Hi,
in a prominent OPES scenario a virus filter is deployed as an OPES service of an intermediate proxy.
That filter belongs to the group of services that wants to see all data of a file completly before it starts to respond. In HTTP this huge latency effect results in an inacceptable surfing experience for the end user when requesting large files; there is no feedback, no progress dialog until the complete files has been received by the filter service.
Today only workarounds are known to this problem that all have a bunch of disadvantages.
I created a draft about a new content encoding for HTTP which could solve this problem for the majority of file types:
http://www.ietf.org/internet-drafts/draft-stecher-lclr-encoding-00.txt
It also explains the problem in more detail.
I would appreciate very much if this group is interested in looking into this and in starting a discussion about this problem and possible solutions.
Regards
Martin