Re: HTTP redirect for HTTP Adaptive Streaming (HAS) in CDN use cases

Hi Julian,
I think clarifications would help relating section 5.1.2 of rfc3986.


   ... For a document that is enclosed
   within another entity, such as a message or archive, the retrieval
   context is that entity.  Thus, the default base URI of a
   representation is the base URI of the entity in which the
   representation is encapsulated.


Now that I know that encapsulating the URI is not encapsulating the the
document itself, it is clear, however since this was under discussion of
quite a few people, before bringing it to HTTPbis, and we all missed it, it
might be good to help the reader by emphasizing this difference.
I think one confusing point was the use of HTML5 embedding tags such as
<embed> or <video> may lead you to the wrong conclusion that your document
is "embedded" within the encapsulation, while it is only logically embedded.

I am not sure what would be a good phrasing for that, but maybe something
along the line of:
"Note that a URI enclosed within another entity is not an encapsulation of
a document.
Therefore the base URI of such a document that is retrieved by such a URI,
must be established according to section 5.1.3"

If it doesn't make sense to add such a clarification, we can do it on an
external document we (the SVA) will be publishing for the video players
development community.

Best regards,
Ori







On Tue, Nov 6, 2018 at 9:08 AM Julian Reschke <julian.reschke@gmx.de> wrote:

> On 2018-11-06 02:51, Ori Finkelman wrote:
> > While I agree that Alt-Svc may be the to better solution looking
> > forward, we still need to resolve the issue for existing HTTP redirect
> > architectures, mainly for HLS as it is still the dominating video
> > streaming protocol, but for DASH also.
> > HTTP redirect is widely in use and clients that don't conform with the
> > relative resolution, as it seems to be the case, degrades qoe and cause
> > a significant performance hit on CDN load balancers.
> >
> > If there is agreement that in case the playlist is requested separately,
> > and it is not embedded within another encapsulating entity, then the
> > playlist base URI is the final retrieval URI, after redirect, it would
> > be great if there could be some clarifications that establish this
> > understanding.
> > ...
>
> Where exactly do you think a clarification is needed?
>
> Best regards, Julian
>


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