Re: Why allow empty STREAM frames when offset is zero?

Dmitri Tikhonov <dtikhonov@litespeedtech.com> Thu, 10 May 2018 18:45 UTC

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Date: Thu, 10 May 2018 14:45:05 -0400
From: Dmitri Tikhonov <dtikhonov@litespeedtech.com>
To: Mike Bishop <mbishop@evequefou.be>
Cc: IETF QUIC WG <quic@ietf.org>
Subject: Re: Why allow empty STREAM frames when offset is zero?
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Is there a real-life use case that is implied here?  I can't see why it
would be useful.

On the other hand, it creates an odd situation for an implementation:
a frame has arrived, yet the higher layer cannot read from it yet, so
an incoming stream is unreadable.

On Thu, May 10, 2018 at 06:25:55PM +0000, Mike Bishop wrote:
> If you want to open a stream (e.g. permit data to be sent in the opposite direction of a bidirectional stream), but don't actually have data ready to send yet.
> 
> -----Original Message-----
> From: QUIC [mailto:quic-bounces@ietf.org] On Behalf Of Dmitri Tikhonov
> Sent: Thursday, May 10, 2018 11:05 AM
> To: IETF QUIC WG <quic@ietf.org>
> Subject: Why allow empty STREAM frames when offset is zero?
> 
> [draft-ietf-quic-transport-11] says the following:
> 
>    A stream frame's Stream Data MUST NOT be empty, unless the offset is
>    0 or the FIN bit is set.
> 
> Why allow empty STREAM frames when the offset is zero?  What is the purpose?
> 
>   - Dmitri.
>