This documentation is here is currently about the philosophical and theoretical background for a SRB. I've focused on why you should/would use a SRB. The manpages are better for how to use MidWay, but there is a usable example in the introduction.
Introduction
The larger picture
The OSI Reference model
The Presentation Layer
Parallelization
The Great Funneling Act
A discussion on SRB vs ORB
The Road Ahead
Statefullness - Conversations
Global Transactions - XA
A comparison to Tuxedo
The API
Manual Pages