Author: masnun

Handling Exceptions in PHP and Python

Post author By masnun
Post date November 2, 2009
1 Comment on Handling Exceptions in PHP and Python

It’s really a very important programming practice to properly handle any possible exceptions… It makes the code more stable, efficient and re-usable.

PHP:
PHP now has a very good exception handling mechanism. Just put a “try” block and then “catch ” the exception if anything goes wrong 🙂

Have a look at the following code:

<?php
function masnun() {
    throw new Exception("Damn!"); }

try {
    masnun();
}
catch (Exception $e) { echo "Exception: ".$e->getMessage()."\n"; }
?>

<?php

function masnun() {

throw new Exception("Damn!"); }

try {

masnun();

}

catch (Exception $e) { echo "Exception: ".$e->getMessage()."\n"; }

The code is self explanatory. But you must use the “Exception” word before $e in the catch block to get things going perfectly. Like I did, you can “throw” a new exception in case there was really something unexpected in your code 🙂

Python:
Python is just a fantastic language. Here’s the Python equivalent of the above code snippet:

#!/usr/bin/env python

def masnun():
	raise Exception("Damn!")

try:
	masnun()

except Exception as e:
	print "Exception:", e

#!/usr/bin/env python

def masnun():

raise Exception("Damn!")

try:

masnun()

except Exception as e:

print "Exception:", e

The only difference in PHP and Python’s exception handling is it’s language structure. In Python, we don’t throw an exception, rather we raise one. Just a bit of politeness! 😉

Conclusion:
Both PHP and Python has very good exception handling techniques. I can’t discuss them all on this blog but you should consult the respective manuals to master them. They are really very essential! 😀

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The eJabberd and Tkabber stories :)

Post author By masnun
Post date October 27, 2009
2 Comments on The eJabberd and Tkabber stories :)

The eJabberd Story

For our on going project, I am playing with ejabberd. It is a Jabber/XMPP instant messaging server, licensed under GPLv2 (Free and Open Source), written in Erlang/OTP. Among other features, ejabberd is cross-platform, fault-tolerant, clusterable and modular. It’s just cool for developing jabber/xmpp bots on your local machine. The big guys often use it to run jabber services on their domain.

I am currently developing a jabber bot and had to install ejabberd on my Ubuntu. Installation was quite easy as I am on Linux. One single command did everything for me:

sudo apt-get install ejabberd

1	sudo apt-get install ejabberd

After installation, I had to check the status of the server. So I used the following command:

ejabberdctl status

1	ejabberdctl status

But I was disappointed to see the “node down” error message. I tried all the commands I knew to revive it but nothing worked right.

Then out of despair, I decided to use root privilege to do that, so I used:

sudo ejabberdctl status

1	sudo ejabberdctl status

Guess what ! 😀 It worked !! Man, I knew in order to start, stop, restart servers, you need root access. Who knew you’ll need root access for checking status as well? And why did the non-sudo code returned “node down” instead of a plain message asking to use root privilege ? I don’t know 🙁 It was really painful !

Now, I had to register a new user from the command line. I used the following command:

sudo ejabberdctl register masnun localhost masnun

1	sudo ejabberdctl register masnun localhost masnun

The format is:

sudo ejabberdctl register username hostname password

1	sudo ejabberdctl register username hostname password

Then I had to configure the ejabberd server to invoke admin access to the user I just created. The easiest way would have been to use nano with sudo to edit the config file. But unaware of what the name of the config file is and how to edit the config file, I explored the entire configuration directory with root access. I used the following trick:

sudo nautilus /etc/ejabberd

1	sudo nautilus /etc/ejabberd

Please Note that the /etc/ejabberd directory can be accessed only by the root user. A simple user can’t even view it’s contents.

The good thing was that I could double click on the config file and edit it with gedit without invoking further root access since I have already applied that to the nautilus window I have opened.

I edited the “%Admin Users” section to add me as an admin.

The eJabberd web admin is available at: http://localhost:5280/admin/ 🙂
The web admin panel is simply cool and you can do all sort of things using it except chatting 😉

The Tkabber

I was running my bot from command line and it hardly cared if I was connected to the internet or not. But I was having problem with the GUI xmpp client. I was using Pidgin. It was first working fine. But it required me to connect to the internet even the xmpp connection was being made to the localhost.

And even worse, later on, whenever I connected to localhost, pidgin crashed. So I was looking for alternatives. I have tried out a few other clients and a few web based clients as well. None of them suited me.

Finally, I found Tkabber. It’s based on TCL/TK and looks very very poor. From the look of it, it seems that it was developed for Unix machines. But matters not as long as it serves my purpose. It connects to the local machine even when I am not connected to the internet. It plays really funny sounds on different events. It has a nice tidy interface as well.

I like it ! 😀

That’s the story I wanted to share.. it’s nothing important… I just wrote it to pass my idle time… 🙂

PHP

PHPRackCloud: RackSpace PHP Client Library from Leevio

Post author By masnun
Post date October 26, 2009

RackSpace Cloud hosting is one of the most popular Cloud hosting services today. For an upcoming product of Leevio, we decided to choose RackSpace for cloud service. RackSpace has a very decent API but quite unfortunately there was no language specific client library available for PHP. The people at Rackspace were developing one for Python but we are solely using PHP for our current project. So we chose to write a PHP Client library ourselves.

As a consequence, a PHP Client library has been released from Leevio and it has been approved by Rackspace. The library is as-expected released under the New BSD license and hosted on it’s own Google Code page.

And lately, we have developed a product page for PHPRackCloud at our website as well.

Official Website: http://leevio.com/phprackcloud

Download: http://code.google.com/p/phprackcloud/

Have a look at the Wiki Page for documentation. Most of the code is self explanatory and adequate examples have been included in the download package.

The team is very happy and excited because of the recognition from RackSpace. We are glad that we have been able to create something really valuable in the first month of our start up.

Don’t forget, Leevio is still too young… But I believe we have a really long way to go… 🙂 Wish us luck !

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