At the risk of stretching the metaphor, what I'm talking about are bearings that separate the wheel from the rest of the car. Maybe you have a thin, outward-fac

At the risk of stretching the metaphor, what I'm talking about are bearings that separate the wheel from the rest of the car. Maybe you have a thin, outward-facing server that does nothing but authenticate, validate, and sanitize input data, and then redirects that to some internal system that knows for sure exactly what it's going to get, and doesn't get to talk to the outside world directly, and therefore doesn't have to worry about attacks.