W3C home > Mailing lists > Public > ietf-http-wg@w3.org > October to December 2012

Re: new version of Flow Control Principles

From: Eliot Lear <lear@cisco.com>
Date: Thu, 13 Dec 2012 09:37:15 +0100
Message-ID: <50C993BB.60809@cisco.com>
To: Gabriel Montenegro <Gabriel.Montenegro@microsoft.com>
CC: "draft-montenegro-httpbis-http2-fc-principles@tools.ietf.org" <draft-montenegro-httpbis-http2-fc-principles@tools.ietf.org>, HTTP Working Group <ietf-http-wg@w3.org>
Osama, Jitu, Will, Roberto, Rob, Salvatore and Gabriel,

That's an excellent draft.  It looks to me like you have largely carried
forward the benefit of the research community's experience with TCP,
where algorithms evolved over a several decades, but the actual control
mechanism has been all but entirely stable.

One or two comments:

>    5.  HTTP 2.0 should only standardize the format of the window update
>        message and its semantics.  In particular, the algorithms used by
>        the receiver to decide when to send window update messages, and
>        how much to update the window by, are not mandated in the spec.
>        The draft should, however, provide some illustrative examples.

The receiver chooses the algorithm through control of the window size. 
Therefore, would it make sense to go further in (5) and state that the
choice of such algorithms is strictly a matter for the receiver?

And then on this point:

>    NOTE: Whether flow control operates on a per-stream basis, on a per-
>    session (per-TCP connection) basis or on both a per-stream and a per-
>    session basis is TBD.

Per-session flow control would certainly be required if you're not using
TCP or SCTP.  If you are, what is the value of additional flow control
at the session level?  Is there any desire for HTTP over UDP (not that I
would necessarily object to the notion)? 

Eliot


On 12/13/12 5:43 AM, Gabriel Montenegro wrote:
>
> Hi,
>
>  
>
> We published a new version of the flow control principles:
>
> http://tools.ietf.org/html/draft-montenegro-httpbis-http2-fc-principles-01
>
>  
>
> The idea is that this is the basic gist of flow control, the basic
> rules, not a given algorithm. Given a basic set of rules like these,
> further refined algorithms can be worked on independently and even
> subsequently to the base specification.
>
>  
>
> Section 2, the basic set of rules, is being offered to the group for
> inclusion in the base spec for HTTP 2.0. There seemed to be some
> support in the room in Atlanta to do so, and hopefully this version
> will make that easier.
>
>  
>
> Osama, Jitu, Will, Roberto, Rob, Salvatore and Gabriel
>
>  
>
Received on Thursday, 13 December 2012 08:37:46 GMT

This archive was generated by hypermail 2.2.0+W3C-0.50 : Thursday, 13 December 2012 08:37:53 GMT