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Thursday, December 14, 2006

Rapid Web App Development — My experiences while developing Catalyst

My talk at the barcamp was titled "Rapid Web App Development — My experiences while developing Catalyst". Catayst is the name of my project management tool. The presentation was created using a modified version of Eric Meyer's S5 presentation tool. The template allows you to create the presentation content in XHTML and style it using CSS. It's really awesome, and I feel a lot more comfortable with it than Powerpoint or OpenOffice. However, there is no place to upload it. Another problem of putting the slides online is that it lacks the voice over and discussion that actually took place. Since the slides by themselves are pretty meaningless, I've added some commentary below.


The goal: Write a web application with one person, one month of work to get to version one. That's what I'm trying to do with Catalyst. I've spent about 80 hours working part time on Catalyst. At that time, it was only a hobby project for me to learn Django, and AJAX. I've worked about 100 hours on it full time since I returned to India. I'm hoping to get to beta before the end of the year.

Catalyst is a project management tool for small, agile and distributed teams. If you have ever been frustrated with the lack of visibility into what everyone else is doing in the project, especially with multiple offices, then Catalyst is for you. But this presentation is not about Catalyst. It is about what I have learnt while attempting to develop an application in a month.

There are six points that I want to discuss, split into two areas. The first area is the philosophy, and the first point is that constraints are good.

The more constraints one imposes, the more one frees one's self. And the arbitrariness of the constraint serves only to obtain precision of execution — Igor Stravinsky

Most of us think of constraints as bad, something that limits our freedom, but constraints can be good. Take the example of the one month limit, an arbitrary constraint. Why develop version 1 in a month? Why not six months or a year? I could have chosen a year and done a lot more features, but the one month constraint forces me to select the most important features and implement them first. In this case, the constraint helps me to focus on what is essential. Constraints can also drive innovation and spur creativity.

Second is the 'less is more' philosophy. There are two angles to this. The first is that the fewer requirements you have, the less you have to design, code and test. In that sense, it obviously help you finish faster and get the product out. The other way of looking at it is simplicity. If you look at Catalyst, it does not have an integrated bug tracking system like many project management systems. Why? By eliminating bug tracking from the list of features, I retain the focus on project management. Not only does it simplify Catalyst, but the users can continue to use their favourite bug tracking tool. In my opinion, this combination is actually worth more than having integrated bug tracking within Catalyst.

The second area I want to focus on is execution. This is the actual development part. How do you speed it up? My favourite is the combination of expressive languages and powerful frameworks. Catalyst is written in python and django. Here is an example: In the project dashboard screen, we need to get all the tasks that are a part of the interation that is currently in progress. The python code to do this is just six lines, with no SQL to be written!

The fifth point is to do smart testing.

There are two ways to write error-free programs; only the third works. — Alan Perlis

You'll never write error free code and since there is only one person, you have to rely on automated tests. Javascript code is unit tested using jsUnit. I am looking to start using the Django extensions to python's unittest module for testing the server side code. Another tool I want to learn is Selenium for automated system tests. Of course manual tests have their place too. I am using catalyst to manage my development work, so that kind of dogfooding helps in areas like usability and finding bugs via basic exploratory testing.

Finally, use libraries! The less code you have to write, the easier it is. Catalyst uses Dojo and Mochikit on the client side. Dojo has a bunch of widgets that really ease development, while Mochikit has a really cool DOM creation API. Catalyst uses both. PIL is used on the server side to generate charts. Apart from this, a lot of repeated code has been refactored into libraries. This is general good practise of course, but its often not done. See how the constraints force you to develop better?

To summarise, here are the six points again
  1. Constraints are good
  2. Less is more
  3. Expressive languages
  4. Powerful frameworks
  5. Smart testing
  6. Libraries

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