This is a purely informative rendering of an RFC that includes verified errata. This rendering may not be used as a reference.

The following 'Verified' errata have been incorporated in this document: EID 5860
Internet Engineering Task Force (IETF)                       N. Williams
Request for Comments: 7464                                  Cryptonector
Category: Standards Track                                  February 2015
ISSN: 2070-1721

            JavaScript Object Notation (JSON) Text Sequences


   This document describes the JavaScript Object Notation (JSON) text
   sequence format and associated media type "application/json-seq".  A
   JSON text sequence consists of any number of JSON texts, all encoded
   in UTF-8, each prefixed by an ASCII Record Separator (0x1E), and each
   ending with an ASCII Line Feed character (0x0A).

Status of This Memo

   This is an Internet Standards Track document.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Further information on
   Internet Standards is available in Section 2 of RFC 5741.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at

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   document authors.  All rights reserved.

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   described in the Simplified BSD License.

Table of Contents

   1. Introduction and Motivation .....................................2
      1.1. Conventions Used in This Document ..........................2
   2. JSON Text Sequence Format .......................................3
      2.1. JSON Text Sequence Parsing .................................3
      2.2. JSON Text Sequence Encoding ................................4
      2.3. Incomplete/Invalid JSON Texts Need Not Be Fatal ............4
      2.4. Top-Level Values: numbers, true, false, and null ...........5
   3. Security Considerations .........................................6
   4. IANA Considerations .............................................6
   5. Normative References ............................................7
   Acknowledgements ...................................................8
   Author's Address ...................................................8

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 one kilobyte
   when encoded -- roughly one gigabyte.  It is often desirable to
   process such a dataset in an incremental manner without having to
   first read all of it before beginning to produce results.
   Traditionally, the way to do this with JSON is to use a "streaming"
   parser, but these are not widely available, widely used, or easy to

   This document describes the concept and format of "JSON text
   sequences", which are specifically not JSON texts themselves but are
   composed of (possible) JSON texts.  JSON text sequences can be parsed
   (and produced) incrementally without having to have a streaming
   parser (nor streaming encoder).

1.1.  Conventions Used in This Document

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "OPTIONAL" in this document are to be interpreted as described in

2.  JSON Text Sequence Format

   Two different sets of ABNF rules are provided for the definition of
   JSON text sequences: one for parsers and one for encoders.  Having
   two different sets of rules permits recovery by parsers from
   sequences where some of the elements are truncated for whatever
   reason.  The syntax for parsers is specified in terms of octet
   strings that are then interpreted as JSON texts, if possible.  The
   syntax for encoders, on the other hand, assumes that sequence
   elements are not truncated.

   JSON text sequences MUST use UTF-8 encoding; other encodings of JSON
   (i.e., UTF-16 and UTF-32) MUST NOT be used.

2.1.  JSON Text Sequence Parsing

   The ABNF [RFC5234] for the JSON text sequence parser is as given in
   Figure 1.

      input-JSON-sequence = *(1*RS possible-JSON)
      RS = %x1E; "record separator" (RS), see RFC 20
               ; Also known as: Unicode Character INFORMATION SEPARATOR
               ;                TWO (U+001E)
      possible-JSON = 1*(not-RS); attempt to parse as UTF-8-encoded
                                ; JSON text (see RFC 7159)
      not-RS = %x00-1d / %x1f-ff; any octets other than RS

                     Figure 1: JSON Text Sequence ABNF

   In prose: a series of octet strings, each containing any octet other
   than a record separator (RS) (0x1E) [RFC20].  All octet strings are
   preceded by an RS byte.  Each octet string in the sequence is to be
   parsed as a JSON text in the UTF-8 encoding [RFC3629].

   If parsing of such an octet string as a UTF-8-encoded JSON text
   fails, the parser SHOULD nonetheless continue parsing the remainder
   of the sequence.  The parser can report such failures to
   applications, which might then choose to terminate parsing of a
   sequence.  Multiple consecutive RS octets do not denote empty
   sequence elements between them and can be ignored.

   This document does not define a mechanism for reliably identifying
   text sequence by position (for example, when sending individual
   elements of an array as unique text sequences).  For applications
   where truncation is a possibility, this means that intended sequence
   elements can be truncated and can even be missing entirely;
   therefore, a reference to an nth element would be unreliable.

   There is no end of sequence indicator.

2.2.  JSON Text Sequence Encoding

   The ABNF for the JSON text sequence encoder is given in Figure 2.

      JSON-sequence = *(RS JSON-text LF)
      RS = %x1E; see RFC 20
               ; Also known as: Unicode Character INFORMATION SEPARATOR
               ;                TWO (U+001E)
      LF = %x0A; "line feed" (LF), see RFC 20
      JSON-text = <given by RFC 7159, using UTF-8 encoding>

                     Figure 2: JSON Text Sequence ABNF

   In prose: any number of JSON texts, each encoded in UTF-8 [RFC3629],
   each preceded by one ASCII RS character, and each followed by a line
   feed (LF).  Since RS is an ASCII control character, it may only
   appear in JSON strings in escaped form (see [RFC7159]), and since RS
   may not appear in JSON texts in any other form, RS unambiguously
   delimits the start of any element in the sequence.  RS is sufficient
   to unambiguously delimit all top-level JSON value types other than
   numbers.  Following each JSON text in the sequence with an LF allows
   detection of truncated JSON texts consisting of a number at the top-
   level; see Section 2.4.

   JSON text sequence encoders are expected to ensure that the sequence
   elements are properly formed.  When the JSON text sequence encoder
   does the JSON text encoding, the sequence elements will naturally be
   properly formed.  When the JSON text sequence encoder accepts
   already-encoded JSON texts, the JSON text sequence encoder ought to
   parse them before adding them to a sequence.

      Note that on some systems it's possible to input RS by typing 

EID 5860 (Verified) is as follows:

Section: 2.2

Original Text:

   Note that on some systems it"s possible to input RS by typing

Corrected Text:

   Note that on some systems it's possible to input RS by typing
The contraction "it's" needs a single apostrophe, not a double-quote mark.
"ctrl-^"; on some system or applications, the correct sequence may be "ctrl-v ctrl-^". This is helpful when constructing a sequence manually with a text editor. 2.3. Incomplete/Invalid JSON Texts Need Not Be Fatal Per Section 2.1, JSON text sequence parsers should not abort when an octet string contains a malformed JSON text. Instead, the JSON text sequence parser should skip to the next RS. Such a situation may arise in contexts where, for example, data that is appended to log files to log files is truncated by the filesystem (e.g., due to a crash or administrative process termination). Incremental JSON text parsers may be used, though of course failure to parse a given text may result after first producing some incremental parse results. Sequence parsers should have an option to warn about truncated JSON texts. 2.4. Top-Level Values: numbers, true, false, and null While objects, arrays, and strings are self-delimited in JSON texts, numbers and the values 'true', 'false', and 'null' are not. Only whitespace can delimit the latter four kinds of values. JSON text sequences use 0x0A as a "canary" octet to detect truncation. Parsers MUST check that any JSON texts that are a top-level number, or that might be 'true', 'false', or 'null', include JSON whitespace (at least one byte matching the "ws" ABNF rule from [RFC7159]) after that value; otherwise, the JSON-text may have been truncated. Note that the LF following each JSON text matches the "ws" ABNF rule. Parsers MUST drop JSON-text sequence elements consisting of non-self- delimited top-level values that may have been truncated (that are not delimited by whitespace). Parsers can report such texts as warnings (including, optionally, the parsed text and/or the original octet string). For example, '<RS>123<RS>' might have been intended to carry the top- level number 1234, but it got truncated. Similarly, '<RS>true<RS>' might have been intended to carry the invalid text 'trueish'. '<RS>truefalse<RS>' is not two top-level values, 'true', and 'false'; it is simply not a valid JSON text. Implementations may produce a value when parsing '<RS>"foo"<RS>' because their JSON text parser might be able to consume bytes incrementally; since the JSON text in this case is a self-delimiting top-level value, the parser can produce the result without consuming an additional byte. Such implementations ought to skip to the next RS byte, possibly reporting any intervening non-whitespace bytes. Detection of truncation of non-self-delimited sequence elements (numbers, true, false, and null) is only possible when the sequence encoder produces or receives complete JSON texts. Implementations where the sequence encoder is not also in charge of encoding the individual JSON texts should ensure that those JSON texts are complete. 3. Security Considerations All the security considerations of JSON [RFC7159] apply. This format provides no cryptographic integrity protection of any kind. As usual, parsers must operate on input that is assumed to be untrusted. This means that parsers must fail gracefully in the face of malicious inputs. Note that incremental JSON text parsers can produce partial results and later indicate failure to parse the remainder of a text. A sequence parser that uses an incremental JSON text parser might treat a sequence like '<RS>"foo"<LF>456<LF><RS>' as a sequence of one element ("foo"), while a sequence parser that uses a non-incremental JSON text parser might treat the same sequence as being empty. This effect, and texts that fail to parse and are ignored, can be used to smuggle data past sequence parsers that don't warn about JSON text failures. Repeated parsing and re-encoding of a JSON text sequence can result in the addition (or stripping) of trailing LF bytes from (to) individual sequence element JSON texts. This can break signature validation. JSON has no canonical form for JSON texts, therefore neither does the JSON text sequence format. 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 RFC 7464, Section 3. Interoperability considerations: Described herein. Published specification: RFC 7464. Applications that use this media type: <> <> <> Fragment identifier considerations: N/A Additional information: o Deprecated alias names for this type: N/A o Magic number(s): N/A o File extension(s): N/A o Macintosh file type code(s): N/A Person & email address to contact for further information: Intended usage: COMMON Author: Nicolas Williams ( Change controller: IETF 5. Normative References [RFC20] Cerf, V., "ASCII format for network interchange", STD 80, RFC 20, October 1969, <>. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997, <>. [RFC3629] Yergeau, F., "UTF-8, a transformation format of ISO 10646", STD 63, RFC 3629, November 2003, <>. [RFC5234] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax Specifications: ABNF", STD 68, RFC 5234, January 2008, <>. [RFC7159] Bray, T., Ed., "The JavaScript Object Notation (JSON) Data Interchange Format", RFC 7159, March 2014, <>. Acknowledgements Phillip Hallam-Baker proposed the use of JSON text sequences for logfiles and pointed out the need for resynchronization. Stephen Dolan created <>, which uses something like JSON text sequences (with LF as the separator between texts on output, and requiring only such whitespace as needed to disambiguate on input). Carsten Bormann suggested the use of ASCII RS, and Joe Hildebrand suggested the use of LF in addition to RS for disambiguating top-level number values. Paul Hoffman shepherded the document. Many others contributed reviews and comments on the JSON Working Group mailing list. Author's Address Nicolas Williams Cryptonector, LLC EMail: