IBrokers - functions: eWrapper and CALLBACKS

Hi

I am trying to program various algorithms using such calls as reqMktData 
- where I have working code with a loop that appears to be working - but 
when I try and use something like reqOpenOrders I can get a result to 
the screen but I am having great difficulty getting at that information 
and using it.

I wondered if someone could point me to anything like Jeff Ryan's pdf 
Real Time Trading in R which concentrates on how the callback works 
using the eWrapper and processMsg.

Hope someone can point me to something useful.

Stephen Choularton PhD, FIoD