Network Working Group J. Sermersheim
Internet-Draft Novell, Inc
Expires: August 5, 2005 H. Chu
Symas Corp.
February 2005
The LDAP Change Sequence Number
draft-sermersheim-ldap-csn-02.txt
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Copyright Notice
Copyright (C) The Internet Society (2005).
Abstract
This document defines a syntax schema element for the Lightweight
Directory Access Protocol (LDAP) which is used to hold a Change
Sequence Number (CSN). In general, a change sequence number
represents the place and time that a directory entity was changed.
It may be used by various attributes for various LDAP replication,
and synchronization applications.
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Discussion Forum
Technical discussion of this document will take place on the IETF
LDAP Extensions mailing list <[email protected]>. Please send
editorial comments directly to the author(s).
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . 3
2. Conventions . . . . . . . . . . . . . . . . . . . . . 4
3. Syntaxes . . . . . . . . . . . . . . . . . . . . . . . 5
3.1. ChangeSequenceNumber Syntax . . . . . . . . . . . . . 5
3.2. UTF8String . . . . . . . . . . . . . . . . . . . . . . 6
4. Matching Rules . . . . . . . . . . . . . . . . . . . . 7
4.1. changeSequenceNumberMatch Matching Rule . . . . . . . 7
4.2. utf8CodePointMatch Matching Rule . . . . . . . . . . . 7
4.3. changeSequenceNumberOrderingMatch Matching Rule . . . 7
4.4. utf8CodePointOrderingMatch Matching Rule . . . . . . . 8
5. Attributes . . . . . . . . . . . . . . . . . . . . . . 9
5.1. entryCSN Attribute . . . . . . . . . . . . . . . . . . 9
6. Security Considerations . . . . . . . . . . . . . . . 10
7. Normative References . . . . . . . . . . . . . . . . . 10
Appendix A. IANA Considerations . . . . . . . . . . . . . . . . . 11
A.1. LDAP Object Identifier Registrations . . . . . . . . . 11
A.2. LDAP Descriptor Registrations . . . . . . . . . . . . 11
Authors' Addresses . . . . . . . . . . . . . . . . . . 15
Intellectual Property and Copyright Statements . . . . 16
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1. Introduction
A number of technologies have been documented, implemented and
experimented with which in one way or another seek to replicate, or
synchronize directory data. A common need among these technologies
is to determine which of two copies of an element represents the
latest or most authoritative data. Part of meeting this need
involves associating a change sequence number to an element copy at
the time of an update to that element. When replication or
synchronization occurs, the change sequence numbers associated with
directory elements can be used to decide which element's data will be
copied to the other element(s).
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2. Conventions
Imperative keywords defined in [RFC2119] are used in this document,
and carry the meanings described there.
The General Considerations of [I-D.ietf-ldapbis-syntaxes] apply to
the syntax definition in this document.
The terms "directory element" and "element" refer to data held in a
directory and may apply to an attribute value, attribute, entry, or
any other identifiable directory entity.
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3. Syntaxes
3.1. ChangeSequenceNumber Syntax
A value of the ChangeSequenceNumber syntax is the time of a change
along with a replicaID which represents the Directory System Agent
(DSA) holding the element when it was changed. There are also two
sequence numbers used to disambiguate directory entities that are
changed at the same time and place.
The Abstract Syntax Notation One (ASN.1)[X680] type corresponding to
this syntax is defined as follows:
ChangeSequenceNumber ::= SEQUENCE {
time GeneralizedTime,
timeCount INTEGER (0 .. MaxInt),
replicaID UTF8String,
changeCount INTEGER (0 .. MaxInt)}
MaxInt INTEGER ::= 2147483647 -- (2^^31 - 1) --
GeneralizedTime is defined in [X680]. Local time without a
differential SHALL NOT be used.
UTF8String is defined below.
The LDAP-specific encoding of a value of this syntax is the Generic
String Encoding Rules (GSER)[RFC3641] encoding of the ASN.1 type.
Example:
{ time "196701160315-0700",
timeCount 0,
replicaID "DSA666",
changeCount 1 }
The following is an LDAP syntax description [RFC2252] suitable for
publication in the subschema.
( IANA-ASSIGNED-OID.1 DESC 'ChangeSequenceNumber' )
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3.2. UTF8String
The UTF8String syntax is used to express a string of characters from
the [ISO.10646-1.1993] character set (a superset of [Unicode]),
encoded following the [UTF-8] algorithm. Note that Unicode
characters U+0000 through U+007F are the same as ASCII 0 through 127,
respectively, and have the same single octet UTF-8 encoding. Other
Unicode characters have a multiple octet UTF-8 encoding.
UTF8String::= OCTET STRING -- UTF-8 encoded,
-- [ISO10646] characters
The LDAP-specific encoding of a value of this syntax are the UTF-8
encoded characters themselves.
The following is an LDAP syntax description [RFC2252] suitable for
publication in the subschema.
( IANA-ASSIGNED-OID.2 DESC 'UTF8String' )
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4. Matching Rules
4.1. changeSequenceNumberMatch Matching Rule
The changeSequenceNumberMatch rule compares an assertion value of the
ChangeSequenceNumber syntax to a value of a syntax (e.g the
ChangeSequenceNumber syntax) whose corresponding ASN.1 type is
ChangeSequenceNumber.
The rule evaluates to TRUE if and only if each of the components of
the two values evaluate to TRUE using the following rules:
o The time component uses generalizedTimeMatch.
o The timeCount and changeCount components use integerMatch.
o The replicaID component uses utf8CodePointMatch.
The following is a LDAP matching rule description [RFC2252] suitable
for publication in the subschema.
( IANA-ASSIGNED-OID.3 NAME changeSequenceNumberMatch SYNTAX IANA-
ASSIGNED-OID.1 )
4.2. utf8CodePointMatch Matching Rule
The utf8CodePointMatch rule compares an assertion value of the
UTF8String syntax to a value of a syntax (e.g the UTF8String syntax)
whose corresponding ASN.1 type is UTF8String. The rule evaluates to
TRUE if and only if the code points [Unicode] of each of the
characters is equal.
The following is a LDAP matching rule description [RFC2252] suitable
for publication in the subschema.
( IANA-ASSIGNED-OID.4 NAME utf8CodePointMatch SYNTAX IANA-ASSIGNED-
OID.2 )
4.3. changeSequenceNumberOrderingMatch Matching Rule
The changeSequenceNumberOrderingMatch rule compares the
ChangeSequenceNumber ordering of an assertion value of the
ChangeSequenceNumber syntax to a value of a syntax (e.g the
ChangeSequenceNumber syntax) whose corresponding ASN.1 type is
ChangeSequenceNumber.
When evaluating ChangeSequenceNumber values for ordering, the
components are evaluated in this order: time, timeCount, replicaID,
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changeCount. If a component evaluates to TRUE using the appropriate
ordering matching rule specified below, then the rule evaluates to
TRUE. Otherwise if the component evaluates to TRUE using the
equality matching rule specified below, the next component is
evaluated. Otherwise the changeSequenceNumberOrderingMatch rule
evaluates to FALSE or Undefined as appropriate.
o The time components of the two values are evaluated for ordering
using GeneralizedTimeOrderingMatch, and evaluated for equality
using GeneralizedTimeMatch.
o The timeCount and changeCount components of the two values are
evaluated for ordering using integerOrderingMatch, and evaluated
for equality using integerMatch.
o The replicaID components of the two values are evaluated for
ordering using utf8CodePointOrderingMatch and evaluated for
equality using utf8CodePointMatch.
The following is a LDAP matching rule description [RFC2252] suitable
for publication in the subschema.
( IANA-ASSIGNED-OID.5 NAME changeSequenceNumberOrderingMatch SYNTAX
SYNTAX IANA-ASSIGNED-OID.1 )
4.4. utf8CodePointOrderingMatch Matching Rule
The utf8CodePointOrderingMatch rule compares the ordering of an
assertion value of the UTF8String syntax to a stored value of a
syntax (e.g. the UTF8String syntax) whose corresponding ASN.1 type is
UTF8String.
The rule evaluates to TRUE if, and only if, in the code point
collation order, the stored value character string appears earlier
than the assertion value character string, i.e., the stored value is
"less than" the assertion value.
The following is a LDAP matching rule description [RFC2252] suitable
for publication in the subschema.
( IANA-ASSIGNED-OID.6 NAME utf8CodePointOrderingMatch SYNTAX IANA-
ASSIGNED-OID.2 )
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5. Attributes
5.1. entryCSN Attribute
The entryCSN operational attribute provides the CSN of the last
update applied to the entry.
The following is a LDAP attribute type description [RFC2252] suitable
for publication in the subschema.
( IANA-ASSIGNED-OID.7 NAME entryCSN DESC 'CSN of the entry content'
EQUALITY changeSequenceNumberMatch ORDERING
changeSequenceNumberOrderingMatch SYNTAX IANA-ASSIGNED-OID.1 SINGLE-
VALUE NO-USER-MODIFICATION USAGE directoryOperation )
Servers MAY assign a CSN to each entry upon its addition to the
directory and provide the entry's CSN as the value of the entryCSN
operational attribute. If the entryCSN attribute is assigned, the
attribute SHOULD be updated upon every update of the entry.
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6. Security Considerations
7. Normative References
[I-D.ietf-ldapbis-syntaxes]
Legg, S., "Lightweight Directory Access Protocol (LDAP):
Syntaxes and Matching Rules",
draft-ietf-ldapbis-syntaxes-11 (work in progress),
June 2005.
[ISO.10646-1.1993]
International Organization for Standardization,
"Information Technology - Universal Multiple-octet coded
Character Set (UCS) - Part 1: Architecture and Basic
Multilingual Plane", ISO Standard 10646-1, May 1993.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2252] Wahl, M., Coulbeck, A., Howes, T., and S. Kille,
"Lightweight Directory Access Protocol (v3): Attribute
Syntax Definitions", RFC 2252, December 1997.
[RFC3383] Zeilenga, K., "Internet Assigned Numbers Authority (IANA)
Considerations for the Lightweight Directory Access
Protocol (LDAP)", BCP 64, RFC 3383, September 2002.
[RFC3641] Legg, S., "Generic String Encoding Rules (GSER) for ASN.1
Types", RFC 3641, October 2003.
[UTF-8] International Organization for Standardization,
"Information Technology - Universal Multiple-octet coded
Character Set (UCS) - Amendment 2: UCS Transformation
Format 8 (UTF-8)", ISO Standard 10646-1 Addendum 2,
October 1996.
[Unicode] The Unicode Consortium, "The Unicode Standard", 2004.
[X680] International Telecommunications Union, "Abstract Syntax
Notation One (ASN.1): Specification of basic notation",
ITU-T Recommendation X.680, July 2002.
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Appendix A. IANA Considerations
Registration of the following values is requested [RFC3383].
A.1. LDAP Object Identifier Registrations
It is requested that IANA register upon Standards Action an LDAP
Object Identifier in identifying the protocol elements defined in
this technical specification. The following registration template is
provided:
Subject: Request for LDAP OID Registration
Person & email address to contact for further information:
Jim Sermersheim
[email protected]
Specification: RFCXXXX
Author/Change Controller: IESG
Comments:
Seven delegations will be made under the assigned OID:
IANA-ASSIGNED-OID.1 ChangeSequenceNumber: LDAP Syntax
IANA-ASSIGNED-OID.2 UTF8String: LDAP Syntax
IANA-ASSIGNED-OID.3 changeSequenceNumberMatch: LDAP Matching Rule
IANA-ASSIGNED-OID.4 utf8CodePointMatch: LDAP Matching Rule
IANA-ASSIGNED-OID.5 changeSequenceNumberOrderingMatch: LDAP
Matching Rule
IANA-ASSIGNED-OID.6 utf8CodePointOrderingMatch: LDAP Matching Rule
IANA-ASSIGNED-OID.7 entryCSN: LDAP Attribute Type
A.2. LDAP Descriptor Registrations
It is requested that IANA register upon Standards Action the LDAP
descriptors described in this document. The following registration
templates are given:
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Subject: Request for LDAP Descriptor Registration
Descriptor (short name): ChangeSequenceNumber
Object Identifier: IANA-ASSIGNED-OID.1
Person & email address to contact for further information:
Jim Sermersheim
[email protected]
Usage: other
Specification: RFCXXXX
Author/Change Controller: IESG
Comments: LDAP Syntax
Subject: Request for LDAP Descriptor Registration
Descriptor (short name): UTF8String
Object Identifier: IANA-ASSIGNED-OID.2
Person & email address to contact for further information:
Jim Sermersheim
[email protected]
Usage: other
Specification: RFCXXXX
Author/Change Controller: IESG
Comments: LDAP Syntax
Subject: Request for LDAP Descriptor Registration
Descriptor (short name): changeSequenceNumberMatch
Object Identifier: IANA-ASSIGNED-OID.3
Person & email address to contact for further information:
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Jim Sermersheim
[email protected]
Usage: other
Specification: RFCXXXX
Author/Change Controller: IESG
Comments: LDAP Matching Rule
Subject: Request for LDAP Descriptor Registration
Descriptor (short name): utf8CodePointMatch
Object Identifier: IANA-ASSIGNED-OID.4
Person & email address to contact for further information:
Jim Sermersheim
[email protected]
Usage: other
Specification: RFCXXXX
Author/Change Controller: IESG
Comments: LDAP Matching Rule
Subject: Request for LDAP Descriptor Registration
Descriptor (short name): changeSequenceNumberOrderingMatch
Object Identifier: IANA-ASSIGNED-OID.5
Person & email address to contact for further information:
Jim Sermersheim
[email protected]
Usage: other
Specification: RFCXXXX
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Author/Change Controller: IESG
Comments: LDAP Matching Rule
Subject: Request for LDAP Descriptor Registration
Descriptor (short name): utf8CodePointOrderingMatch
Object Identifier: IANA-ASSIGNED-OID.6
Person & email address to contact for further information:
Jim Sermersheim
[email protected]
Usage: other
Specification: RFCXXXX
Author/Change Controller: IESG
Comments: LDAP Matching Rule
Subject: Request for LDAP Descriptor Registration
Descriptor (short name): entryCSN
Object Identifier: IANA-ASSIGNED-OID.7
Person & email address to contact for further information:
Jim Sermersheim
[email protected]
Usage: Attribute Type
Specification: RFCXXXX
Author/Change Controller: IESG
Comments: LDAP Attribute Type
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Authors' Addresses
Jim Sermersheim
Novell, Inc
1800 South Novell Place
Provo, Utah 84606
USA
Phone: +1 801 861-3088
Email: [email protected]
Howard Chu
Symas Corp.
18740 Oxnard Street, Suite 313A
Tarzana, California 91356
USA
Phone: +1 818 757-7087
Email: [email protected]
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