The leaf and nonLeaf Object Classes M. Smith
INTERNET-DRAFT T. Howes
University of Michigan
21 November 1995
Definition of the leaf and nonLeaf Object Classes
Filename: draft-ietf-asid-leafnonleaf-00.txt
Status of this Memo
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This Internet Draft expires on 21 May 1995.
Abstract
Applications of X.500, LDAP, and similar directory services need to
be able to efficiently and unambiguously determine if an entry is a
leaf entry (no entries exist beneath the entry) or a non-leaf entry
(entries do exist beneath the entry). While some implementations use
proprietary object classes to allow directory clients to make the
distinction, there is no standard defined. This document defines two
object classes that may be used by all implementations to allow
directory clients to distinguish leaf entries from non-leaf entries.
Background and Intended Usage
This document defines two object classes (leaf and nonLeaf) that may
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INTERNET-DRAFT leaf and nonLeaf Object Classes 21 November 1995
be used by X.500 [1], LDAP [2], and other directory implementations
to allow applications to distinguish leaf entries from non-leaf
entries. A leaf entry is one that does not have any other entries
beneath it (that is, it is not a container). A non-leaf entry is one
that does have other entries beneath it (that is, it is a container
for other entries). Each entry in the directory is one of these two
types.
Directory servers that comply with this specification should
automatically include the leaf object class value in all entries that
do not have other entries beneath them. Similarly, the nonLeaf
object class value should be included in all other entries. If one
of these two object class values is present in an entry, directory
clients can unambiguously know whether an entry may have other
entries beneath it. This capability is particularly useful when
browsing the directory in a hierarchical fashion. If neither value
is present, the client must use other means (such as a one-level or
subtree search based at the entry in question to see if any "child"
entries are present).
It is intended that the schema elements defined in this document will
be progressed according to the process defined by the Internet X.500
Schema Working Group [3].
Definition of the leaf Object Class
Name: leaf
Description: object that does not contain other entries
OID: umichObjectClass.19 (1.3.6.1.4.1.250.3.19)
SubclassOf: top
MustContain:
MayContain:
Definition of the nonLeaf Object Class
Name: nonLeaf
Description: object that contains other entries
OID: umichObjectClass.20 (1.3.6.1.4.1.250.3.20)
SubclassOf: top
MustContain:
MayContain: numberOfChildren, numberOfDescendants
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Definition of the numberOfChildren Attribute
Name: numberOfChildren
ShortName:
OID: umichAttributeType.62 (1.3.6.1.4.1.250.1.62)
Syntax: Integer
SizeRestriction: none
SingleValued: TRUE
MatchesFor:
Definition of the numberOfDescendants Attribute
Name: numberOfDescendants
ShortName:
OID: umichAttributeType.63 (1.3.6.1.4.1.250.1.63)
Syntax: Integer
SizeRestriction: none
SingleValued: TRUE
MatchesFor:
Discussion of the Object Class and Attribute Schema
Entries that do not have other entries beneath them belong to the
leaf object class. Entries that have other entries beneath them
belong to the nonLeaf object class.
The numberOfChildren attribute, if present, contains a count of the
entries that are listed directly below the non-leaf entry (that is,
the number of entries that are in the single-level beneath the
entry). The numberOfDescendants attribute, if present, contains a
count of the total number of entries that are listed anywhere beneath
the non-leaf entry (that is, the total number of entries that are
contained in the directory subtree beneath the entry).
References
[1] Information Processing Systems -- Open Systems Interconnection --
The Directory: Overview of Concepts, Models and Service. ISO/IEC JTC
1/SC21; International Standard 9594-1, 1988.
[2] Yeong, W., Howes, T., and S. Kille, "Lightweight Directory Access
Protocol", RFC 1777, Performance Systems International, University of
Michigan, ISODE Consortium, March 1995,
<URL:ftp://ds.internic.net/rfc/rfc1777.txt>
[3] Howes, T., Rossen, K., Sataluri, S., and Wright, R., "Procedures
for Formalizing, Evolving, and Maintaining the Internet X.500
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INTERNET-DRAFT leaf and nonLeaf Object Classes 21 November 1995
Directory Schema", Internet Draft (Work In Progress) of the Schema
Working Group, <URL:ftp://ds.internic.net/internet-drafts/
draft-howes-x500-schema-03.txt>
Security Considerations
Security considerations are not discussed in this memo.
Acknowledgments
This material is based upon work supported by the National Science
Foundation under Grant No. NCR-9416667.
Authors' Addresses
Mark Smith
University of Michigan
Information Technology Division
535 W. William St.
Ann Arbor, MI 48103-4943, USA
Phone: +1 313 764-2277
EMail: mcs@umich.edu
Tim Howes
University of Michigan
Information Technology Division
535 W. William St.
Ann Arbor, MI 48103-4943, USA
Phone: +1 313 747-4454
EMail: tim@umich.edu
This Internet Draft expires on 21 May 1995.
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