Confronta il testo

Trova la differenza tra due file di testo

Editor live

Comprimi invariate

Senza a capo

Layout

Livello di dettaglio

Evidenziazione sintassi

Diffchecker Desktop Il modo più sicuro per usare Diffchecker. Ottieni l'app Diffchecker Desktop: i tuoi diff non lasciano mai il tuo computer!Ottieni Desktop

RFC 7159 and RFC 8259

Creato 6 anni faIl diff non scade mai

275 rimozioni

Linee
Totale
Rimosso

Caratteri
Totale
Rimosso

Per continuare a utilizzare questa funzione, aggiorna a Diffchecker Pro Visualizza prezzi

761 linee

307 aggiunte

Linee
Totale
Aggiunto

Caratteri
Totale
Aggiunto

Per continuare a utilizzare questa funzione, aggiorna a Diffchecker Pro Visualizza prezzi

810 linee

Internet Engineering Task Force (IETF) T. Bray, Ed.

Request for Comments: 8259 Textuality

Request for Comments: 7159 Google, Inc.

Obsoletes: 7159 December 2017

Obsoletes: 4627, 7158 March 2014

Category: Standards Track

ISSN: 2070-1721

The JavaScript Object Notation (JSON) Data Interchange Format

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 removes inconsistencies with other specifications of

JSON, repairs specification errors, and offers experience-based

interoperability guidance.

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 7841.

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

https://www.rfc-editor.org/info/rfc8259.

http://www.rfc-editor.org/info/rfc7159.

Bray Standards Track [Page 1]

RFC 8259 JSON December 2017

RFC 7159 JSON March 2014

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

(http://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 and restrictions with respect

to this document. Code Components extracted from this document must

include Simplified BSD License text as described in Section 4.e of

the Trust Legal Provisions and are provided without warranty as

described in the Simplified BSD License.

This document may contain material from IETF Documents or IETF

Contributions published or made publicly available before November

10, 2008. The person(s) controlling the copyright in some of this

material may not have granted the IETF Trust the right to allow

modifications of such material outside the IETF Standards Process.

Without obtaining an adequate license from the person(s) controlling

the copyright in such materials, this document may not be modified

outside the IETF Standards Process, and derivative works of it may

not be created outside the IETF Standards Process, except to format

it for publication as an RFC or to translate it into languages other

than English.

Bray Standards Track [Page 2]

RFC 8259 JSON December 2017

RFC 7159 JSON March 2014

Table of Contents

1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3

1. Introduction ....................................................3

1.1. Conventions Used in This Document . . . . . . . . . . . . 4

1.1. Conventions Used in This Document ..........................4

1.2. Specifications of JSON . . . . . . . . . . . . . . . . . 4

1.2. Specifications of JSON .....................................4

1.3. Introduction to This Revision . . . . . . . . . . . . . . 5

1.3. Introduction to This Revision ..............................4

2. JSON Grammar . . . . . . . . . . . . . . . . . . . . . . . . 5

2. JSON Grammar ....................................................4

3. Values . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

3. Values ..........................................................5

4. Objects . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

4. Objects .........................................................6

5. Arrays . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

5. Arrays ..........................................................6

6. Numbers . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

6. Numbers .........................................................6

7. Strings . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

7. Strings .........................................................8

8. String and Character Issues . . . . . . . . . . . . . . . . . 9

8. String and Character Issues .....................................9

8.1. Character Encoding . . . . . . . . . . . . . . . . . . . 9

8.1. Character Encoding .........................................9

8.2. Unicode Characters . . . . . . . . . . . . . . . . . . . 10

8.2. Unicode Characters .........................................9

8.3. String Comparison . . . . . . . . . . . . . . . . . . . . 10

8.3. String Comparison ..........................................9

9. Parsers . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

9. Parsers ........................................................10

10. Generators . . . . . . . . . . . . . . . . . . . . . . . . . 10

10. Generators ....................................................10

11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11

11. IANA Considerations ...........................................10

12. Security Considerations . . . . . . . . . . . . . . . . . . . 12

12. Security Considerations .......................................11

13. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . 12

13. Examples ......................................................12

14. References . . . . . . . . . . . . . . . . . . . . . . . . . 14

14. Contributors ..................................................13

14.1. Normative References . . . . . . . . . . . . . . . . . . 14

15. References ....................................................13

14.2. Informative References . . . . . . . . . . . . . . . . . 14

15.1. Normative References .....................................13

Appendix A. Changes from RFC 7159 . . . . . . . . . . . . . . . 16

15.2. Informative References ...................................13

Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Appendix A. Changes from RFC 4627 .................................15

Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 16

1. Introduction

JavaScript Object Notation (JSON) is a text format for the

serialization of structured data. It is derived from the object

literals of JavaScript, as defined in the ECMAScript Programming

Language Standard, Third Edition [ECMA-262].

JSON can represent four primitive types (strings, numbers, booleans,

and null) and two structured types (objects and arrays).

A string is a sequence of zero or more Unicode characters [UNICODE].

Note that this citation references the latest version of Unicode

rather than a specific release. It is not expected that future

changes in the Unicode specification will impact the syntax of JSON.

changes in the UNICODE specification will impact the syntax of JSON.

An object is an unordered collection of zero or more name/value

pairs, where a name is a string and a value is a string, number,

boolean, null, object, or array.

An array is an ordered sequence of zero or more values.

Bray Standards Track [Page 3]

RFC 8259 JSON December 2017

RFC 7159 JSON March 2014

The terms "object" and "array" come from the conventions of

JavaScript.

JSON's design goals were for it to be minimal, portable, textual, and

a subset of JavaScript.

1.1. Conventions Used in This Document

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",

"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and

"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this

"OPTIONAL" in this document are to be interpreted as described in BCP

document are to be interpreted as described in [RFC2119].

14 [RFC2119] [RFC8174] when, and only when, they appear in all

capitals, as shown here.

The grammatical rules in this document are to be interpreted as

described in [RFC5234].

1.2. Specifications of JSON

This document replaces [RFC7159]. [RFC7159] obsoleted [RFC4627],

This document updates [RFC4627], which describes JSON and registers

which originally described JSON and registered the media type

the media type "application/json".

"application/json".

JSON is also described in [ECMA-404].

The reference to ECMA-404 in the previous sentence is normative, not

with the usual meaning that implementors need to consult it in order

to understand this document, but to emphasize that there are no

inconsistencies in the definition of the term "JSON text" in any of

its specifications. Note, however, that ECMA-404 allows several

practices that this specification recommends avoiding in the

interests of maximal interoperability.

The intent is that the grammar is the same between the two documents,

although different descriptions are used. If there is a difference

found between them, ECMA and the IETF will work together to update

both documents.

If an error is found with either document, the other should be

examined to see if it has a similar error; if it does, it should be

fixed, if possible.

If either document is changed in the future, ECMA and the IETF will

work together to ensure that the two documents stay aligned through

the change.

Text moved to lines 388-392

Bray Standards Track [Page 4]

A description of JSON in ECMAScript terms appears in Version 5.1 of

the ECMAScript specification [ECMA-262], Section 15.12. JSON is also

RFC 8259 JSON December 2017

described in [ECMA-404].

All of the specifications of JSON syntax agree on the syntactic

elements of the language.

1.3. Introduction to This Revision

In the years since the publication of RFC 4627, JSON has found very

wide use. This experience has revealed certain patterns that, while

wide use. This experience has revealed certain patterns, which,

allowed by its specifications, have caused interoperability problems.

while allowed by its specifications, have caused interoperability

problems.

Also, a small number of errata have been reported regarding RFC 4627

Also, a small number of errata have been reported (see RFC Errata IDs

(see RFC Errata IDs 607 [Err607] and 3607 [Err3607]) and regarding

607 [Err607] and 3607 [Err3607]).

RFC 7159 (see RFC Errata IDs 3915 [Err3915], 4264 [Err4264], 4336

[Err4336], and 4388 [Err4388]).

This document's goal is to apply the errata, remove inconsistencies

with other specifications of JSON, and highlight practices that can

lead to interoperability problems.

2. JSON Grammar

A JSON text is a sequence of tokens. The set of tokens includes six

structural characters, strings, numbers, and three literal names.

A JSON text is a serialized value. Note that certain previous

specifications of JSON constrained a JSON text to be an object or an

Text moved with changes from lines 447-454 (95.4% similarity)

Bray Standards Track [Page 4]

RFC 7159 JSON March 2014

array. Implementations that generate only objects or arrays where a

JSON text is called for will be interoperable in the sense that all

implementations will accept these as conforming JSON texts.

JSON-text = ws value ws

These are the six structural characters:

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

name-separator = ws %x3A ws ; : colon

value-separator = ws %x2C ws ; , comma

Text moved with changes to lines 555-566 (94.6% similarity)

Bray Standards Track [Page 5]

RFC 8259 JSON December 2017

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

3. Values

A JSON value MUST be an object, array, number, or string, or one of

the following three literal names:

false

false null true

null

true

The literal names MUST be lowercase. No other literal names are

allowed.

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

false = %x66.61.6c.73.65 ; false

null = %x6e.75.6c.6c ; null

true = %x74.72.75.65 ; true

Text moved with changes from lines 558-566 (95.1% similarity)

Bray Standards Track [Page 5]

RFC 7159 JSON March 2014

4. Objects

An object structure is represented as a pair of curly brackets

surrounding zero or more name/value pairs (or members). A name is a

string. A single colon comes after each name, separating the name

from the value. A single comma separates a value from a following

name. The names within an object SHOULD be unique.

object = begin-object [ member *( value-separator member ) ]

end-object

member = string name-separator value

An object whose names are all unique is interoperable in the sense

that all software implementations receiving that object will agree on

the name-value mappings. When the names within an object are not

unique, the behavior of software that receives such an object is

unpredictable. Many implementations report the last name/value pair

only. Other implementations report an error or fail to parse the

Text moved with changes to lines 670-678 (95.4% similarity)

Bray Standards Track [Page 6]

RFC 8259 JSON December 2017

object, and some implementations report all of the name/value pairs,

including duplicates.

JSON parsing libraries have been observed to differ as to whether or

not they make the ordering of object members visible to calling

software. Implementations whose behavior does not depend on member

ordering will be interoperable in the sense that they will not be

affected by these differences.

5. Arrays

An array structure is represented as square brackets surrounding zero

or more values (or elements). Elements are separated by commas.

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

There is no requirement that the values in an array be of the same

type.

6. Numbers

The representation of numbers is similar to that used in most

programming languages. A number is represented in base 10 using

decimal digits. It contains an integer component that may be

prefixed with an optional minus sign, which may be followed by a

fraction part and/or an exponent part. Leading zeros are not

allowed.

A fraction part is a decimal point followed by one or more digits.

An exponent part begins with the letter E in uppercase or lowercase,

Bray Standards Track [Page 6]

RFC 7159 JSON March 2014

An exponent part begins with the letter E in upper or lower case,

which may be followed by a plus or minus sign. The E and optional

sign are followed by one or more digits.

Numeric values that cannot be represented in the grammar below (such

as Infinity and NaN) are not permitted.

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

Text moved with changes to lines 448-454 (95.7% similarity)

Bray Standards Track [Page 7]

RFC 8259 JSON December 2017

int = zero / ( digit1-9 *DIGIT )

minus = %x2D ; -

plus = %x2B ; +

zero = %x30 ; 0

This specification allows implementations to set limits on the range

and precision of numbers accepted. Since software that implements

IEEE 754 binary64 (double precision) numbers [IEEE754] is generally

IEEE 754-2008 binary64 (double precision) numbers [IEEE754] is

available and widely used, good interoperability can be achieved by

generally available and widely used, good interoperability can be

implementations that expect no more precision or range than these

achieved by implementations that expect no more precision or range

provide, in the sense that implementations will approximate JSON

than these provide, in the sense that implementations will

numbers within the expected precision. A JSON number such as 1E400

approximate JSON numbers within the expected precision. A JSON

or 3.141592653589793238462643383279 may indicate potential

number such as 1E400 or 3.141592653589793238462643383279 may indicate

interoperability problems, since it suggests that the software that

potential interoperability problems, since it suggests that the

created it expects receiving software to have greater capabilities

software that created it expects receiving software to have greater

for numeric magnitude and precision than is widely available.

capabilities for numeric magnitude and precision than is widely

available.

Note that when such software is used, numbers that are integers and

are in the range [-(2**53)+1, (2**53)-1] are interoperable in the

sense that implementations will agree exactly on their numeric

values.

Text moved from lines 220-224

Bray Standards Track [Page 7]

RFC 7159 JSON March 2014

7. Strings

The representation of strings is similar to conventions used in the C

family of programming languages. A string begins and ends with

quotation marks. All Unicode characters may be placed within the

quotation marks, except for the characters that MUST be escaped:

quotation marks, except for the characters that must be escaped:

quotation mark, reverse solidus, and the control characters (U+0000

through U+001F).

Any character may be escaped. If the character is in the Basic

Multilingual Plane (U+0000 through U+FFFF), then it may be

represented as a six-character sequence: a reverse solidus, followed

by the lowercase letter u, followed by four hexadecimal digits that

encode the character's code point. The hexadecimal letters A through

encode the character's code point. The hexadecimal letters A though

F can be uppercase or lowercase. So, for example, a string

F can be upper or lower case. So, for example, a string containing

containing only a single reverse solidus character may be represented

only a single reverse solidus character may be represented as

as "\u005C".

"\u005C".

Alternatively, there are two-character sequence escape

representations of some popular characters. So, for example, a

string containing only a single reverse solidus character may be

represented more compactly as "\\".

Text moved with changes to lines 223-230 (95.4% similarity)

Bray Standards Track [Page 8]

RFC 8259 JSON December 2017

To escape an extended character that is not in the Basic Multilingual

Plane, the character is represented as a 12-character sequence,

encoding the UTF-16 surrogate pair. So, for example, a string

containing only the G clef character (U+1D11E) may be represented as

"\uD834\uDD1E".

string = quotation-mark *char quotation-mark

char = unescaped /

escape (

%x22 / ; " quotation mark U+0022

%x5C / ; \ reverse solidus U+005C

%x2F / ; / solidus U+002F

%x62 / ; b backspace U+0008

%x66 / ; f form feed U+000C

%x6E / ; n line feed U+000A

%x72 / ; r carriage return U+000D

%x74 / ; t tab U+0009

%x75 4HEXDIG ) ; uXXXX U+XXXX

escape = %x5C ; \

quotation-mark = %x22 ; "

unescaped = %x20-21 / %x23-5B / %x5D-10FFFF

Text moved with changes from lines 392-398 (95.7% similarity)

Bray Standards Track [Page 8]

RFC 7159 JSON March 2014

8. String and Character Issues

8.1. Character Encoding

JSON text exchanged between systems that are not part of a closed

JSON text SHALL be encoded in UTF-8, UTF-16, or UTF-32. The default

ecosystem MUST be encoded using UTF-8 [RFC3629].

encoding is UTF-8, and JSON texts that are encoded in UTF-8 are

interoperable in the sense that they will be read successfully by the

Previous specifications of JSON have not required the use of UTF-8

maximum number of implementations; there are many implementations

when transmitting JSON text. However, the vast majority of JSON-

that cannot successfully read texts in other encodings (such as

based software implementations have chosen to use the UTF-8 encoding,

UTF-16 and UTF-32).

to the extent that it is the only encoding that achieves

interoperability.

Implementations MUST NOT add a byte order mark (U+FEFF) to the

beginning of a networked-transmitted JSON text. In the interests of

interoperability, implementations that parse JSON texts MAY ignore

the presence of a byte order mark rather than treating it as an

error.

Text moved to lines 758-764

Bray Standards Track [Page 9]

RFC 8259 JSON December 2017

Implementations MUST NOT add a byte order mark to the beginning of a

JSON text. In the interests of interoperability, implementations

that parse JSON texts MAY ignore the presence of a byte order mark

rather than treating it as an error.

8.2. Unicode Characters

When all the strings represented in a JSON text are composed entirely

of Unicode characters [UNICODE] (however escaped), then that JSON

text is interoperable in the sense that all software implementations

that parse it will agree on the contents of names and of string

values in objects and arrays.

However, the ABNF in this specification allows member names and

string values to contain bit sequences that cannot encode Unicode

characters; for example, "\uDEAD" (a single unpaired UTF-16

surrogate). Instances of this have been observed, for example, when

a library truncates a UTF-16 string without checking whether the

truncation split a surrogate pair. The behavior of software that

receives JSON texts containing such values is unpredictable; for

example, implementations might return different values for the length

of a string value or even suffer fatal runtime exceptions.

8.3. String Comparison

Software implementations are typically required to test names of

object members for equality. Implementations that transform the

textual representation into sequences of Unicode code units and then

perform the comparison numerically, code unit by code unit, are

interoperable in the sense that implementations will agree in all

cases on equality or inequality of two strings. For example,

implementations that compare strings with escaped characters

unconverted may incorrectly find that "a\\b" and "a\u005Cb" are not

equal.

Text moved with changes from lines 615-622 (94.5% similarity)

Bray Standards Track [Page 9]

RFC 7159 JSON March 2014

9. Parsers

A JSON parser transforms a JSON text into another representation. A

JSON parser MUST accept all texts that conform to the JSON grammar.

A JSON parser MAY accept non-JSON forms or extensions.

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.

10. Generators

A JSON generator produces JSON text. The resulting text MUST

strictly conform to the JSON grammar.

Text moved with changes to lines 278-286 (95.1% similarity)

Bray Standards Track [Page 10]

RFC 8259 JSON December 2017

11. IANA Considerations

The media type for JSON text is application/json.

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

Type name: application

Subtype name: json

Required parameters: n/a

Optional parameters: n/a

Encoding considerations: binary

Security considerations: See RFC 8259, Section 12

Security considerations: See [RFC7159], Section 12.

Interoperability considerations: Described in RFC 8259

Interoperability considerations: Described in [RFC7159]

Published specification: RFC 8259

Published specification: [RFC7159]

Applications that use this media type:

JSON has been used to exchange data between applications written

in all of these programming languages: ActionScript, C, C#,

Clojure, ColdFusion, Common Lisp, E, Erlang, Go, Java, JavaScript,

Lua, Objective CAML, Perl, PHP, Python, Rebol, Ruby, Scala, and

Scheme.

Text moved with changes from lines 273-286 (94.6% similarity)

Bray Standards Track [Page 10]

RFC 7159 JSON March 2014

Additional information:

Magic number(s): n/a

File extension(s): .json

Macintosh file type code(s): TEXT

Person & email address to contact for further information:

IESG

<iesg@ietf.org>

Intended usage: COMMON

Restrictions on usage: none

Author:

Douglas Crockford

<douglas@crockford.com>

Change controller:

IESG

<iesg@ietf.org>

Text moved with changes to lines 501-510 (94.5% similarity)

Bray Standards Track [Page 11]

RFC 8259 JSON December 2017

Note: No "charset" parameter is defined for this registration.

Adding one really has no effect on compliant recipients.

12. Security Considerations

Generally, there are security issues with scripting languages. JSON

is a subset of JavaScript but excludes assignment and invocation.

Since JSON's syntax is borrowed from JavaScript, it is possible to

use that language's "eval()" function to parse most JSON texts (but

use that language's "eval()" function to parse JSON texts. This

not all; certain characters such as U+2028 LINE SEPARATOR and U+2029

PARAGRAPH SEPARATOR are legal in JSON but not JavaScript). This

generally constitutes an unacceptable security risk, since the text

could contain executable code along with data declarations. The same

consideration applies to the use of eval()-like functions in any

other programming language in which JSON texts conform to that

language's syntax.

Text moved with changes from lines 663-678 (94.5% similarity)

Bray Standards Track [Page 11]

RFC 7159 JSON March 2014

13. Examples

This is a JSON object:

{

"Image": {

"Width": 800,

"Height": 600,

"Title": "View from 15th Floor",

"Thumbnail": {

"Url": "http://www.example.com/image/481989943",

"Height": 125,

"Width": 100

"Animated" : false,

"IDs": [116, 943, 234, 38793]

}

Its Image member is an object whose Thumbnail member is an object and

whose IDs member is an array of numbers.

Text moved with changes to lines 604-622 (94.5% similarity)

Bray Standards Track [Page 12]

RFC 8259 JSON December 2017

This is a JSON array containing two objects:

[

{

"precision": "zip",

"Latitude": 37.7668,

"Longitude": -122.3959,

"Address": "",

"City": "SAN FRANCISCO",

"State": "CA",

"Zip": "94107",

"Country": "US"

{

"precision": "zip",

"Latitude": 37.371991,

"Longitude": -122.026020,

"Address": "",

"City": "SUNNYVALE",

"State": "CA",

"Zip": "94085",

"Country": "US"

}

]

Text moved with changes from lines 335-342 (95.4% similarity)

Bray Standards Track [Page 12]

RFC 7159 JSON March 2014

Here are three small JSON texts containing only values:

"Hello world!"

true

14. Contributors

RFC 4627 was written by Douglas Crockford. This document was

constructed by making a relatively small number of changes to that

document; thus, the vast majority of the text here is his.

15. References

15.1. Normative References

[IEEE754] IEEE, "IEEE Standard for Floating-Point Arithmetic", IEEE

Standard 754, August 2008,

<http://grouper.ieee.org/groups/754/>.

[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.

[UNICODE] The Unicode Consortium, "The Unicode Standard",

<http://www.unicode.org/versions/latest/>.

15.2. Informative References

[ECMA-262] Ecma International, "ECMAScript Language Specification

Edition 5.1", Standard ECMA-262, June 2011,

<http://www.ecma-international.org/publications/standards/

Ecma-262.htm>.

[ECMA-404] Ecma International, "The JSON Data Interchange Format",

Standard ECMA-404, October 2013,

<http://www.ecma-international.org/publications/standards/

Ecma-404.htm>.

[Err3607] RFC Errata, Errata ID 3607, RFC 3607,

<http://www.rfc-editor.org>.

Bray Standards Track [Page 13]

RFC 7159 JSON March 2014

[Err607] RFC Errata, Errata ID 607, RFC 607,

<http://www.rfc-editor.org>.

[RFC4627] Crockford, D., "The application/json Media Type for

JavaScript Object Notation (JSON)", RFC 4627, July 2006.

Text moved from lines 499-505

Bray Standards Track [Page 13]

Bray Standards Track [Page 14]

RFC 8259 JSON December 2017

RFC 7159 JSON March 2014

14. References

Appendix A. Changes from RFC 4627

14.1. Normative References

This section lists changes between this document and the text in RFC

4627.

[ECMA-404] Ecma International, "The JSON Data Interchange Format",

o Changed the title and abstract of the document.

Standard ECMA-404,

<http://www.ecma-international.org/publications/

standards/Ecma-404.htm>.

[IEEE754] IEEE, "IEEE Standard for Floating-Point Arithmetic",

o Changed the reference to [UNICODE] to be not version specific.

IEEE 754.

[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate

o Added a "Specifications of JSON" section.

Requirement Levels", BCP 14, RFC 2119,

DOI 10.17487/RFC2119, March 1997,

<https://www.rfc-editor.org/info/rfc2119>.

[RFC3629] Yergeau, F., "UTF-8, a transformation format of ISO

o Added an "Introduction to This Revision" section.

10646", STD 63, RFC 3629, DOI 10.17487/RFC3629, November

2003, <https://www.rfc-editor.org/info/rfc3629>.

[RFC5234] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax

o Changed the definition of "JSON text" so that it can be any JSON

Specifications: ABNF", STD 68, RFC 5234,

value, removing the constraint that it be an object or array.

DOI 10.17487/RFC5234, January 2008,

<https://www.rfc-editor.org/info/rfc5234>.

[RFC8174] Leiba, B., "Ambiguity

o Added language about duplicate object member names, member

ordering, and interoperability.

Diff salvati

Testo originale

Apri file

Internet Engineering Task Force (IETF)                      T. Bray, Ed.
Request for Comments: 8259                                    Textuality
Obsoletes: 7159                                            December 2017
Category: Standards Track
ISSN: 2070-1721

The JavaScript Object Notation (JSON) Data Interchange Format

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 removes inconsistencies with other specifications of
   JSON, repairs specification errors, and offers experience-based
   interoperability guidance.

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 7841.

Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   https://www.rfc-editor.org/info/rfc8259.

Bray                         Standards Track                    [Page 1]

RFC 8259                          JSON                     December 2017

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 and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

This document may contain material from IETF Documents or IETF
   Contributions published or made publicly available before November
   10, 2008.  The person(s) controlling the copyright in some of this
   material may not have granted the IETF Trust the right to allow
   modifications of such material outside the IETF Standards Process.
   Without obtaining an adequate license from the person(s) controlling
   the copyright in such materials, this document may not be modified
   outside the IETF Standards Process, and derivative works of it may
   not be created outside the IETF Standards Process, except to format
   it for publication as an RFC or to translate it into languages other
   than English.

Bray                         Standards Track                    [Page 2]

RFC 8259                          JSON                     December 2017

Table of Contents

1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.1.  Conventions Used in This Document . . . . . . . . . . . .   4
     1.2.  Specifications of JSON  . . . . . . . . . . . . . . . . .   4
     1.3.  Introduction to This Revision . . . . . . . . . . . . . .   5
   2.  JSON Grammar  . . . . . . . . . . . . . . . . . . . . . . . .   5
   3.  Values  . . . . . . . . . . . . . . . . . . . . . . . . . . .   6
   4.  Objects . . . . . . . . . . . . . . . . . . . . . . . . . . .   6
   5.  Arrays  . . . . . . . . . . . . . . . . . . . . . . . . . . .   7
   6.  Numbers . . . . . . . . . . . . . . . . . . . . . . . . . . .   7
   7.  Strings . . . . . . . . . . . . . . . . . . . . . . . . . . .   8
   8.  String and Character Issues . . . . . . . . . . . . . . . . .   9
     8.1.  Character Encoding  . . . . . . . . . . . . . . . . . . .   9
     8.2.  Unicode Characters  . . . . . . . . . . . . . . . . . . .  10
     8.3.  String Comparison . . . . . . . . . . . . . . . . . . . .  10
   9.  Parsers . . . . . . . . . . . . . . . . . . . . . . . . . . .  10
   10. Generators  . . . . . . . . . . . . . . . . . . . . . . . . .  10
   11. IANA Considerations . . . . . . . . . . . . . . . . . . . . .  11
   12. Security Considerations . . . . . . . . . . . . . . . . . . .  12
   13. Examples  . . . . . . . . . . . . . . . . . . . . . . . . . .  12
   14. References  . . . . . . . . . . . . . . . . . . . . . . . . .  14
     14.1.  Normative References . . . . . . . . . . . . . . . . . .  14
     14.2.  Informative References . . . . . . . . . . . . . . . . .  14
   Appendix A.  Changes from RFC 7159  . . . . . . . . . . . . . . .  16
   Contributors  . . . . . . . . . . . . . . . . . . . . . . . . . .  16
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .  16

1.  Introduction

JavaScript Object Notation (JSON) is a text format for the
   serialization of structured data.  It is derived from the object
   literals of JavaScript, as defined in the ECMAScript Programming
   Language Standard, Third Edition [ECMA-262].

JSON can represent four primitive types (strings, numbers, booleans,
   and null) and two structured types (objects and arrays).

A string is a sequence of zero or more Unicode characters [UNICODE].
   Note that this citation references the latest version of Unicode
   rather than a specific release.  It is not expected that future
   changes in the Unicode specification will impact the syntax of JSON.

An object is an unordered collection of zero or more name/value
   pairs, where a name is a string and a value is a string, number,
   boolean, null, object, or array.

An array is an ordered sequence of zero or more values.

Bray                         Standards Track                    [Page 3]

RFC 8259                          JSON                     December 2017

The terms "object" and "array" come from the conventions of
   JavaScript.

JSON's design goals were for it to be minimal, portable, textual, and
   a subset of JavaScript.

1.1.  Conventions Used in This Document

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in BCP
   14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

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

1.2.  Specifications of JSON

This document replaces [RFC7159].  [RFC7159] obsoleted [RFC4627],
   which originally described JSON and registered the media type
   "application/json".

JSON is also described in [ECMA-404].

The reference to ECMA-404 in the previous sentence is normative, not
   with the usual meaning that implementors need to consult it in order
   to understand this document, but to emphasize that there are no
   inconsistencies in the definition of the term "JSON text" in any of
   its specifications.  Note, however, that ECMA-404 allows several
   practices that this specification recommends avoiding in the
   interests of maximal interoperability.

The intent is that the grammar is the same between the two documents,
   although different descriptions are used.  If there is a difference
   found between them, ECMA and the IETF will work together to update
   both documents.

If an error is found with either document, the other should be
   examined to see if it has a similar error; if it does, it should be
   fixed, if possible.

If either document is changed in the future, ECMA and the IETF will
   work together to ensure that the two documents stay aligned through
   the change.

Bray                         Standards Track                    [Page 4]

RFC 8259                          JSON                     December 2017

1.3.  Introduction to This Revision

In the years since the publication of RFC 4627, JSON has found very
   wide use.  This experience has revealed certain patterns that, while
   allowed by its specifications, have caused interoperability problems.

Also, a small number of errata have been reported regarding RFC 4627
   (see RFC Errata IDs 607 [Err607] and 3607 [Err3607]) and regarding
   RFC 7159 (see RFC Errata IDs 3915 [Err3915], 4264 [Err4264], 4336
   [Err4336], and 4388 [Err4388]).

This document's goal is to apply the errata, remove inconsistencies
   with other specifications of JSON, and highlight practices that can
   lead to interoperability problems.

2.  JSON Grammar

A JSON text is a sequence of tokens.  The set of tokens includes six
   structural characters, strings, numbers, and three literal names.

A JSON text is a serialized value.  Note that certain previous
   specifications of JSON constrained a JSON text to be an object or an
   array.  Implementations that generate only objects or arrays where a
   JSON text is called for will be interoperable in the sense that all
   implementations will accept these as conforming JSON texts.

JSON-text = ws value ws

These are the six structural characters:

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

name-separator  = ws %x3A ws  ; : colon

value-separator = ws %x2C ws  ; , comma

Bray                         Standards Track                    [Page 5]

RFC 8259                          JSON                     December 2017

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

3.  Values

A JSON value MUST be an object, array, number, or string, or one of
   the following three literal names:

false
      null
      true

The literal names MUST be lowercase.  No other literal names are
   allowed.

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

false = %x66.61.6c.73.65   ; false

null  = %x6e.75.6c.6c      ; null

true  = %x74.72.75.65      ; true

4.  Objects

An object structure is represented as a pair of curly brackets
   surrounding zero or more name/value pairs (or members).  A name is a
   string.  A single colon comes after each name, separating the name
   from the value.  A single comma separates a value from a following
   name.  The names within an object SHOULD be unique.

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

member = string name-separator value

An object whose names are all unique is interoperable in the sense
   that all software implementations receiving that object will agree on
   the name-value mappings.  When the names within an object are not
   unique, the behavior of software that receives such an object is
   unpredictable.  Many implementations report the last name/value pair
   only.  Other implementations report an error or fail to parse the

Bray                         Standards Track                    [Page 6]

RFC 8259                          JSON                     December 2017

object, and some implementations report all of the name/value pairs,
   including duplicates.

JSON parsing libraries have been observed to differ as to whether or
   not they make the ordering of object members visible to calling
   software.  Implementations whose behavior does not depend on member
   ordering will be interoperable in the sense that they will not be
   affected by these differences.

5.  Arrays

An array structure is represented as square brackets surrounding zero
   or more values (or elements).  Elements are separated by commas.

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

There is no requirement that the values in an array be of the same
   type.

6.  Numbers

The representation of numbers is similar to that used in most
   programming languages.  A number is represented in base 10 using
   decimal digits.  It contains an integer component that may be
   prefixed with an optional minus sign, which may be followed by a
   fraction part and/or an exponent part.  Leading zeros are not
   allowed.

A fraction part is a decimal point followed by one or more digits.

An exponent part begins with the letter E in uppercase or lowercase,
   which may be followed by a plus or minus sign.  The E and optional
   sign are followed by one or more digits.

Numeric values that cannot be represented in the grammar below (such
   as Infinity and NaN) are not permitted.

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

Bray                         Standards Track                    [Page 7]

RFC 8259                          JSON                     December 2017

int = zero / ( digit1-9 *DIGIT )

minus = %x2D               ; -

plus = %x2B                ; +

zero = %x30                ; 0

This specification allows implementations to set limits on the range
   and precision of numbers accepted.  Since software that implements
   IEEE 754 binary64 (double precision) numbers [IEEE754] is generally
   available and widely used, good interoperability can be achieved by
   implementations that expect no more precision or range than these
   provide, in the sense that implementations will approximate JSON
   numbers within the expected precision.  A JSON number such as 1E400
   or 3.141592653589793238462643383279 may indicate potential
   interoperability problems, since it suggests that the software that
   created it expects receiving software to have greater capabilities
   for numeric magnitude and precision than is widely available.

Note that when such software is used, numbers that are integers and
   are in the range [-(2**53)+1, (2**53)-1] are interoperable in the
   sense that implementations will agree exactly on their numeric
   values.

7.  Strings

The representation of strings is similar to conventions used in the C
   family of programming languages.  A string begins and ends with
   quotation marks.  All Unicode characters may be placed within the
   quotation marks, except for the characters that MUST be escaped:
   quotation mark, reverse solidus, and the control characters (U+0000
   through U+001F).

Any character may be escaped.  If the character is in the Basic
   Multilingual Plane (U+0000 through U+FFFF), then it may be
   represented as a six-character sequence: a reverse solidus, followed
   by the lowercase letter u, followed by four hexadecimal digits that
   encode the character's code point.  The hexadecimal letters A through
   F can be uppercase or lowercase.  So, for example, a string
   containing only a single reverse solidus character may be represented
   as "\u005C".

Alternatively, there are two-character sequence escape
   representations of some popular characters.  So, for example, a
   string containing only a single reverse solidus character may be
   represented more compactly as "\\".

Bray                         Standards Track                    [Page 8]

RFC 8259                          JSON                     December 2017

To escape an extended character that is not in the Basic Multilingual
   Plane, the character is represented as a 12-character sequence,
   encoding the UTF-16 surrogate pair.  So, for example, a string
   containing only the G clef character (U+1D11E) may be represented as
   "\uD834\uDD1E".

string = quotation-mark *char quotation-mark

char = unescaped /
          escape (
              %x22 /          ; "    quotation mark  U+0022
              %x5C /          ; \    reverse solidus U+005C
              %x2F /          ; /    solidus         U+002F
              %x62 /          ; b    backspace       U+0008
              %x66 /          ; f    form feed       U+000C
              %x6E /          ; n    line feed       U+000A
              %x72 /          ; r    carriage return U+000D
              %x74 /          ; t    tab             U+0009
              %x75 4HEXDIG )  ; uXXXX                U+XXXX

escape = %x5C              ; \

quotation-mark = %x22      ; "

unescaped = %x20-21 / %x23-5B / %x5D-10FFFF

8.  String and Character Issues

8.1.  Character Encoding

JSON text exchanged between systems that are not part of a closed
   ecosystem MUST be encoded using UTF-8 [RFC3629].

Previous specifications of JSON have not required the use of UTF-8
   when transmitting JSON text.  However, the vast majority of JSON-
   based software implementations have chosen to use the UTF-8 encoding,
   to the extent that it is the only encoding that achieves
   interoperability.

Implementations MUST NOT add a byte order mark (U+FEFF) to the
   beginning of a networked-transmitted JSON text.  In the interests of
   interoperability, implementations that parse JSON texts MAY ignore
   the presence of a byte order mark rather than treating it as an
   error.

Bray                         Standards Track                    [Page 9]

RFC 8259                          JSON                     December 2017

8.2.  Unicode Characters

When all the strings represented in a JSON text are composed entirely
   of Unicode characters [UNICODE] (however escaped), then that JSON
   text is interoperable in the sense that all software implementations
   that parse it will agree on the contents of names and of string
   values in objects and arrays.

However, the ABNF in this specification allows member names and
   string values to contain bit sequences that cannot encode Unicode
   characters; for example, "\uDEAD" (a single unpaired UTF-16
   surrogate).  Instances of this have been observed, for example, when
   a library truncates a UTF-16 string without checking whether the
   truncation split a surrogate pair.  The behavior of software that
   receives JSON texts containing such values is unpredictable; for
   example, implementations might return different values for the length
   of a string value or even suffer fatal runtime exceptions.

8.3.  String Comparison

Software implementations are typically required to test names of
   object members for equality.  Implementations that transform the
   textual representation into sequences of Unicode code units and then
   perform the comparison numerically, code unit by code unit, are
   interoperable in the sense that implementations will agree in all
   cases on equality or inequality of two strings.  For example,
   implementations that compare strings with escaped characters
   unconverted may incorrectly find that "a\\b" and "a\u005Cb" are not
   equal.

9.  Parsers

A JSON parser transforms a JSON text into another representation.  A
   JSON parser MUST accept all texts that conform to the JSON grammar.
   A JSON parser MAY accept non-JSON forms or extensions.

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.

10.  Generators

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

Bray                         Standards Track                   [Page 10]

RFC 8259                          JSON                     December 2017

11.  IANA Considerations

The media type for JSON text is application/json.

Type name:  application

Subtype name:  json

Required parameters:  n/a

Optional parameters:  n/a

Encoding considerations:  binary

Security considerations:  See RFC 8259, Section 12

Interoperability considerations:  Described in RFC 8259

Published specification:  RFC 8259

Applications that use this media type:
      JSON has been used to exchange data between applications written
      in all of these programming languages: ActionScript, C, C#,
      Clojure, ColdFusion, Common Lisp, E, Erlang, Go, Java, JavaScript,
      Lua, Objective CAML, Perl, PHP, Python, Rebol, Ruby, Scala, and
      Scheme.

Additional information:
      Magic number(s): n/a
      File extension(s): .json
      Macintosh file type code(s): TEXT

Person & email address to contact for further information:
      IESG
      <iesg@ietf.org>

Intended usage:  COMMON

Restrictions on usage:  none

Author:
      Douglas Crockford
      <douglas@crockford.com>

Change controller:
      IESG
      <iesg@ietf.org>

Bray                         Standards Track                   [Page 11]

RFC 8259                          JSON                     December 2017

Note:  No "charset" parameter is defined for this registration.
      Adding one really has no effect on compliant recipients.

12.  Security Considerations

Generally, there are security issues with scripting languages.  JSON
   is a subset of JavaScript but excludes assignment and invocation.

Since JSON's syntax is borrowed from JavaScript, it is possible to
   use that language's "eval()" function to parse most JSON texts (but
   not all; certain characters such as U+2028 LINE SEPARATOR and U+2029
   PARAGRAPH SEPARATOR are legal in JSON but not JavaScript).  This
   generally constitutes an unacceptable security risk, since the text
   could contain executable code along with data declarations.  The same
   consideration applies to the use of eval()-like functions in any
   other programming language in which JSON texts conform to that
   language's syntax.

13.  Examples

This is a JSON object:

{
        "Image": {
            "Width":  800,
            "Height": 600,
            "Title":  "View from 15th Floor",
            "Thumbnail": {
                "Url":    "http://www.example.com/image/481989943",
                "Height": 125,
                "Width":  100
            },
            "Animated" : false,
            "IDs": [116, 943, 234, 38793]
          }
      }

Its Image member is an object whose Thumbnail member is an object and
   whose IDs member is an array of numbers.

Bray                         Standards Track                   [Page 12]

RFC 8259                          JSON                     December 2017

This is a JSON array containing two objects:

[
        {
           "precision": "zip",
           "Latitude":  37.7668,
           "Longitude": -122.3959,
           "Address":   "",
           "City":      "SAN FRANCISCO",
           "State":     "CA",
           "Zip":       "94107",
           "Country":   "US"
        },
        {
           "precision": "zip",
           "Latitude":  37.371991,
           "Longitude": -122.026020,
           "Address":   "",
           "City":      "SUNNYVALE",
           "State":     "CA",
           "Zip":       "94085",
           "Country":   "US"
        }
      ]

Here are three small JSON texts containing only values:

"Hello world!"

true

Bray                         Standards Track                   [Page 13]

RFC 8259                          JSON                     December 2017

14.  References

14.1.  Normative References

[ECMA-404] Ecma International, "The JSON Data Interchange Format",
              Standard ECMA-404,
              <http://www.ecma-international.org/publications/
              standards/Ecma-404.htm>.

[IEEE754]  IEEE, "IEEE Standard for Floating-Point Arithmetic",
              IEEE 754.

[RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/info/rfc2119>.

[RFC3629]  Yergeau, F., "UTF-8, a transformation format of ISO
              10646", STD 63, RFC 3629, DOI 10.17487/RFC3629, November
              2003, <https://www.rfc-editor.org/info/rfc3629>.

[RFC5234]  Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax
              Specifications: ABNF", STD 68, RFC 5234,
              DOI 10.17487/RFC5234, January 2008,
              <https://www.rfc-editor.org/info/rfc5234>.

[RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/info/rfc8174>.

[UNICODE]  The Unicode Consortium, "The Unicode Standard",
              <http://www.unicode.org/versions/latest/>.

14.2.  Informative References

[ECMA-262] Ecma International, "ECMAScript Language Specification",
              Standard ECMA-262, Third Edition, December 1999,
              <http://www.ecma-international.org/publications/files/
              ECMA-ST-ARCH/
              ECMA-262,%203rd%20edition,%20December%201999.pdf>.

[Err3607]  RFC Errata, Erratum ID 3607, RFC 4627,
              <https://www.rfc-editor.org/errata/eid3607>.

[Err3915]  RFC Errata, Erratum ID 3915, RFC 7159,
              <https://www.rfc-editor.org/errata/eid3915>.

Bray                         Standards Track                   [Page 14]

RFC 8259                          JSON                     December 2017

[Err4264]  RFC Errata, Erratum ID 4264, RFC 7159,
              <https://www.rfc-editor.org/errata/eid4264>.

[Err4336]  RFC Errata, Erratum ID 4336, RFC 7159,
              <https://www.rfc-editor.org/errata/eid4336>.

[Err4388]  RFC Errata, Erratum ID 4388, RFC 7159,
              <https://www.rfc-editor.org/errata/eid4388>.

[Err607]   RFC Errata, Erratum ID 607, RFC 4627,
              <https://www.rfc-editor.org/errata/eid607>.

[RFC4627]  Crockford, D., "The application/json Media Type for
              JavaScript Object Notation (JSON)", RFC 4627,
              DOI 10.17487/RFC4627, July 2006,
              <https://www.rfc-editor.org/info/rfc4627>.

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

Bray                         Standards Track                   [Page 15]

RFC 8259                          JSON                     December 2017

Appendix A.  Changes from RFC 7159

This section lists changes between this document and the text in
   RFC 7159.

o  Section 1.2 has been updated to reflect the removal of a JSON
      specification from ECMA-262, to make ECMA-404 a normative
      reference, and to explain the particular meaning of "normative".

o  Section 1.3 has been updated to reflect errata filed against
      RFC 7159, not RFC 4627.

o  Section 8.1 was changed to require the use of UTF-8 when
      transmitted over a network.

o  Section 12 has been updated to increase the precision of the
      description of the security risk that follows from using the
      ECMAScript "eval()" function.

o  Section 14.1 has been updated to include ECMA-404 as a normative
      reference.

o  Section 14.2 has been updated to remove ECMA-404, update the
      version of ECMA-262, and refresh the errata list.

Contributors

RFC 4627 was written by Douglas Crockford.  This document was
   constructed by making a relatively small number of changes to that
   document; thus, the vast majority of the text here is his.

Author's Address

Tim Bray (editor)
   Textuality

Email: tbray@textuality.com

Bray                         Standards Track                   [Page 16]

Testo modificato

Apri file

Internet Engineering Task Force (IETF)                      T. Bray, Ed.
Request for Comments: 7159                                  Google, Inc.
Obsoletes: 4627, 7158                                         March 2014
Category: Standards Track
ISSN: 2070-1721

The JavaScript Object Notation (JSON) Data Interchange Format

Abstract

This document removes inconsistencies with other specifications of
   JSON, repairs specification errors, and offers experience-based
   interoperability guidance.

Status of This Memo

This is an Internet Standards Track document.

Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   http://www.rfc-editor.org/info/rfc7159.

Bray                         Standards Track                    [Page 1]

RFC 7159                          JSON                        March 2014

This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://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 and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Bray                         Standards Track                    [Page 2]

RFC 7159                          JSON                        March 2014

Table of Contents

1. Introduction ....................................................3
      1.1. Conventions Used in This Document ..........................4
      1.2. Specifications of JSON .....................................4
      1.3. Introduction to This Revision ..............................4
   2. JSON Grammar ....................................................4
   3. Values ..........................................................5
   4. Objects .........................................................6
   5. Arrays ..........................................................6
   6. Numbers .........................................................6
   7. Strings .........................................................8
   8. String and Character Issues .....................................9
      8.1. Character Encoding .........................................9
      8.2. Unicode Characters .........................................9
      8.3. String Comparison ..........................................9
   9. Parsers ........................................................10
   10. Generators ....................................................10
   11. IANA Considerations ...........................................10
   12. Security Considerations .......................................11
   13. Examples ......................................................12
   14. Contributors ..................................................13
   15. References ....................................................13
      15.1. Normative References .....................................13
      15.2. Informative References ...................................13
   Appendix A. Changes from RFC 4627 .................................15

1.  Introduction

JSON can represent four primitive types (strings, numbers, booleans,
   and null) and two structured types (objects and arrays).

A string is a sequence of zero or more Unicode characters [UNICODE].
   Note that this citation references the latest version of Unicode
   rather than a specific release.  It is not expected that future
   changes in the UNICODE specification will impact the syntax of JSON.

An object is an unordered collection of zero or more name/value
   pairs, where a name is a string and a value is a string, number,
   boolean, null, object, or array.

An array is an ordered sequence of zero or more values.

Bray                         Standards Track                    [Page 3]

RFC 7159                          JSON                        March 2014

The terms "object" and "array" come from the conventions of
   JavaScript.

JSON's design goals were for it to be minimal, portable, textual, and
   a subset of JavaScript.

1.1.  Conventions Used in This Document

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].

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

1.2.  Specifications of JSON

This document updates [RFC4627], which describes JSON and registers
   the media type "application/json".

A description of JSON in ECMAScript terms appears in Version 5.1 of
   the ECMAScript specification [ECMA-262], Section 15.12.  JSON is also
   described in [ECMA-404].

All of the specifications of JSON syntax agree on the syntactic
   elements of the language.

1.3.  Introduction to This Revision

In the years since the publication of RFC 4627, JSON has found very
   wide use.  This experience has revealed certain patterns, which,
   while allowed by its specifications, have caused interoperability
   problems.

Also, a small number of errata have been reported (see RFC Errata IDs
   607 [Err607] and 3607 [Err3607]).

This document's goal is to apply the errata, remove inconsistencies
   with other specifications of JSON, and highlight practices that can
   lead to interoperability problems.

2.  JSON Grammar

A JSON text is a sequence of tokens.  The set of tokens includes six
   structural characters, strings, numbers, and three literal names.

A JSON text is a serialized value.  Note that certain previous
   specifications of JSON constrained a JSON text to be an object or an

Bray                         Standards Track                    [Page 4]

RFC 7159                          JSON                        March 2014

array.  Implementations that generate only objects or arrays where a
   JSON text is called for will be interoperable in the sense that all
   implementations will accept these as conforming JSON texts.

JSON-text = ws value ws

These are the six structural characters:

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

name-separator  = ws %x3A ws  ; : colon

value-separator = ws %x2C ws  ; , comma

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

3.  Values

A JSON value MUST be an object, array, number, or string, or one of
   the following three literal names:

false null true

The literal names MUST be lowercase.  No other literal names are
   allowed.

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

false = %x66.61.6c.73.65   ; false

null  = %x6e.75.6c.6c      ; null

true  = %x74.72.75.65      ; true

Bray                         Standards Track                    [Page 5]

RFC 7159                          JSON                        March 2014

4.  Objects

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

member = string name-separator value

5.  Arrays

An array structure is represented as square brackets surrounding zero
   or more values (or elements).  Elements are separated by commas.

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

There is no requirement that the values in an array be of the same
   type.

6.  Numbers

A fraction part is a decimal point followed by one or more digits.

Bray                         Standards Track                    [Page 6]

RFC 7159                          JSON                        March 2014

An exponent part begins with the letter E in upper or lower case,
   which may be followed by a plus or minus sign.  The E and optional
   sign are followed by one or more digits.

Numeric values that cannot be represented in the grammar below (such
   as Infinity and NaN) are not permitted.

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

This specification allows implementations to set limits on the range
   and precision of numbers accepted.  Since software that implements
   IEEE 754-2008 binary64 (double precision) numbers [IEEE754] is
   generally available and widely used, good interoperability can be
   achieved by implementations that expect no more precision or range
   than these provide, in the sense that implementations will
   approximate JSON numbers within the expected precision.  A JSON
   number such as 1E400 or 3.141592653589793238462643383279 may indicate
   potential interoperability problems, since it suggests that the
   software that created it expects receiving software to have greater
   capabilities for numeric magnitude and precision than is widely
   available.

Bray                         Standards Track                    [Page 7]

RFC 7159                          JSON                        March 2014

7.  Strings

The representation of strings is similar to conventions used in the C
   family of programming languages.  A string begins and ends with
   quotation marks.  All Unicode characters may be placed within the
   quotation marks, except for the characters that must be escaped:
   quotation mark, reverse solidus, and the control characters (U+0000
   through U+001F).

Any character may be escaped.  If the character is in the Basic
   Multilingual Plane (U+0000 through U+FFFF), then it may be
   represented as a six-character sequence: a reverse solidus, followed
   by the lowercase letter u, followed by four hexadecimal digits that
   encode the character's code point.  The hexadecimal letters A though
   F can be upper or lower case.  So, for example, a string containing
   only a single reverse solidus character may be represented as
   "\u005C".

string = quotation-mark *char quotation-mark

escape = %x5C              ; \

quotation-mark = %x22      ; "

unescaped = %x20-21 / %x23-5B / %x5D-10FFFF

Bray                         Standards Track                    [Page 8]

RFC 7159                          JSON                        March 2014

8.  String and Character Issues

8.1.  Character Encoding

JSON text SHALL be encoded in UTF-8, UTF-16, or UTF-32.  The default
   encoding is UTF-8, and JSON texts that are encoded in UTF-8 are
   interoperable in the sense that they will be read successfully by the
   maximum number of implementations; there are many implementations
   that cannot successfully read texts in other encodings (such as
   UTF-16 and UTF-32).

Implementations MUST NOT add a byte order mark to the beginning of a
   JSON text.  In the interests of interoperability, implementations
   that parse JSON texts MAY ignore the presence of a byte order mark
   rather than treating it as an error.

8.2.  Unicode Characters

8.3.  String Comparison

Bray                         Standards Track                    [Page 9]

RFC 7159                          JSON                        March 2014

9.  Parsers

A JSON parser transforms a JSON text into another representation.  A
   JSON parser MUST accept all texts that conform to the JSON grammar.
   A JSON parser MAY accept non-JSON forms or extensions.

10.  Generators

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

11.  IANA Considerations

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

Type name:  application

Subtype name:  json

Required parameters:  n/a

Optional parameters:  n/a

Encoding considerations:  binary

Security considerations:  See [RFC7159], Section 12.

Interoperability considerations:  Described in [RFC7159]

Published specification:  [RFC7159]

Bray                         Standards Track                   [Page 10]

RFC 7159                          JSON                        March 2014

Additional information:
      Magic number(s): n/a
      File extension(s): .json
      Macintosh file type code(s): TEXT

Person & email address to contact for further information:
      IESG
      <iesg@ietf.org>

Intended usage:  COMMON

Restrictions on usage:  none

Author:
      Douglas Crockford
      <douglas@crockford.com>

Change controller:
      IESG
      <iesg@ietf.org>

Note:  No "charset" parameter is defined for this registration.
      Adding one really has no effect on compliant recipients.

12.  Security Considerations

Generally, there are security issues with scripting languages.  JSON
   is a subset of JavaScript but excludes assignment and invocation.

Since JSON's syntax is borrowed from JavaScript, it is possible to
   use that language's "eval()" function to parse JSON texts.  This
   generally constitutes an unacceptable security risk, since the text
   could contain executable code along with data declarations.  The same
   consideration applies to the use of eval()-like functions in any
   other programming language in which JSON texts conform to that
   language's syntax.

Bray                         Standards Track                   [Page 11]

RFC 7159                          JSON                        March 2014

13.  Examples

This is a JSON object:

Its Image member is an object whose Thumbnail member is an object and
   whose IDs member is an array of numbers.

This is a JSON array containing two objects:

Bray                         Standards Track                   [Page 12]

RFC 7159                          JSON                        March 2014

Here are three small JSON texts containing only values:

"Hello world!"

true

14.  Contributors

RFC 4627 was written by Douglas Crockford.  This document was
   constructed by making a relatively small number of changes to that
   document; thus, the vast majority of the text here is his.

15.  References

15.1.  Normative References

[IEEE754]  IEEE, "IEEE Standard for Floating-Point Arithmetic", IEEE
              Standard 754, August 2008,
              <http://grouper.ieee.org/groups/754/>.

[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.

[UNICODE]  The Unicode Consortium, "The Unicode Standard",
              <http://www.unicode.org/versions/latest/>.

15.2.  Informative References

[ECMA-262] Ecma International, "ECMAScript Language Specification
              Edition 5.1", Standard ECMA-262, June 2011,
              <http://www.ecma-international.org/publications/standards/
              Ecma-262.htm>.

[ECMA-404] Ecma International, "The JSON Data Interchange Format",
              Standard ECMA-404, October 2013,
              <http://www.ecma-international.org/publications/standards/
              Ecma-404.htm>.

[Err3607]  RFC Errata, Errata ID 3607, RFC 3607,
              <http://www.rfc-editor.org>.

Bray                         Standards Track                   [Page 13]

RFC 7159                          JSON                        March 2014

[Err607]   RFC Errata, Errata ID 607, RFC 607,
              <http://www.rfc-editor.org>.

[RFC4627]  Crockford, D., "The application/json Media Type for
              JavaScript Object Notation (JSON)", RFC 4627, July 2006.

Bray                         Standards Track                   [Page 14]

RFC 7159                          JSON                        March 2014

Appendix A.  Changes from RFC 4627

This section lists changes between this document and the text in RFC
   4627.

o  Changed the title and abstract of the document.

o  Changed the reference to [UNICODE] to be not version specific.

o  Added a "Specifications of JSON" section.

o  Added an "Introduction to This Revision" section.

o  Changed the definition of "JSON text" so that it can be any JSON
      value, removing the constraint that it be an object or array.

o  Added language about duplicate object member names, member
      ordering, and interoperability.

o  Clarified the absence of a requirement that values in an array be
      of the same JSON type.

o  Applied erratum #607 from RFC 4627 to correctly align the artwork
      for the definition of "object".

o  Changed "as sequences of digits" to "in the grammar below" in the
      "Numbers" section, and made base-10-ness explicit.

o  Added language about number interoperability as a function of
      IEEE754, and added an IEEE754 reference.

o  Added language about interoperability and Unicode characters and
      about string comparisons.  To do this, turned the old "Encoding"
      section into a "String and Character Issues" section, with three
      subsections: "Character Encoding", "Unicode Characters", and
      "String Comparison".

o  Changed guidance in the "Parsers" section to point out that
      implementations may set limits on the range "and precision" of
      numbers.

o  Updated and tidied the "IANA Considerations" section.

o  Made a real "Security Considerations" section and lifted the text
      out of the previous "IANA Considerations" section.

Bray                         Standards Track                   [Page 15]

RFC 7159                          JSON                        March 2014

o  Applied erratum #3607 from RFC 4627 by removing the security
      consideration that begins "A JSON text can be safely passed" and
      the JavaScript code that went with that consideration.

o  Added a note to the "Security Considerations" section pointing out
      the risks of using the "eval()" function in JavaScript or any
      other language in which JSON texts conform to that language's
      syntax.

o  Added a note to the "IANA Considerations" clarifying the absence
      of a "charset" parameter for the application/json media type.

o  Changed "100" to 100 and added a boolean field, both in the first
      example.

o  Added examples of JSON texts with simple values, neither objects
      nor arrays.

o  Added a "Contributors" section crediting Douglas Crockford.

o  Added a reference to RFC 4627.

o  Moved the ECMAScript reference from Normative to Informative and
      updated it to reference ECMAScript 5.1, and added a reference to
      ECMA 404.

Author's Address

Tim Bray (editor)
   Google, Inc.

EMail: tbray@textuality.com

Bray                         Standards Track                   [Page 16]