INTERNET-DRAFT                                      Kurt D. Zeilenga
Intended Category: Experimental                  OpenLDAP Foundation
Expires in six months                                17 October 2004


                     LDAP Modify-Increment Extension
                    <draft-zeilenga-ldap-incr-00.txt>


Status of this Memo

  This document is intended to be, after appropriate review and
  revision, submitted to the RFC Editor as an Experimental 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

  This document describes an extension to the Lightweight Directory
  Access Protocol (LDAP) Modify operation to support an increment



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  capability.  This extension is useful in provisioning applications,
  especially when combined with the assertion control and/or the
  pre-read or post-read control extension.


1.  Background and Intended Use

  The Lightwieght Directory Access Protocol [Roadmap] does not currently
  provide an operation to increment values of an attribute.  A client
  must read the values of the attribute, then modify those values to
  increment them by the desired amount.  As the values may be updated by
  other clients between this add and modify, the client must be careful
  to construct the modify request so that it fails in this case, and
  upon failure, re-read the values and construct a new modify request.

  This document extends the LDAP Modify Operation [Protocol] to support
  an increment values capability.  This feature is intended to be used
  with either the LDAP pre-read or post-read control extension
  [READENTRY].  This feature may be used with the LDAP assertion control
  [ASSERT] to provide test-and-increment functionality.

  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].


2.  The Modify-Increment Extension

  This document extends the LDAP Modify request to support a increment
  values capability.  Implementations of this extension SHALL support an
  additional ModifyRequest operation enumeration value increment (3) as
  described herein.  Implementations not supporting this extension will
  treat this value as they would an unlisted value, e.g., as a protocol
  error.

  The increment (3) operation value specifies that an increment values
  modification is requested.   All existing values of the modification
  attribute are to be incremented by the listed value.  The modification
  attribute must be appropriate for request, e.g., must have INTEGER or
  other incrementable values, and the modification must provide one and
  only value.

  Servers supporting this feature SHOULD publish the object identifier
  (OID) OID-TBD 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.





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  3. LDIF Support

  To represent Modify-Increment requests in LDAP Data Interchange Format
  [RFC2849], the ABNF [RFC2234] production <mod-spec> is extended as
  follows:

      mod-spec /= "increment:" FILL AttributeDescription SEP
           attrval-spec "-" SEP

  For example,

      # Increment uidNumber
      dn: cn=max-assigned uidNumber,dc=example,dc=com
      changetype: modify
      increment: uidNumber
      uidNumber: 1
      -

  This LDIF fragment represents a Modify request to increment the
  value(s) of uidNumber by 1.


4.  Security Considerations

  General LDAP security considerations [Roadmap], as well as those
  specific to the LDAP Modify [Protocol], apply to this Modify-Increment
  extension.  Beyond these considerations, it is noted that introduction
  of this extension should reduce application complexity (by provide one
  operation what presently requires multiple operation) and, hence, may
  aide in the production of correct and secure implementations.


5.  IANA Considerations

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

      Subject: Request for LDAP Protocol Mechanism Registration
      Object Identifier: OID-TBD
      Description: Modify-Increment
      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





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6.  Author's Address

  Kurt D. Zeilenga
  OpenLDAP Foundation
  <Kurt@OpenLDAP.org>


7. 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.

  [RFC2849]     Good, G., "The LDAP Data Interchange Format (LDIF) -
                Technical Specification", RFC 2849, June 2000.

  [Features]    Zeilenga, K., "Feature Discovery in LDAP", RFC 3674,
                December 2003.

  [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.


8. Informative References

  [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.

  [ASSERT]      Zeilenga, K., "LDAP Assertion Control",
                draft-zeilenga-ldap-assert-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.





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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
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