chaining front ends?

I have a backend with lots of frontends. I want one of those frontends to be a listener on port 80. The port 80 listener needs to route traffic based on the Host http request header. After traffic is split based on the Host header, I want to do further header manipulation and rate limiting speci

how to associate front and back ends?

I have 3 back end environments. qa (q), uat (u), and live (l). I want to provide many listeners on different ports with different connection limits that I will point different clients at. I used to do this by using "listen" everywhere. I had listen statements for the q, u and t server pools