Artan Ismaili's Weblog

Windows Live Messenger Has Stopped Working – How to fix it

artan — Sat, 14 Aug 2010 07:53:26 +0000

Sometimes if you are running the Windows Live Messenger 14.0 version, you will get a crash error upon startup, or whlie it is already running. I am not sure why the issue is happening, but I found a post that describes how to fix it and for me it worked like magic.

http://windowslivehelp.com/solution.aspx?solutionid=17e5dddf-4156-4725-a1a5-f3a10a76e12f

Lab 6

artan — Fri, 17 Apr 2009 02:04:12 +0000

I did this lab in Netbeans and used a java libary that David Wilcox blogged about. It took me all 2 hours to finish this lab. I initially started it in PHP, but didn’t want to learn php gtk, so I just took advantage of the drag-n-drop functionality of netbeans, to create the UI. The code for actually approving the images/comments was pretty easy with this library, and boy did I appreciate using a statically typed language as opposed to PHP’s dumb errors that you only get to find out after you’ve ran the code, and in the process screw up some comments or images.

Lab 5

artan — Fri, 17 Apr 2009 01:59:43 +0000

This was a breeze lab, after lab4. I found some really good tutorials on manipulating images with PHP’s gd libary. This lab didn’t take very long at all. One thing I would like to do (which is very simple) is to delete the images from my hard drive whenver I’m done storing them into the S3.
One problem I ran into with this lab is testing. Someone had left their image processing deamon running and I was never able to test mine live on the cloud. That issue replicated into another app server deamon, where messages were taken out of the /imageresults queue to the /approvalprocess queue. It turns out that the image description, submituser, and submitdate, were being put as arrays into the /approvalprocess sqs. It took me about a half hour to find out that before encoding the message into json, I had to enclose the description, submituser, and submitdate variables into double quotes so only the value got stored.

So, when creating the array instead of doing

$msg = array(…, ‘description’ => $description, …)

I had to do,

$msg = array(…, ‘description’ => “$description”, …)

Lab 4

artan — Fri, 17 Apr 2009 01:02:15 +0000

Like for lab 3, I used PHP with the Tarzan libary to implement this lab. I had some rough patches along the way especially dealing with getting the images from the web server and putting them on to S3. Also, this was a good practice with the SQS queues for this lab.
The deamon’s weren’t so hard to write either. I just had all my deamons in separate files that would only run once, but had a deamons starter program that would loop endlessly starting up each deamon script every time through the loop.
Also, big thanks to Jeff Peters for putting the image and comment timelines all in one place, as they travel from the user through the different servers and Amazon aws’s.

Lab 3 – Implementation Notes

artan — Mon, 13 Apr 2009 10:53:59 +0000

Lab 3 went pretty well. I used PHP to implement it with a library called Tarzan. Tarzan is pretty straightforward and has a very intuitive interface with some exceptions as far as documentation is concerned. After getting some pointers from Kekoa, I was able to finish it up quickly.

Currently, I’m struggling with Lab4, and have hit some dead end points so far, specifically using tarzan to send an image to S3 and creating new items in the domains. Tarzan is not very specific on this particular issue, so I don’t know whether I’m doing the right thing or not. Also, my extremely slow internet connection has been a pain to work on this lab.

appserver image submission

artan — Thu, 09 Apr 2009 00:35:47 +0000

I’ve been thinking of several ways of generating the imagekey (and commentkey) but seems like there is some sort of convention going on. In fact, I don’t think I’ve seen any other format for these guids in our simpleDB other than “21a4ddf4-c23e-11dd-ad2d-123139026094″.
What are you guys doing to generate such things. I tried to see for a pattern, but can’t really tell so far. I thought about getting the IP and timestamp in milliseconds, concatenate them together to make the GUID, that would ensure uniqueness.

Creating and Persisting an AMI

artan — Wed, 04 Mar 2009 07:23:00 +0000

This lab went pretty good. It wasn’t difficult at all, as long as you knew what you were doing. I spent a considerable amount of time understanding what the lab was supposed to do, and I don’t think I got it until I read the first few chapters of the O’Riley’s book “Programming Amazon Web Services”.
Once I understood the idea of Amazon web services, it was much clearer as to what I needed to do, and so I was able to complete the lab without much obstacles.

After I started an instance of a preconfigured AMI, I went ahead and installed all the software that I thought I will need for my AMI to have whenever I boot it up. Since I persited my AMI based on a Fedora Core OS, I just used ‘yum’ to install the packages such as java, mysql, python, modpython, boto, php, httpd, and some others.

Then I created a boostrapping script that would deploy my locally developed code to the AMI. I wrote the sample “Hello, World” web page in PHP, just to make sure my server on the cloud works properly, and used python for the bootstrapping script.

CS 462 – Large-Scale Distributed System Design

artan — Wed, 04 Mar 2009 07:15:59 +0000

This class (coded as CS 462) at BYU is a project-oriented class, where we will be spending the entire semester building a large scale distributed system based on the Amazon.com web services. The system we will be building, is a photo-sharing web site where users can view/post pictures, make comments, and rate the pictures.

So far, the class has been fascinating, especially that it is being taught by one of the pioneers of online applications and someone who has vast experience with building large scale systems. It has been a joy attending the lectures from Dr. Phil Windley as we discuss very interesting issues regarding distributed systems.

The labs on this class are structured so that each piece can work as a standalone part of the distributed system, and as each lab is implemented, it will be integrated with the rest of the system. By the end of the class, we will have a complete working distributed system by integrating all six labs.

How to enable MultiViews in Apache

artan — Thu, 05 Feb 2009 17:19:03 +0000

Sometimes, your URLs need to look something like http://hostname.com/list/popular, where popular is not a directory but a popular.php file inside the list directory and you don’t want to specify the file extensions. One reason for this could be that if you are only implementing the view of a web application that calls web services on an application server, the application server may have the URLs implemented that way, so you want to map the same URL paths and format.
Apache makes this easy with the MultiView option, which can be set within Normal 0 false false false MicrosoftInternetExplorer4 , or section in httpd.conf.

The format of the Options directive is:

Options [option 1]  [option 2] … [option n]

So, to enable MultiView, you would set that with the Options directive. For example:

Normal 0 false false false MicrosoftInternetExplorer4


   #Other directives here...
   Options Indexes FollowSymLinks Includes MultiViews

Normal 0 false false false MicrosoftInternetExplorer4

   #Other directives here...

Now, by having MultiViews as an option to the Options directive, I can just type http://hostname.com/list/popular, instead of http://hostname.com/list/popular.php

Bash Keyboard Shortcuts

artan — Thu, 29 Jan 2009 17:38:17 +0000

In the past I have spent so much time using the mouse to navigate through directories and have largely avoided using the bash because I never really knew keyboard shortcuts that are used in bash. I have found myself to be much more productive when I use bash commands rather than navigating with my mouse. Here are a list of bash keyboard shortcuts that I find very useful. Some I use more than others, but this list is a good reference of the most common shortucts, taken from Ubuntu Pocket Guide and Reference . Even though they are listed as Ubuntu shortcuts, they are essentially the same for most operating systems based on the Linux kernel.

Key Combination	Description
Up/down cursor key	Scroll through command history
Ctrl+left/right cursor key	Move cursor from word to word
Tab	Autocomplete command or filename/path
Ctrl+A	Move to beginning of line
Ctrl+E	Move to end of line
Ctrl+W/Alt+Backspace	Delete word behind cursor
Alt+D	Delete word in front of cursor
Ctrl+U	Delete to beginning of line
Ctrl+K	Delete to end of line
Ctrl+Y	Restore text you’ve deleted
Ctrl+L	Clear screen (actually, this simply moves the prompt to the top of the screen; existing commands are still visible if the terminal window is scrolled)
Ctrl+C	Quit current program
Ctrl+Z	Switch current program to background
Ctrl+R	Search through command history
Ctrl+D	Logout (technically, terminate input)
Ctrl+T	Swap the two characters behind cursor