stream state management was: 1xx (informational) responses affect on stream management

Hi Greg-



On Wednesday,06 August 2014 00:38, gregw@intalio.com<mailto:gregw@intalio.com> wrote:

> [SNIP]

>

> So I think your streaming layer should pretty much allow any frame type

> sequence through, and only look at frame type just enough to look for

> END_STREAM.....   maybe it must also handle CONTINUATIONs and

> END_HEADERS because of their particular requirements  (more conflation of

> HTTP semantics to the framing layer).    But let it be relaxed about non-http

> frame sequences in a stream, as hopefully we eventually will see non-http

> travelling over streams.

>



AFAICT, the state machine [1] transitions *are tied to frame type*.  e.g. the transition from IDLE to OPEN occurs on a HEADERS frame, the transition from IDLE to RESERVED happens on a PUSH_PROMISE frame, and the transition to CLOSED can happen on a RST_STREAM frame.



Are you saying that one’s streaming layer could simply transition to OPEN on the first frame received for a particular stream ID?  And one could transition to closed the first time the END_STREAM flag is set (with the obvious caveat that the generic closed state has to allow additional frames for some time e.g. for CONTINUATION and/or other frames that may have already been queued or in-flight).  And then the next layer, the protocol-specific framing layer, worries about whether the frame sequence is valid???



If that’s what you are suggesting, I like it :)  I just wish it was cleanly called out in the spec so all could easily see this non-obvious* option.  In fact it would have been better to have an agnostic streaming layer upon which HTTP/2 is built.



-keith



*non-obvious IMO



[1] http://http2.github.io/http2-spec/#StreamStates










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