





INTERNET-DRAFT                                      Kurt D. Zeilenga
Intended Category: Informational                    OpenLDAP Foundation
Expires in six months                               18 July 2005



               Requesting Attributes by Object Class in the
                  Lightweight Directory Access Protocol
                   <draft-zeilenga-ldap-adlist-11.txt>


Status of this Memo

  This document is intended to be, after appropriate review and
  revision, submitted to the RFC Editor as an Informational document.
  Distribution of this memo is unlimited.  Technical discussion of this
  document will take place on the IETF LDAP Extensions mailing list
  <ldapext@ietf.org>.  Please send editorial comments directly to the
  author <Kurt@OpenLDAP.org>.

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  Copyright (C) The Internet Society (2005).  All Rights Reserved.

  Please see the Full Copyright section near the end of this document
  for more information.






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Abstract

  The Lightweight Directory Access Protocol (LDAP) search operation
  provides mechanisms for clients to request all user application
  attributes, all operational attributes, and/or attributes selected by
  their description.  This document extends LDAP to support a mechanism
  that LDAP clients may use to request the return of all attributes of
  an object class.


1.  Background and Intended Use

  In the Lightweight Directory Access Protocol (LDAP) [Roadmap], the
  search operation [Protocol] support requesting the return of a set of
  attributes.  This set is determined by a list of attribute
  descriptions.  Two special descriptors are defined to request all user
  attributes ("*") [Protocol] and all operational attributes ("+")
  [RFC3673].  However, there is no convenient mechanism for requesting
  pre-defined sets of attributes such as the set of attributes used to
  represent a particular class of object.

  This document extends LDAP to allow an object class identifier to be
  specified in attributes lists, such as in Search requests, to request
  the return all attributes belonging to an object class.  The
  COMMERCIAL AT ("@", U+0040) character is used to distinguish an object
  class identifier from an attribute descriptions.

  For example, the attribute list of "@country" is equivalent to the
  attribute list of 'c', 'searchGuide', 'description', and
  'objectClass'.  This object class is described in [Schema].

  This extension is intended primarily to be used where the user is in
  direct control of the parameters of the LDAP search operation, for
  instance when entering a LDAP URL [LDAPURL] into a web browser.  For
  example,      <ldap:///dc=example,dc=com?@organization?base>.

2. Terminology

  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 BCP 14 [RFC2119].

  DSA stands for Directory System Agent (or server).
  DSE stands for DSA-specific Entry.


3.  Return of all Attributes of an Object Class




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  This extension allows object class identifiers is to be provided in
  the attributes field of the LDAP SearchRequest [Protocol] or other
  request values of the AttributeSelection data type (e.g., attributes
  field in pre/post read controls [ReadEntry]) and/or
  <attributeSelector> production (e.g., attributes of an LDAP URL
  [LDAPURL]).  For each object class identified in the attributes field,
  the request is to be treated as if each attribute allowed by that
  class (by "MUST" or "MAY", directly or by "SUP"erior) [Models] was
  itself listed.

  This extension extends attributeSelector [Protocol] production as
  indicated by the following ABNF [ABNF]:

       attributeSelector /= objectclassdescription
       objectclassdescription = ATSIGN oid options
       ATSIGN = %x40 ; COMMERCIAL AT ("@" U+0040)

  where <oid> and <options> productions are as defined in [Models].

  The <oid> component of an <objectclassdescription> production
  identifies the object class by short name (descr) or object identifier
  (numericoid).  If the value of the <oid> component is unrecognized or
  does not refer to an object class, the object class description is be
  treated an an unrecognized attribute description.

  The <options> production is included in the grammar for extensibility
  purposes.  An object class description with an unrecognized or
  inappropriate option is to be treated as an unrecognized.

  While object class description options and attribute description
  options share the same syntax, they are not semantically related.
  This document does not define any object description option.

  Servers supporting this feature SHOULD publish the object identifier
  (OID) 1.3.6.1.4.1.4203.1.5.2 as a value of the 'supportedFeatures'
  [Models] attribute in the root DSE.  Clients supporting this feature
  SHOULD NOT use the feature unless they have knowledge the server
  supports it.


3.  Security Considerations

  This extension provides a shorthand for requesting all attributes of
  an object class.  As these attributes which could have been listed
  individually, introduction of this shorthand is not believed to raise
  additional security considerations.

  Implementors of this LDAP extension should be familiar with security



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  considerations applicable to the LDAP search operation [Protocol], as
  well as general LDAP security considerations [Roadmap].


4.  IANA Considerations

  Registration of the LDAP Protocol Mechanism [BCP64bis] defined in
  document is requested.

      Subject: Request for LDAP Protocol Mechanism Registration
      Object Identifier: 1.3.6.1.4.1.4203.1.5.2
      Description: OC AD Lists
      Person & email address to contact for further information:
           Kurt Zeilenga <kurt@openldap.org>
      Usage: Feature
      Specification: RFC XXXX
      Author/Change Controller: Kurt Zeilenga <kurt@openldap.org>
      Comments: none

  This OID was assigned [ASSIGN] by OpenLDAP Foundation, under its
  IANA-assigned private enterprise allocation [PRIVATE], for use in this
  specification.


5.  Author's Address

  Kurt D. Zeilenga
  OpenLDAP Foundation

  Email: Kurt@OpenLDAP.org


6. References

  [[Note to the RFC Editor: please replace the citation tags used in
  referencing Internet-Drafts with tags of the form RFCnnnn where
  possible.]]


6.1. Normative References

  [RFC2119]     Bradner, S., "Key words for use in RFCs to Indicate
                Requirement Levels", BCP 14 (also RFC 2119), March 1997.

  [ABNF]        Crocker, D. and P. Overell, "Augmented BNF for Syntax
                Specifications: ABNF", draft-crocker-abnf-rfc2234bis, a
                work in progress.




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  [Roadmap]     Zeilenga, K. (editor), "LDAP: Technical Specification
                Road Map", draft-ietf-ldapbis-roadmap-xx.txt, a work in
                progress.

  [Protocol]    Sermersheim, J. (editor), "LDAP: The Protocol",
                draft-ietf-ldapbis-protocol-xx.txt, a work in progress.

  [Models]      Zeilenga, K. (editor), "LDAP: Directory Information
                Models", draft-ietf-ldapbis-models-xx.txt, a work in
                progress.

  [LDAPURL]     Smith, M. (editor), "LDAP: Uniform Resource Locator",
                draft-ietf-ldapbis-url-xx.txt, a work in progress.

  [X.680]       International Telecommunication Union -
                Telecommunication Standardization Sector, "Abstract
                Syntax Notation One (ASN.1) - Specification of Basic
                Notation", X.680(2002) (also ISO/IEC 8824-1:2002).


6.2. Informative References

  [RFC3673]     Zeilenga, K., "LDAPv3: All Operational Attributes", RFC
                3673, December 2003.

  [Schema]      Dally, K. (editor), "LDAP: User Schema",
                draft-ietf-ldapbis-user-schema-xx.txt, a work in
                progress.

  [BCP64bis]    Zeilenga, K., "IANA Considerations for LDAP",
                draft-ietf-ldapbis-bcp64-xx.txt, a work in progress.

  [ReadEntry]   Zeilenga, K., "LDAP Read Entry Controls",
                draft-zeilenga-ldap-readentry-xx.txt, a work in
                progress.

  [ASSIGN]      OpenLDAP Foundation, "OpenLDAP OID Delegations",
                http://www.openldap.org/foundation/oid-delegate.txt.

  [PRIVATE]     IANA, "Private Enterprise Numbers",
                http://www.iana.org/assignments/enterprise-numbers.



Full Copyright

  Copyright (C) The Internet Society (2005).




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