Update to diagram on page 9

[<marchadr@wellsfargo.com>]

William,

Here is an update for the illustration on page 9.

I tried to also incorporate the message type concepts as well.
Basically I added a bit more finesse, not UML compliant but illustrative of the concepts. :)

Let me know if I didn't capture it correctly. 
I think the message types is a pretty key concept to illustrate.

 <<Overview.zip>> 

Thanks,

Dan

Overview.zip