Re: [rtcweb] PPID, UTF-16 and DOMString (Re: RTCWEB Data Channel: Usage of PPID for protocol multiplexing)

That's good. Glad to see that no one liked the complex alternate option... yet! :-)
I just put it there for completeness and some discussion.
With "utf-8 on wire", which I too think is the right approach, there is some spec work todo:
1. Define IANA utf-8 ppid. Creating a new one is better instead of replacing existing DOMString as DOMString may be used by browsers for sometime to come and also to have backward compatibility/interworking.
2. Data channel core spec (http://tools.ietf.org/html/draft-ietf-rtcweb-data-channel-06#section-6.6) need to specify explictly the wire format is utf-8.

Then browsers need to do the conversion from utf-16 DOMstring to utf-8 before writing on wire also in the reverse direction. 

-Raju

> -----Original Message-----
> From: Christer Holmberg [mailto:christer.holmberg@ericsson.com]
> Sent: Friday, February 07, 2014 6:01 PM
> To: Martin Thomson; Makaraju, Maridi Raju (Raju)
> Cc: rtcweb@ietf.org
> Subject: RE: [rtcweb] PPID, UTF-16 and DOMString (Re: RTCWEB Data Channel:
> Usage of PPID for protocol multiplexing)
> 
> 
> + 1
> 
> Regards,
> 
> Christer
> 
> ________________________________________
> From: rtcweb [rtcweb-bounces@ietf.org] on behalf of Martin Thomson
> [martin.thomson@gmail.com]
> Sent: Saturday, 08 February 2014 1:45 AM
> To: Makaraju, Maridi Raju (Raju)
> Cc: rtcweb@ietf.org
> Subject: Re: [rtcweb] PPID, UTF-16 and DOMString (Re: RTCWEB Data Channel:
> Usage of PPID for protocol multiplexing)
> 
> I don't think that we need any complication here.  It's a string.
> 
> Strings are UTF-8 on the wire.
> 
> Strings are UTF-16 (mostly) in JavaScript.
> 
> Anything else would generate pain.
> 
> On 7 February 2014 14:01, Makaraju, Maridi Raju (Raju)
> <Raju.Makaraju@alcatel-lucent.com> wrote:
> >> >> Also, I think "DOMString" PPID is too specific to Javascript, instead
> it
> >> should probably have a generic name like "UTF-16 String". The send API
> can
> >> still use DOMString as this is Javascript API.
> >> > Any comments from others?
> >>
> >> Note: The WebSockets protocol defines the transferred strings as UTF-8.
> >> http://tools.ietf.org/html/rfc6455#section-5.6
> >>
> >> As far as I can tell, we've always intended to follow that example.
> >>
> >> The fact that Javascript implementations currently choose to represent
> >> text strings as UTF-16 at their API is sad, but not an argument for
> >> sending that particular text representation over the wire, or reflecting
> >> the name in the API.
> >
> > [Raju] I agree that using UTF-8 is desired and more appropriate! Then,
> should the PPID be changed from "DOMString" to "UTF-8"? Javascript based
> apps have to use some library to do the conversion of DOMString/UTF-16 to
> UTF-8. Alternatively, browsers can do this conversion under the APIs (send
> and onmessage) before sending and after receiving UTF-8 PPID data.
> > Without such conversion webrtc interworking between browsers and native
> clients will be problematic (basically, will not work).
> >
> > Another option, which is more flexible, is to define PPIDs for different
> encodings like "UTF-8", "UTF-16" (or even "base64" for binary to text
> instead of using "binary" directly); then pass this encoding information to
> send() and onmessage() calls, which will use these PPIDs. Passing encoding
> information might be implicit (like Javavscript DOMString) in most languages
> by the type of the argument to send. This way it is upto the application to
> deal with the encoding conversions as it see fits.
> >
> > The latter approach is best suitable for interworking between clients of
> similar type (web or native); but it is bit painful (to do conversions) for
> clients of different types.
> >
> > I am wondering what kind of API calls native WebRTC API stacks (e.g.
> Google Chrome's http://www.webrtc.org/webrtc-native-code-package) provide
> for data channel send/onmessage ()? UTF-16 strings? Or UTF-8?
> >
> > -Raju
> >
> > _______________________________________________
> > rtcweb mailing list
> > rtcweb@ietf.org
> > https://www.ietf.org/mailman/listinfo/rtcweb
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