December 01, 2002

Architectural Cross-Pollination

Mark Baker's recent thoughts on John McDowall's "Architecture by Intent" weblog posting got me thinking that maybe we all have too much of a one-track-mind at times, and sometimes we need to take a step back and be more open to the cross-pollination of ideas from a wider range of sources.

When I first read Jorgen's blog, I assumed that John was talking about Web services; I have a one track mind, I know.

I believe software architects do need to be more open to ideas and past experiences from a far wider range of current and previous technologies and systems, because there are many valuable leassons to be learned from these.

As an example, consider one of the most successful examples of a distributed computing system I know of, which is the UK National Lottery

This was the world's largest networked lottery system when it was launched in November-1994 with 10,000 terminals. It now has about 25,000 terminals, and always has some extremely high system availability and peak volume processing requirements. Just before the ticket sales cutoff point at 19:30 on Saturdays and Wednesdays, you can pretty much guarentee that the network access will achieve close to 100% concurrency, especially for Roll-over or other special draws. Contrast this with other big networked systems of this size where on a bad day you may get up to 5% concurrency. Also, there are very severe reputational and good-will risks, not to mention customer anger, if the system is ever down - and particularly if it crashes just before the ticket sale cut-off time. To my knowledge, this has only ever happened once or maybe twice in the last 8 years.

Compare the Lottery load with some of the largest web sites - even hundreds of millions of hits per day probably does not generate as much simultaneous concurrent requests as the 19:30 peak on the Lottery network.

If looking at the experience of running the National Lottery network doesn't have something to tell us about building large mission-critical scalable systems, then I don't know what will.

Incidently, one of my other claims to fame is that I wrote the computer system to track and monitor the production line quality for the UK Lottery terminals for the launch back in 1994 while working for ICL Manufacturing. Small world!

Entry categories: Architecture
Posted by Jorgen Thelin at December 1, 2002 03:00 PM - [PermaLink]