Internet DRAFT - draft-ietf-appsawg-media-type-suffix-regs
draft-ietf-appsawg-media-type-suffix-regs
Network Working Group T. Hansen
Internet-Draft AT&T Laboratories
Updates: 3023 (if approved) A. Melnikov
Intended status: Informational Isode Ltd
Expires: May 9, 2013 November 5, 2012
Additional Media Type Structured Syntax Suffixes
draft-ietf-appsawg-media-type-suffix-regs-08
Abstract
A content media type name sometimes includes partitioned meta-
information distinguish by a Structured Syntax, to permit noting an
attribute of the media as a suffix to the name. This document
defines several Structured Syntax Suffixes for use with media type
registrations. In particular, it defines and registers the "+json",
"+ber", "+der", "+fastinfoset", "+wbxml" and "+zip" Structured Syntax
Suffixes, and provides a Message Type Structured Syntax Suffix
registration form for the "+xml" Structured Syntax Suffix.
Status of this Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
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
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on May 9, 2013.
Copyright Notice
Copyright (c) 2012 IETF Trust and the persons identified as the
document authors. All rights reserved.
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
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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.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. When to Use these Structured Syntax Suffixes . . . . . . . . . 3
3. Initial Structured Syntax Suffix Definitions . . . . . . . . . 4
3.1. The +json Structured Syntax Suffix . . . . . . . . . . . . 4
3.2. The +ber Structured Syntax Suffixes . . . . . . . . . . . 5
3.3. The +der Structured Syntax Suffixes . . . . . . . . . . . 6
3.4. The +fastinfoset Structured Syntax Suffix . . . . . . . . 8
3.5. The +wbxml Structured Syntax Suffix . . . . . . . . . . . 9
3.6. The +zip Structured Syntax Suffix . . . . . . . . . . . . 10
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11
5. Security Considerations . . . . . . . . . . . . . . . . . . . 13
6. References . . . . . . . . . . . . . . . . . . . . . . . . . . 13
6.1. Normative References . . . . . . . . . . . . . . . . . . . 13
6.2. Informative References . . . . . . . . . . . . . . . . . . 14
Appendix A. Change History . . . . . . . . . . . . . . . . . . . 14
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 15
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1. Introduction
[RFC3023] created the +xml suffix convention that can be used when
defining names for media types whose representation uses XML
underneath. That is, they could have been successfully parsed as if
the media type had been application/xml in addition to their being
parsed as their media type that is using the +xml suffix.
[I-D.ietf-appsawg-media-type-regs] defines the Message Type
Structured Syntax Suffixes registry to be used for such Structured
Syntax Suffixes.
A variety of Structured Syntax Suffixes have already been used in
some media type registrations, in particular "+json", "+der",
"+fastinfoset" and "+wbxml". This document defines and registers
these Structured Syntax Suffixes in the Structured Syntax Suffix
registry, along with "+ber" and "+zip". In addition, this document
updates [RFC3023] to formally register the "+xml" Structured Syntax
Suffix according to procedure defined in
[I-D.ietf-appsawg-media-type-regs].
Discussion of this document should occur in the Apps Area Working
Group (apps-discuss@ietf.org). [RFC Editor note: remove this
paragraph.]
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
2. When to Use these Structured Syntax Suffixes
Each of the Structured Syntax Suffixes defined in this document is
appropriate for use when the media type identifies the semantics of
the protocol payload. That is, knowing the semantics of the specific
media type provides for more specific processing of the content than
that afforded by generic processing of the underlying representation.
At the same time, using the suffix allows receivers of the media
types to do generic processing of the underlying representation in
cases where
they do not need to perform special handling of the particular
semantics of the exact media type, and,
there is no special knowledge needed by such a generic processor
in order to parse that underlying representation other than what
would be needed to parse any example of that underlying
representation.
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3. Initial Structured Syntax Suffix Definitions
3.1. The +json Structured Syntax Suffix
[RFC4627] defines the "application/json" media type. The suffix
"+json" MAY be used with any media type whose representation follows
that established for "application/json". The Message Type Structured
Syntax Suffix registration form follows. See
[I-D.ietf-appsawg-media-type-regs] for definitions of each of the
registration form headings.
Name: JavaScript Object Notation (JSON)
+suffix: +json
References: [RFC4627]
Encoding considerations: Per [RFC4627], JSON is allowed to be
represented using UTF-8, UTF-16, or UTF-32. When
JSON is written in UTF-8, JSON is 8bit compatible
([RFC2045]). When JSON is written in UTF-16 or
UTF-32, JSON is binary ([RFC2045]).
Fragment identifier considerations:
The syntax and semantics of fragment
identifiers specified for +json SHOULD be as
specified for "application/json". (At
publication of this document, there is no
fragment identification syntax defined for
"application/json".)
The syntax and semantics for fragment
identifiers for a specific "xxx/yyy+json"
SHOULD be processed as follows:
For cases defined in +json, where the
fragment identifier resolves per the +json
rules, then as specified in +json.
For cases defined in +json, where the
fragment identifier does not resolve per
the +json rules, then as specified in "xxx/
yyy+json".
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For cases not defined in +json, then as
specified in "xxx/yyy+json".
Interoperability considerations: n/a
Security considerations: See [RFC4627]
Contact: Apps Area Working Group (apps-discuss@ietf.org)
Author/Change controller: The Apps Area Working Group. IESG has
change control over this registration.
3.2. The +ber Structured Syntax Suffixes
The ITU defined the Basic Encoding Rules (BER) message transfer
syntax in [ITU.X690.2008]. The suffix "+ber" MAY be used with any
media type whose representation follows the BER message transfer
syntax. (The expert reviewer for Message Type Structured Syntax
Suffix registrations ought to be aware of the relationship between
BER and DER to aid in selecting the proper suffix.) The Message Type
Structured Syntax Suffix registration form for +ber follows:
Name: Basic Encoding Rules (BER) message transfer
syntax
+suffix: +ber
References: [ITU.X690.2008]
Encoding considerations: BER is a binary encoding.
Fragment identifier considerations:
At publication of this document, there is no
fragment identification syntax defined for
+ber.
The syntax and semantics for fragment
identifiers for a specific "xxx/yyy+ber"
SHOULD be processed as follows:
For cases defined in +ber, where the
fragment identifier resolves per the +ber
rules, then as specified in +ber.
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For cases defined in +ber, where the
fragment identifier does not resolve per
the +ber rules, then as specified in "xxx/
yyy+ber".
For cases not defined in +ber, then as
specified in "xxx/yyy+ber".
Interoperability considerations: n/a
Security considerations: Each individual media type registered with
a +ber suffix can have additional security
considerations.
BER has a type-length-value structure, and it is
easy to construct malicious content with invalid
length fields that can cause buffer overrun
conditions.
BER allows for arbitrary levels of nesting, which
may make it possible to construct malicious
content that will cause a stack overflow.
Interpreters of the BER structures should be
aware of these issues and should take appropriate
measures to guard against buffer overflows and
stack overruns in particular and malicious
content in general.
Contact: Apps Area Working Group (apps-discuss@ietf.org)
Author/Change controller: The Apps Area Working Group. IESG has
change control over this registration.
3.3. The +der Structured Syntax Suffixes
The ITU defined the Distinguished Encoding Rules (DER) message
transfer syntax in [ITU.X690.2008]. The suffix "+der" MAY be used
with any media type whose representation follows the DER message
transfer syntax. (The expert reviewer for Message Type Structured
Syntax Suffix registrations ought to be aware of the relationship
between BER and DER to aid in selecting the proper suffix.) The
Message Type Structured Syntax Suffix registration form for +der
follows:
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Name: Distinguished Encoding Rules (DER) message
transfer syntax
+suffix: +der
References: [ITU.X690.2008]
Encoding considerations: DER is a binary encoding.
Fragment identifier considerations:
At publication of this document, there is no
fragment identification syntax defined for
+der.
The syntax and semantics for fragment
identifiers for a specific "xxx/yyy+der"
SHOULD be processed as follows:
For cases defined in +der, where the
fragment identifier resolves per the +der
rules, then as specified in +der.
For cases defined in +der, where the
fragment identifier does not resolve per
the +der rules, then as specified in "xxx/
yyy+der".
For cases not defined in +der, then as
specified in "xxx/yyy+der".
Interoperability considerations: n/a
Security considerations: Each individual media type registered with
a +der suffix can have additional security
considerations.
DER has a type-length-value structure, and it is
easy to construct malicious content with invalid
length fields that can cause buffer overrun
conditions.
DER allows for arbitrary levels of nesting, which
may make it possible to construct malicious
content that will cause a stack overflow.
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Interpreters of the DER structures should be
aware of these issues and should take appropriate
measures to guard against buffer overflows and
stack overruns in particular and malicious
content in general.
Contact: Apps Area Working Group (apps-discuss@ietf.org)
Author/Change controller: The Apps Area Working Group. IESG has
change control over this registration.
3.4. The +fastinfoset Structured Syntax Suffix
The ITU defined the Fast Infoset document format as a binary
representation of the XML Information Set in [ITU.X891.2005]. These
documents further define the "application/fastinfoset" media type.
The suffix "+fastinfoset" MAY be used with any media type whose
representation follows that established for "application/
fastinfoset". The Message Type Structured Syntax Suffix registration
form follows:
Name: Fast Infoset document format
+suffix: +fastinfoset
References: [ITU.X891.2005]
Encoding considerations: Fast Infoset is a binary encoding. The
binary, quoted-printable and base64 content-
transfer-encodings are suitable for use with Fast
Infoset.
Fragment identifier considerations:
The syntax and semantics of fragment
identifiers specified for +fastinfoset SHOULD
be as specified for "application/fastinfoset".
(At publication of this document, there is no
fragment identification syntax defined for
"application/fastinfoset".)
The syntax and semantics for fragment
identifiers for a specific "xxx/
yyy+fastinfoset" SHOULD be processed as
follows:
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For cases defined in +fastinfoset, where
the fragment identifier resolves per the
+fastinfoset rules, then as specified in
+fastinfoset.
For cases defined in +fastinfoset, where
the fragment identifier does not resolve
per the +fastinfoset rules, then as
specified in "xxx/yyy+fastinfoset".
For cases not defined in +fastinfoset, then
as specified in "xxx/yyy+fastinfoset".
Interoperability considerations: n/a
Security considerations: There are no security considerations
inherent in Fast Infoset. Each individual media
type registered with a +fastinfoset suffix can
have additional security considerations.
Contact: Apps Area Working Group (apps-discuss@ietf.org)
Author/Change controller: The Apps Area Working Group. IESG has
change control over this registration.
3.5. The +wbxml Structured Syntax Suffix
The WAP Forum has defined the WAP Binary XML (WBXML) document format
as a binary representation of XML in [WBXML]. This document further
defines the "application/vnd.wap.wbxml" media type. The suffix
"+wbxml" MAY be used with any media type whose representation follows
that established for "application/vnd.wap.wbxml". The Message Type
Structured Syntax Suffix registration form follows:
Name: WAP Binary XML (WBXML) document format
+suffix: +wbxml
References: [WBXML]
Encoding considerations: WBXML is a binary encoding.
Fragment identifier considerations:
The syntax and semantics of fragment
identifiers specified for +wbxml SHOULD be as
specified for "application/vnd.wap.wbxml".
(At publication of this document, there is no
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fragment identification syntax defined for
"application/vnd.wap.wbxml".)
The syntax and semantics for fragment
identifiers for a specific "xxx/yyy+wbxml"
SHOULD be processed as follows:
For cases defined in +wbxml, where the
fragment identifier resolves per the +wbxml
rules, then as specified in +wbxml.
For cases defined in +wbxml, where the
fragment identifier does not resolve per
the +wbxml rules, then as specified in
"xxx/yyy+wbxml".
For cases not defined in +wbxml, then as
specified in "xxx/yyy+wbxml".
Interoperability considerations: n/a
Security considerations: There are no security considerations
inherent in WBXML. Each individual media type
registered with a +wbxml suffix can have
additional security considerations.
Contact: Apps Area Working Group (apps-discuss@ietf.org)
Author/Change controller: The Apps Area Working Group. IESG has
change control over this registration.
3.6. The +zip Structured Syntax Suffix
The ZIP format is a public domain, cross-platform, interoperable file
storage and transfer format, originally defined by PKWARE, Inc.; it
supports compression and encryption and is used as the underlying
representation by a variety of file formats. The media type
"application/zip" has been registered for such files. The suffix
"+zip" MAY be used with any media type whose representation follows
that established for "application/zip". The Message Type Structured
Syntax Suffix registration form follows:
Name: ZIP file storage and transfer format
+suffix: +zip
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References: [ZIP]
Encoding considerations: ZIP is a binary encoding.
Fragment identifier considerations:
The syntax and semantics of fragment
identifiers specified for +zip SHOULD be as
specified for "application/zip". (At
publication of this document, there is no
fragment identification syntax defined for
"application/zip".)
The syntax and semantics for fragment
identifiers for a specific "xxx/yyy+zip"
SHOULD be processed as follows:
For cases defined in +zip, where the
fragment identifier resolves per the +zip
rules, then as specified in +zip.
For cases defined in +zip, where the
fragment identifier does not resolve per
the +zip rules, then as specified in "xxx/
yyy+zip".
For cases not defined in +zip, then as
specified in "xxx/yyy+zip".
Interoperability considerations: n/a
Security considerations: ZIP files support two forms of encryption:
Strong Encryption and AES 128-bit, 192-bit and
256-bit encryption; see the specification for
further details. Each individual media type
registered with a +zip suffix can have additional
security considerations.
Contact: Apps Area Working Group (apps-discuss@ietf.org)
Author/Change controller: The Apps Area Working Group. IESG has
change control over this registration.
4. IANA Considerations
See the Message Type Structured Syntax Suffix registration forms in
Section 3.1 - Section 3.6.
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The following Structured Syntax Suffix registration for "+xml" shall
be used to reflect the information found in [RFC3023], with the
addition of fragment identifier considerations:
Name: Extensible Markup Language (XML)
+suffix: +xml
References: [RFC3023]
Encoding considerations: Per [RFC3023], XML is allowed to be
represented using both 7-bit and 8-bit encodings.
When XML is written in UTF-8, XML is 8bit
compatible ([RFC2045]). When XML is written in
UTF-16 or UTF-32, XML is binary ([RFC2045]).
Fragment identifier considerations:
The syntax and semantics of fragment
identifiers specified for +xml SHOULD be as
specified for "application/xml". (At
publication of this document, the fragment
identification syntax considerations for
"application/xml" are defined in [RFC3023],
sections 5 and 7.)
The syntax and semantics for fragment
identifiers for a specific "xxx/yyy+xml"
SHOULD be processed as follows:
For cases defined in +xml, where the
fragment identifier resolves per the +xml
rules, then as specified in +xml.
For cases defined in +xml, where the
fragment identifier does not resolve per
the +xml rules, then as specified in "xxx/
yyy+xml".
For cases not defined in +xml, then as
specified in "xxx/yyy+xml".
Interoperability considerations: See [RFC3023].
Security considerations: See [RFC3023]
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Contact: Apps Area Working Group (apps-discuss@ietf.org)
Author/Change controller: The Apps Area Working Group. IESG has
change control over this registration.
5. Security Considerations
See the Security considerations sections found in the Message Type
Structured Syntax Suffix registration forms from Section 3.1 -
Section 3.5.
When updating a +<suffix> registration, care should be taken to
review all previously-registered xxx/yyy+<suffix> media types as to
whether they might be affected by the updated +<suffix> registration.
Because the generic fragment identifier processing rules take
precedence over media-type-specific rules, introducing new or
changing existing definitions may break the existing registrations of
specific media types, as well as particular implementations of
applications that process affected media types. Such changes can
introduce interoperability and security issues.
When updating the fragment identifier processing rules for a specific
xxx/yyy+<suffix> media type, care should be taken to review the
generic fragment identifier processing rules for the +<suffix>
registration and not introduce any conflicts. Because the generic
fragment identifier processing rules take precedence over media-type-
specific rules, such conflicting processing requirements should be
ignored by an implementation, but such conflicts can introduce
interoperability and security issues.
Note that [FRAGID-BP] provides additional advice to designers of
fragment identifier rules for media type suffixes and specific media
types.
6. References
6.1. Normative References
[RFC4627] Crockford, D., "The application/json Media Type for
JavaScript Object Notation (JSON)", RFC 4627, July 2006.
[ITU.X690.2008]
International Telecommunications Union, "Recommendation
ITU-T X.690 | ISO/IEC 8825-1 (2008), ASN.1 encoding rules:
Specification of basic encoding Rules (BER), Canonical
encoding rules (CER) and Distinguished encoding rules
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(DER)", ITU-T Recommendation X.690, November 2008.
[ITU.X891.2005]
International Telecommunications Union, "Recommendation
ITU-T X.891 | ISO/IEC 24824-1 (2007), Generic applications
of ASN.1: Fast infoset", ITU-T Recommendation X.891,
May 2005.
[WBXML] Open Mobile Alliance, "Binary XML Content Format
Specification", OMA Wireless Access Protocol WAP-192-
WBXML-20010725-a, July 2001.
[ZIP] PKWARE, Inc., "APPNOTE.TXT - .ZIP File Format
Specification", PKWARE .ZIP File Format Specification -
Version 6.3.2, September 2007.
[RFC2045] Freed, N. and N. Borenstein, "Multipurpose Internet Mail
Extensions (MIME) Part One: Format of Internet Message
Bodies", RFC 2045, November 1996.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3023] Murata, M., St. Laurent, S., and D. Kohn, "XML Media
Types", RFC 3023, January 2001.
6.2. Informative References
[I-D.ietf-appsawg-media-type-regs]
Freed, N., Klensin, J., and T. Hansen, "Media Type
Specifications and Registration Procedures",
draft-ietf-appsawg-media-type-regs-14 (work in progress),
June 2012.
[FRAGID-BP]
Tennison, J., "Best Practices for Fragment Identifiers and
Media Type Definitions", July 2012,
<http://www.w3.org/TR/fragid-best-practices/>.
Appendix A. Change History
This section is to be removed before publication.
draft-ietf-appsawg-media-type-suffix-regs-07 Added information based
on IANA and GEN-ART reviews.
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draft-ietf-appsawg-media-type-suffix-regs-06 Clarified why this
document updates RFC 3023.
draft-ietf-appsawg-media-type-suffix-regs-05 Added an Informative
reference to
http://www.w3.org/TR/fragid-best-practices/.
Minor editorial changes.
draft-ietf-appsawg-media-type-suffix-regs-03 Added generic fragment
idenfier rules to +ber/+der to make them
consistant with other registrations.
Added some warning about how adding/changing
fragment identifier rules for a +suffix can
affect fragment identifier processing rules for
previously registered xxx/yyy+suffix media types.
draft-ietf-appsawg-media-type-suffix-regs-02 Added BER/DER security
considerations.
Reworked fragment identifier wording some more.
draft-ietf-appsawg-media-type-suffix-regs-01 Reordered the sections.
Cleaned up some MUSTard.
Fixed some references.
Added encoding considerations.
Reworked fragment identifier wording.
draft-ietf-appsawg-media-type-suffix-regs-00 Added the fragment
identifier consideration sections.
Added a note about +xml fragment identifier
considerations.
draft-hansen-media-type-suffix-regs-02 Added +zip.
Fixed up the ISO document references.
Minor changes.
draft-hansen-media-type-suffix-regs-01 Added +ber.
Minor changes.
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Authors' Addresses
Tony Hansen
AT&T Laboratories
200 Laurel Ave. South
Middletown, NJ 07748
USA
Email: tony+sss@maillennium.att.com
Alexey Melnikov
Isode Ltd
5 Castle Business Village
36 Station Road
Hampton, Middlesex TW12 2BX
UK
Email: Alexey.Melnikov@isode.com
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