Re: HTTP/2 Priority <draft-ietf-httpbis-http2-17>

[Ben Niven-Jenkins <[e-mail]>]

Bob,


> On 6 Mar 2015, at 19:18, Bob Briscoe <[e-mail]> wrote:
> 
> This follows up my own post, 'cos I forgot one point...
> 
>> Date: Fri, 06 Mar 2015 16:40:54 +0000
>> From: Bob Briscoe <[e-mail]>
>> ===Priority===
> 
> I believe HTTP/2 was intended to be retrofittable to an HTTP/1.1 implementation. I think that will largely be true, except it seems an API is needed to drive stream priorities from script logic. But I don't see any mention of an API in the spec tho.
> 
> Explanation: Presumably something has to determine the dependencies between all the streams and assign the priority values. This might either be manual, automated, or a hybrid. Assuming automated, that means something at the HTTP/2 layer needs to parse all the content and analyse its dependencies. A Web developer is unlikely to be able to precalculate priorities, except for simple static content. In general, script interactions with the client will alter the priorities. So APIs to set priorities will have to be included in scripting languages, and developers will have to write to these new APIs.
> 
> So I think this means that HTTP/1.x content will rarely 'just work' over HTTP/2. 

Priority is optional in HTTP/2 and doesn't exist in HTTP/1.x so I'm not sure what makes you think HTTP/1.x content will rarely "just work". It will work just fine. 

Ben