Saturday, December 22, 2007

Christmas reading: Classic essays on software development


There are many, many books about software development. The technical ones alone (e.g. Java, C++, Apache, .NET, etc. etc.) take up meters and meters of shelf space. The ones about project management take up a bit less space but they are still plentiful, and the ones about people in the process take up even less space but are longer lasting.

It is the later category that interests me most theses days. Some books seem perennially relevant and may never go out of print, books like:

Mythical Man Month by Fred Brooks
Psychology of Computer Programming by Gerry Weinberg
Peopleware by Tom DeMarco and Timothy Lister

But often you don’t need a full book to make a point. On these occasions an essay or journal article will do. Often they make the point better simply because they are shorter. Unfortunately these tend to be overlooked too often - books get all the publicity. I would like to highlight half a dozen essays which I think are perennially relevant and often overlooked. In some cases this is because the articles can be hard to get hold of or, more likely, people don’t know they exist.

1. How do committee invent? by Melvin Conway - the origin Conway’s Law. Although written in 1968 this piece is truer than ever. Arguments made by Conway explain much of what actually happens in software development. I’ve examined and looked at this subject myself elsewhere.

Conway suggests that organization that create systems (not specifically software systems) will create copies of their organizations. So, if you have one developer writing the entire system it will be all entangled, few interfaces and difficult for anyone else to work with. And if you have half a dozen developers who don’t communicate you will get six different coding styles, and six versions of most common functions.

What Conway didn’t foresee is that many of system now create the reverse force. Organizations are limited by the systems they use, thus their structures become copies of the systems in use.

2. Worse is Better by Richard ‘Dick’ Gabriel - this started as a keynote talk, became an essay and then a series of letters in which Dick argued anonymously with himself.

If you are one of these developers who think the best code will always win the day you need to read this. Dick suggests that sometimes the solution which is technically worse is economically superior. In a similar vein see Brian Foote’s Big Ball of Mud pattern.

3. No Silver Bullets from the author of Mythical Man Month, Fred Brooks. This piece came out in the mid 1980’s. The Wikipedia summary is here, otherwise you will need to by the Anniversary edition of Mythical Man Month to read it.

Brooks argues that software development is hard, and there is no ‘silver bullet’ which will make it easier. No language, no operating system, no methodology or any other tool will fix it. I have been told that Brooks has since said the if there is a Silver Bullet it is Agile Software Development but I can’t find this quoted anywhere so I don’t completely believe it.

4. A Rational Development Process and How to Fake It by Dave Parnas. Originally published by the IEEE this also appear in Software Fundamentals: The Collected Papers of David L. Parnas. You might also find some copies stashed on the Internet. Dave Parnas deserves to be more widely read by software engineers today so it you haven’t read much of his work buy the collected papers, well worth reading.

In this paper Parnas argues that while we may want to use a rational development process, and while it makes sense to do so it is impossible. This is because software development requires intuition and inspiration - or as I would put it learning. And since you can’t schedule these things or guarantee they will happen the chances of following a rational process are negligible.

However, in order to make our work accessible to those who come after us we need to fake the development process so it looks like we followed a rational process.

I like the logic, I agree with much of it but I have one disagreement. Each generation of software engineers comes along and believes the previous generation were rational and get confused by what they find. They slowly learn that they cannot be rational - causing a lot of angst. They also wonder how the previous generation made such a mess. So frustration is built up.

5. Cathedral and the Bazaar - by Eric Raymond: an explanation of Open Source software. And an explanation of why software created in corporations is frequently a mess. I don’t think Open Source is the answer to all our problems, but I think it is an answer to some and is here to stay.

6. Enrolment Management by Peter Conklin: until recently this was one you really have to hunt down, but it is worth it. Originally published in the Digital Technical Journal (Digital as in DEC or Digital Equipment) in 1992 it was republished by the IEEE in July 1996. HP now have back issues of the Digital Journal online so you can read it here.

This piece tells the story of the Alpha AXP programme in the late 1980’s and early 1999’s. In theory, on paper, on GANTT charts the project couldn’t be done. The author tells how enrollment management was used to engage those working on the project. Although written in 1992 this paper is about Agile development. And it is about Agile development in the large - over 2,000 engineers worked on the project.

I wrote about this article before, a few years go. One of the small stories in this paper always brings a smile to my face. The OpenVMS team committed to a delivery schedule and said ‘We don’t know how to achieve this, but we commit to finding a way.’

So there you have it. Six essays I recommend you read. And if you only have time for one? Well, chances are you know about Open Source and the Silver Bullet so I recommend you read Enrolment Management or A Rational Process, and if you push me more I’ll say: Enrolment Management.