Problematic nature of software development

Interestingly, the nature of software development process imposes a very unique difficulty compared to other engineering process. And it is generally overlooked. That is incremental engineering effort on previous product. In other words, ‘versioning’ And I believe this particular fact actually causes lots of trouble to software development teams. Throughout years of experience, software project teams have come up with several good solution for these. I’ll explain how this trouble leads to those solutions later point. There are many books and articles about building a good software product from architectural perspective. And often times we can see that authors use metaphors like building skyscrapers and bridges to explain their points. However, building software is still significantly different from building skyscrapers or bridges even if we consider planning, designing, engineering effort, duration of work and delivery are conceptually the same. If I were to use metaphors to explain software development process, I will describe it as following with a little bit of exaggeration to point out the difference. ‘Software development is like finishing Empire State Building today and adding 50 more stories two years later. Software development is delivering Golden Gate Bridge today and adding 16 more lanes next year.’ Do you see the trouble here? Let me explain with some more specific example. Let’s say Boeing delivered ‘787 Dreamliner’ airplane a few years ago. And they are planning to build ‘797 Wright Brothers’ as the next generation of the product line. The requirements for this airplane is basically adding 250 more seats inside airplane. But Boeing engineers only allow to build 797 by physically modifying existing 787 airplane. What has to be changed? I don’t know much about plane, but I can imagine that they have to decide if 797 will be fatter or longer, which changes aerodynamics. It will also affects the size of wings and horizontal/vertical stabilizer. It will changes the weight of the airplane, so engine has to be changed. Then it might require extra gas tank. It requires more power supply and oxygen. It may require longer runway for taking off and landing. They also need to consider hitting by lightening or dealing with turbulence. The need to consider not only the airplane structure but also travelers. Extra bathrooms, emergency exits, flight attendant station have to be changed. Seating for first class and business class might be changed as well. I guess we can go on and on. And remember we’re modifying existing 787 physically. This is the nature of software development. There is no hard end product like buildings or bridges in software world. It is just the nature and we'll continue to do this. Reasonably small requirement for business can impact engineering effort significantly. Adding or modifying existing feature exposes various risks in the software product. Some feature may not be needed any more or doesn’t make sense any more, but it’s not easy to take out those dead code or features. Let’s think about how we can minimize these risk. On the next blog. :)