Re: [Json] Last Call: <draft-ietf-json-rfc4627bis-07.txt> (The JSON Data Interchange Format) to Proposed Standard

[Julian Reschke <[e-mail]>]

Hi there,

below are my editorial comments:

Abstract

    JavaScript Object Notation (JSON) is a lightweight, text-based,
    language-independent data interchange format.  It was derived from
    the ECMAScript Programming Language Standard.  JSON defines a small
    set of formatting rules for the portable representation of structured
    data.

    This document makes no changes to the definition of JSON; it repairs
    specification errors and offers experience-based interoperability
    guidance.

I believe historical considerations do not belong into the abstract (but 
into the Introduction)

Status of This Memo

    This Internet-Draft is submitted in full conformance with the
    provisions of BCP 78 and BCP 79.

    Internet-Drafts are working documents of the Internet Engineering
    Task Force (IETF).  Note that other groups may also distribute
    working documents as Internet-Drafts.  The list of current Internet-
    Drafts is at http://datatracker.ietf.org/drafts/current/.

    Internet-Drafts are draft documents valid for a maximum of six months
    and may be updated, replaced, or obsoleted by other documents at any
    time.  It is inappropriate to use Internet-Drafts as reference
    material or to cite them other than as "work in progress."

    This Internet-Draft will expire on May 10, 2014.

Are we sure that we do not need the "pre-5378 escape clause" here? 
(Section 4 of <http://trustee.ietf.org/docs/IETF-Copyright-FAQ.pdf>)

    The grammatical rules in this document are to be interpreted as
    described in [RFC5234].

Maybe note which productions are imported as well (HEXDIG and DIGIT it 
seems).

    This revision does not change any of the rules of the specification;
    all texts which were legal JSON remain so, and none which were not
    JSON become JSON.  The revision's goal is to fix the errata and
    highlight practices which can lead to interoperability problems.

s/fix errata/apply errata/ ?

    Insignificant whitespace is allowed before or after any of the six
    structural characters.

    ws = *(
            %x20 /              ; Space
            %x09 /              ; Horizontal tab
            %x0A /              ; Line feed or New line
            %x0D )              ; Carriage return

We *could* use SP, HTAB, LF, and CR here.

    JSON text SHALL be encoded in Unicode.  The default encoding is
    UTF-8.

That's a bit misleading. How do I "encode in Unicode"? I think what it 
tries to say is that one of the Unicode-compatible character encoding 
schemes needs to be used.

    Since the first two characters of a JSON text will always be ASCII
    characters [RFC0020], it is possible to determine whether an octet
    stream is UTF-8, UTF-16 (BE or LE), or UTF-32 (BE or LE) by looking
    at the pattern of nulls in the first four octets.

    00 00 00 xx  UTF-32BE
    00 xx 00 xx  UTF-16BE
    xx 00 00 00  UTF-32LE
    xx 00 xx 00  UTF-16LE
    xx xx xx xx  UTF-8

I'm ok to sticking with this, but I'm also with AvK that it would be 
good to recommend (not necessarily RECOMMEND) UTF-8.

    An implementation may set limits on the size of texts that it
    accepts.  An implementation may set limits on the maximum depth of
    nesting.  An implementation may set limits on the range and precision
    of numbers.  An implementation may set limits on the length and
    character contents of strings.

Maybe this should be a bullet list?

10.  Generators

    A JSON generator produces JSON text.  The resulting text MUST
    strictly conform to the JSON grammar.

"strictly"?

    Encoding considerations:  8bit if UTF-8; binary if UTF-16 or UTF-32.
       JSON may be represented using UTF-8, UTF-16, or UTF-32.  When JSON
       is written in UTF-8, JSON is 8bit compatible.  When JSON is
       written in UTF-16 or UTF-32, the binary content-transfer-encoding
       must be used.

As mentioned before, please clarify that there is no such thing as 
content-transfer-encoding in binary transports such as HTTP.


    Person & email address to contact for further information:  IESG
       <[e-mail]

Missing ">"?

    Change controller:  IESG
       <[e-mail]

Ditto.

    o  Changed Working Group attribution to JSON Working Group.

...this is a change that will not be visible in the RFC.


Furthermore, it would be great if the spec made it crystal-clear that 
application/json really really has no charset parameter; maybe as a NOTE?

Finally, I did check the ABNF using Bill's ABNF Parser, and the result 
is good except for DIGIT and HEXDIG being defined elsewhere:

> array = begin-array [ value *( value-separator value ) ] end-array
> begin-array = ws "[" ws
> begin-object = ws "{" ws
> end-array = ws "]" ws
> end-object = ws "}" ws
> name-separator = ws ":" ws
> value-separator = ws "," ws
> ws = *( " " / %x09 / %x0A / %x0D )
> value = false / null / true / object / array / number / string
> false = %x66.61.6C.73.65
> null = %x6E.75.6C.6C
> true = %x74.72.75.65
> object = begin-object [ member *( value-separator member ) ] end-object
> member = string name-separator value
> number = [ minus ] int [ frac ] [ exp ]
> decimal-point = "."
> digit1-9 = %x31-39
> e = %x65 / %x45
> ; DIGIT UNDEFINED
> exp = e [ minus / plus ] 1*DIGIT
> frac = decimal-point 1*DIGIT
> int = zero / ( digit1-9 *DIGIT )
> minus = "-"
> plus = "+"
> zero = "0"
> string = quotation-mark *char quotation-mark
> ; HEXDIG UNDEFINED
> char = unescaped / ( escape ( %x22 / "\" / "/" / %x62 / %x66 / %x6E / %x72 / %x74 / ( %x75 4HEXDIG ) ) )
> escape = "\"
> quotation-mark = %x22
> unescaped = %x20-21 / %x23-5B / %x5D-10FFFF



Best regards, Julian