[erlang-questions] process hierarchy and passing references

[Schneider]

Hi list,

Since I am very new to Erlang, I am not sure how to layout process 
hierarchies in the following case:

Besides the domain specific functionality, every program has a RPC 
middleman and an XML-RPC interface, each implemented as gen_servers. In 
the current setup, the main gen_server process starts the RPC middleman, 
passing it its Pid, and the RPC gen_server starts the XML-RPC server 
which is passed the RPC middleman's Pid.
Using the passed in Pid's, the XML-RPC server can do a 
gen_server:call()/cast() back to the RPC server which on its turn can 
call the main server. Works ok, but I would like to have the RPC 
middleman and XML-RPC controller under the control of a supervisor. The 
main supervisor should start the main gen_server process plus a 
supervisor that on its turn should start the RPC midleman and the 
XML-RPC handler.
The thing I can't figure out is how the XML-RPC process should find the 
RPC middleman process and how that process should locate the main server 
when using supervision. Since there can be many RPC middlemen and 
XMP-RPC servers around, each belonging to different main servers, naming 
and registering seems a little hard.
So how to pass references around?

Any help will be very much appreciated.

Frans