Thursday, April 24, 2008

Applying Usability to the Software Development Process

In order for something to become widely adopted, it has to provide an advantage that is significantly greater than whatever it replaces, and the advantage has to be easily accessible to a mainstream audience. Another way to describe “easily accessible” is to use the term “usability.” That which has high usability is more likely to become mainstream.

There’s a lot of literature on the usability of both software and everyday objects. But what does usability mean when applied to the process of software development itself? If we think of the myriad steps we use to produce software as the implementation of a software development process, then we can think of that implementation as software and consider its usability.

To consider the usability of a particular process, we first have to have a measuring stick for usability. Here’s a set of categories loosely based on some of the chapters from Joel Spolsky’s excellent book “User Interface Design for Programmers” and also adding in “visibility.”

We get feedback our whole lives. When we first come into the world, we need constant feedback in order to learn how to survive. Touching something hot is painful, going without food is painful, falling down stairs is painful. In school we get feedback as to which subjects we are good at and which subjects we are not so good at. We can use this feedback to decide what to do more of, what to avoid and as an aid to improve, if we are able to.

The software development process, along with its rules, is just one process that you are a part of. Process, rules, and laws are all around you. You don’t have to consciously think about them but you are constantly reacting to them and they are second nature to you. On your way to work you drive on the correct side of the road, you stop at stop signs, and you stay in your own lane. When you go to lunch, you pay for your food. After work you go to your house instead of going to somebody else’s house.

It is easy to remember the laws, rules, and processes because you interact with them every day and you get feedback in the form of reminders and possibly even unpleasant consequences when you go astray. A great example of this is the rumble strip that has become commonplace on the side of highways. If for some reason you start to drift off the road, you’ll hear a loud warning noise as your tires hit the rumble strip. If you are really violating the law, you’ll hear an even louder sound accompanied by flashing lights. This is also known as feedback.

With traditional development, the development timeframe is much longer and thus the feedback loop is much longer. With Agile, the feedback loop is usually no longer than a month and often on a weekly basis.

An important part of absorbing all of these laws, rules, and processes is that they are clearly defined, easy to understand, and easy to remember. For instance, once you have mastered basic physical laws such as the fact that running at full speed into a door is painful, it is easy to understand the reasoning behind having an upper limit on the speed of vehicles on public roads. You may disagree with that limit, but you can generally guess what the limit is for a given stretch of road and it is posted at regular intervals to help you score your guesses. Sometimes there is even a referee.

In traditional development, the long timeframe makes it difficult to absorb what the actual process is and usually everybody has a different mental model of that process. When people have different mental models for the same process, bad things happen. In Agile development, the process is far simpler and much easier to absorb. You have a chance to see the full process from start to finish on a very regular basis.

Expected Behavior
When something happens unexpectedly, it interrupts our train of thought and slows us down. It is a little bit like taking a wrong turn and becoming lost. We have to take time to figure out where we are and how to get back to familiar territory. Most of the time, when working on a software project we are concentrating on a single task that we alone are responsible for.

Consider software development from your own perspective. I’ll bet that you identify with most or all of the following statements:
  • When working on a software project on your own, you make changes and use the new version right away.
  • One of the reasons that you got into software development is the fact that you can make a change and see the result right away.
  • When you have something new working for the first time, you want to show it to somebody.
  • It isn’t easy to create something that the customer thinks is exactly right the first time.
  • Even when creating something for yourself, it isn’t easy to create what you want the first time.
Most software projects are part of a larger scope, even if we are the sole developer. Somebody has to test it, and there are usually organizational standards that must be adhered to. In any case, you will spend a fair amount of time developing according to the rules of the organization (“the process”) rather than the way you would do it naturally if it was an individual project just for yourself. Whenever the way that you would develop software naturally conflicts with “the process,” the more you have to slow down and think about the correct next step and the greater the usability problem.

With traditional development, there is generally much more process to cope with the greater complexity of trying to develop a much larger increment of functionality over a much longer time period. Because of the large gap between how one would develop software on one’s own and how one develops software as part of a much larger process, the steps in the process are often counter-intuitive and thus it is much harder to establish a natural rhythm.

It is hard to know what to do next if you aren’t sure where you are. Visibility is akin to project status. Do you feel like you know exactly where you are and what to do next at every step of the process? Or do you feel pulled in a million different directions at once and lose track of what you’ve already done and what you need to do next? If you do feel like you’ve finally “got” how software is developed in your organization, how long did it take to get to that point?

In a traditional project, it is almost impossible to see at a glance what the real project status and progress are. You know that you won’t really know until sometime after code freeze. In an Agile project, the next milestone is much closer, so it is much simpler to see where you are. Granted, if your real goal is six iterations out, you don’t have the same sort of visibility into the next five iterations, but the chances of risks hiding out until code freeze is substantially reduced.

The Usability of the Software Development Process
Based on just these few criteria, it is clear that traditional software development suffers from poor usability and hinders the ability of otherwise competent people to get their work done. While it is true that people can succeed on projects that have very long timeframes and involve a high degree of stress at the end, that mode of working does not align well with our strengths as human beings.

People are much more productive and much less prone to error when they work at a constant and sustainable pace. This also means that when there are unforeseen circumstances, people are more likely to be able to respond well.

Agile Development provides frequent feedback via short iterations, a simple process which is more in keeping with natural human rhythms and capabilities, and significantly more visibility into project status and progress. This creates a highly usable and people-oriented software development environment.

Next: It is Not the Bug That Bends, it is Ourselves

1 comment:

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