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Re: Adopting postMessage and MessageChannel from HTML5?

From: Maciej Stachowiak <mjs@apple.com>
Date: Sat, 09 Jan 2010 09:53:42 -0800
Cc: public-webapps <public-webapps@w3.org>, ext Ian Hickson <ian@hixie.ch>
Message-id: <2A86FB55-EF6A-4937-A461-37175C83F796@apple.com>
To: Arthur Barstow <art.barstow@nokia.com>

On Jan 9, 2010, at 6:30 AM, Arthur Barstow wrote:

> Hixie, All,
>
> On Jan 9, 2010, at 3:00 AM, ext Ian Hickson wrote:
>
>> Would this working group be interested in adopting the  
>> Window.postMessage
>> and MessageChannel/MessagePort features from HTML5? It was recently  
>> split
>> from the main HTML5 spec into a subspec, but some people have  
>> suggested it
>> might be best in the webapps group. I'd be happy to continue  
>> editing it,
>> it would just mean a change in the headers, as with Web Storage,  
>> etc (and
>> would similarly remain in the WHATWG "complete" spec).
>
> Why is this functionality being removed from HTML5?

Some Working Group members requested that it be split into a separate  
spec. The reasons cited were that this functionality is not directly  
related to HTML5, and that it is potentially reusable with other  
languages. In that respect, it is much like Web Workers, Web Sockets,  
or Web Storage.

>
> I would also like to understand: the status of the specification  
> maturity, in particular, its closeness to being ready for LCWD; and  
> the spec's implementation status.

I believe postMessage (cross-document-messaging) is implemented and  
shipping in every major browser. I am not sure about channel  
messaging. MessageChannel is implemented and shipping at least in  
WebKit (both Safari and Chrome) but I am not sure about other browser  
engines.

>
> Additionally, I don't see a direct connection to any of WebApps'  
> current deliverables although I'm not familiar with this  
> functionality:
>
> http://www.w3.org/2008/webapps/charter/#deliverables

What this functionality allows is communication among frames, windows  
and workers, including possibly ones from separate domains. It enables  
cross-domain APIs similar to what you can do with XHR2, but without  
any network traffic. It also enables widgets/gadgets embedded in a Web  
page to communicate with their containing page. And it is a critical  
dependency for Web Workers. You are correct that neither cross- 
document messaging or channel messaging is explicitly called out as a  
deliverable, but it does seem to bear a close relationship to other  
Web Apps specs that used to be part of HTML5.

>
> Is the HTML WG not interested in owning this new "subspec"?

I don't believe the HTML WG has rejected it, but some participants  
thought the Web Apps WG should get first crack at it, since it seems  
very related to other Web Apps WG deliverables and is not HTML-specific.

Regards,
Maciej
Received on Saturday, 9 January 2010 17:54:17 GMT

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