Internet DRAFT - draft-hallambaker-jsonbcd

draft-hallambaker-jsonbcd







Network Working Group                                 P. M. Hallam-Baker
Internet-Draft                                              28 June 2023
Intended status: Informational                                          
Expires: 30 December 2023


Binary Encodings for JavaScript Object Notation: JSON-B, JSON-C, JSON-D
                      draft-hallambaker-jsonbcd-24

Abstract

   Three binary encodings for JavaScript Object Notation (JSON) are
   presented.  JSON-B (Binary) is a strict superset of the JSON encoding
   that permits efficient binary encoding of intrinsic JavaScript data
   types.  JSON-C (Compact) is a strict superset of JSON-B that supports
   compact representation of repeated data strings with short numeric
   codes.  JSON-D (Data) supports additional binary data types for
   integer and floating-point representations for use in scientific
   applications where conversion between binary and decimal
   representations would cause a loss of precision.

   This document is also available online at
   http://mathmesh.com/Documents/draft-hallambaker-jsonbcd.html.

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
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   This Internet-Draft will expire on 30 December 2023.

Copyright Notice

   Copyright (c) 2023 IETF Trust and the persons identified as the
   document authors.  All rights reserved.






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   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents (https://trustee.ietf.org/
   license-info) in effect on the date of publication of this document.
   Please review these documents carefully, as they describe your rights
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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Objectives  . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Definitions . . . . . . . . . . . . . . . . . . . . . . . . .   4
     2.1.  Requirements Language . . . . . . . . . . . . . . . . . .   4
     2.2.  Defined Terms . . . . . . . . . . . . . . . . . . . . . .   4
     2.3.  Related Specifications  . . . . . . . . . . . . . . . . .   5
     2.4.  Terminology . . . . . . . . . . . . . . . . . . . . . . .   5
   3.  Extended JSON Grammar . . . . . . . . . . . . . . . . . . . .   5
   4.  JSON-B  . . . . . . . . . . . . . . . . . . . . . . . . . . .   7
     4.1.  JSON-B Examples . . . . . . . . . . . . . . . . . . . . .   9
   5.  JSON-C  . . . . . . . . . . . . . . . . . . . . . . . . . . .  10
     5.1.  JSON-C Examples . . . . . . . . . . . . . . . . . . . . .  11
   6.  JSON-D (Data) . . . . . . . . . . . . . . . . . . . . . . . .  12
   7.  JBCD Frames and Records . . . . . . . . . . . . . . . . . . .  13
   8.  JSON-BCD Application Binding  . . . . . . . . . . . . . . . .  15
     8.1.  JSON Binding  . . . . . . . . . . . . . . . . . . . . . .  15
     8.2.  JSON-B Binding  . . . . . . . . . . . . . . . . . . . . .  16
     8.3.  Examples  . . . . . . . . . . . . . . . . . . . . . . . .  17
   9.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  17
   10. Security Considerations . . . . . . . . . . . . . . . . . . .  17
   11. IANA Considerations . . . . . . . . . . . . . . . . . . . . .  18
   12. Normative References  . . . . . . . . . . . . . . . . . . . .  18
   13. Informative References  . . . . . . . . . . . . . . . . . . .  19

1.  Introduction

   JavaScript Object Notation (JSON) is a simple text encoding for the
   JavaScript Data model that has found wide application beyond its
   original field of use.  In particular JSON has rapidly become a
   preferred encoding for Web Services.

   JSON encoding supports just four fundamental data types (integer,
   floating point, string and boolean), arrays and objects which consist
   of a list of tag-value pairs.









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   Although the JSON encoding is sufficient for many purposes it is not
   always efficient.  In particular there is no efficient representation
   for blocks of binary data.  Use of base64 encoding increases data
   volume by 33%. This overhead increases exponentially in applications
   where nested binary encodings are required making use of JSON
   encoding unsatisfactory in cryptographic applications where nested
   binary structures are frequently required.

   Another source of inefficiency in JSON encoding is the repeated
   occurrence of object tags.  A JSON encoding containing an array of a
   hundred objects such as {"first":1,"second":2} will contain a hundred
   occurrences of the string "first" (seven bytes) and a hundred
   occurrences of the string "second" (eight bytes).  Using two byte
   code sequences in place of strings allows a saving of 11 bytes per
   object without loss of information, a saving of 50%.

   A third objection to the use of JSON encoding is that floating point
   numbers can only be represented in decimal form and this necessarily
   involves a loss of precision when converting between binary and
   decimal representations.  While such issues are rarely important in
   network applications they can be critical in scientific applications.
   It is not acceptable for saving and restoring a data set to change
   the result of a calculation.

1.1.  Objectives

   The following were identified as core objectives for a binary JSON
   encoding:

   *  Easy to convert existing encoders and decoders to add binary
      support

   *  Efficient encoding of binary data

   *  Ability to convert from JSON to binary encoding in a streaming
      mode (i.e. without reading the entire binary data block before
      beginning encoding.

   *  Lossless encoding of JavaScript data types

   *  The ability to support JSON tag compression and extended data
      types are considered desirable but not essential for typical
      network applications.

   Three binary encodings are defined:

   JSON-B (Binary)  Encodes JSON data in binary.  Only the JavaScript




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      data model is supported (i.e. atomic types are integers, double or
      string).  Integers may be 8, 16, 32 or 64 bits either signed or
      unsigned.  Floating points are IEEE 754 binary64 format [IEEE754].
      Supports chunked encoding for binary and UTF-8 string types.

   JSON-C (Compact)  As JSON-B but with support for representing JSON
      tags in numeric code form (16 bit code space).  This is done for
      both compact encoding and to allow simplification of encoders/
      decoders in constrained environments.  Codes may be defined inline
      or by reference to a known dictionary of codes referenced via a
      digest value.

   JSON-D (Data)  As JSON-C but with support for representing additional
      data types without loss of precision.  In particular other IEEE
      754 floating point formats, both binary and decimal and Intel's 80
      bit floating point, plus 128 bit integers and bignum integers.

   Each encoding is a proper superset of JSON, JSON-C is a proper
   superset of JSON-B and JSON-D is a proper superset of JSON-C.  Thus a
   single decoder MAY be used for all three new encodings and for JSON.
   Figure 1 shows these relationships graphically:

   (Artwork only available as svg: No external link available, see
   draft-hallambaker-jsonbcd-24.html for artwork.)

                     Figure 1: Encoding Relationships.

2.  Definitions

   This section presents the related specifications and standard, the
   terms that are used as terms of art within the documents and the
   terms used as requirements language.

2.1.  Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in [RFC2119].

2.2.  Defined Terms

   The terms of art used in this document are described in the _Mesh
   Architecture Guide_ [draft-hallambaker-mesh-architecture].








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2.3.  Related Specifications

   The JSON-B, JSON-C and JSON-D encodings are all based on the JSON
   grammar [RFC7159].  IEEE 754 Floating Point Standard is used for
   encoding floating point numbers [IEEE754],

2.4.  Terminology

   No new terms of art are defined

3.  Extended JSON Grammar

   The JSON-B, JSON-C and JSON-D encodings are all based on the JSON
   grammar [RFC7159] using the same syntactic structure but different
   lexical encodings.

   JSON-B0 and JSON-C0 replace the JSON lexical encodings for strings
   and numbers with binary encodings.  JSON-B1 and JSON-C1 allow either
   lexical encoding to be used.  Thus, any valid JSON encoding is a
   valid JSON-B1 or JSON-C1 encoding.

   The grammar of JSON-B, JSON-C and JSON-D is a superset of the JSON
   grammar.  The following productions are added to the grammar:

   x-value  Binary encodings for data values.  As the binary value
      encodings are all self-delimiting

   x-member  An object member where the value is specified as an X-value
      and thus does not require a value-separator.

   b-value  Binary data encodings defined in JSON-B.

   b-string  Defined length string encoding defined in JSON-B.

   c-def  Tag code definition defined in JSON-C.  These may only appear
      before the beginning of an Object or Array and before any
      preceding white space.

   c-tag  Tag code value defined in JSON-C.

   d-value  Additional binary data encodings defined in JSON-D for use
      in scientific data applications.

   The JSON grammar is modified to permit the use of x-value productions
   in place of ( value value-separator ) :






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   JSON-text = (object / array)

   object = *cdef begin-object [
            *( member value-separator | x-member )
            (member | x-member) ] end-object

   member = tag value
   x-member = tag x-value

   tag = string name-separator | b-string | c-tag

   array = *cdef begin-array [  *( value value-separator | x-value )
    (value | x-value) ] end-array

   x-value = b-value / d-value

   value = false / null / true / object / array / number / string

   name-separator  = ws %x3A ws  ; : colon
   value-separator = ws %x2C ws  ; , comma


   The following lexical values are unchanged:
   begin-array     = ws %x5B ws  ; [ left square bracket
   begin-object    = ws %x7B ws  ; { left curly bracket
   end-array       = ws %x5D ws  ; ] right square bracket
   end-object      = ws %x7D ws  ; } right curly bracket

   ws = *( %x20 %x09 %x0A  %x0D )

   false = %x66.61.6c.73.65   ; false
   null  = %x6e.75.6c.6c      ; null
   true  = %x74.72.75.65      ; true

   The productions number and string are defined as before:
















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   number = [ minus ] int [ frac ] [ exp ]
   decimal-point = %x2E       ; .
   digit1-9 = %x31-39         ; 1-9
   e = %x65 / %x45            ; e E
   exp = e [ minus / plus ] 1*DIGIT
   frac = decimal-point 1*DIGIT
   int = zero / ( digit1-9 *DIGIT )
   minus = %x2D               ; -
   plus = %x2B                ; +
   zero = %x30                ; 0

   string = quotation-mark *char quotation-mark
   char = unescaped /
   escape ( %x22 / %x5C / %x2F / %x62 / %x66 /
   %x6E / %x72 / %x74 /  %x75 4HEXDIG )

   escape = %x5C              ; \
   quotation-mark = %x22      ; "
   unescaped = %x20-21 / %x23-5B / %x5D-10FFFF

4.  JSON-B

   The JSON-B encoding defines the b-value and b-string productions:

   b-value = b-atom | b-string | b-data | b-integer |
   b-float

   b-string = *( string-chunk ) string-term
   b-data = *( data-chunk ) data-last

   b-integer = p-int8 | p-int16 | p-int32 | p-int64 | p-bignum16 |
   n-int8 | n-int16 | n-int32 | n-int64 | n-bignum16

   b-float = binary64

   The lexical encodings of the productions are defined in the following
   tables where the column 'tag' specifies the byte code that begins the
   production, 'Fixed' specifies the number of data bytes that follow
   and 'Length' specifies the number of bytes used to define the length
   of a variable length field following the data bytes:

        +==============+=====+=======+========+==================+
        | Production   | Tag | Fixed | Length | Data Description |
        +==============+=====+=======+========+==================+
        | string-term  | x80 | -     | 1      | Terminal String  |
        |              |     |       |        | 8 bit length     |
        +--------------+-----+-------+--------+------------------+
        | string-term  | x81 | -     | 2      | Terminal String  |



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        |              |     |       |        | 16 bit length    |
        +--------------+-----+-------+--------+------------------+
        | string-term  | x82 | -     | 4      | Terminal String  |
        |              |     |       |        | 32 bit length    |
        +--------------+-----+-------+--------+------------------+
        | string-term  | x83 | -     | 8      | Terminal String  |
        |              |     |       |        | 64 bit length    |
        +--------------+-----+-------+--------+------------------+
        | string-chunk | x84 | -     | 1      | Terminal String  |
        |              |     |       |        | 8 bit length     |
        +--------------+-----+-------+--------+------------------+
        | string-chunk | x85 | -     | 2      | Terminal String  |
        |              |     |       |        | 16 bit length    |
        +--------------+-----+-------+--------+------------------+
        | string-chunk | x86 | -     | 4      | Terminal String  |
        |              |     |       |        | 32 bit length    |
        +--------------+-----+-------+--------+------------------+
        | string-chunk | x87 | -     | 8      | Terminal String  |
        |              |     |       |        | 64 bit length    |
        +--------------+-----+-------+--------+------------------+
        | data-term    | x88 | -     | 1      | Terminal String  |
        |              |     |       |        | 8 bit length     |
        +--------------+-----+-------+--------+------------------+
        | data-term    | x89 | -     | 2      | Terminal String  |
        |              |     |       |        | 16 bit length    |
        +--------------+-----+-------+--------+------------------+
        | data-term    | x8A | -     | 4      | Terminal String  |
        |              |     |       |        | 32 bit length    |
        +--------------+-----+-------+--------+------------------+
        | data-term    | x8B | -     | 8      | Terminal String  |
        |              |     |       |        | 64 bit length    |
        +--------------+-----+-------+--------+------------------+
        | data-chunk   | X8C | -     | 1      | Terminal String  |
        |              |     |       |        | 8 bit length     |
        +--------------+-----+-------+--------+------------------+
        | data-chunk   | x8D | -     | 2      | Terminal String  |
        |              |     |       |        | 16 bit length    |
        +--------------+-----+-------+--------+------------------+
        | data-chunk   | x8E | -     | 4      | Terminal String  |
        |              |     |       |        | 32 bit length    |
        +--------------+-----+-------+--------+------------------+
        | data-chunk   | x8F | -     | 8      | Terminal String  |
        |              |     |       |        | 64 bit length    |
        +--------------+-----+-------+--------+------------------+

                                 Table 1

   Table 1: Codes for String and Data items



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      +============+=====+=======+========+=========================+
      | Production | Tag | Fixed | Length | Data Description        |
      +============+=====+=======+========+=========================+
      | p-int8     | xA0 | 1     | -      | Positive 8 bit Integer  |
      +------------+-----+-------+--------+-------------------------+
      | p-int16    | xa1 | 2     | -      | Positive 16 bit Integer |
      +------------+-----+-------+--------+-------------------------+
      | p-int32    | xa2 | 4     | -      | Positive 32 bit Integer |
      +------------+-----+-------+--------+-------------------------+
      | p-int64    | xa3 | 8     | -      | Positive 64 bit Integer |
      +------------+-----+-------+--------+-------------------------+
      | p-bignum16 | Xa7 | -     | 2      | Positive Bignum         |
      +------------+-----+-------+--------+-------------------------+
      | n-int8     | xA8 | 1     | -      | Negative 8 bit Integer  |
      +------------+-----+-------+--------+-------------------------+
      | n-int16    | xA9 | 2     | -      | Negative 16 bit Integer |
      +------------+-----+-------+--------+-------------------------+
      | n-int32    | xAA | 4     | -      | Negative 32 bit Integer |
      +------------+-----+-------+--------+-------------------------+
      | n-int64    | xAB | 8     | -      | Negative 64 bit Integer |
      +------------+-----+-------+--------+-------------------------+
      | n-bignum16 | xAF | -     | 2      | Negative Bignum         |
      +------------+-----+-------+--------+-------------------------+
      | binary64   | x92 | 8     | -      | IEEE 754 Floating Point |
      |            |     |       |        | Binary 64 bit           |
      +------------+-----+-------+--------+-------------------------+
      | b-value    | xB0 | -     | -      | True                    |
      +------------+-----+-------+--------+-------------------------+
      | b-value    | xB1 | -     | -      | False                   |
      +------------+-----+-------+--------+-------------------------+
      | b-value    | xB2 | -     | -      | Null                    |
      +------------+-----+-------+--------+-------------------------+

                                  Table 2

   Table 2: Codes for Integers, 64 Bit Floating Point, Boolean and Null
   items.

   A data type commonly used in networking that is not defined in this
   scheme is a datetime representation.  To define such a data type, a
   string containing a date-time value in Internet type format is
   typically used.

4.1.  JSON-B Examples

   The following examples show examples of using JSON-B encoding:





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   A0 2A                            42 (as 8 bit integer)
   A1 00 2A                         42 (as 16 bit integer)
   A2 00 00 00 2A                   42 (as 32 bit integer)
   A3 00 00 00 00 00 00 00 2A       42 (as 64 bit integer)
   A5 00 01 42                      42 (as Bignum)

   80 05 48 65 6c 6c 6f             "Hello" (single chunk)
   81 00 05 48 65 6c 6c 6f          "Hello" (single chunk)
   84 05 48 65 6c 6c 6f 80 00       "Hello" (as two chunks)

   92 3f f0 00 00 00 00 00 00       1.0
   92 40 24 00 00 00 00 00 00       10.0
   92 40 09 21 fb 54 44 2e ea       3.14159265359
   92 bf f0 00 00 00 00 00 00       -1.0

   B0                               true
   B1                               false
   B2                               null

5.  JSON-C

   JSON-C (Compressed) permits numeric code values to be substituted for
   strings and binary data.  Tag codes MAY be 8, 16 or 32 bits long
   encoded in network byte order.

   Tag codes MUST be defined before they are referenced.  A Tag code MAY
   be defined before the corresponding data or string value is used or
   at the same time that it is used.

   A dictionary is a list of tag code definitions.  An encoding MAY
   incorporate definitions from a dictionary using the dict-hash
   production.  The dict hash production specifies a (positive) offset
   value to be added to the entries in the dictionary followed by the
   UDF fingerprint [draft-hallambaker-udf] of the dictionary to be used.

















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   +============+=====+=======+========+===============================+
   | Production | Tag | Fixed | Length | Data Description              |
   +============+=====+=======+========+===============================+
   | c-tag      | xC0 | 1     | -      | 8 bit tag code                |
   +------------+-----+-------+--------+-------------------------------+
   | c-tag      | xC1 | 2     | -      | 16 bit tag code               |
   +------------+-----+-------+--------+-------------------------------+
   | c-tag      | xC2 | 4     | -      | 32 bit tag code               |
   +------------+-----+-------+--------+-------------------------------+
   | c-def      | xC4 | 1     | -      | 8 bit tag definition          |
   +------------+-----+-------+--------+-------------------------------+
   | c-def      | xC5 | 2     | -      | 16 bit tag definition         |
   +------------+-----+-------+--------+-------------------------------+
   | c-def      | xC6 | 4     | -      | 32 bit tag definition         |
   +------------+-----+-------+--------+-------------------------------+
   | c-tag      | xC8 | 1     | -      | 8 bit tag code and            |
   |            |     |       |        | definition                    |
   +------------+-----+-------+--------+-------------------------------+
   | c-tag      | xC9 | 2     | -      | 16 bit tag code and           |
   |            |     |       |        | definition                    |
   +------------+-----+-------+--------+-------------------------------+
   | c-tag      | xCA | 4     | -      | 32 bit tag code and           |
   |            |     |       |        | definition                    |
   +------------+-----+-------+--------+-------------------------------+
   | c-def      | xCC | 1     | -      | 8 bit tag dictionary          |
   |            |     |       |        | definition                    |
   +------------+-----+-------+--------+-------------------------------+
   | c-def      | xCD | 2     | -      | 16 bit tag dictionary         |
   |            |     |       |        | definition                    |
   +------------+-----+-------+--------+-------------------------------+
   | c-def      | xCE | 4     | -      | 32 bit tag dictionary         |
   |            |     |       |        | definition                    |
   +------------+-----+-------+--------+-------------------------------+
   | dict-hash  | xD0 | 4     | 1      | UDF fingerprint of            |
   |            |     |       |        | dictionary                    |
   +------------+-----+-------+--------+-------------------------------+

                                  Table 3

   Table 3: Codes Used for Compression

   All integer values are encoded in Network Byte Order (most
   significant byte first).

5.1.  JSON-C Examples

   The following examples show examples of using JSON-C encoding:




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   C8 20 80 05 48 65 6c 6c 6f       "Hello"    20 = "Hello"
   C4 21 80 05 48 65 6c 6c 6f                  21 = "Hello"
   C0 20                            "Hello"
   C1 00 20                         "Hello"

   D0 00 00 01 00 20             Insert dictionary at code 256
   e3 b0 c4 42 98 fc 1c 14
   9a fb f4 c8 99 6f b9 24
   27 ae 41 e4 64 9b 93 4c
   a4 95 99 1b 78 52 b8 55       UDF (C4 21 80 05 48 65 6c 6c 6f)

6.  JSON-D (Data)

   JSON-B and JSON-C only support the two numeric types defined in the
   JavaScript data model: Integers and 64 bit floating point values.
   JSON-D (Data) defines binary encodings for additional data types that
   are commonly used in scientific applications.  These comprise
   positive and negative 128 bit integers, six additional floating point
   representations defined by IEEE 754 [IEEE754] and the Intel extended
   precision 80 bit floating point representation [INTEL].

   Should the need arise, even bigger bignums could be defined with the
   length specified as a 32 bit value permitting bignums of up to 2^35
   bits to be represented.

   d-value = d-integer | d-float

   d-float = binary16 | binary32 | binary128 | binary80 |
   decimal32 | decimal64 | decimal 128

   The codes for these values are as follows:




















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     +============+=====+=======+========+==========================+
     | Production | Tag | Fixed | Length | Data Description         |
     +============+=====+=======+========+==========================+
     | p-int128   | xA4 | 16    | -      | Positive 128 bit Integer |
     +------------+-----+-------+--------+--------------------------+
     | n-int128   | xAC | 16    | -      | Negative 128 bit Integer |
     +------------+-----+-------+--------+--------------------------+
     | binary16   | x90 | 2     | -      | IEEE 754 Floating Point  |
     |            |     |       |        | Binary 16 bit            |
     +------------+-----+-------+--------+--------------------------+
     | binary32   | x91 | 4     | -      | IEEE 754 Floating Point  |
     |            |     |       |        | Binary 32 bit            |
     +------------+-----+-------+--------+--------------------------+
     | binary128  | x94 | 16    | -      | IEEE 754 Floating Point  |
     |            |     |       |        | Binary 64 bit            |
     +------------+-----+-------+--------+--------------------------+
     | Intel80    | x95 | 10    | -      | Intel extended Floating  |
     |            |     |       |        | Point 80 bit             |
     +------------+-----+-------+--------+--------------------------+
     | decimal32  | x96 | 4     | -      | IEEE 754 Floating Point  |
     |            |     |       |        | Decimal 32               |
     +------------+-----+-------+--------+--------------------------+
     | Decimal64  | x97 | 8     | -      | IEEE 754 Floating Point  |
     |            |     |       |        | Decimal 64               |
     +------------+-----+-------+--------+--------------------------+
     | Decimal128 | x98 | 16    | -      | IEEE 754 Floating Point  |
     |            |     |       |        | Decimal 128              |
     +------------+-----+-------+--------+--------------------------+

                                 Table 4

   Table 4: Additional Codes for Scientific Data

7.  JBCD Frames and Records

   Tag codes in the range xF0-XFF are reserved for specifying markers
   for _frames_ and _records_. These tags are not used to encode JSON
   data, they are only used to encapsulate opaque binary data blobs as a
   unit.

   A JBCD record consists of consist of the tag, a length and the data
   item.  The length indication provided by the record format allows
   efficient traversal of a sequence of records in the forward direction
   only.







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   A JBCD Frames consists of consist of the tag, a length and the data
   item followed by the tag-length sequence repeated with the bytes
   written in the reverse order.  The first length indication allows
   efficient traversal of a sequence of records in the forward direction
   and the second allows efficient traversal in the reverse direction.

   (Artwork only available as svg: No external link available, see
   draft-hallambaker-jsonbcd-24.html for artwork.)

                     Figure 2: JBCD Records and Frames

   The JBCD-Frame tags currently defined are:

     +============+=========+=======+========+=======================+
     | Production | Tag     | Fixed | Length | Data Description      |
     +============+=========+=======+========+=======================+
     | uframe     | xF0     | -     | 1      | Record, 8 bit length  |
     +------------+---------+-------+--------+-----------------------+
     | uframe     | xF1     | -     | 2      | Record, 16 bit length |
     +------------+---------+-------+--------+-----------------------+
     | uframe     | xF2     | -     | 4      | Record, 32 bit length |
     +------------+---------+-------+--------+-----------------------+
     | uframe     | xF3     | -     | 8      | Record, 64 bit length |
     +------------+---------+-------+--------+-----------------------+
     | bframe     | xF4     | -     | 1      | Frame, 8 bit length   |
     +------------+---------+-------+--------+-----------------------+
     | bframe     | xF5     | -     | 2      | Frame, 16 bit length  |
     +------------+---------+-------+--------+-----------------------+
     | bframe     | xF6     | -     | 4      | Frame, 32 bit length  |
     +------------+---------+-------+--------+-----------------------+
     | bframe     | xF7     | -     | 8      | Frame, 64 bit length  |
     +------------+---------+-------+--------+-----------------------+
     |            | xF8-xFF | -     | -      | Reserved              |
     +------------+---------+-------+--------+-----------------------+

                                  Table 5

   The author does not expect additional framing tags to be added but
   codes F8-FF are reserved in case this is desired.

   It may prove convenient to represent message digest values as large
   integers rather than binary strings.  While very few platforms or
   programming languages support mathematical operations on fixed size
   integers larger than 64, this is not a major concern since message
   digests are rarely used for any purpose other than comparison for
   equality.





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     +============+=====+=======+========+==========================+
     | Production | Tag | Fixed | Length | Data Description         |
     +============+=====+=======+========+==========================+
     | p-int128   | Xa4 | 16    | -      | Positive 128 bit Integer |
     +------------+-----+-------+--------+--------------------------+
     | p-int256   | Xa5 | 32    | -      | Positive 256 bit Integer |
     +------------+-----+-------+--------+--------------------------+
     | p-int512   | Xa6 | 64    | -      | Positive 512 bit Integer |
     +------------+-----+-------+--------+--------------------------+

                                 Table 6


8.  JSON-BCD Application Binding

   The JSON serialization format is intentionally limited in the range
   of data types it supports.  To serialize data not supported by the
   JSON data model, it is necessary to specify a means of transforming
   the unsupported data type into a supported one.

   In particular JSON does not provide a Date-Time object or a means of
   encoding binary data except as an array of bytes.

   The JSON-BCD Application Binding specifies a data model designed to
   support the needs of specifying network protocols and associated
   static data.  The data model is close to that of JSON with three
   additional types:

   *  Binary data

   *  DateTime

   *  Object of specified type

8.1.  JSON Binding

   The following data field types are specified:

   Integer

   Integer values are encoded as JSON number values.

   Float

   Float values are encoded as JSON number values.

   String




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   Test strings are encoded as JSON text strings.

   Boolean

   Boolean values are encoded as JSON 'false', 'true' or 'null' tokens
   according to value.

   Sequence

   Sequences of data items that are encoded as JSON arrays

   Object of known type

   Objects whose type is known to the receiver are encoded as JSON
   objects

   Object of variable type

   Objects whose type is not known to the receiver are encoded as JSON
   objects containing a single field whose name describes the type of
   the object value and whose value contains the value.

   Binary Data

   Byte sequences are converted to BASE64-url encoding [RFC4648] and
   encoded as JSON string values.

   Date Time

   Date Time values are converted to Internet time format as described
   in [RFC3339] and encoded as JSON string values.

8.2.  JSON-B Binding

   The JSON-B value allows a superset of the JSON encodings to be used.

   Integer

   Integer values are encoded as JSON number values or as JSON-B
   b-integer values.

   Float

   Float values are encoded as JSON number values or as JSON-B b-integer
   or b-float values.

   String




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   Test strings are encoded as JSON text strings or as JSON-B b-string
   values.

   Boolean

   Boolean values are encoded as JSON 'false', 'true' or 'null' tokens
   or as JSON-B b-atom values according to value

   Sequence

   Sequences of data items that are encoded as JSON arrays

   Object of known type

   Objects whose type is known to the receiver are encoded as JSON
   objects

   Object of variable type

   Objects whose type is not known to the receiver are encoded as JSON
   objects containing a single field whose name describes the type of
   the object value and whose value contains the value.

   Binary Data

   Byte sequences are converted to BASE64-url encoding [RFC4648] and
   encoded as JSON string values or as JSON-B b-data values.

   Date Time

   Date Time values are converted to Internet time format as described
   in [RFC3339] and encoded as JSON string values or as JSON-B b-string
   values.

8.3.  Examples

9.  Acknowledgements

   This work was assisted by conversations with Nico Williams and other
   participants on the applications area mailing list.

10.  Security Considerations

   A correctly implemented data encoding mechanism should not introduce
   new security vulnerabilities.  However, experience demonstrates that
   some data encoding approaches are more prone to introduce
   vulnerabilities when incorrectly implemented than others.




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   In particular, whenever variable length data formats are used, the
   possibility of a buffer overrun vulnerability is introduced.  While
   best practice suggests that a coding language with native mechanisms
   for bounds checking is the best protection against such errors, such
   approaches are not always followed.  While such vulnerabilities are
   most commonly seen in the design of decoders, it is possible for the
   same vulnerabilities to be exploited in encoders.

   A common source of such errors is the case where nested length
   encodings are used.  For example, a decoder relies on an outermost
   length encoding that specifies a length on 50 bytes to allocate
   memory for the entire result and then attempts to copy a string with
   a declared length of 1000 bytes within the sequence.

   The extensions to the JSON encoding described in this document are
   designed to avoid such errors.  Length encodings are only used to
   define the length of x-value constructions which are always terminal
   and cannot have nested data entries.

11.  IANA Considerations

   [TBS list out all the code points that require an IANA registration]

12.  Normative References

   [draft-hallambaker-udf]
              Hallam-Baker, P., "Uniform Data Fingerprint (UDF)", Work
              in Progress, Internet-Draft, draft-hallambaker-udf-12, 6
              January 2019, <https://datatracker.ietf.org/doc/html/
              draft-hallambaker-udf-12>.

   [IEEE754]  IEEE Computer Society, "IEEE Standard for Floating-Point
              Arithmetic", IEEE 754-2008,
              DOI 10.1109/IEEESTD.2008.4610935, 29 August 2008,
              <https://doi.org/10.1109/IEEESTD.2008.4610935>.

   [INTEL]    Intel Corp., "Unknown".

   [RFC3339]  Klyne, G. and C. Newman, "Date and Time on the Internet:
              Timestamps", RFC 3339, DOI 10.17487/RFC3339, July 2002,
              <https://www.rfc-editor.org/rfc/rfc3339>.

   [RFC4648]  Josefsson, S., "The Base16, Base32, and Base64 Data
              Encodings", RFC 4648, DOI 10.17487/RFC4648, October 2006,
              <https://www.rfc-editor.org/rfc/rfc4648>.






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   [RFC7159]  Bray, T., "The JavaScript Object Notation (JSON) Data
              Interchange Format", RFC 7159, DOI 10.17487/RFC7159, March
              2014, <https://www.rfc-editor.org/rfc/rfc7159>.

13.  Informative References

   [draft-hallambaker-mesh-architecture]
              Hallam-Baker, P., "Mathematical Mesh 3.0 Part I:
              Architecture Guide", Work in Progress, Internet-Draft,
              draft-hallambaker-mesh-architecture-21, 23 October 2022,
              <https://datatracker.ietf.org/doc/html/draft-hallambaker-
              mesh-architecture-21>.







































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