It seems that I misunderstood the whole concept.
I am glad you asked these questions, then! Clearly, predraft needs to
do a better job at defining OPES messages.
No, sorry, it more seems that I didn't read version 01 of the predraft
carefully enough.
[...}
I was thinking that OPES transactions might correspond to OPES
connections. That is why I did not introduce them into the draft yet,
waiting to hear more opinions on the connection management issues. It
is probably about time for me to make a specific proposal though.
Callout transactions and connections are not the same due to the
requirements draft. This is the message hierachy as I see it today.
Please correct if I am wrong:
1. Transport layer connection between OPES processor and callout server
can have one or multiplex multiple (3.4 of opes-protocol-reqs)
2. Callout connections (3.4 of opes-protocol-reqs)
consists out of multiple (3.4 of opes-protocol-reqs)
3. Callout transactions (3.3 of opes-protocol-reqs)
consists out of one or multiple (t.b.d)
4. Application transactions (protocol predraft)
consists out of multiple (protocol predraft)
5. Application messages (protocol predraft)
The mapping between 3 and 4 is not yet determined.
I suggest to go for a relationship where one callout transaction
consists out of multiple application transactions. And then move
the "services" parameter of the "xaction-start" message to the
callout transaction init message.
This way we can minimize the overhead of callout transaction
specific meta data in application transactions.
In your experience, what kind of metadata/state would be associated
with an OPES transaction (separate from the application transaction)?
Same service IDs? Dispatcher- and callout-server-specific
info? Anything else?
If you look into ICAP's OPTIONS message we could move some or all of
these parameters into the callout transaction init phase. Other meta
data for a callout transaction would be "requested services",
"processor identification", "callout service database version (see
ISTAG header of ICAP)".
Meta data of an application transaction would then be information
about the requesting user for instance.
Regards
Martin