using Ruby as a front end for a trading system

RoR is very simple to set up as n-tiered… it has things built in out of the box for doing so, and for the few things that can’t be done easily with out of the box Rails, there are plugins for.

And, yes, it is extremely simple to do what you said with RoR -> web service -> Delphi -> DB.

A lot of people at larger companies who can’t afford to go RoR wholeheartedly to begin with do it via this step… set up web service front ends to all of your current code, and put an RoR face on it… then, as your other developers become more and more familiary with RoR, and as you begin to see the obvious advantages of using it, you can refactor your code to become more of a Ror -> DB situation.