Theres been some work towards that: https://github.com/hackerschool/Meddle.jl is "middleware", and https://github.com/hackerschool/Morsel.jl is a framework. The main issue right now is that no one is particularly pushing/has a strong need for that kind of thing right now. I speculate that math-heavy services like the one described in this post will probably sit side-by-side with other services written in more traditional languages in the short to mid-term.