Re: Issue with "bytes" Range Unit and live streaming

[Mark Nottingham <[e-mail]>]

Hi Darshak,

I don't think that's where we're at. Based on the discussion so far, it seems like there are two possible paths forward:

1. Changing the 'bytes' range-unit to allow this use case
2. Minting a new range-unit

As discussed, both have downsides. What we need is data about how current implementations -- especially caching intermediaries -- behave when faced with a) 'bytes' used in the desired way, and b) a new range-unit.

Cheers,


> On 11 May 2016, at 5:57 AM, Darshak Thakore <[e-mail]> wrote:
> 
> Hi all,
> 
> Based on feedback on this thread, it seems like the need for being able to send an open ended (read as unknown-last-byte-pos) Range response has been discussed a couple of times (with different use cases). Also there seems to be somewhat general agreement that the Content-Range ABNF in RFC 7233 is deficient in providing this. The initial argument has been, “is there a compelling enough need” and i think with different use cases popping up (log files, media streaming, gzip… others ??) there seems to be some value in defining a non-application specific Range unit that plugs this gap. Clearly fixing RFC 7233 is invasive and will result in thing breaking in unknown ways so that’s a no-go. With that, we can:
> 	• Ensure that the scope of this work item is narrow and restricted only to fixing the gap in RFC 7233
> 	• Define a new range unit (anything with “bytes” in it seems like a bad idea, so maybe call it “live-octets”, “blive”, “b-add" - suggestions welcome….)
> 	• Decide if there is enough interest/reason to do this as a WG item
> Any objects/suggestions to any of the above ?
> 
> Regards,
> Darshak 
> 
> 
> From: "[e-mail]" <[e-mail]>
> Date: Thursday, April 21, 2016 at 4:25 AM
> To: 'Craig Pratt' <[e-mail]>, "[e-mail]" <[e-mail]>
> Cc: "[e-mail]" <[e-mail]>
> Subject: RE: Issue with "bytes" Range Unit and live streaming
> Resent-From: <[e-mail]>
> Resent-Date: Thursday, April 21, 2016 at 4:25 AM
> 
> On Thursday,21 April 2016 05:18 [e-mail] wrote: 
> > 
> > Re: Representation caching
> > 
> > Whether a representation is considered cacheable in this use case is at
> > the discretion of the origin server and specific to the use
> > case/application - as it should be (imho). There's no *necessity* in
> > having a periodically-appended resource marked non-cachable, correct? If
> > the resource mutates, it's not cacheable. If it's just being appended
> > to, it is cacheable. And if an appended resource stops being appended
> > to, it doesn't invalidate the cached representation.
> > 
>  
> I couldn't agree more. However, it seemed the prevailing sentiment when we tried to resolve the related issue of ranges before content codings, with a new bbcc unit (bytes-before-content-coding), was that the use cases for append-only growth represent an insignificant portion of HTTP traffic. “We live by app-specific protocols to handle these cases. What is so special ... that it must be addressed by http (in a very ugly way)?” [1]
>  
> [1] https://lists.w3.org/Archives/Public/ietf-http-wg/2014AprJun/1383.html
>  
>  
>  
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--
Mark Nottingham   https://www.mnot.net/