JavaScript Object Notation (JSON) Text Sequences

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Author Nicol├ís Williams 
Last updated 2014-04-28
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json                                                         N. Williams
Internet-Draft                                              Cryptonector
Intended status: Standards Track                          April 28, 2014
Expires: October 30, 2014

            JavaScript Object Notation (JSON) Text Sequences


   This document describes the JSON text sequence format and associated
   media type.

Status of this Memo

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

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   This Internet-Draft will expire on October 30, 2014.

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Table of Contents

   1.    Introduction and Motivation . . . . . . . . . . . . . . . . . 3
   1.1.  Conventions used in this document . . . . . . . . . . . . . . 3
   2.    JSON Text Sequence Format . . . . . . . . . . . . . . . . . . 4
   3.    Security Considerations . . . . . . . . . . . . . . . . . . . 5
   4.    IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
   5.    Normative References  . . . . . . . . . . . . . . . . . . . . 7
         Author's Address  . . . . . . . . . . . . . . . . . . . . . . 8

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1.  Introduction and Motivation

   The JavaScript Object Notation (JSON) [RFC7159] is a very handy
   serialization format.  However, when serializing a large sequence of
   values as an array, or a possibly indeterminate-length or never-
   ending sequence of values, JSON becomes difficult to work with.

   Consider a sequence of one million values, each possibly 1 kilobyte
   when encoded, which would be roughly one gigabyte.  If processing
   such a dataset requires first parsing it entirely, then the result is
   very inefficient and the processing will be limited by virtual
   memory.  "Online" (a.k.a., "streaming") parsers help, but they are
   neither widely available or widely used, nor are they easy to use.

   Ideally such datasets could be parsed and processed one element at a
   time.  Even if each element must be parsed in a not-online manner due
   to local choice of parser, the result will usually be sufficiently
   online: limited by the size of the biggest element in the sequence
   rather than by the size of the sequence.

   This document describes the concept and format of "JSON text
   sequences", which are specifically not JSON texts themselves but are
   composed of JSON texts.

1.1.  Conventions used in this document

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   document are to be interpreted as described in [RFC2119].

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2.  JSON Text Sequence Format

   The ABNF [RFC5234] for the JSON text sequence format is as follows:

     JSON-sequence = *(JSON-text 1*(ws))
     ws = %x20 / %x09 / %x0A / %x0D
     JSON-text = <given by RFC7159>

                     Figure 1: JSON text sequence ABNF

   A JSON text sequence is a sequence of JSON texts, each followed by
   JSON whitespace (see the 'ws' rule in the JSON ABNF) separator.


   o  JSON text sequence encoders MUST emit one or more JSON whitespace
      separator characters immediately after any JSON text.

   o  JSON text sequence parsers MUST NOT interpret any sequence of two
      or more contiguous whitespace as a sequence of empty JSON texts.
      Two contiguous separators do not denote an empty JSON text between
      them as there is no such thing as an empty JSON text.

   An input of 'truefalse' is not a valid sequence of two JSON values,
   true and false!  Neither is 'true0' a valid sequence of true and
   zero.  Some existing JSON parsers that might be used to construct
   sequence parsers might in fact accept such sequences, erroneous
   parsing when of sequences of two or more numbers.  E.g., a sequence
   of two numbers, 4 and 2, encoded without the required whitespace
   between them would parse incorrectly as the number 42.  This
   ambiguity is resolved by requiring that encoders never omit the

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3.  Security Considerations

   All the security considerations of JSON [RFC7159] apply.

   There is no end of sequence indicator.  This means that "end of
   file", "end of transmission", and so on, can be indistinguishable
   form a logical end of sequence.  Applications where this matters
   should denote end of sequence by convention (e.g., Content-Length in

   JSON text sequence parsers based on non-incremental, non-online JSON
   text parsers will not be able to efficiently parser JSON texts in
   which newlines appear; attempting to parse such sequences with non-
   incremental, non-online JSON text parsers creates a compute resource
   exhaustion vulnerability.

   The first requirement given in Section 2 (otherwise-ambiguous JSON
   texts must be separated by whitespace) is critical and must be
   adhered to.  It is best to always emit a whitespace separator after
   every JSON text emitted.

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4.  IANA Considerations

   The MIME media type for JSON text sequences is application/json-seq.

   Type name: application

   Subtype name: json-seq

   Required parameters: n/a

   Optional parameters: n/a

   Encoding considerations: binary

   Security considerations: See <this document, once published>,
   Section 3.

   Interoperability considerations: Described herein.

   Published specification: <this document, once published>.

   Applications that use this media type: JSON text sequences have been
   used in applications written with the jq programming language.

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5.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC5234]  Crocker, D. and P. Overell, "Augmented BNF for Syntax
              Specifications: ABNF", STD 68, RFC 5234, January 2008.

   [RFC7159]  Bray, T., "The JavaScript Object Notation (JSON) Data
              Interchange Format", RFC 7159, March 2014.

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Author's Address

   Nicolas Williams
   Cryptonector, LLC


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