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Re: UMP / CORS: Implementor Interest

From: Maciej Stachowiak <mjs@apple.com>
Date: Thu, 13 May 2010 03:48:16 -0700
Cc: nathan@webr3.org, Devdatta <dev.akhawe@gmail.com>, Jonas Sicking <jonas@sicking.cc>, Tyler Close <tyler.close@gmail.com>, Ian Hickson <ian@hixie.ch>, Arthur Barstow <Art.Barstow@nokia.com>, Anne van Kesteren <annevk@opera.com>, public-webapps <public-webapps@w3.org>, Adam Barth <w3c@adambarth.com>
Message-id: <3B969BE3-4731-4D66-9FD4-AB2F372FD15D@apple.com>
To: Julian Reschke <julian.reschke@gmx.de>

On May 13, 2010, at 3:05 AM, Julian Reschke wrote:

> On 12.05.2010 22:39, Nathan wrote:
>> Devdatta wrote:
>>>> As for the "should CORS exist" discussion, I'll bow out of those until
>>>> we're starting to move towards officially adopting a WG decision one
>>>> way or another, or genuinely new information is provided which would
>>>> affect such a decision (for the record, I don't think I've seen any
>>>> new information provided since last fall's TPAC).
>>> 
>>> exactly -- I don't see this thread getting anywhere.
>> 
>> Vendors & Spec writers,
>> 
>> What would be really nice is if you gave us server admins, application
>> server-side developers and data publishers a say in this.
>> 
>> Thus I'll propose a new header:
>> 
>> Allow-XHR = "Allow-XHR" ":" Allow-XHR-v
>> Allow-XHR-v = "none" | "negotiate" | "all"
>> 
>> "none" defines no XHR access
>> 
>> "negotiate" defines the UA should negotiate CORS or UMP headers (leave
>> that up to you guys to decide what's best ;)
>> 
>> "all" defines that the UA should process the XHR request as a normal
>> client HTTP request leaving all information + headers intact.
>> ...
> 
> From the side line: I hear that people were worried about having to add new response headers just for CORS & friends. Was it ever discussed to send these response headers only based on something in the *request*?

That's already how CORS works, essentially. You don't need to send the Access-Control-Allow-Origin header or other headers, unless you see a request with a non-same origin Origin header. The no-credentials subset of CORS is a bit weaker. It sends "Origin: null", which could also be triggered by something like traversing a link. UMP doesn't provide for this at all - there is no required header in a UMP request that can distinguish it from any other request.

(Regarding the proposal you quoted, I don't understand how the new header is materially different from CORS/UMP, which are both use opt-in response headers that allow cross-origin access.)

Regards,
Maciej
Received on Thursday, 13 May 2010 10:49:22 GMT

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