-php .php

AddType application/x-httpd-php-source .phps

Copy “web” folder to httpd document root location

Edit conf.php in web folder:
define("RRDTOOL", "/opt/rrdtool-1.4.4/bin/rrdtool");

RRDTOOL should point to rrdtool path

# /sbin/service httpd restart

You can point your browser to the web front end location and it should display you the graphs.

Extjs + PHP - How to embed Treepanel, Gridpanel and Formpanel in a page?

2010-07-25T19:57:00.003-07:00

Here is a step by step procedure to get started with a basic extjs application. It covers handling data rendering in gridpanel as well.

1. Download ExtJS and unzip it to your web path.

2. Create an html file (say test_page.html) with these contents. This will be used to render the page.

<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title> Main Page </title>
<link rel="stylesheet" type="text/css" href="ext/resources/css/ext-all.css" />
<script type="text/javascript" src="ext/adapter/ext/ext-base.js"></script>
<script type="text/javascript" src="ext/ext-all.js"> </script>
<script type="text/javascript" src="javascripts/test_ext_widget.js"> </script>
</head>
<body>
<div id="header">
</div>
</body>
</html>

3. Create php file (extjs.php) with the following contents. This file return a JSON object which will be rendered by extjs.

<?php
$start = @$_REQUEST["start"];
$limit = @$_REQUEST["limit"];

$start = $start ? $start : 0;
$limit = $limit ? $limit : 5;

$data = array(
array("first"=>'Jack', "last"=>'Shephard',"bpay"=>7.75,"cpay"=>8.75,"email"=>'jackx@clemsonx.edu',"uid"=>'jackx', "hiredate"=>'8/1 12:00am'),
array("first"=>'James', "last"=>'Ford',"bpay"=>7.75,"cpay"=>8.75, "email"=>'jamesx@clemson.edu',"uid"=>'jamesx', "hiredate"=>'9/1 12:00am'),
array("first"=>'Kate',"last"=>'Austen', "bpay"=>7.75,"cpay"=>8.75, "email"=>'katex@clemson.edu',"uid"=>'katex', "hiredate"=>'10/1 12:00am'),
array("first"=>'Juliet',"last"=>'Burke',"bpay"=>7.75,"cpay"=>8.75, "email"=>'julietx@clemson.edu',"uid"=>'julietx', "hiredate"=>'9/1 10:00am'),
array("first"=>'Sayid',"last"=>'Jarrah',"bpay"=>7.75,"cpay"=>8.75, "email"=>'sayidx@clemson.edu',"uid"=>'sayidx', "hiredate"=>'9/1 11:00am'),
);

$a = array();
for($i = $start; $i < 5; $i++) {
$a[] = $data[$i];
}
$o = array(
"success"=>true
,"totalCount"=>sizeof($data)
,"rows"=>$a
);

echo json_encode($o);
?>

4. Finally a js file (say test_ext_widget.js) which will contain the javascript to render the page. This would render a page with three panel objects (gridpanel, formpanel, treepanel).

Ext.ns('app_harpreet');

Ext.BLANK_IMAGE_URL = 'ext/resources/images/default/s.gif';

var item_list = [ {xtype : 'textfield', fieldLabel : 'First name'},
{xtype : 'textfield', fieldLabel : 'Last name'},
{xtype : 'textfield', fieldLabel : 'Email'},
{xtype : 'textfield', fieldLabel : 'Student ID'},
{xtype : 'textfield', fieldLabel : 'Current Pay'},
{xtype : 'textfield', fieldLabel : 'Base Pay'},
{xtype : 'datefield', fieldLabel : 'Hire Date'}
];

var final_cbox = new Ext.form.Checkbox( {
name : 'final_question',
id : 'final_question',
inputValue : 1,
fieldLabel : 'Suspended',
checked : true

});
item_list.push(final_cbox);

var btns = [];
btns.push( {text : 'Save', scope : this});
btns.push( {text : 'Cancel', scope : this});

// now the actual form
var uForm = new Ext.form.FormPanel( {
id:'u_form', region:'center', bodyStyle:'padding:30px', items:item_list, buttons:btns});

var window1 = new Ext.Window( {
id : 'user_edit_win',
title : 'Edit',
width : 900,
height : 650,
minWidth : 500,
minHeight : 600,
layout : 'border',
plain : true,
modal : true,
bodyStyle : 'padding:55px;',
items : [ uForm ]
});
// Custom grid pre-configured class
app_harpreet.Grid = Ext.extend(Ext.grid.GridPanel, {
//double click on user row opens a pop up window which can be used for updating record
_user_row_click : function() {window1.show();},

initComponent : function() {
var config = {
store : new Ext.data.JsonStore( {
id : 'members',
totalProperty : 'totalCount',
root : 'rows',
url : 'extjs.php',
fields : [ {name : 'first'},
{name : 'last'},
{name : 'email'},
{name : 'uid'},
{name : 'cpay', type : 'float'},
{name : 'bpay', type : 'float'},
{name : 'hiredate', type : 'date', dateFormat : 'n/j h:ia'}
]
}),
listeners : {
rowdblclick : this._user_row_click,
scope : this
},
columns : [ {
id : 'uid',
header : "UID",
width : 40,
sortable : true,
dataIndex : 'uid'
},{
id : 'first',
header : "First",
width : 40,
sortable : true,
dataIndex : 'first'
},{
id : 'last',
header : "Last",
width : 40,
sortable : true,
dataIndex : 'last'
}, {
id : 'base',
header : "Base Pay",
width : 40,
sortable : true,
renderer: Ext.util.Format.usMoney,
dataIndex : 'bpay'
}, {
id : 'pay',
header : "Current Pay",
width : 40,
sortable : true,
renderer: Ext.util.Format.usMoney,
dataIndex : 'cpay'
},{
id : 'email',
header : "Email",
width : 40,
sortable : true,
dataIndex : 'email'
}, {
header : "Hire Date",
width : 20,
sortable : true,
renderer : Ext.util.Format.dateRenderer('m/d/Y'),
dataIndex : 'hiredate'
},{
id : 'suspend',
header : "Suspend Until",
width : 40,
sortable : true,
dataIndex : 'suspend'
}],
viewConfig : {forceFit : true}
};

// apply config
Ext.apply(this, Ext.apply(this.initialConfig, config));

this.bbar = new Ext.PagingToolbar( {
store : this.store,
displayInfo : true,
pageSize : 10,
items : [ { xtype : 'textfield' } ]
});

// call parent
app_harpreet.Grid.superclass.initComponent.apply(this, arguments);
}

,
onRender : function() {
// call parent
app_harpreet.Grid.superclass.onRender.apply(this, arguments);
// load the store
this.store.load( {params : {start : 0,limit : 10}});
}});

Ext.reg('membergrid', app_harpreet.Grid);
var item_list1 = [ {xtype : 'textfield',fieldLabel : 'First name'},
{xtype : 'textfield',fieldLabel : 'Last name'},
{xtype : 'textfield', fieldLabel : 'Email'},
{xtype : 'textfield', fieldLabel : 'Student ID'} ];

var btns1 = [];
btns1.push( { text : 'Edit' });

Ext.onReady(function() {
var viewport = new Ext.Viewport( {
layout : 'border',
items : [ { //left tree panel
xtype : 'treepanel',
region : 'west',
collapsible : true,
title : 'Navigation',
id : 'tpNavigation',
root : new Ext.tree.AsyncTreeNode( {
expanded : true,
text : 'Home',
children : [ {text : 'User',leaf : true},
{text : 'Manage users',leaf : true},
{text : 'Clients',leaf : true}]
}),
rootVisible : false,
width : 200
// the west region uses a TreePanel with Accordion layout
}, { //bottom panel
region : 'south',
title : 'Search',
collapsible : true,
height : 200,
minHeight : 200,
items : [ {
xtype : 'form',
items : item_list1,
buttons : btns1
} ]
}, { // main panel to dispay records
region : 'center',
layout : 'fit',
title : 'Center',
xtype : 'membergrid'
} ]
});
});

Now you can point your browser to your html page to render the treepanel, formpanel and gridpanel. The page would make a call to extjs.php, to retrieve the data, as a Json object.
You can double click on the rows to open a pop up window, which can be used to update the data in the row.(row update is not accomplished in the above code)

Please let me know of any improvements/corrections.

Perl - How to create a tcp socket?

2010-07-25T15:25:00.001-07:00

The following program can be used to create a tcp connection to a host on a specified port.
The program attempts connection at a periodic interval, which is passed as 'execution_interval'.

#!/usr/bin/perl
use IO::Socket;
use POSIX qw/strftime/;
if (@ARGV != 4)
{
usage();
exit;
}
my $hostname = $ARGV[0];
my $port = $ARGV[1];
my $timeout = $ARGV[2];
my $interval = $ARGV[3];

my $logdir = "/tmp/";
my $datestamp = strftime('%m-%d-%y_%H:%M:%S',localtime);
$mday = (localtime(time))[3];

my $logfile = $logdir."$hostname\_$port\_tcp_socket\_$datestamp.log";
open LOG, ">>","$logfile" or die $!;
LOG->autoflush(1);
while(1) {
    my $sock = new IO::Socket::INET (PeerAddr => $hostname,
                                    PeerPort => $port,
                                    Proto => 'tcp',
                                    Timeout => $timeout);
    $cur_datestamp = strftime('%m-%d-%y_%H:%M:%S',localtime);
    $cur_mday = (localtime(time))[3];
    if(!$sock) {
        print LOG "\n$cur_datestamp : Error - Could not create socket to $hostname on $port: $!";
        sleep $interval;
        next;
    }
    if($cur_mday != $mday) {
        close(LOG);
        $logfile = $logdir."$hostname\_$port\_tcp_socket\_$datestamp.log";
        open LOG, ">>","$logfile" or die $!;
        LOG->autoflush(1);
        $mday = $cur_mday;
    }

    print LOG "\n$cur_datestamp : Socket created to $hostname on $port";
    close($sock);
    sleep $interval;
}

close(LOG);

sub usage
{
print "Invalid parameters \nUsage: ./tcp_socket.pl \n";
}

Please let me know, of any corrections/improvements.

Perl - send email without using sendmail

2010-07-25T14:57:00.001-07:00

In a recent exercise, I was required to write a script which would attempt sending email through an smtp server instead of sendmail. At a periodic interval, the script would check if the smtp server is able to send emails or not. Basically, this script ran as a background process.

#!/usr/bin/perl

use Net::SMTP;
use POSIX qw/strftime/;
if (@ARGV != 5)
{
usage();
exit;
}

my $smtpmailhost = $ARGV[0];
my $from_address = $ARGV[1];
my $to_address = $ARGV[2];
my $timeout = $ARGV[3];
my $interval = $ARGV[4];

my $logdir = "/tmp/email_logs/";

my $datestamp = strftime('%m-%d-%y_%H:%M:%S',localtime);
$mday = (localtime(time))[3];

my $logfile = $logdir."$smtpmailhost\_email_log\_$datestamp.log";
open LOG, ">>","$logfile" or die $!;
LOG->autoflush(1);
while(1) {
    $smtp = Net::SMTP->new($smtpmailhost,
                            Timeout => $timeout);
    $cur_datestamp = strftime('%m-%d-%y_%H:%M:%S',localtime);
    $cur_mday = (localtime(time))[3];
    if(!$smtp) {
        print LOG "\n$cur_datestamp : Error creating smtp object for $smtpmailhost: $!";
        sleep $interval;
        next;
    }
    if($cur_mday != $mday) {
        close(LOG);
        $logfile = $logdir."$smtpmailhost\_email_log\_$cur_datestamp.log";
        open LOG, ">>","$logfile" or die $!;
        LOG->autoflush(1);
        $mday = $cur_mday;
    }
    $smtp->mail($from_address);
    $smtp->to($to_address);
    $smtp->data();
    $smtp->datasend("Subject: $smtpmailhost - Test email message\n");
    $smtp->datasend("\n");
    $smtp->datasend("Test email has been sent successfully at $cur_datestamp!");
    $smtp->dataend();
    $smtp->quit;
    print LOG "\n$cur_datestamp : Test Email sent via $smtpmailhost!";
     sleep $interval;
}

close(LOG);
sub usage
{
print "Invalid parameters \nUsage: ./smtpemail_send.pl \n";
}

Please let me know, of any corrections/improvements.

Yii + MySql + Wamp

2010-06-20T23:30:00.007-07:00

First, I installed WampServer, which is a package of Apache, Php and MySql coupled into one. In the httpd.conf file I pointed the “DocumentRoot” and “Directory” configurations to the directory, where I would have my application and Yii framework.

I copied the Yii framwork in "d:/workspace/app_demo/”

To create the stub application from yii, I executed these commands for my setup:

>cd D:\workspace\app_demo

>yii\framework\yiic webapp myapp

-------

This created an application “myapp” under “app_demo” folder.

The “/app_demo/myapp/protected/config/main.php” file contains the database configurations. By default the database was pointed to an sqlite database. I changed that, to point to Mysql database. So I had these settings for my mysql database.

/* 'db'=>array(

'connectionString' => 'sqlite:'.dirname(__FILE__).'/../data/testdrive.db',

),*/

'db'=>array(

'connectionString' => 'mysql:host=localhost;dbname=pages_db',

'emulatePrepare' => true,

'username' => 'root',

'password' => '',

'charset' => 'utf8',

I also enabled logging through this file to look like this:

'log'=>array(

'class'=>'CLogRouter',

'routes'=>array( array('class'=>'CFileLogRoute',

'levels'=>'error, warning',

array('class'=>'CWebLogRoute',

), ), ),

-------

My database had two tables (user and address). The sql is shown below:

CREATE TABLE IF NOT EXISTS `address` (

`addressid` int(11) NOT NULL AUTO_INCREMENT,

`firstline` varchar(45) DEFAULT NULL,

`secondline` varchar(45) DEFAULT NULL,

`city` varchar(45) DEFAULT NULL,

`state` varchar(45) DEFAULT NULL,

`country` varchar(45) DEFAULT NULL,

PRIMARY KEY (`addressid`)

) ENGINE=InnoDB DEFAULT CHARSET=latin1;

CREATE TABLE IF NOT EXISTS `user` (

`userid` bigint(20) NOT NULL AUTO_INCREMENT COMMENT 'This contains the userid of the user',

`fname` varchar(128) NOT NULL COMMENT 'This contains the first name of the user',

`lname` varchar(128) DEFAULT NULL COMMENT 'This contains the last name of the user',

`sex` varchar(1) NOT NULL COMMENT 'This contains the sex of the user',

`age` int(100) DEFAULT NULL COMMENT 'This contains the age of the user',

`creation_date` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP COMMENT 'This contains the user account creation',

`user_addressid` int(11) DEFAULT NULL,

PRIMARY KEY (`userid`),

KEY `fk_user_address` (`user_addressid`)

) ENGINE=InnoDB DEFAULT CHARSET=latin1;

ALTER TABLE `user` ADD CONSTRAINT `fk_user_address` FOREIGN KEY

(`user_addressid`) REFERENCES `address` (`addressid`) ON DELETE NO ACTION ON

UPDATE NO ACTION;

-------

I had to create corresponding models for the tables. After the database configuration, I ran the following commands to create the models in my app.

cd app_demo\myapp

D:\workspace\app_demo\myapp>protected\yiic shell index.php

This opened the Yii Interactive Tool.

Yii Interactive Tool v1.1 (based on Yii v1.1.2)

Please type 'help' for help. Type 'exit' to quit.

>> model *

The following model classes (tables) match your criteria:

1. Address (address)

2. User (user)

Do you want to generate the above classes? [Yes|No] yes

generate models/Address.php

generate fixtures/address.php

generate unit/AddressTest.php

generate models/User.php

generate fixtures/user.php

generate unit/UserTest.php

The following model classes are successfully generated:

Address, User

If you have a 'db' database connection, you can test these models now with:

$model=User::model()->find();

print_r($model);

-------

After this, I edited the actionIndex function in SiteController.php to look like this:

public function actionIndex()

{

// renders the view file 'protected/views/site/index.php'

// using the default layout 'protected/views/layouts/main.php'

$this->render('index', array(

'user' => User::model()->findAll()

));

}

In the index.php, I added the following table to display the records from the database:

foreach($user AS $us):?>

 echo $us->fname;?>

echo $us->lname;?>

echo $us->age;?>

echo $us->user_address->city;?>

 endforeach;?>

Then I pointed my browser to http://localhost/myapp/index.php and this generated a table with the results.

Spidvid: Let's create better videos!

2010-04-11T08:39:00.007-07:00

The start-up scene is always sprawling with action. Individuals keep coming up with brilliant ideas to tackle a problem at hand. If you ever heard of Youtube, you can relate to the fact, that the online video sharing platform is filled with low quality videos. Enter the new service round the corner - Spidvid. It is a platform which brings together video creators and professionals, who would ultimately produce quality entertaining videos. It doesn't end here; they go further, distribute the videos and generate compensation for their contribution to the effort.

It is an inventive concept accented by a beautiful user interface. It is easy to use and very responsive. You can choose any role you want on the video creation life cycle. You may be a video creator, a professional who can act, write, edit or even an amateur who has video ideas which, you would like to be created by others. This way you get in touch with people with similar interests and learn from their experiences.

Spidvid will raise the bar for online videos. It brings together people from different corners of the planet, with a common goal of producing quality videos. Right now, Spidvid is offered as a beta service. As more and more users join the bandwagon, the talent pool will get richer, as you have more contributors.

Getting content onto the website is a task which the marketing team needs to pay attention to. I would like to have a section to see some clips of the videos created on Spidvid.

Overall, it is a good beginning to a new frontier in video collaboration. Spidvid has given users the tools which they need to connect and develop videos outside a single fortified studio. By making it open to public, the content will cross the geographical boundaries and be enjoyed by a wide range of viewers.

So, let's get started and create some videos!

Windows - the Seventh

2009-10-20T14:52:00.005-07:00

“And the SEVENTH angel poured out his vial into the air; and there came a great voice out of the temple of heaven, from the throne saying, It is DONE.” (Revelation 16 : 17)

The number 'Seven' has a lot of significance. There are seven days in a week and it was on the seventh day that the world was completed. 'Seven' symbolizes completeness or perfection. Perfection is only divine. At an earthly level, I would attribute seven to refinement. In that respect, Microsoft has achieved elegance with W7. A few things I like about W7 are:
1. The annoying UAC has become much more placid. Introduced in Vista, as a security measure, it turned out to irritate the users with its frequent pop-ups.
2. The boot performance is significantly faster. Windows 7 should have achieved a 15-sec boot up by the time it is up for final release.
3. W7 lets the users connect to wireless networks instantly with fewer clicks which will prove to be of lot of help, for users without much technical know-how.
4. The footprint of the OS is much lighter compared to Vista. It installs faster and occupies lesser space on the hard disk. Some of additional software like Windows Mail have been made optional downloads instead of default installations.
5. The new OS uses lesser battery power and is known to save energy by 20%. That is a very good news for netbook makers as, Windows 7 will prove to be the OS for netbooks, too.
6. There are some cool mouse gestures included: Aero Peek and Aero Shake. Aero Peek makes all the open windows transparent and lets the users peek through their desktop revealing hidden gadgets and icons while, Aero Shake lets the users minimize unnecessary windows from the desktop by shaking the required window.
7. The OS supports backward compatibility. Legacy applications can run in a Windows XP mode, inside of Window 7.

And, something I don't like about W7:
1. Microsoft failed to come up with a suitable strategy for integrating the cloud. With computing being the talk of the town, and Microsoft itself working on Azure, the Software as a Service(Saas) integration seems to have been lost in translation. Microsoft could have amalgamated its Live Mesh with Windows 7 for data backup.
2. W7 still lives on to the concept of one partition OS. I would have liked this to change. The data like Documents, Music, Pictures and other user settings should reside on a different partition than the OS itself. This would be of great value in case of a system crash or an OS reinstall.

Overall, W7 is a nice compact mixture of niceties and removes some of the nuisances of Vista.

Opera innovations

2009-07-03T10:27:00.009-07:00

When I read about Opera's "Reinvent the Web" campaign on Techcrunch, I was a bit excited and a bit cynical about it's legitimacy. Similar tall claims have been made earlier but with little success. Initially, I thought it was a mere marketing gimmick but, Opera did excite me on June 16, 2009. Some of the innovative features by Opera are:

1. Appearance: The Opera browser has a very polished look. It is very much a Windows 7 product. Firefox looks too XPed, IE never excited me and I have never used an Apple.

2. Mouse Gestures: One of the first things I tried to experiment was mouse gestures. Hold your right mouse in the tab and flick it to left, it performs the "Back" functionality of the browser.

3. Speed Dial: This is such a handy feature which has been there on mobile phones for years, but nobody thought of incorporating it in the browser.

4. Closed tabs: If you close any of your tabs accidentally, Opera lets you open them instantly. More important is the accessibility of this button. It is right there where I would want it to be.

5. Unite: This is something which has a potential to change the way the web works. It allows you to share files from your system rather than some third party service. By giving the user, control of his information, Opera makes the user, the master of his information. But I feel it is little too early for something like this to become an instant hit. Poor Internet speeds, limited hardware resources would be some key limitations for Unite's success. Nevertheless the idea deserves credit.

6. Widgets: These are web applications which run in the browser but without showing the browser controls. They are very easy to use and also very easy to build using client side programming languages. I have been playing around with them and will write more about how to create your own widgets, but that is later.

7. Anti Cloud: Yes Opera is anti-cloud. The world has been focusing on centralizing services across the Internet for quite some time now. With a few big names in the fray, the race has heated up. But, Opera has different plans. By providing an individual to host his own web server inside a browser, Opera has de-centralized information.

Cross domain calls

2009-06-23T06:01:00.017-07:00

The XMLHTTPRequest object is used to make an http request directly to a web server and load the server response data back into the scripting language. But this techniques works only when you are making a request to the same web server with in the same domain. Here is how to make a call from www.site1.com/user.html to www.site2.com/usercheck.aspx :

1. Create a web page on www.site1.com which would make a call to another server www.site2.com. Documentation available inline.

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" lang="en-US">
<head>
<title>Check username availability</title>
</head>
<body>
<form id="form1" runat="server">
<div>
Enter Username:

<input type="text" name="user" onchange="createScriptTag(this); return false;"/>
<span id="outputmessage"></span>
<input id='submit_button' name='submit_button' type='submit' value='submit' />
</div>
</form>

<script language="javascript" type="text/javascript">

//Create a script tag which loads javascript from a remote source
function createScriptTag(e){
var headElement;
var scriptTag;
var inputValue = e.value;
var url = 'http://www.site2.com/usercheck.aspx?username=' + inputValue + '&rnd=' + new Date().getTime();
headElement = document.getElementsByTagName("head").item(0);
scriptTag = document.createElement("script");
scriptTag.setAttribute("id", "user_script");
scriptTag.setAttribute("type", "text/javascript");
scriptTag.setAttribute("src", url);
headElement.appendChild(scriptTag);

// Creates issue with IE so remove the script tag later at an appropriate place
//headElement.removeChild(scriptTag);

}

//function to be executed on callback from the above request. The callback returns a response similar to "isAvailable({'status':1})"
function isAvailable(response){
if (response.status == 1){
document.getElementById("outputmessage").innerHTML = "Username is still available";
}
else {
document.getElementById("outputmessage").innerHTML = "Username already exists";
}
}

</script>
</body>
</html>

2. The www.site2.com/usercheck.aspx page accepts querystring parameters,

implements a business logic and returns the function to be executed on client side as response.

using System;
using System.Collections;
using System.Configuration;
using System.Data;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;

public partial class keygenerator : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
Response.ContentType = "text/plain";
if (Request.QueryString.Count > 0)
{
string username = Request.QueryString[0];

//array of names to check against
ArrayList arlExistingUsernames = new ArrayList();
arlExistingUsernames.Add("harpreet");
arlExistingUsernames.Add("singh");

if (!arlExistingUsernames.Contains(username))
{
Response.Write("isAvailable({'status':1})");
}

else
{
Response.Write("isAvailable({'status':0})");
}
}
else
{
Response.Write("isAvailable({'status':0})");
}
Response.End();
}
}

For more cross domain calling options check out:

http://snook.ca/archives/javascript/cross_domain_aj/

http://ox.no/posts/ajast-cross-domain-rest-calls-using-json-injection

http://developer.yahoo.com/javascript/howto-proxy.html

Technorati Tags: Cross domain,ajast,javascript

Turbogears debugging in Eclipse

2009-06-20T00:44:00.007-07:00

Setting up debug enabled environment for a Turbogears application in Eclipse is not really straightforward. I struggled a lot before I could set it up. Initially I wasnt even sure if I could set up break points and debug the application like in microsoft visual studio. It is very much possible although some of the things are not very obvious. Here is a list of things to check up, if you are facing problems.

1. You can install Pydev by following the instructions mentioned on pydev website. You can also have a look at this ibm site which helps you make the necessary settings in Eclipse.

2. You can patch the Decorators file from pydev blog. If you are facing any problems drop your email id I will send you the patched file.

3. Pydev gives problems with certain turbojson package versions. You may try to downgrade and install a previous version of turbojson package. Use the following command to do so:
>easy_install -U turbojson==1.1.4

>easy_install -U DecoratorTools==1.4

4. Remember, you will still see the following error when you start the debug session.

PYDEV DEBUGGER WARNING:

sys.settrace() should not be used when the debugger is being used.

This may cause the debugger to stop working correctly.

If this is needed, please check:

http://pydev.blogspot.com/2007/06/why-cant-pydev-debugger-work-with.html

to see how to restore the debug tracing back correctly.

Call Location:

File "C:\Python24\lib\site-packages\decoratortools-1.4-py2.4.egg\peak\util\decorators.py", line 562, in uninstall

But, wait for a few seconds and eclipse will start the debug session after the error message.

Asp.Net and Python-cgi communication

2009-06-16T11:23:00.010-07:00

Technorati Tags: asp.net,python,cgi

I recently had my first shot at writing cgi scripts in python. It was an altogether different experience having come from a .Net and Turbogears background. I also got my hands on a Linux server. Infact, it was the first time I got to use vi, ls, cat, cp etc, since college. It is really amazing how much you can do with just the shell commands on Linux.

The Linux machine had an apache server which ran some cgi scripts to do some basic tasks like creating a new user record in the database, deleting, editing etc. I think that was the reason they did not go beyond cgi. These tasks were manually done by an admin after logging into the application. Now, these scripts were required to be made callable from an asp.net web application.

ASP.NET application <===========> Python cgi scripts
CreateDemo.aspx _____________ create_demo.cgi
(collects user info
for demo record) _____________ (requires authentication)

So, we decided to create another script, let us say 'authenticate.cgi', in which we used urllib python library to by pass the authentication on create_demo.cgi and then CreateDemo.aspx would call authenticate.cgi. Here is the new flow-

CreateDemo.aspx --> authenticate.cgi --> create_demo.cgi

This write-up addresses two key areas:
1. How to communicate with a python cgi script from an asp.net web page?

//Request url and request method

HttpWebRequest httpRequest = HttpWebRequest)WebRequest.Create("http://192.1.1.1/no_auth/authenticate.cgi?name=harpreet”);

httpRequest.KeepAlive = false;

httpRequest.Method = "GET";

//Read the web response from the URI

string strResponse = string.Empty;

using (WebResponse webResponse = (WebResponse)httpRequest.GetResponse())

{

System.Text.Encoding enc = System.Text.Encoding.GetEncoding(1252);

using (StreamReader srResponseStream = new StreamReader(webResponse.GetResponseStream(), enc))

{

//Read the response into a string or you could use XML also

strResponse = srResponseStream.ReadToEnd();

}

}

2. How to by pass basic authentication on cgi script using urllib?

#!/usr/bin/env /usr/local/bin/python

import urllib2,urllib

import sys,os,cgi,cgitb

import re,datetime

import base64

from urlparse import urlparse

def handler():

form = cgi.FieldStorage()

if form.list:

data = {}

for field in flds:

data[field]=form.getvalue(field,'')

theurl = 'http://localhost/admin/create_demo.cgi’

# you'll need to supply a protected page with your username and password

username = 'scott'

password = 'tiger' # a very bad password

req = urllib2.Request(theurl)

try:

handle = urllib2.urlopen(req, urllib.urlencode(data))

except IOError, e:

# do whatever you want to handle the exception here, 'pass' in this example

pass

else:

# If we don't fail then the page isn't protected

print "This page is not protected by any authentication."

sys.exit(1)

if not hasattr(e, 'code') or e.code != 401:

# we got an error - but not a 401 error

print "This page is not protected by any authentication."

print 'Some other reason for failure'

sys.exit(1)

authheader = e.headers['www-authenticate']

# this gets the www-authenticate line from the headers

# which would contain the authentication scheme and realm

authobj = re.compile(r'''(?:\s*www-authenticate\s*:)?\s*(\w*)\s+realm=['"]([^'"]+)['"]''',re.IGNORECASE)

# this RE is used to extract scheme and realm

matchobj = authobj.match(authheader)

# if the authheader isn't matched by the regular expression

# then there is probably some error in the header

if not matchobj:

print 'The authentication header is badly formed.'

    print authheader 

sys.exit(1)

scheme = matchobj.group(1)

realm = matchobj.group(2)

# check schem (this example works for basic authorization only

if scheme.lower() != 'basic':

print 'This example only works for BASIC Authorization.'

sys.exit(1)

base64string = base64.encodestring('%s:%s' % (username, password))[:-1]

authheader = "Basic %s" % base64string

req.add_header("Authorization", authheader)

try:

handle = urllib2.urlopen(req,urllib.urlencode(data))

except IOError, e:

print "The username or password is not valid."

sys.exit(1)

thepage = handle.read()

print "Content-type: text/html; charset=utf-8"

print thepage

handler()

Security was not really a major concern for this cgi, but an IP based security was added to limit unwanted access.

* The code snippets are not really tested but, will hopefully work :-)

Will the history repeat itself, with Grabbler?

2009-05-01T14:22:00.005-07:00

Word games have been around the corner for quite some time now. Some give clues to guess the word, some give letters to make maximum possible words. Each one trying out a different strategy but to obtain a simple objective - form words. I remember to have played a few word games during my childhood days Scrabble, Word Crosswords being the notable ones. Well, times change, paper-pen games are remnants of the bygone days and now its an era of games on Facebook.

On and off, I had been playing Scrabble on Facebook, until i found Grabbler. It is a multi-player game which tests your word making skills, with its unique cubes. Err...on second thoughts, not so unique cubes. Actually, the possiblity that you would get the same cube again in a game is 144 in 26!/20! i.e. 1 in 1,151,150. Hence, the not so unique cubes. Over the last 45 days I have been hooked on to the game. I think I have even played a few moves in my sleep. And, tonight, I have decided I will stop playing it, at least for a few weeks. I would like to catch up more sleep in the coming few days. This decision has come after a lot of deliberations. The addict wanting to sniff more and the reasonable self in me wanting to shun it.

But, this does not stop me from appreciating the game. After a long time, a game caught my imagination. The game has a pleasant interface and has the right combination of skill and luck. It is well matched with a test of patience too. It has been fun, having beaten some very good players and remaining invincible. The eye catching feeds have been such a delight to post on the profile. Although, the game has been introduced very recently, I think this game will definitely climb the ladder pretty fast. Moreover, it is a good change for some one bored by the age old Scrabble.

That reminds me of the fact that Scrabble was created by Alfred Mosher Butts during the Great Depression in the 1930s and the game went on to occupy space in every other household. Almost eight decades later, the world is going through another major economic slowdown and Grabbler has been created. Will the history repeat itself?

Well that remains to be seen, but for now, it is adios Grabbler,for me.

How I set up my Turbogears based development environment...

2009-03-07T05:07:00.007-08:00

The start of 2009 brought along a new project for me. It was based on Turbogears 1.0.4.4 with Postgresql 8.3 as the database. Here is a list of steps I followed to setup my development environment.

1. Installed Python 2.4.4.

2. I was working on a windows platform and required support for it so I installed extensions for windows. PyWin32 is a collection of modules for advanced windows-specific support. These include utilities for COM, Win32 API calls, Registry, Event Log and MFC user interfaces.

3. Installed setuptools, so as to be able to build and distribute packages. It includes a utility easy_install, which lets you automatically download, build, install, and manage Python packages and their dependencies.

4. Installed the Turbogears web application framework by running the command:

>easy_install-2.4 -f http://files.turbogears.org/ "TurboGears==1.0.4.4"

5. Installed win-psycopg, a windows port of the psycopg python-postgresql database interface.

6. Installed SQLObject, an Object Relational Manager which provides an object interface to your database, with tables as classes, rows as instances, and columns as attributes. Used the following command to install it:

>easy_install-2.4 "SQLObject==0.10.2"

7. Installed other packages like PyPDF 1.9, ElementTree 1.2.6, ElementTidy and PyLucene for my text based application.

8. Installed TinyMCE 1.0.6, a JavaScript HTML WYSIWYG editor control, using the following command:

>easy_install-2.4 "TurboTinyMCE==1.0.6"

9. Downloaded the ExtJS 2.2 Library. It has some excellent built-in components ready to use.

10. Installed Eclipse 3.2 IDE and added the PyDev plugin using the manual and configured it accordingly.

There I was, ready to play!

Remote access to PostgreSQL Server

2009-03-06T07:08:00.007-08:00

Error: "could not connect to Server: Connection refused"

The resolution is a five step process : -

1. Firstly, check if your firewall allows the port (default is 5432) to establish a connection.

2. By default, PostgreSQL does not allow remote incoming connections. This has been implemented in this way, because of security concerns. You need to enable incoming TCP/IP connection requests from the client. This can be done by adding

#
listen_addresses = '*'
#

in the configuration file postgresql.conf. This configuration is valid for postgresql 8.x.

3. You will have to inform Postgresql who can connect to the server. This has to be done by modifying the configuration file pg_hba.conf

host all all 127.0.0.1/32 trust
host all all 192.168.0.0/16 trust

This would allow any user on the local network to access all the databases on the server in "trust" mode.

4. After you have saved the configuration files you will have to restart the server. Remember, these configuration files are read on server startup.

5. Test your config. Go to the command prompt and run the following command.

>psql -h serverIP -U postgresUser -d postgresdb

And, you should be set for remote access to postgresql server.

JSON

2009-03-05T11:09:00.016-08:00

JSON is an acronym for JavaScript Object Notation. It is a means of transferring serialized JavaScript objects so that a JavaScript application can evaluate them and transform them into JavaScript objects which, the application can utilize to perform its operations. In short, JSON is a data interchange format. It is easy to parse and generate in almost any language.

A sample JSON:-

{"continents": {
             "asia":[{"country": "india",
                      "code": "101"
                     },
                     {"country": "japan",
                      "code": "102"
                     }],
             "europe":[{"country": "france",
                        "code": "401"
                     }]
                  }
}

The most notable features of JSON are:-

1. It is basically a collection of name-value pairs ("key": "value") separated by a colon.
2. It is not only easy to read for humans but also easy to parse by the machines.
3. Values can be a string, an integer, an object or an array.
    Standard literals like True, False, null are also acceptable.
4. Each object is placed between {...}.
5. Arrays are place between [...] and are comma separated.
6. It can be passed using httpWebRequest.
7. Reserved keywords from JavaScript are not allowed in JSON.
8. JSON can be parsed using the eval() method in JavaScript.
9. It uses Unicode.


Common errors like the "missing } after property list" can be corrected
using a JSON validator like www.jsonlint.com

Existing database tables and SQLObject

2009-03-03T08:55:00.007-08:00

Define the existing table "Bookmark" as a class in python:-

class Bookmark(SQLObject):

_fromDatabase = True # the table structure will be loaded from the database
BookmarkName = StringCol (dbName="bookmark_name")
# dbName is the name of the column in the database, BookmarkName is the name reference in code.
ProjectId = IntCol(dbName="project_id")

(Make sure the indentation is correct)

Connecting to an existing database using TurboGears framework

2009-03-03T08:55:00.003-08:00

Your application would need a DB connection to access the database. A connection is how you tell SQLObject to locate your database. SQLObject is an object relational mapper, a software layer that maps data stored in a relational database to an object model in an object-oriented programming language. The connection string resembles a URI in the following format:

scheme://[user[:password]@]host[:port]/database[?parameters]
For instance:
postgres://user:pwd@localhost:5432/db

SQLObject provides a debug mechanism, which can be turned on easily by appending ?debug=True to the end of your database URI in the dev.cfg file.

postgres://user:pwd@localhost:5432/db?debug=True
This would publish the query generated onto the console.
              ..........

Define the existing table Bookmark as a class in model.py:-

class Bookmark(SQLObject):

_fromDatabase = True # the table schema be loaded from the database

BookmarkName = StringCol (dbName="bookmark_name")

ProjectId = IntCol(dbName="project_id")

# dbName is the name of the column in the database, BookmarkName is the name reference in code.
..........
Using the following code in controller.py you should be able to retrieve the second record from the Bookmark table

b=Bookmark.select()
print ":  %s " % b[2].BookmarkName

Chrome Finish

2008-09-03T07:24:00.001-07:00

Woke up with sleepy eyes, rubbed them to clear my hazy vision. Opened my laptop and saw my news of the day. Google releases new web browser "Chrome". My mid-week holiday was certainly going to be busy. Putting on my "testing goggles" I started looking for the download link. Google made sure my hunt was easy. The link started downloading a 475 KB file. A web browser setup? 475 KB? Looking at it in disbelief, I let it continue. After all, who knows with Google.

The setup file when clicked started another download and installation process. So that was it. A 475 KB application to download the actual setup. The download failed at least a couple of time. It was disappointing. Few times it simply hung and the other times it returned me some weird exception message. The link on the error dialog, lead me to no help. Some divine intervention and all of a sudden it finished installation. Few clicks for importing favorites, history etc from my darling Firefox and I see my new browser.

There I am, greeted with the new interface which made my screen look larger. The Chrome certainly gives you a lot of web space, since it removes a lot of not-so-frequently used buttons and tool bars. It makes you forget that you are using a web browser. It keeps it simple and means business i.e. web browsing. The sole focus of the Chrome is the web application and not the browser itself.

I was expecting it to load a default homepage on the first run, which is kinda customary for other web browsers, on the contrary I see my recently visited sites and bookmarks nicely laid out. The address bar has the auto-complete feature, so my butter-fingers will get some rest. I was falling for it.

Performed a few of my mundane tasks, checking emails, browsing, reading news, blogs, watching videos etc., most of the websites opened visibly fast. I wasn't sure but it did appear to be fast. I read about the technology behind Chrome, it certainly is impressive. It has the new Javascript virtual machine, V8, which is said to be a better solution for rich Web applications. So operations like "drag and drop" which were not very smooth earlier would be a breeze in the Chrome. Each tab is said to work inside a new process, which makes the life of malwares difficult. If a bad Java script was using lot of resources you can simply kill it. The Chrome has an all new task manager. Yes, a task manager(shift+esc) just like the windows to terminate a web application which is using lot of CPU/memory resource. Google has moved up, in this respect by treating each open tab as a different web application. With the Chrome, Web applications will now begin to be treated at par with desktop applications. 'One-tab one-process' also makes me believe, the web browser is a purely multi-threaded application. So, one slow web application should not affect loading the other.

One of the cool features, I found was, I could tear a certain tab away from the rest of the tabs. This is particularly useful for some one like me, who doesn't close his tabs during my day. Only when the number comes to about 30-40 open tabs do I think of closing the ones not being used. Now, I can tear away the tabs I would still need(lesser in number), and close the rest(more in number) one-shot.

If I am not wrong the FF introduced the 'open in new tab', similarly the Chrome has a new right click context menu feature, 'Open link in new incognito window'. So my privacy has been taken care of. Anything I open in this window is not saved on the system. This window runs completed isolated from the system.

I am contemplating a shift from FF to the Chrome, but it will take a while as I cant do without my darling FF's plug-ins and most important, the Chrome doesn't have a progress bar. How could you guys have missed it? My serious concern is over the amount of data Google would share with the advertisers. Google generates a lot of revenue from ads. I wonder, if they now get to know every site I open from the Chrome. Does it mean I would be spam-ed more? It raises my personal fear of, 'Google will control the world!'. Web search, Social networking, Email system, Document editing, Photo Storage, Video storage, Mobile platform and now a web browser? Whats next, an operating system?

Keeping all this aside, I would continue to use the Chrome. I am a technology freak. I will continue to use and admire the innovation, as and when it comes.

Final verdict, the Chrome has the shine but lacks the finish.