Sunday, July 1, 2007

Understanding The Fuzz About Engineering In Software Development

Steve McConnell responds to Eric Wise's article Rejecting Software Engineering that Rumors of Software Engineering's Death are Greatly Exaggerated". There's a lot of fuzz about the usage of the word "engineering" when it comes to software development. What's this all about?

What is engineering?

According to wikipedia, engineering is defined by the ECPD as

The creative application of scientific principles to design or develop structures, machines, apparatus, or manufacturing processes, or works utilizing them singly or in combination; or to construct or operate the same with full cognizance of their design; or to forecast their behavior under specific operating conditions; all as respects an intended function, economics of operation and safety to life and property.

When I look at this definition I don't really see anything that would not be applicable to software development. Steve McConnell generously points out that software engineering is recognized and practiced for some time now, so where does this new-fashioned stubborn refusal to call the child by it's name come from?

The engineering process

The real problem comes to light when you look at the engineering process. You'll find a description of the engineering process on wikipedia. The article describes the engineering process in four stages:

  • Conceive

  • Design

  • Realize

  • Service

Now there are some engineers who map the engineering stages to software development in a rather funny way: They think that "Design" is the process of drawing good looking UML diagrams and that "Realize" is "Coding". When you look at the wikipedia article, you'll see that for engineers "Realize" stands for "Manufacturing". In a software context, manufacturing means running the compiler and pressing some CDs or deploying some binary over the Internet.

So when engineers claim that software developers should look at how engineers do their design and all this talk about software processes would be settled once and for all, they're ignoring that software development is a design-only activity and that software has a lot less problems with the "Realization" stage than traditional engineering.

When a software developer writes code she is building an executable, mathematical model of reality.


When software developers prefer not to use the title "engineer" to describe what they're doing, they're trying to avoid a mapping of the engineering process onto the software development process that is wrong. In the end, software developers will build mathematical models (source code) and apply scientific methods (complexity analysis) to solve problems. If this is not engineering, than we're not engineers.