Having recently recommended Dan Weinreb’s blog, I dropped by to see what he might have added. Besides the distress of discovering I called somebody “middle-aged” who’s only a year older than I am, I found a post with some metrics describing just what his company, ITA Software, runs in Lisp. To wit:
I currently work at ITA Software, a.k.a “the 800-pound gorilla of Common Lisp”. If you use Orbitz and ask “how do I get from Boston to Chicago on 10/4/2000 at 2pm …”, we provide an excellent set of choices of the cheapest routes and fares for which seats are available. This program, known as QPX, is written in Common Lisp.
I am working on our new product, an airline reservation system. It’s an online transaction-processing system that must be up 99.99% of the time, maintaining maximum response time (e.g. on www.aircanada.com). It’s a very, very complicated system. The presentation layer is written in Java using conventional techniques. The business rule layer is written in Common Lisp; about 500,000 lines of code (plus another 100,000 or so of open source libraries). The database layer is Oracle RAC. We operate our own data centers, some here in Massachusetts and a disaster-recovery site in Canada (separate power grid).
I’m sure we can come up with a few examples in, say, the financial services arena. But overall, not many OLTP systems are harder-core than an airline reservation app.
