Nginx : Reverse Proxy + Redis


I have an existing Nginx setup up and running to get an reverse proxy
working with caching support(Nginx InMemory). I have integrated it with
LUA to get some
customizations for changing request as per some biz rules. The system is
used for serving XML out the reverse proxy being a SOA server.

Now what I want is to have the below setup working with Redis Cache. (
Reason of using Redis is to keep the response broked up in way that the
next requests can use exploit even partial data from earlier responses.
I would merge the responses back to send the final xml. )

Request -> Check Redis Cache(Not Found) -> Go_To_Actual_Upstream Server
-> Save_Response_Back_To_Redis(asynch) -> Send the result back to client

Was wondering how to move ahead with the approach/design. Also from an
implementation point too.

I am a kind of newbie here.