Re: [Sip] language info in SIP headers

[Henning Schulzrinne <hgs@cs.columbia.edu>]

> The reason I prefer this approach is that SIP messages must be small
> if it runs over UDP. "language tag" will add only few bytes.
> 
> Problem is backward compatibility with widely deployed SIP implementations.
> Another option is use MIME part3 with small modification.
> Since current MIME part3 did not allow to use any 8 bit flagged
> characters in MIME headers, encoding always escapes UTF-8 characters.
> 
> This is an example of MIME part3 header.
> 
> From: =?UTF-8*JP?B?<base64 encoded utf-8 string>?= <sip:foo@bar.org>
> 
> "base64" part is escaped and increased its size with 1.5 times or more.
> 
> If we define new encoding, say 'U', which only escape special
> charactors ('=','?',and '%' with '%xx' escaping).
> 
> From: =?UTF-8*JP?U?<raw utf-8 string>?= <sip:foo@bar.org>
> 
> This extension saves overhead on 8 bit charactors, and will not
> suffer any older implementations.
> 
> Additionally, if we can assume utf-8 and 'U' encoding, then we can
> minimize the escaping syntax too.
> 
> From: =?JP?<raw utf-8 string>?= <sip:foo@bar.org>
> 
> This still valid as display name value.
> 
> Both Keith and Ned suggested me that if we define 'U' encoding, it
> should be limited within SIP specification.
> 

I would suggest you write up a short I-D on the subject.



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