I think we need to stick with the terms "OPES processor" and "callout
servers". If it helps, think that the terms are abbreviations for
"OPES-enabled proxy processor" and "a server performing OPES services
in response to requests from an OPES-enabled proxy processor".
It seems like a good idea to me to have OCP headers that mean "The
OPES processor A expects OPES service X to be applied to this data"
(these might even be ordered) and "callout server B applied OPES
service X to this data". That doesn't mean that the headers MUST be
copied to the tracing data on the messages that are part of the
proxied data (but they COULD be).
I'm skeptical about using these headers to avoid loop detection,
though. That's a local implementation matter. Sometimes it will
work, sometimes the services might actually have loops (apply
unbase64, translate gif to jpg, apply base64, apply unbase64,
translate color to bw, apply base64). Still, the headers would be
useful for workflow organization, even if loops are OK.
Hilarie