ISO/IEC 9594-9:2014

Information technology — Open Systems Interconnection — The Directory — Part 9: Replication

ISO/IEC 9594 has been produced to facilitate the interconnection of information processing systems to provide directory services. A set of such systems, together with the directory information that they hold, can be viewed as an integrated whole, called the Directory. The information held by the Directory, collectively known as the Directory Information Base (DIB), is typically used to facilitate communication between, with or about objects such as application entities, people, terminals and distribution lists. ISO/IEC 9594-9:2014 specifies a shadow service which Directory system agents (DSAs) may use to replicate Directory information. The service allows Directory information to be replicated among DSAs to improve service to Directory users, and provides for the automatic updating of this information.

Technologies de l'information — Interconnexion de systèmes ouverts (OSI) — L'annuaire — Partie 9: Duplication

General Information

• Status: Withdrawn
• Publication Date: 24-Feb-2014
• Withdrawal Date: 24-Feb-2014
• ICS: 35.100.70 - Application layer
• Technical Committee: ISO/IEC JTC 1/SC 6 - Telecommunications and information exchange between systems
• Drafting Committee: ISO/IEC JTC 1/SC 6 - Telecommunications and information exchange between systems
• Current Stage: 9599 - Withdrawal of International Standard
• Completion Date: 05-May-2017

Relations

• Revised: ISO/IEC 9594-9:2017 - Information technology — Open Systems Interconnection — The Directory — Part 9: Replication
• Effective Date: 10-Dec-2016
• Revises: ISO/IEC 9594-9:2008 - Information technology — Open Systems Interconnection — The Directory: Replication — Part 9:
• Effective Date: 31-Aug-2013

Standards Content (Sample)

INTERNATIONAL ISO/IEC
STANDARD 9594-9
Sixth edition
2014-03-01


Information technology — Open Systems
Interconnection — The Directory —
Part 9:
Replication
Technologies de l'information — Interconnexion de systèmes ouverts
(OSI) — L'annuaire
Partie 9: Duplication





Reference number
ISO/IEC 9594-9:2014(E)
©
ISO/IEC 2014

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ISO/IEC 9594-9:2014(E)

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ii © ISO/IEC 2014 – All rights reserved

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ISO/IEC 9594-9:2014(E)
Foreword
ISO (the International Organization for Standardization) and IEC (the International Electrotechnical
Commission) form the specialized system for worldwide standardization. National bodies that are members of
ISO or IEC participate in the development of International Standards through technical committees
established by the respective organization to deal with particular fields of technical activity. ISO and IEC
technical committees collaborate in fields of mutual interest. Other international organizations, governmental
and non-governmental, in liaison with ISO and IEC, also take part in the work. In the field of information
technology, ISO and IEC have established a joint technical committee, ISO/IEC JTC 1.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of the joint technical committee is to prepare International Standards. Draft International
Standards adopted by the joint technical committee are circulated to national bodies for voting. Publication as
an International Standard requires approval by at least 75 % of the national bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO and IEC shall not be held responsible for identifying any or all such patent rights.
ISO/IEC 9594-9 was prepared by Joint Technical Committee ISO/IEC JTC 1, Information technology,
Subcommittee SC 6, Telecommunications and information exchange between systems, in collaboration with
ITU-T. The identical text is published as Rec. ITU-T X.525 (10/2012).
This sixth edition cancels and replaces the fifth edition (ISO/IEC 9594-9:2008), which has been
technically revised. It also incorporates the Technical Corrigendum ISO/IEC 9594-9:2008/Cor.1:2011.
ISO/IEC 9594 consists of the following parts, under the general title Information technology — Open Systems
Interconnection — The Directory:
— Part 1: Overview of concepts, models and services
— Part 2: Models
— Part 3: Abstract service definition
— Part 4: Procedures for distributed operation
— Part 5: Protocol specifications
— Part 6: Selected attribute types
— Part 7: Selected object classes
— Part 8: Public-key and attribute certificate frameworks
— Part 9: Replication

© ISO/IEC 2014 – All rights reserved

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CONTENTS
Page
1 Scope . 1
2 Normative references . 1
2.1 Identical Recommendations | International Standards . 1
3 Definitions . 2
3.1 Basic Directory definitions . 2
3.2 Directory model definitions . 2
3.3 Abstract service definitions . 2
3.4 Distributed operation definitions . 2
3.5 Protocol definitions . 2
3.6 Replication definitions . 2
4 Abbreviations . 3
5 Conventions . 4
6 Replication in the Directory . 4
6.1 Caching . 4
6.2 Shadowing . 4
6.3 Shadowing functional model . 5
7 Shadowing in the Directory . 6
7.1 Shadowing agreement . 7
7.2 Shadowed information . 7
7.3 Shadow operations . 11
7.4 DSA Shadow Bind and DSA Shadow Unbind operation . 12
8 Shadow operational binding . 12
8.1 Shadow operational binding type characteristics . 12
8.2 DSA procedures for operational binding management . 13
8.3 Operational binding . 14
9 Shadowing agreement . 15
9.1 Shadowing agreement specification . 15
9.2 Unit of replication . 16
9.3 Update mode . 21
10 Directory information shadow service . 22
10.1 Shadow supplier initiated service . 22
10.2 Shadow consumer initiated service . 23
11 Shadow operations . 23
11.1 Coordinate Shadow Update operation . 23
11.2 Request Shadow Update operation . 25
11.3 Update Shadow operation . 27
12 Shadow error . 30
12.1 Shadow error problems . 31
12.2 Last update . 31
12.3 Update window . 31
12.4 Common results . 32
Annex A – Directory shadow abstract service in ASN.1 . 33
Annex B – Amendments and corrigenda . 39


 Rec. ITU-T X.525 (10/2012) iii

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Introduction
This Recommendation | International Standard, together with other Recommendations | International Standards, has
been produced to facilitate the interconnection of information processing systems to provide Directory services. A set of
such systems, together with the Directory information that they hold, can be viewed as an integrated whole, called the
Directory. The information held by the Directory, collectively known as the Directory Information Base (DIB) is
typically used to facilitate communication between, with or about objects such as application-entities, people, terminals
and distribution lists.
The Directory plays a significant role in Open Systems Interconnection, whose aim is to allow, with a minimum of
technical agreement outside of the interconnection standards themselves, the interconnection of information processing
systems:
– from different manufacturers;
– under different managements;
– of different levels of complexity; and
– of different ages.
This Recommendation | International Standard defines the replication capabilities provided by Directory system agents
(DSAs) to improve the level of service to Directory users.
This Recommendation | International Standard provides the foundation frameworks upon which industry profiles can be
defined by other standards groups and industry forums. Many of the features defined as optional in these frameworks
may be mandated for use in certain environments through profiles. This seventh edition technically revises and
enhances the sixth edition of this Recommendation | International Standard.
This seventh edition specifies versions 1 and 2 of the Directory protocols.
The first and second editions specified only version 1. Most of the services and protocols specified in this edition are
designed to function under version 1. However, some enhanced services and protocols, e.g., signed errors, will not
function unless all Directory entities involved in the operation have negotiated version 2. Whichever version has been
negotiated, differences between the services and between the protocols defined in the six editions, except for those
specifically assigned to version 2, are accommodated using the rules of extensibility defined in Rec. ITU-T X.519 |
ISO/IEC 9594-5.
Annex A, which is an integral part of this Recommendation | International Standard, provides the ASN.1 module for the
Directory shadow abstract service.
Annex B, which is not an integral part of this Recommendation | International Standard, lists the amendments and
defect reports that have been incorporated to form this edition of this Recommendation | International Standard.
iv Rec. ITU-T X.525 (10/2012)

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ISO/IEC 9594-9:2014 (E)
INTERNATIONAL STANDARD

RECOMMENDATION ITU-T
Information technology – Open Systems Interconnection –
The Directory: Replication
1 Scope
This Recommendation | International Standard specifies a shadow service which Directory system agents (DSAs) may
use to replicate Directory information. The service allows Directory information to be replicated among DSAs to
improve service to Directory users. The shadowed information is updated, using the defined protocol, thereby
improving the service provided to users of the Directory.
2 Normative references
The following Recommendations and International Standards contain provisions which, through reference in this text,
constitute provisions of this Recommendation | International Standard. At the time of publication, the editions indicated
were valid. All Recommendations and Standards are subject to revision, and parties to agreements based on this
Recommendation | International Standard are encouraged to investigate the possibility of applying the most recent
edition of the Recommendations and Standards listed below. Members of IEC and ISO maintain registers of currently
valid International Standards. The Telecommunication Standardization Bureau of the ITU maintains a list of currently
valid ITU-T Recommendations.
2.1 Identical Recommendations | International Standards
– Recommendation ITU-T X.200 (1994) | ISO/IEC 7498-1:1994, Information technology – Open Systems
Interconnection – Basic Reference Model: The Basic Model.
– Recommendation ITU-T X.500 (2012) | ISO/IEC 9594-1:2014, Information technology – Open Systems
Interconnection – The Directory: Overview of concepts, models and services.
– Recommendation ITU-T X.501 (2012) | ISO/IEC 9594-2:2014, Information technology – Open Systems
Interconnection – The Directory: Models.
– Recommendation ITU-T X.509 (2012) | ISO/IEC 9594-8:2014, Information technology – Open Systems
Interconnection – The Directory: Public-key and attribute certificate frameworks.
– Recommendation ITU-T X.511 (2012) | ISO/IEC 9594-3:2014, Information technology – Open Systems
Interconnection – The Directory: Abstract service definition.
– Recommendation ITU-T X.518 (2012) | ISO/IEC 9594-4:2014, Information technology – Open Systems
Interconnection – The Directory: Procedures for distributed operation.
– Recommendation ITU-T X.519 (2012) | ISO/IEC 9594-5:2014, Information technology – Open Systems
Interconnection – The Directory: Protocol specifications.
– Recommendation ITU-T X.520 (2012) | ISO/IEC 9594-6:2014, Information technology – Open Systems
Interconnection – The Directory: Selected attribute types.
– Recommendation ITU-T X.521 (2012) | ISO/IEC 9594-7:2014, Information technology – Open Systems
Interconnection – The Directory: Selected object classes.
– Recommendation ITU-T X.680 (2008) | ISO/IEC 8824-1:2008, Information technology – Abstract
Syntax Notation One (ASN.1): Specification of basic notation.
– Recommendation ITU-T X.681 (2008) | ISO/IEC 8824-2:2008, Information technology – Abstract
Syntax Notation One (ASN.1): Information object specification.
– Recommendation ITU-T X.682 (2008) | ISO/IEC 8824-3:2008, Information technology – Abstract
Syntax Notation One (ASN.1): Constraint specification.
– Recommendation ITU-T X.683 (2008) | ISO/IEC 8824-4:2008, Information technology – Abstract
Syntax Notation One (ASN.1): Parameterization of ASN.1 specifications.
 Rec. ITU-T X.525 (10/2012) 1

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ISO/IEC 9594-9:2014 (E)
3 Definitions
For the purposes of this Recommendation | International Standard, the following definitions apply.
3.1 Basic Directory definitions
The following term is defined in Rec. ITU-T X.500 | ISO/IEC 9594-1:
– (the) Directory.
3.2 Directory model definitions
The following terms are defined in Rec. ITU-T X.501 | ISO/IEC 9594-2:
a) distinguished name;
b) Directory information tree (DIT);
c) DSA-specific entry (DSE);
d) DSA information model;
e) DSA information tree;
f) Directory system agent (DSA).
3.3 Abstract service definitions
The following term is defined in Rec. ITU-T X.511 | ISO/IEC 9594-3:
a) request;
b) requestor.
3.4 Distributed operation definitions
The following terms are defined in Rec. ITU-T X.518 | ISO/IEC 9594-4:
a) access point;
b) knowledge information;
c) name resolution;
d) naming context;
e) non-specific subordinate reference;
f) subordinate reference.
3.5 Protocol definitions
The following term is defined in Rec. ITU-T X.519 | ISO/IEC 9594-5:
a) application-association.
3.6 Replication definitions
The following terms are defined in this Recommendation | International Standard:
3.6.1 area prefix: The sequence of RDNs and associated administrative information common to all entries within a
replicated area.
3.6.2 attribute completeness: Indicates whether or not all user attributes are included in an entry-copy.
3.6.3 cache-copy: A copy of an entry (or part of an entry) whose consistency with its corresponding entry is
maintained by means outside the scope of this Directory Specification.
3.6.4 caching: The process of creating cache copies. This process is outside the scope of this Directory
Specification.
3.6.5 consumer reference: The access point of the shadow consumer.
3.6.6 entry-copy: Shadowed information from an entry.
2 Rec. ITU-T X.525 (10/2012)

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ISO/IEC 9594-9:2014 (E)
3.6.7 extended knowledge: Those subordinate and non-specific subordinate references that would be included as
subordinate knowledge if the replicated area were extended to the lower boundary of the naming context.
3.6.8 master DSA: The DSA which has administrative authority for a naming context. All adds, deletes and
modifications to entries in this naming context are done by the master DSA. The master DSA may enter into shadowing
agreements with other DSAs to provide copies of a subset of a naming context (see unit of replication).
3.6.9 primary shadowing: Shadowing where the shadow supplier is the master DSA.
3.6.10 replicated area: A subtree of the DIT for purposes of shadowing.
3.6.11 replication: The process by which copies of entry and operational information are held by DSAs other than
the master DSA.
3.6.12 replication base entry: The distinguished name of the root vertex of a replicated area.
3.6.13 secondary shadowing: Shadowing where the shadow supplier is not the master DSA.
3.6.14 shadow consumer: A DSA that receives shadowed information.
3.6.15 shadow operational binding: The relationship between two DSAs, one acting as a supplier of replicated
information and the other as its consumer.
3.6.16 shadow service: The service provided to perform shadowing between two DSAs that have entered into one or
more shadowing agreements.
3.6.17 shadow supplier: A DSA that provides shadowed information. This DSA may or may not be the master
DSA.
3.6.18 shadowed DSA specific entry (SDSE): A unit of shadowed information which is associated with a specific
name; it represents the information taken from a DSE which is shadowed.
3.6.19 shadowed information: The complete set of information associated with a unit of replication. Shadowed
information is conceptually held both by the shadow supplier and the shadow consumer for the purposes of the shadow
protocol and comprises a tree shaped structure of shadowed DSEs.
3.6.20 shadowing: Replication between two DSAs whereby shadowed information is copied and maintained using
the Directory Information Shadowing Protocol.
3.6.21 shadowing agreement: The terms specific to a particular agreement required for shadowing to occur between
a pair of DSAs.
3.6.22 subordinate completeness: Indicates whether or not subordinate knowledge is complete for an entry-copy.
3.6.23 supplier reference: The access point of the shadow supplier.
3.6.24 unit of replication: A specification of the information to be shadowed, including (optionally) subordinate
knowledge information.
4 Abbreviations
For the purposes of this Recommendation | International Standard, the following abbreviations apply:
ACI Access Control Information
DIB Directory Information Base
DISP Directory Information Shadowing Protocol
DIT Directory Information Tree
DMD Directory Management Domain
DSA Directory System Agent
DSE DSA-Specific Entry
DUA Directory User Agent
LDAP Lightweight Directory Access Protocol
RDN Relative Distinguished Name
SDSE Shadowed DSA-Specific Entry
TCP/IP Transmission Control Protocol/Internet Protocol
 Rec. ITU-T X.525 (10/2012) 3

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ISO/IEC 9594-9:2014 (E)
5 Conventions
The term "Directory Specification" (as in "this Directory Specification") shall be taken to mean Rec. ITU-T X.525 |
ISO/IEC 9594-9. The term "Directory Specifications" shall be taken to mean the X.500-series Recommendations and all
parts of ISO/IEC 9594.
This Directory Specification uses the term first edition systems to refer to systems conforming to the first edition of the
Directory Specifications, i.e., the 1988 edition of the CCITT X.500-series Recommendations and the
ISO/IEC 9594:1990 edition.
This Directory Specification uses the term second edition systems to refer to systems conforming to the second edition
of the Directory Specifications, i.e., the 1993 edition of the ITU-T X.500-series Recommendations and the
ISO/IEC 9594:1995 edition.
This Directory Specification uses the term third edition systems to refer to systems conforming to the third edition of the
Directory Specifications, i.e., the 1997 edition of the ITU-T X.500-series Recommendations and the
ISO/IEC 9594:1998 edition.
This Directory Specification uses the term fourth edition systems to refer to systems conforming to the fourth edition of
the Directory Specifications, i.e., the 2001 editions of Recs ITU-T X.500, ITU-T X.501, ITU-T X.511, ITU-T X.518,
ITU-T X.519, ITU-T X.520, ITU-T X.521, ITU-T X.525, and ITU-T X.530, the 2000 edition of ITU-T X.509, and
parts 1-10 of the ISO/IEC 9594:2001 edition.
This Directory Specification uses the term fifth edition systems to refer to systems conforming to the fifth edition of the
Directory Specifications, i.e., the 2005 edition of the ITU-T X.500-series Recommendations and the
ISO/IEC 9594:2005 edition.
This Directory Specification uses the term sixth edition systems to refer to systems conforming to the sixth edition of
the Directory Specifications, i.e., the 2008 edition of the ITU-T X.500-series Recommendations and the
ISO/IEC 9594:2008 edition.
This Directory Specification uses the term seventh edition systems to refer to systems conforming to the seventh edition
of the Directory Specifications, i.e., the 2012 edition of the ITU-T X.500-series Recommendations and the
ISO/IEC 9594:2014 edition.
This Directory Specification presents ASN.1 notation in the bold Courier New typeface. When ASN.1 types and values
are referenced in normal text, they are differentiated from normal text by presenting them in the bold Courier New
typeface. The names of procedures, typically referenced when specifying the semantics of processing, are differentiated
from normal text by displaying them in bold Times New Roman. Access control permissions are presented in italicized
Times New Roman.
If the items in a list are numbered (as opposed to using "–" or letters), then the items shall be considered steps in a
procedure.
6 Replication in the Directory
Replicated (copied) information can exist in the Directory. Shadowing is the mechanism for replication defined in this
Directory Specification. Directory information can also be replicated by means outside this Directory Specification,
such as caching. Any such alternative means of replication will need to ensure that exactly one instance of each
replicated entry is identified as the master copy if the Directory and DSA abstract services are to be used.
Service controls provide the ability to control whether replicated information may be used in support of Directory
operations, regardless of the replication mechanism used to acquire the copy. DISP is protected by the underlying
protocol as defined in Rec. ITU-T X.519 | ISO/IEC 9594-5.
6.1 Caching
One method of replicating Directory information is caching. Caching procedures are considered to be almost entirely
governed by local policies, and therefore outside the scope of this Directory Specification.
6.2 Shadowing
Another method of replicating Directory information is shadowing. An overview of the Directory information shadow
service is found in clause 7. Before shadowing can occur, an agreement, covering the conditions under which
shadowing may occur is required. Although such agreements may be established in a variety of ways, such as policy
statements covering all DSAs within a given Directory management domain (DMD), the shadowing is always between
4 Rec. ITU-T X.525 (10/2012)

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ISO/IEC 9594-9:2014 (E)
a pair of DSA. The technical parameters for the subsequent shadowing are specified as part of the resulting shadowing
agreement. Components of the shadowing agreement are defined in clause 9.
Once the terms of the agreement have been established, the DSAs may initiate, modify and subsequently terminate the
shadowing agreement. This may be done through a shadow operational binding as defined in clause 8.
This shadowing service for the Directory is based on the models established in Rec. ITU-T X.501 | ISO/IEC 9594-2, to
satisfy the requirements outlined in Rec. ITU-T X.500 | ISO/IEC 9594-1. The protocol specification for shadowing and
conformance requirements are provided in Rec. ITU-T X.519 | ISO/IEC 9594-5. In addition, this Directory
Specification provides the definition of an operational binding for the purpose of initiating, modifying, and terminating
shadowing agreements between DSAs. This operational binding type is defined using the tools specified in
Rec. ITU-T X.501 | ISO/IEC 9594-2.
The Directory information shadow service is defined in clause 10. The actual shadowing occurs through the set of
operations defined in clause 11. These operations accommodate the transfer of Directory information and updates to the
shadowed information.
The use of shadowed information by a DSA to satisfy a Directory request is described in Rec. ITU-T X.518 |
ISO/IEC 9594-4.
6.3 Shadowing functional model
In the standardized form of Directory replication, termed shadowing, a DSA may assume the role of shadow supplier,
the source of shadowed information, or shadow consumer, the recipient of shadowed information. The role played by a
DSA when engaging in standardized replication activities (shadow supplier or shadow consumer) is always with respect
to another DSA which plays the reciprocal role (shadow consumer or shadow supplier).
A given DSA may assume both roles, either:
– with respect to different DSAs for the same or different units of replication; or
– with respect to a single DSA (which plays the reciprocal role) for different units of replication.
The shadowing functional model addresses two approaches to shadowing Directory information:
– a primary shadowing policy requires that each shadow consumer receives its updates directly from the
master DSA for the unit of replication;
– a secondary shadowing policy permits a shadow consumer to assume the shadow supplier role with
respect to shadow consumers not having a shadowing agreement directly with the master DSA.
The characteristics of these two policies and their approach to addressing performance, availability, reliability and
recovery are described below.
6.3.1 Primary shadowing
Figure 1 depicts primary shadowing. In this case, the shadowing policy in effect has the following characteristics:
a) the master DSA is the only shadow supplier for a replicated area;
b) each shadow consumer has a direct shadowing agreement with the master DSA;
c) only read, compare, search, and list operations may be performed at a shadow consumer holding
shadowed information. All modification operations are directed to the master DSA.
Because it allows for the placement of copies of often requested information, or knowledge of it, closer to the requestor,
this approach may be used to satisfy the performance requirement. Also, because this approach provides for the
redundancy of individual entry or knowledge information, it is possible, in a primitive sense, to provide for availability,
reliability, and recovery.
 Rec. ITU-T X.525 (10/2012) 5

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ISO/IEC 9594-9:2014 (E)
Shadow
DUA or
Master
consumer
LDAP
DSA
DSA
client
Shadow Shadow
DUA or
consumer consumer
LDAP
DUA or
DSA DSA
client
LDAP
client
Shadow updates
X.525(12)_
...