Hi Alex,
[...]
Am I downplaying the importance of change-probability and progress
fields? Do you expect implementations hack them in as OPES extensions
if we do not define them? Are there corresponding ICAP extensions
already?
[...]
There is no message like this in ICAP today and I am not aware of
an extension for change-probability.
The result is that ICAP servers start to implement the donwload
progress indication / data trickling features and as you pointed out
this belongs in the OPES processor.
But the OPES processor needs to have some input to determine whether
and what latency fighting method to use.
The overall question is: If I (the OPES processor) start to forward
original application message data (by data trickling or LateClearance
content encoding), how likely is it that I will get into deep trouble
when the callout server sends modified data?
It can only know if the callout server has sent some information
about this likelihood.
And regarding progress: Let's assume there is a way to forward progress
indication to the consumer, then the OPES processor can better work with
a numeric value (e.g. "still 10 seconds to go" or "30% done") rather
then only "the callout server is still working on it".
I know that there was some work to get this feature into an ICAP
extension but it has not yet been implemented.
Regards
Martin