Tom Gilb on Systems Enterprise Architecture

A few days ago my friend Tom Gilb asked me to comment on his new book on SEA (Systems Enterprise Architecture).

I've followed Tom's work since he wrote an inspirational and iconoclastic column in Computer Weekly back in the 1980s. 

Tom has always been sceptical of claims made in IT without quantified evidence. Early in SEA he tells us 'There comes a threshold of complexity in all disciplines where quantification becomes a necessary tool. The time has come for IT Enterprise Architecture to really make use of quantification, and not just talk about doing it.'

He's right, and many traditional IT departments need to mend their ways, but I think Tom underestimates the extent to which the Smart Kids already practice what he preaches. They know that gives them a competitive edge, and for that reason they tend not to broadcast what they do. I'm lucky enough to know a few of them, so I get to hear a little of what they are up to and how they do it.

The TDD world has always placed a lot of emphasis on verifying functional correctness through automated testing. Tom has always placed additional emphasis on the (non-functional) qualities of software: reliability, usability, performance, security and so forth. These are vital to the delivery of business value but they need much more skill to quantify and test. That's why most requirements documents have paid lip service to the qualities without specifying quantified goals and the means of measurement.

While traditional IT often fails in that respect, most young, successful cloud-based businesses live or die by the efficiency, availability, usability, and reliability of their software. They measure these qualities in real-time and deploy changes in real-time to fix problems when they detect them. I'm sure they could do better, and I'm sure that Tom's book could help them to do that, but they are already way ahead of traditional IT.

Tom's expertise can help those who are already doing the right things; for others, his approach would be a game-changer. Sadly I fear few will take advantage of it. They would have to change from being an expert in the old ways to being a novice in the new, and that's always a difficult thing to do.

If you'd like to take a look at the SEA book, you can download a free PDF here:


  1. Thanks Romilly. There is a secret in that in the SEA References is a lot of other free downloads!
    You are right in that my methods are not for old style IT people, but their project failure rate is an international shame. And you are right that an elite is using my ideas, sometime massively in large smart corporations, like Intel. But they are never IT people, they are smart industrial engineers. And they have a much better success rate!


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