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Network Working Group S. Legg
Request for Comments: 4913 eB2Bcom
Category: Experimental July 2007
Abstract Syntax Notation X (ASN.X) Representation
of Encoding Instructions for
the Generic String Encoding Rules (GSER)
Status of This Memo
This memo defines an Experimental Protocol for the Internet
community. It does not specify an Internet standard of any kind.
Discussion and suggestions for improvement are requested.
Distribution of this memo is unlimited.
Copyright Notice
Copyright (C) The IETF Trust (2007).
Abstract
Abstract Syntax Notation X (ASN.X) is an Extensible Markup Language
(XML) representation for Abstract Syntax Notation One (ASN.1)
specifications. This document specifies the ASN.X representation of
encoding instructions for the Generic String Encoding Rules (GSER).
Table of Contents
1. Introduction ....................................................2
2. Conventions .....................................................2
3. EncodingInstructionAssignmentList Translation ...................3
4. EncodingInstruction Translation .................................3
4.1. ChoiceOfStringsInstruction Translation .....................3
5. Security Considerations .........................................4
6. Normative References ............................................4
Appendix A. ASN.1 for GSER Encoding Instruction Notation ...........6
Appendix B. ASN.X for GSER Encoding Instruction Notation ...........7
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RFC 4913 ASN.X: GSER Encoding Instructions July 2007
1. Introduction
Abstract Syntax Notation X (ASN.X) [ASN.X] is an Extensible Markup
Language (XML) [XML10][XML11] representation for Abstract Syntax
Notation One (ASN.1) [X.680] specifications. The ASN.X
representation for the ASN.1 basic notation [X.680] [X.680-1] is
described elsewhere [ASN.X].
The grammar of ASN.1 permits the application of encoding instructions
[X.680-1], through type prefixes and encoding control sections, that
modify how abstract values are encoded by nominated encoding rules.
The generic notation for type prefixes and encoding control sections
is defined by the ASN.1 basic notation; however, the notation for
specific encoding instructions, i.e., the EncodingInstruction and
EncodingInstructionAssignmentList productions of the notation, are
defined separately for each set of encoding rules using encoding
instructions. This document specifies the ASN.X representation for
EncodingInstructionAssignmentList and EncodingInstruction as they are
defined for the Generic String Encoding Rules (GSER) [GSER][GSEREI].
ASN.X is defined in terms of rules for translating from an ASN.1
specification. This does not preclude an ASN.X module being written
directly without a pre-existing ASN.1 module; however, such an ASN.X
module is considered valid if and only if there exists, in principle,
an ASN.1 module that when translated would yield the ASN.X module.
By design, an ASN.X module is also the Robust XML Encoding Rules
(RXER) [RXER] encoding of an ASN.1 value. The ASN.1 type definitions
for such values, insofar as they pertain to the ASN.1 basic notation,
are provided elsewhere [ASN.X]; however, this document provides the
ASN.1 type definitions for representing GSER encoding instructions as
abstract values. These definitions appear in Appendix A.
The ASN.X translation of the ASN.1 module in Appendix A is presented
in Appendix B.
The General Considerations of the specification for ASN.X [ASN.X]
also apply here.
2. Conventions
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", and "MAY" in this document are
to be interpreted as described in BCP 14, RFC 2119 [BCP14]. The key
word "OPTIONAL" is exclusively used with its ASN.1 meaning.
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RFC 4913 ASN.X: GSER Encoding Instructions July 2007
A reference to an ASN.1 production [X.680] (e.g., Type, NamedType) is
a reference to the text in an ASN.1 specification corresponding to
that production.
The description of the translation of GSER encoding instructions into
ASN.X makes use of definitions from the XML Information Set (Infoset)
[INFOSET]. In particular, information item property names follow the
Infoset convention of being shown in square brackets, e.g.,
[local name]. Literal values of Infoset properties are enclosed in
double quotes; however, the double quotes are not part of the
property values. In the sections that follow, "information item"
will be abbreviated to "item", e.g., "element information item" is
abbreviated to "element item". Element items will be referred to by
their [local name] in angle brackets, e.g., "the <type> element item"
means the element item with the [local name] "type".
3. EncodingInstructionAssignmentList Translation
As described in the specification for ASN.X [ASN.X], the translation
of an EncodingControlSection for GSER is an element item with the
[local name] "GSER". The translation of the
EncodingInstructionAssignmentList in such an EncodingControlSection
determines the content of the <GSER> element item.
The EncodingInstructionAssignmentList for GSER is currently defined
to be empty [GSEREI]; therefore, the [attributes] and [children] of
the <GSER> element item are both empty.
4. EncodingInstruction Translation
The translation of an EncodingInstruction for GSER can appear in the
translation of an EncodingPrefix. The translation for an
EncodingPrefix is described by the specification for ASN.X.
The translation of an EncodingInstruction for GSER is the translation
of the ChoiceOfStringsInstruction in the EncodingInstruction
(currently the only defined encoding instruction for GSER).
4.1. ChoiceOfStringsInstruction Translation
The translation of a ChoiceOfStringsInstruction is an element item
with the [local name] "choiceOfStrings".
If the ChoiceOfStringsInstruction has an AlternativesPrecedence, then
an attribute item with the [local name] "precedence" SHALL be added
to the [attributes] of the <choiceOfStrings> element item. The
[normalized value] of this attribute item is the white space
separated list of qualified names for the expanded names [XMLNS10] of
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RFC 4913 ASN.X: GSER Encoding Instructions July 2007
the NamedType instances (see [RXEREI]) corresponding to the
identifiers nested in the PrecedenceList in the
AlternativesPrecedence.
Example
[GSER:CHOICE-OF-STRINGS PRECEDENCE utf8 visible] CHOICE {
visible [RXER:NAME "ascii"] VisibleString,
utf8 UTF8String
}
<type xmlns:asnx="urn:ietf:params:xml:ns:asnx">
<prefixed>
<GSER><choiceOfStrings precedence="utf8 ascii"/></GSER>
<type>
<choice>
<element name="ascii" identifier="visible"
type="asnx:VisibleString"/>
<element name="utf8" type="asnx:UTF8String"/>
</choice>
</type>
</prefixed>
</type>
5. Security Considerations
The ASN.X translation of a GSER encoding instruction is semantically
equivalent to the original GSER encoding instruction. The security
considerations that apply to an application built from an original
ASN.1 specification with GSER encoding instructions apply equally to
an application built from the ASN.X translation of the ASN.1
specification.
See the main specification for ASN.X [ASN.X] for security
considerations related to ASN.X modules.
6. Normative References
[BCP14] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[GSER] Legg, S., "Generic String Encoding Rules (GSER) for ASN.1
Types", RFC 3641, October 2003.
[GSEREI] Legg, S., "Encoding Instructions for the Generic String
Encoding Rules (GSER)", RFC 4792, January 2007.
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RFC 4913 ASN.X: GSER Encoding Instructions July 2007
[RXER] Legg, S. and D. Prager, "Robust XML Encoding Rules (RXER)
for Abstract Syntax Notation One (ASN.1)", RFC 4910, July
2007.
[RXEREI] Legg, S., "Encoding Instructions for the Robust XML
Encoding Rules (RXER)", RFC 4911, July 2007.
[ASN.X] Legg, S., "Abstract Syntax Notation X (ASN.X)", RFC 4912,
July 2007.
[X.680] ITU-T Recommendation X.680 (07/02) | ISO/IEC 8824-1,
Information technology - Abstract Syntax Notation One
(ASN.1): Specification of basic notation.
[X.680-1] ITU-T Recommendation X.680 (2002) Amendment 1 (10/03) |
ISO/IEC 8824-1:2002/Amd 1:2004, Support for EXTENDED-XER.
[XML10] Bray, T., Paoli, J., Sperberg-McQueen, C., Maler, E. and
F. Yergeau, "Extensible Markup Language (XML) 1.0 (Fourth
Edition)", W3C Recommendation,
http://www.w3.org/TR/2006/REC-xml-20060816, August 2006.
[XML11] Bray, T., Paoli, J., Sperberg-McQueen, C., Maler, E.,
Yergeau, F., and J. Cowan, "Extensible Markup Language
(XML) 1.1 (Second Edition)", W3C Recommendation,
http://www.w3.org/TR/2006/REC-xml11-20060816, August 2006.
[XMLNS10] Bray, T., Hollander, D., Layman, A., and R. Tobin,
"Namespaces in XML 1.0 (Second Edition)", W3C
Recommendation,
http://www.w3.org/TR/2006/REC-xml-names-20060816, August
2006.
[INFOSET] Cowan, J. and R. Tobin, "XML Information Set (Second
Edition)", W3C Recommendation,
http://www.w3.org/TR/2004/REC-xml-infoset-20040204,
February 2004.
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RFC 4913 ASN.X: GSER Encoding Instructions July 2007
Appendix A. ASN.1 for GSER Encoding Instruction Notation
This appendix is normative.
GSER-EncodingInstructionNotation
{ iso(1) identified-organization(3) dod(6)
internet(1) private(4) enterprise(1)
xmled(21472) asnx(1) module(0) gser-ei-notation(2) }
-- Copyright (C) The IETF Trust (2007). This version of
-- this ASN.1 module is part of RFC 4913; see the RFC itself
-- for full legal notices.
--
-- Regarding this ASN.1 module or any portion of it, the author
-- makes no guarantees and is not responsible for any damage
-- resulting from its use. The author grants irrevocable permission
-- to anyone to use, modify, and distribute it in any way that does
-- not diminish the rights of anyone else to use, modify, and
-- distribute it, provided that redistributed derivative works do
-- not contain misleading author or version information.
-- Derivative works need not be licensed under similar terms.
DEFINITIONS
RXER INSTRUCTIONS
AUTOMATIC TAGS
EXTENSIBILITY IMPLIED ::= BEGIN
IMPORTS
PrecedenceList
FROM AbstractSyntaxNotation-X
{ iso(1) identified-organization(3) dod(6)
internet(1) private(4) enterprise(1)
xmled(21472) asnx(1) module(0) notation(1) }
;
GSER-EncodingInstruction ::= [SINGULAR-INSERTIONS] CHOICE {
choiceOfStrings GSER-ChoiceOfStringsInstruction
}
GSER-EncodingInstructionAssignmentList ::= SEQUENCE { }
GSER-ChoiceOfStringsInstruction ::= SEQUENCE {
precedence [ATTRIBUTE] PrecedenceList OPTIONAL
}
ENCODING-CONTROL RXER
SCHEMA-IDENTITY "urn:oid:1.3.6.1.4.1.21472.1.0.2"
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TARGET-NAMESPACE "urn:ietf:params:xml:ns:asnx" PREFIX "asnx"
END
Appendix B. ASN.X for GSER Encoding Instruction Notation
This appendix is non-normative.
<?xml version="1.0"?>
<asnx:module xmlns:asnx="urn:ietf:params:xml:ns:asnx"
name="GSER-EncodingInstructionNotation"
identifier="1.3.6.1.4.1.21472.1.0.2"
schemaIdentity="urn:oid:1.3.6.1.4.1.21472.1.0.2"
targetNamespace="urn:ietf:params:xml:ns:asnx"
targetPrefix="asnx"
extensibilityImplied="true">
<annotation>
Copyright (C) The IETF Trust (2007). This version of
this ASN.X module is part of RFC 4913; see the RFC itself
for full legal notices.
Regarding this ASN.X module or any portion of it, the author
makes no guarantees and is not responsible for any damage
resulting from its use. The author grants irrevocable permission
to anyone to use, modify, and distribute it in any way that does
not diminish the rights of anyone else to use, modify, and
distribute it, provided that redistributed derivative works do
not contain misleading author or version information.
Derivative works need not be licensed under similar terms.
</annotation>
<import name="AbstractSyntaxNotation-X"
identifier="1.3.6.1.4.1.21472.1.0.1"
schemaIdentity="urn:oid:1.3.6.1.4.1.21472.1.0.1"
namespace="urn:ietf:params:xml:ns:asnx"/>
<namedType name="GSER-EncodingInstruction">
<type>
<choice insertions="singular">
<element name="choiceOfStrings"
type="asnx:GSER-ChoiceOfStringsInstruction"/>
</choice>
</type>
</namedType>
<namedType name="GSER-EncodingInstructionAssignmentList">
<type>
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RFC 4913 ASN.X: GSER Encoding Instructions July 2007
<sequence/>
</type>
</namedType>
<namedType name="GSER-ChoiceOfStringsInstruction">
<type>
<sequence>
<optional>
<attribute name="precedence" type="asnx:PrecedenceList"/>
</optional>
</sequence>
</type>
</namedType>
</asnx:module>
Author's Address
Dr. Steven Legg
eB2Bcom
Suite 3, Woodhouse Corporate Centre
935 Station Street
Box Hill North, Victoria 3129
AUSTRALIA
Phone: +61 3 9896 7830
Fax: +61 3 9896 7801
EMail: steven.legg@eb2bcom.com
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RFC 4913 ASN.X: GSER Encoding Instructions July 2007
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