draft-ietf-json-i-json-06.txt   rfc7493.txt 
Network Working Group T. Bray, Ed. Internet Engineering Task Force (IETF) T. Bray, Ed.
Internet-Draft Textuality Services Request for Comments: 7493 Textuality Services
Intended status: Standards Track January 27, 2015 Category: Standards Track March 2015
Expires: July 31, 2015 ISSN: 2070-1721
The I-JSON Message Format The I-JSON Message Format
draft-ietf-json-i-json-06
Abstract Abstract
I-JSON is a restricted profile of JSON designed to maximize I-JSON (short for "Internet JSON") is a restricted profile of JSON
interoperability and increase confidence that software can process it designed to maximize interoperability and increase confidence that
successfully with predictable results. software can process it successfully with predictable results.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This is an Internet Standards Track document.
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months This document is a product of the Internet Engineering Task Force
and may be updated, replaced, or obsoleted by other documents at any (IETF). It represents the consensus of the IETF community. It has
time. It is inappropriate to use Internet-Drafts as reference received public review and has been approved for publication by the
material or to cite them other than as "work in progress." Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 5741.
This Internet-Draft will expire on July 31, 2015. 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/rfc7493.
Copyright Notice Copyright Notice
Copyright (c) 2015 IETF Trust and the persons identified as the Copyright (c) 2015 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://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 publication of this document. Please review these documents
skipping to change at page 2, line 13 skipping to change at page 2, line 13
described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 2 1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 2
1.2. Requirements Language . . . . . . . . . . . . . . . . . . 2 1.2. Requirements Language . . . . . . . . . . . . . . . . . . 2
2. I-JSON Messages . . . . . . . . . . . . . . . . . . . . . . . 3 2. I-JSON Messages . . . . . . . . . . . . . . . . . . . . . . . 3
2.1. Encoding and Characters . . . . . . . . . . . . . . . . . 3 2.1. Encoding and Characters . . . . . . . . . . . . . . . . . 3
2.2. Numbers . . . . . . . . . . . . . . . . . . . . . . . . . 3 2.2. Numbers . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.3. Object constraints . . . . . . . . . . . . . . . . . . . 3 2.3. Object Constraints . . . . . . . . . . . . . . . . . . . 3
3. Software Behavior . . . . . . . . . . . . . . . . . . . . . . 4 3. Software Behavior . . . . . . . . . . . . . . . . . . . . . . 4
4. Protocol-design Recommendations . . . . . . . . . . . . . . . 4 4. Recommendations for Protocol Design . . . . . . . . . . . . . 4
4.1. Top-level Constructs . . . . . . . . . . . . . . . . . . 4 4.1. Top-Level Constructs . . . . . . . . . . . . . . . . . . 4
4.2. Must-ignore Policy . . . . . . . . . . . . . . . . . . . 4 4.2. Must-Ignore Policy . . . . . . . . . . . . . . . . . . . 4
4.3. Time and Date Handling . . . . . . . . . . . . . . . . . 5 4.3. Time and Date Handling . . . . . . . . . . . . . . . . . 5
4.4. Binary Data . . . . . . . . . . . . . . . . . . . . . . . 5 4.4. Binary Data . . . . . . . . . . . . . . . . . . . . . . . 5
5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 5 5. Security Considerations . . . . . . . . . . . . . . . . . . . 5
6. Security Considerations . . . . . . . . . . . . . . . . . . . 5 6. Normative References . . . . . . . . . . . . . . . . . . . . 5
7. Normative References . . . . . . . . . . . . . . . . . . . . 5 Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 6
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 6 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 6
1. Introduction 1. Introduction
RFC 7159 describes the JSON data interchange format, which is widely RFC 7159 describes the JSON data interchange format, which is widely
used in Internet protocols. For historical reasons, that used in Internet protocols. For historical reasons, that
specification allows the use of language idioms and text encoding specification allows the use of language idioms and text encoding
patterns which are likely to lead to interoperability problems and patterns that are likely to lead to interoperability problems and
software breakage, particularly when a program receiving JSON data software breakage, particularly when a program receiving JSON data
uses automated software to map it into native programming-language uses automated software to map it into native programming-language
structures or database records. RFC 7159 describes practices which structures or database records. RFC 7159 describes practices that
may be used to avoid these interoperability problems. may be used to avoid these interoperability problems.
This document specifies I-JSON, short for "Internet JSON". The unit This document specifies I-JSON, short for "Internet JSON". The unit
of definition is the "I-JSON message". I-JSON messages are also of definition is the "I-JSON message". I-JSON messages are also
"JSON texts" as defined in RFC 7159 but with certain extra "JSON texts" as defined in RFC 7159 but with certain extra
constraints which enforce the good interoperability practices constraints that enforce the good interoperability practices
described in that specification. described in that specification.
1.1. Terminology 1.1. Terminology
The terms "object", "member", "array", "number", "name", and "string" The terms "object", "member", "array", "number", "name", and "string"
in this document are to be interpreted as described in RFC 7159 in this document are to be interpreted as described in RFC 7159
[RFC7159]. [RFC7159].
1.2. Requirements Language 1.2. Requirements Language
skipping to change at page 3, line 14 skipping to change at page 3, line 14
2. I-JSON Messages 2. I-JSON Messages
An I-JSON message is a JSON text, as defined by RFC 7159. An I-JSON message is a JSON text, as defined by RFC 7159.
2.1. Encoding and Characters 2.1. Encoding and Characters
I-JSON messages MUST be encoded using UTF-8 [RFC3629]. I-JSON messages MUST be encoded using UTF-8 [RFC3629].
Object member names, and string values in arrays and object members, Object member names, and string values in arrays and object members,
MUST NOT include code points which identify Surrogates or MUST NOT include code points that identify Surrogates or
Noncharacters [UNICODE] (Section 2.4). Noncharacters as defined by [UNICODE].
This applies both to characters encoded directly in UTF-8 and to This applies both to characters encoded directly in UTF-8 and to
those which are escaped; thus, "\uDEAD" is invalid because it is an those which are escaped; thus, "\uDEAD" is invalid because it is an
unpaired surrogate, while "\uD800\uDEAD" would be legal. unpaired surrogate, while "\uD800\uDEAD" would be legal.
2.2. Numbers 2.2. Numbers
Software which implements IEEE 754-2008 binary64 (double precision) Software that implements IEEE 754-2008 binary64 (double precision)
numbers [IEEE754] is generally available and widely used. numbers [IEEE754] is generally available and widely used.
Implementations which generate I-JSON messages cannot assume that Implementations that generate I-JSON messages cannot assume that
receiving implementations can process numeric values with greater receiving implementations can process numeric values with greater
magnitude or precision than provided by those numbers. I-JSON magnitude or precision than provided by those numbers. I-JSON
messages SHOULD NOT include numbers which express greater magnitude messages SHOULD NOT include numbers that express greater magnitude or
or precision than an IEEE 754 double precision number provides, for precision than an IEEE 754 double precision number provides, for
example 1E400 or 3.141592653589793238462643383279. example, 1E400 or 3.141592653589793238462643383279.
An I-JSON sender cannot expect a receiver to treat an integer whose An I-JSON sender cannot expect a receiver to treat an integer whose
absolute value is greater than 9007199254740991 (i.e., that is absolute value is greater than 9007199254740991 (i.e., that is
outside the range [-(2**53)+1, (2**53)-1]) as an exact value. outside the range [-(2**53)+1, (2**53)-1]) as an exact value.
For applications which require the exact interchange of numbers with For applications that require the exact interchange of numbers with
greater magnitude or precision, it is RECOMMENDED to encode them in greater magnitude or precision, it is RECOMMENDED to encode them in
JSON string values. This requires that the receiving program JSON string values. This requires that the receiving program
understand the intended semantic of the value. An example would be understand the intended semantic of the value. An example would be
64-bit integers, even though modern hardware can deal with them, 64-bit integers, even though modern hardware can deal with them,
because of the limited scope of JavaScript numbers. because of the limited scope of JavaScript numbers.
2.3. Object constraints 2.3. Object Constraints
Objects in I-JSON messages MUST NOT have members with duplicate Objects in I-JSON messages MUST NOT have members with duplicate
names. In this context, "duplicate" means that the names, after names. In this context, "duplicate" means that the names, after
processing any escaped characters, are identical sequences of Unicode processing any escaped characters, are identical sequences of Unicode
characters. characters.
The order of object members in an I-JSON message does not change the The order of object members in an I-JSON message does not change the
meaning of an I-JSON message. A receiving implementation MAY treat meaning of an I-JSON message. A receiving implementation MAY treat
two I-JSON messages as equivalent if they differ only in the order of two I-JSON messages as equivalent if they differ only in the order of
the object members. the object members.
3. Software Behavior 3. Software Behavior
A major advantage of using I-JSON is that receivers can avoid A major advantage of using I-JSON is that receivers can avoid
ambiguous semantics in the JSON messages they receive. This allows ambiguous semantics in the JSON messages they receive. This allows
receivers to reject or otherwise disregard messages which do not receivers to reject or otherwise disregard messages that do not
conform to the requirements in this document for I-JSON messages. conform to the requirements in this document for I-JSON messages.
Protocols that use I-JSON message can be written so that receiving Protocols that use I-JSON messages can be written so that receiving
implementations are required to reject (or, as in the case of implementations are required to reject (or, as in the case of
security protocols, not trust) messages that do not satisfy the security protocols, not trust) messages that do not satisfy the
constraints of I-JSON. constraints of I-JSON.
Designers of protocols which use I-JSON messages SHOULD provide a Designers of protocols that use I-JSON messages SHOULD provide a way,
way, in this case, for the receiver of the erroneous data to signal in this case, for the receiver of the erroneous data to signal the
the problem to the sender. problem to the sender.
4. Protocol-design Recommendations 4. Recommendations for Protocol Design
I-JSON is designed for use in Internet protocols. The following I-JSON is designed for use in Internet protocols. The following
recommendations apply to the use of I-JSON in such protocols. recommendations apply to the use of I-JSON in such protocols.
4.1. Top-level Constructs 4.1. Top-Level Constructs
An I-JSON message can be any JSON value. However, there are software An I-JSON message can be any JSON value. However, there are software
implementations, coded to the older [RFC4627] specification, which implementations, coded to the older specification [RFC4627], which
only accept JSON objects or JSON arrays at the top level of JSON only accept JSON objects or JSON arrays at the top level of JSON
texts. For maximum interoperability with such implementations, texts. For maximum interoperability with such implementations,
protocol designers SHOULD NOT use top-level JSON texts which are protocol designers SHOULD NOT use top-level JSON texts that are
neither objects nor arrays. neither objects nor arrays.
4.2. Must-ignore Policy 4.2. Must-Ignore Policy
It is frequently the case that changes to protocols are required It is frequently the case that changes to protocols are required
after they have been put in production. Protocols which allow the after they have been put in production. Protocols that allow the
introduction of new protocol elements in a way that does not disrupt introduction of new protocol elements in a way that does not disrupt
the operation of existing software have proven advantageous in the operation of existing software have proven advantageous in
practice. practice.
This can be referred to as a "Must-Ignore" policy, meaning that when This can be referred to as a "Must-Ignore" policy, meaning that when
an implementation encounters a protocol element which it does not an implementation encounters a protocol element that it does not
recognize, it should treat the rest of the protocol transaction as if recognize, it should treat the rest of the protocol transaction as if
the new element simply did not appear, and in particular MUST NOT the new element simply did not appear, and in particular, the
treat this as an error condition. The converse "Must-Understand" implementation MUST NOT treat this as an error condition. The
policy does not tolerate the introduction of new protocol elements, converse "Must-Understand" policy does not tolerate the introduction
and while this has proven necessary in certain protocol designs, in of new protocol elements, and while this has proven necessary in
general it has been found to be overly restrictive and brittle. certain protocol designs, in general it has been found to be overly
restrictive and brittle.
A good way to support the use of Must-Ignore in I-JSON protocol A good way to support the use of Must-Ignore in I-JSON protocol
designs is to require that top-level protocol elements must be JSON designs is to require that top-level protocol elements must be JSON
objects, and to specify that members whose names are unrecognized objects, and to specify that members whose names are unrecognized
MUST be ignored. MUST be ignored.
4.3. Time and Date Handling 4.3. Time and Date Handling
Protocols often contain data items which are designed to contain Protocols often contain data items that are designed to contain
timestamps or time durations. It is RECOMMENDED that all such data timestamps or time durations. It is RECOMMENDED that all such data
items be expressed as string values in ISO 8601 format, as specified items be expressed as string values in ISO 8601 format, as specified
in [RFC3339], with the additional restrictions that uppercase rather in [RFC3339], with the additional restrictions that uppercase rather
than lowercase letters be used, that the timezone be included not than lowercase letters be used, that the timezone be included not
defaulted, and that optional trailing seconds be included even when defaulted, and that optional trailing seconds be included even when
their value is "00". It is also RECOMMENDED that all data items their value is "00". It is also RECOMMENDED that all data items
containing time durations conform to the "duration" production in containing time durations conform to the "duration" production in
Appendix A of RFC3339, with the same additional restrictions. Appendix A of RFC 3339, with the same additional restrictions.
4.4. Binary Data 4.4. Binary Data
When it is required that an I-JSON protocol element contain arbitrary When it is required that an I-JSON protocol element contain arbitrary
binary data, it is RECOMMENDED that this data be encoded in a string binary data, it is RECOMMENDED that this data be encoded in a string
value in base64url; see Section 5 of [RFC4648]. value in base64url; see Section 5 of [RFC4648].
5. Acknowledgements 5. Security Considerations
I-JSON is entirely dependent on the design of JSON, largely due to
Douglas Crockford. The specifics were strongly influenced by the
contributors to the design of RFC 7159 on the IETF JSON Working
Group.
6. Security Considerations
All the security considerations which apply to JSON (see RFC 7159) All the security considerations that apply to JSON (see RFC 7159)
apply to I-JSON. There are no additional security considerations apply to I-JSON. There are no additional security considerations
specific to I-JSON. specific to I-JSON.
Since I-JSON forbids the use of certain JSON idioms that can lead to Since I-JSON forbids the use of certain JSON idioms that can lead to
unpredictable behavior in receiving software, it may prove a more unpredictable behavior in receiving software, it may prove a more
secure basis for Internet protocols, and may be a good choice for secure basis for Internet protocols and may be a good choice for
protocol designers with special security needs. protocol designers with special security needs.
7. Normative References 6. Normative References
[IEEE754] IEEE, "IEEE Standard for Floating-Point Arithmetic", 2008, [IEEE754] IEEE, "IEEE Standard for Floating-Point Arithmetic", IEEE
<http://grouper.ieee.org/groups/754/>. 754-2008, 2008, <http://grouper.ieee.org/groups/754/>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>.
[RFC3339] Klyne, G., Ed. and C. Newman, "Date and Time on the [RFC3339] Klyne, G. and C. Newman, "Date and Time on the Internet:
Internet: Timestamps", RFC 3339, July 2002. Timestamps", RFC 3339, July 2002,
<http://www.rfc-editor.org/info/rfc3339>.
[RFC3629] Yergeau, F., "UTF-8, a transformation format of ISO [RFC3629] Yergeau, F., "UTF-8, a transformation format of ISO
10646", STD 63, RFC 3629, November 2003. 10646", STD 63, RFC 3629, November 2003,
<http://www.rfc-editor.org/info/rfc3629>.
[RFC4627] Crockford, D., "The application/json Media Type for [RFC4627] Crockford, D., "The application/json Media Type for
JavaScript Object Notation (JSON)", RFC 4627, July 2006. JavaScript Object Notation (JSON)", RFC 4627, July 2006,
<http://www.rfc-editor.org/info/rfc4627>.
[RFC4648] Josefsson, S., "The Base16, Base32, and Base64 Data [RFC4648] Josefsson, S., "The Base16, Base32, and Base64 Data
Encodings", RFC 4648, October 2006. Encodings", RFC 4648, October 2006,
<http://www.rfc-editor.org/info/rfc4648>.
[RFC7159] Bray, T., "The JavaScript Object Notation (JSON) Data [RFC7159] Bray, T., Ed., "The JavaScript Object Notation (JSON) Data
Interchange Format", RFC 7159, March 2014. Interchange Format", RFC 7159, March 2014,
<http://www.rfc-editor.org/info/rfc7159>.
[UNICODE] The Unicode Consortium, "The Unicode Standard", 2003-, [UNICODE] The Unicode Consortium, "The Unicode Standard",
<http://www.unicode.org/versions/latest/>. <http://www.unicode.org/versions/latest/>.
Note that this reference is to the latest version of Acknowledgements
Unicode, rather than to a specific release. It is not
expected that future changes in the UNICODE specification I-JSON is entirely dependent on the design of JSON, largely due to
will affect the referenced classifications. Douglas Crockford. The specifics were strongly influenced by the
contributors to the design of RFC 7159 in the IETF JSON Working
Group.
Author's Address Author's Address
Tim Bray (editor) Tim Bray (editor)
Textuality Services Textuality Services
Email: tbray@textuality.com EMail: tbray@textuality.com
URI: https://www.tbray.org/ URI: https://www.tbray.org/
 End of changes. 45 change blocks. 
85 lines changed or deleted 83 lines changed or added

This html diff was produced by rfcdiff 1.42. The latest version is available from http://tools.ietf.org/tools/rfcdiff/