- From: Maciej Stachowiak <mjs@apple.com>
- Date: Mon, 26 Oct 2009 20:05:27 -0700
- To: Ian Hickson <ian@hixie.ch>
- Cc: Michael Nordman <michaeln@google.com>, Jonas Sicking <jonas@sicking.cc>, Arthur Barstow <art.barstow@nokia.com>, public-webapps <public-webapps@w3.org>
On Oct 26, 2009, at 7:07 PM, Ian Hickson wrote: > On Sun, 25 Oct 2009, Michael Nordman wrote: >> >> I'm not sure this would really need a notion of "critial" messages. >> That >> may just be complicating things unnecessarily. >> >> If an application is sending data with those kind of >> characteristics, it >> could be handled at the application level. It can send a "keyFrame" >> bit >> of its own and drop non key frames on the client side until it comes >> across the first key it observes. > > Maybe. I was expecting some systems to send a single "keyframe" as the > first event, which would be important for the interpretation of the > rest, > without ever repeating it. I think a single keyframe that is valid independent of subsequent events is not very likely. A very likely kind of "keyframe" is to dump a full fresh state before sending change notifications, but it's not useful without all of the subsequent events. A keyframe that stays valid indefinitely regardless of subsequent events does not seem likely to me in any realistic scenario. What seems more likely is sending periodic "keyframes" (with full state) and incremental "delta frames" in between - that would let the client support sharing by dropping everything *before* the most recent keyframe but resending every event starting with the most recent keyframe, on the assumption that they are deltas relative to the keyframe. That would match the analogy of keyframes in video compression, and would likely work for use cases where the client is staying in sync with a remote state. > But either way, we can figure this out when we get to it; we'll need > implementation experience to know what people really want from this. I'm curious if there's any use case for where there are no critical events or "keyframes". Regards, Maciej
Received on Tuesday, 27 October 2009 03:06:03 UTC