Page 46 and onwards in this document talks about scriptable DPH
DevTest 8.0 - Scripting Guide - V1.1.pdf
What I do with this kind of message is create arrays of field_name and field_length, and then parse the request message using the field_length values as substring values, grabbing the substring data, matching them to the field_names and saving them as parameters. It's a bit of work up-front, but everything after that becomes trivial (operation name, the field_name containing BOB, correlating response values to request values, time-shifting, etc).
Opaque Data Processing is a transport protocol first introduced in DevTest v7.5.
The Magic of Opaque Data Processing, Revealed
Its goal is to not need to do any of the understanding listed above, and work out for itself what each byte in the response should be from inspecting a reasonable number of requests & responses.