[Json] Scope: Wire format or runtime format?

Norbert Lindenberg <ietf@lindenbergsoftware.com> Thu, 13 June 2013 22:47 UTC

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Cc: Norbert Lindenberg <ietf@lindenbergsoftware.com>
Subject: [Json] Scope: Wire format or runtime format?
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In looking over older messages on this list, I found a message that made clear to me why we're having this endless discussion about Unicode surrogates - it's because we're not clear whether we're designing a wire format or a format that also for use at runtime:
http://www.ietf.org/mail-archive/web/json/current/msg00355.html

Some people are coming from the runtime point of view, especially ECMAScript, where it's accepted practice to use ill-formed UTF-16 or even non-text in strings. At least the ill-formed UTF-16 is legitimized by section 2.7 of the Unicode standard.

Other people are coming from the wire protocol point of view, where clean formats are expected, in particular well-formed Unicode code unit sequences according to section 3.9 of the Unicode standard.

So which one shall it be?

If we adopt the wire protocol point of view and require well-formed code unit sequences, then ECMAScript will have to define its own extension of JSON (which it has already by allowing JSON values at the top level).

If we adopt the runtime point of view and allow all code points as in RFC 4627, then there probably should be separate verbiage defining a restricted version for use over the wire.

Norbert