




INTERNET-DRAFT                                      Kurt D. Zeilenga
Intended Category: Informational                    OpenLDAP Foundation
Expires in six months                               18 July 2004


               Requesting Attributes by Object Class in the
                  Lightweight Directory Access Protocol
                   <draft-zeilenga-ldap-adlist-08.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>.

  By submitting this Internet-Draft, I accept the provisions of Section
  4 of RFC 3667.  By submitting this Internet-Draft, I certify that any
  applicable patent or other IPR claims of which I am aware have been
  disclosed, or will be disclosed, and any of which I become aware will
  be disclosed, in accordance with RFC 3668.

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  Copyright (C) The Internet Society (2004).  All Rights Reserved.

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


Abstract

  The Lightweight Directory Access Protocol (LDAP) search operation



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  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
  belonging to an object class.


1.  Overview

  In the Lightweight Directory Access Protocol (LDAP) [RFC3377], the
  search operation [RFC2251] support requesting a sets of attributes.
  This set is determined by a list of attribute descriptions.  Two
  special descriptors are defined to request all user attributes ("*")
  [RFC2251] and all operational attributes ("+") [RFC3673].  However,
  there is no convenient mechanism for requesting pre-defined sets of
  attributes.

  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 and its attributes are described in
  [RFC2256].

  This extension is intended to be used where the user is in direct
  control of the parameters of the LDAP search operation, such as when
  entering a LDAP URL [RFC2255] into a web browser.


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

  This extension allows object class identifiers is to be provided in
  the attributes field of the LDAP SearchRequest [RFC2251] or other
  request structures who borrow the attributes field and its semantics



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  (e.g., attributes field in pre/post read controls [READENTRY]).  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) was itself listed.

  If the object class identifier is unrecognized, it is be treated an an
  unrecognized attribute description.

  This extension redefines the attributes field of the SearchRequest to
  be a DescriptionList described by the following ASN.1 [X.680] data
  type:

       DescriptionList ::= SEQUENCE OF Description
       Description ::= LDAPString

  The Description is string conforming to the ABNF [RFC2234]:

       Description = AttributeDescription | ObjectClassDescription.
       ObjectClassDescription = AtSign ObjectClass *( ";" options )
       AtSign = "@" ; U+0040

  where <AttributeDescription> and <options> productions are as defined
  in Section 4.1.5 of [RFC2251] and an <ObjectClass> is an object
  identifier, in either <numericoid> or <descr> form [RFC2252], of an
  object class.

  <ObjectClassDescription> <options> are provided for extensibility.
  This document only defines semantics of <ObjectClassDescription>s with
  zero options in the attributes field of a SearchRequest.  Other uses
  may be defined in future specifications.

  Servers supporting this feature SHOULD publish the object identifier
  (OID) IANA-ASSIGNED-OID as a value of the 'supportedFeatures'
  [RFC3674] 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, this shorthand is not believed to raise additional
  security considerations.

  Implementors of this (or any) LDAP extension should be familiar with
  general LDAP security considerations [RFC3377].




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4.  IANA Considerations

  Registration of the LDAP Protocol Mechanism [RFC3383] 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. Normative References

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

  [RFC2234]     Crocker, D. and P. Overell, "Augmented BNF for Syntax
                Specifications: ABNF", RFC 2234, November 1997.

  [RFC2251]     Wahl, M., T. Howes and S. Kille, "Lightweight Directory
                Access Protocol (v3)", RFC 2251, December 1997.

  [RFC2252]     Wahl, M., A. Coulbeck, T. Howes, and S. Kille,
                "Lightweight Directory Access Protocol (v3):  Attribute
                Syntax Definitions", RFC 2252, December 1997.

  [RFC3377]     Hodges, J. and R. Morgan, "Lightweight Directory Access
                Protocol (v3): Technical Specification", RFC 3377,
                September 2002.

  [Features]    Zeilenga, K., "Feature Discovery in LDAP", RFC 3674,



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                December 2003.

  [X.680]       International Telecommunication Union -
                Telecommunication Standardization Sector, "Abstract
                Syntax Notation One (ASN.1) - Specification of Basic
                Notation", X.680(1997) (also ISO/IEC 8824-1:1998).


7. Informative References

  [RFC2255]     Howes, T. and M. Smith, "The LDAP URL Format", RFC 2255,
                December, 1997.

  [RFC2256]     Wahl, M., "A Summary of the X.500(96) User Schema for
                use with LDAPv3", RFC 2256, December 1997.

  [RFC3383]     Zeilenga, K., "IANA Considerations for LDAP", BCP 64
                (also RFC 3383), September 2002.

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

  [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 (2004).  This document is subject
  to the rights, licenses and restrictions contained in BCP 78, and
  except as set forth therein, the authors retain all their rights.

  This document and the information contained herein are provided on an
  "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
  OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET
  ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED,
  INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE
  INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
  WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.




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