Tohir
Software Engineer
Posts by Tohir
Electricity Tariff Increase Calculator
Feb 24th
The National Energy Regulator of South Africa on Wednesday granted state-owned utility Eskom a 24,8% tariff increase for the 2010/11 financial year, falling short of the power firm’s request for a 35% hike. For the following two financial years, Eskom was granted increases of 25,8% and 25,9% respectively.
How much does that amount to for you? Try the calculator below:
Read the story on Mail and Guardian
Road Closures for opening of Parliament
Feb 8th
Here’s a Google Map of the road closures for the opening of South African Parliament
View Opening of Parliament 2010 in a larger map
Would it not have been easier for them to stick to DeWaal Drive, Roeland Street?
MySQL – getting two items per source in a single query
Feb 4th
Assume you have the following table called stories with the following data. And you have run the following query:
SELECT * FROM stories ORDER BY storydate DESC
| id | source | title | storydate |
| 10 | cnn | Story 10 | 2010-01-21 |
| 9 | bbcnews | Story 9 | 2010-01-20 |
| 8 | bbcnews | Story 8 | 2010-01-19 |
| 7 | skynews | Story 7 | 2010-01-18 |
| 6 | cnn | Story 6 | 2010-01-17 |
| 5 | bbcnews | Story 5 | 2010-01-16 |
| 4 | cnn | Story 4 | 2010-01-15 |
| 3 | skynews | Story 3 | 2010-01-14 |
| 2 | skynews | Story 2 | 2010-01-13 |
| 1 | cnn | Story 1 | 2010-01-12 |
Now for the challenge. What happens if you are required to get the top two stories from each source? One option is to first get the order of the sources, and then loop through each one of them:
SELECT DISTINCT source FROM stories ORDER BY storydate DESC
<loop “source” as “sourceid”>
SELECT * FROM stories WHERE source = "{sourceid}" ORDER BY storydate DESC LIMIT 2
</loop>
Another option is to do the in MySQL itself! Unsure if there is a better way of doing this, but here’s mine using UNION and Sub Selects:
(SELECT * FROM stories WHERE source = (SELECT DISTINCT source FROM stories ORDER BY storydate DESC LIMIT 0,1) ORDER BY storydate DESC LIMIT 2) UNION (SELECT * FROM stories WHERE source = (SELECT DISTINCT source FROM stories ORDER BY storydate DESC LIMIT 1,1) ORDER BY storydate DESC LIMIT 2) UNION (SELECT * FROM stories WHERE source = (SELECT DISTINCT source FROM stories ORDER BY storydate DESC LIMIT 2,1) ORDER BY storydate DESC LIMIT 2)
Explanation:
The bold section are subselects and form the WHERE clause of the query. Here we want the first, second and third as per source, but only one at a time. Once we have two results per item, we use UNION to join them together.
One thing to note though. Even though it returns the latest two stories per source, the final table is not sorted by storydate! This can be done using PHP sorting techniques. Is there a way of doing this one time in MySQL?
Getting started with Wireshark, the Fiddler for Ubuntu
Feb 1st
Fiddler is a useful tool for tracking http requests and responses. It’s similar to the Net tag in Firebug, except that it can be used to track all requests, not only browser-based ones.
For Ubuntu users, the recommended alternative is Wireshark. Wireshark is noted as being more powerful than Fiddler, but the focus will be on the features most commonly used by web developers for tracking.
Installation
Wireshark is found in the Ubuntu repositories, so simply search for wireshark in Synaptic, or enter sudo apt-get install wireshark
Usage
Under Applications > Internet, you will notice there are two options. Wireshark and Wireshark (as root). Run the second one (as root) as this gives you more data to track.
After wireshark has started, the process is straightforward:
- Choose which network interfaces to capture traffic from
- Start capturing
- Filter captured requests
1. Choosing which network interfaces to capture traffic from. From the menu, choose: Capture > Interfaces
This will bring up a list of network devices.
2. Since my work involves debugging work off my laptop (http://localhost etc), I only start device lo (127.0.0.1). This is useful as it immediately ignores all other traffic.
3. The one thing you will notice is that fiddler will log both the TCP and HTTP requests. For the purpose of debugging AJAX, etc., we are only interested in HTTP requests, TCP requests are not required. These can be hidden by adding a filter.
In the field next to Filter:, enter http and click on Apply.
The steps will now show all traffic coming on 127.0.0.1 via HTTP. The last step is picking up the AJAX parts for debugging. Notice that for each request, there is a response. Unlike Fiddler, Wireshark does not combine the request and the response. So click on the response line, and then expand the Line-based text data row. This will show the text of the AJAX response.
Conclusion
Wireshark takes more steps than Fiddler, and Fiddler is a more focussed program than Wireshark. Wireshark also captures traffic without having to install a plugin into firefox, etc., so it’s useful for debugging applications as well. The biggest improvement to make Wireshark truly replace Fiddler is to turn off truncation of the response text. Wish I knew how!
Before you commit sin, ask yourself
Jan 8th
Before you commit sin, ask yourself:
Do you know what day it is today?
Is it not perhaps Friday, the day of Jumuah?
Is it not perhaps Thursday, the day after Jumuah?
Is it not perhaps Saturday, the day after Jumuah?
Is it not perhaps Monday, the day the Prophet was born?
Would you like to commit sin on such a day?
Do you know what Islamic month it is?
Is it not perhaps the Holy month of Muharram, that start of the new year, where we resolve to rid ourselves of past bad ways?
Is it not perhaps the Holy month of Ramadaan, the month of fasting, where the Shaytaan is chained?
Is it not perhaps the Holy months of Hajj?
Whatever time it is, do you really have to commit that sin
Advice on Hajj and Old People
Nov 3rd
This year, I have the fortune to be on the Hajj or Muslim Pilgrimage. I am sharing this experience with many people, some of them double my age. Travelling with old people is both humbling and rewarding.
Humbling to note that despite their age and the accompanying reduced health and strength, they haven’t given up on undertaking this magnificent journey. Humbling because they are the ones who prevail calm, patience and sabr at long queues and bureacratic annoyances.
Rewarding because it provides us younger people with the opportunity to assist them in the holiest cities where the Prophet Muhammad (PBUH) said: “The best of people are those who are most beneficial and helpful to people”.
On my journey, I’ve compiled a list of a few short tips aimed at the children of old people, and what they can do to make their parent’s journey much easier.
Cellphones:
1) Provide them with a cellphone that has a distinct on/off button.
Cellphones need to be switched off on aeroplanes. To save space, some cellphones link the switching on/off button to an existing button, but this grouping confuses some old people
2) Disable the sim-card pin
Sim-card pin are there for protection, but it also means having to remember their number. Many are not aware this even exists, as they’ve needed to switch their phones on/off before.
3) Activate international roaming – even if just for sms
Some people have this activated, and they may not have. Explaining international roaming, and that it has to be done prior to leaving South Africa for it to be activated takes some effort.
4) Convert all essential contact numbers to an international dial out.
For example, a house number in Cape Town locally would be: 021 555 1234. Rather convert this to +27 21 555 1234. +27 is South Africa’s dialling code, 21 is for 021 minus the zero, and the rest is the number.
This way, older people do not have to remember to add the +27, and drop the one zero, etc.
5) If possible, provide them with a slide-out keyboard.
It’s painful to watch someone spend five minutes typing out an SMS
Bags:
It would be easier said that done, but encourage them to travel with as few bags as possible, and rather a bigger overnight bag, than multiple small bags. South Africans are usually provided with a shoe bag which gets used as an additional stuffed travel bag. Take into account that they will have with them:
a) overnight bag
b) Haj operator bag for carrying passport/documents
c) Chair for Salaah
d) Shoe bag
Quite a lot to not only carry, but also manage.
Camera:
Even one fitted to a cellphone will allow them to capture moments that are special to them. However, bare in mind they will probably have no place to download their photos to. My suggestion is to provide them with a large memory card or multiple memory cards so that they wouldn’t have to delete any photos they might have already taken.
How to use ExtJS Abstract functions
Sep 22nd
For some methods in ExtJS, you will see:
Class Ext.grid.GridDragZone
…
onDrag( Event e ) : void
Abstract method called during the onMouseMove event while dragging an object.
Parameters:
e : Event
the mousemove event
Returns:Class Ext.grid.GridDragZone
void
In this case, GridDragZone is part of GridView which is part of GridPanel. Accessing it will be, GridPanel->GridView->GridDragZone.
The GridDragZone gets implemented for a GridPanel when you set enableDragDrop to true, but it only becomes available when the grid renders, so:
var grid = new Ext.grid.GridPanel({
// etc
});
grid.on('render', function(obj) {
obj.getView().dragZone.onDrag=function(evt){
alert('being dragged');
}
});
Simple Drag and Drop from Adobe AIR
Aug 21st
Quite a few articles and tutorials show you how to drag and drop a file onto an Adobe AIR application. This one will show you how to drag one FROM an Adobe AIR application TO YOUR DESKTOP (or any other location you provide. The code is really simple:
Drag Me to the Desktop
Download: Source Code
To run, extract files from archive, and then run: adl application.xml
