





INTERNET-DRAFT                                      Kurt D. Zeilenga
Intended Category: Standard Track                OpenLDAP Foundation
Expires in six months                                     3 May 2003


                      LDAP Cancel Extended Operation
                   <draft-zeilenga-ldap-cancel-08.txt>


1.      Status of this Memo

  This document is an Internet-Draft and is in full conformance with all
  provisions of Section 10 of RFC2026.

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

  Internet-Drafts are working documents of the Internet Engineering Task
  Force (IETF), its areas, and its working groups.  Note that other
  groups may also distribute working documents as Internet-Drafts.
  Internet-Drafts are draft documents valid for a maximum of six months
  and may be updated, replaced, or obsoleted by other documents at any
  time.  It is inappropriate to use Internet-Drafts as reference
  material or to cite them other than as ``work in progress.''

  The list of current Internet-Drafts can be accessed at
  <http://www.ietf.org/ietf/1id-abstracts.txt>. The list of
  Internet-Draft Shadow Directories can be accessed at
  <http://www.ietf.org/shadow.html>.

  Copyright 2003, The Internet Society.  All Rights Reserved.

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


Abstract

  This specification describes a Lightweight Directory Access Protocol
  (LDAP) extended operation to cancel (or abandon) an outstanding
  operation.   Unlike the LDAP Abandon operation but like the X.511
  Directory Access Protocol (DAP) Abandon operation, this operation has
  a response which provides an indication of its outcome.




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Conventions

  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].

  Protocol elements are described using ASN.1 [X.680].  The term
  "BER-encoded" means the element is to be encoded using the Basic
  Encoding Rules [X.690] under the restrictions detailed in Section 5.1
  of [RFC2251].


1. Background and Intent of Use

  The Lightweight Directory Access Protocol (LDAP) [RFC3377] provides an
  Abandon operation [RFC2251] which clients may use to cancel other
  operations.  The Abandon operation does not have a response and calls
  for there to be no response of the abandoned operation.  These
  semantics provide the client with no clear indication of the outcome
  of the Abandon operation.

  X.511 Directory Access Protocol (DAP) [X.511] provides an Abandon
  operation which does have a response and also requires the abandoned
  operation to return a response indicating it was canceled.  The Cancel
  operation is modeled after the DAP Abandon operation.

  The Cancel operation SHOULD be used instead of the LDAP Abandon
  operation when the client needs an indication of the outcome.  This
  operation may be used to cancel both interrogation and update
  operations.


2. Cancel Operation

  The Cancel operation is defined as a LDAP Extended Operation [RFC2251,
  Section 4.12] identified by the IANA-ASSIGNED-OID.  This section
  details the syntax of the Cancel request and response messages and
  defines additional LDAP resultCodes.

      cancelRequestValue ::= SEQUENCE {
          cancelID        MessageID
      }


2.1. Cancel Request

  The Cancel request is an ExtendedRequest with the requestName field
  containing the IANA-0IGNED-OID and a requestValue field which contains



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  a BER-encoded cancelRequestValue value.  The cancelID field contains
  the message id associated with the operation to be canceled.


2.2. Cancel Response

  A Cancel response is an ExtendedResponse where the responseName and
  response fields are absent.


2.3. Additional Result Codes

  Implementations of this specification SHALL recognize the following
  additional resultCode values:

      canceled        (IANA-ASSIGNED-1)
      noSuchOperation (IANA-ASSIGNED-2)
      tooLate         (IANA-ASSIGNED-3)
      cannotCancel    (IANA-ASSIGNED-4)


3. Operational Semantics

  The function of the Cancel Operation is to request that the server
  cancel an outstanding operation issued within the same session.

  The client requests the cancelation of an outstanding operation by
  issuing a Cancel Response with a cancelID with the message id
  identifying the outstanding operation.  The Cancel Request itself has
  a distinct message id.  Clients SHOULD NOT request cancelation of an
  operation multiple times.

  If the server is willing and able to cancel the outstanding operation
  identified by the cancelId, the server SHALL return a Cancel Response
  with a success resultCode and the canceled operation SHALL fail with
  canceled resultCode.  Otherwise the Cancel Response SHALL have a
  non-success resultCode and SHALL NOT have impact upon the outstanding
  operation (if it exists).

  The protocolError resultCode is returned if the server is unable to
  parse the requestValue or the requestValue is absent,

  The noSuchOperation resultCode is returned if the server has no
  knowledge of the operation requested to be canceled.

  The cannotCancel resultCode is returned if the identified operation
  does not support cancelation or the cancel operation could not be
  performed.  The following classes of operations are not cancelable:



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    - operations which have no response,

    - operations which associate or disassociate authentication and/or
      authorization associations,

    - operations which establish or tear-down security services, and

    - operations which abandon or cancel other operations.

  Specifically, the Abandon, Bind, Start TLS [RFC2830], Unbind and
  Cancel operations are not cancelable.

  The tooLate resultCode is returned to indicate that it is too late to
  cancel the outstanding operation.  For example, the server may return
  tooLate for a request to cancel an outstanding modify operation which
  as already commited updates to the underlying datastore.

  Servers SHOULD indicate their support for this extended operation by
  providing IANA-ASSIGNED-OID as a value of the supportedExtension
  attribute type in their root DSE.  A server MAY choose to advertise
  this extension only when the client is authorized to use this
  operation.


4. Security Considerations

  This operation is intended to allow a user to cancel operations they
  previously issued.  No user should be allowed to cancel an operation
  issued by another user.

  Some operations should not be cancelable for security reasons.  This
  specification disallows cancelation of Bind operation and Start TLS
  extended operation so as to avoid adding complexity to authentication,
  authorization, and security layer semantics.  Designers of future
  extended operations and/or controls should disallow abandonment and
  cancelation when appropriate.


5.  IANA Considerations

  Registration of the following values [RFC3383] is requested.


5.1.  Object Identifier

  It is requested that IANA register upon Standards Action an LDAP
  Object Identifier to identify the LDAP Cancel Extended Operation as
  defined in this document.



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  The following registration template is suggested:

      Subject: Request for LDAP Object Identifier Registration
      Person & email address to contact for further information:
           Kurt Zeilenga <kurt@OpenLDAP.org>
      Specification: RFCXXXX
      Author/Change Controller: IESG
      Comments:
           Identifies the LDAP Cancel Extended Operation


5.2.  LDAP Protocol Mechanism

  It is requested that IANA register upon Standards Action the LDAP
  Protocol Mechanism described in this document.

      Subject: Request for LDAP Protocol Mechansism Registration
      Object Identifier: IANA-ASSIGNED-OID
      Description: LDAP Cancel Extended Operation
      Person & email address to contact for further information:
           Kurt Zeilenga <kurt@openldap.org>
      Usage: Extended Operation
      Specification: RFCXXXX
      Author/Change Controller: IESG
      Comments: none
      in 2


5.3.  LDAP Result Codes

      It is requested that IANA register upon Standards Action the LDAP
      Result Codes described in this document.

      Subject: LDAP Result Code Registration
      Person & email address to contact for further information:
           Kurt Zeilenga <kurt@OpenLDAP.org>
      Result Code Name: canceled
      Result Code Name: noSuchOperation
      Result Code Name: tooLate
      Result Code Name: cannotCancel
      Specification: RFCXXXX
      Author/Change Controller: IESG
      Comments:  request four consecutive result codes be assigned


6. Acknowledgment

  The LDAP Cancel operation is modeled after the X.511 DAP Abandon



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  operation.


7. Normative References

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

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

  [RFC2830] J. Hodges, R. Morgan, and M. Wahl, "Lightweight Directory
            Access Protocol (v3): Extension for Transport Layer
            Security", RFC 2830, May 2000.

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

  [X.680]   ITU-T, "Abstract Syntax Notation One (ASN.1) - Specification
            of Basic Notation", X.680, 1994.

  [X.690]   ITU-T, "Specification of ASN.1 encoding rules:  Basic,
            Canonical, and Distinguished Encoding Rules", X.690, 1994.


8. Informative References

  [RFC3383] K. Zeilenga, "IANA Considerations for LDAP", RFC 3383,
            September 2002.

  [X.511]   ITU-T, "The Directory: Abstract Service Definition", X.511,
            1993.


9. Author's Address

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


Copyright 2003, The Internet Society.  All Rights Reserved.

  This document and translations of it may be copied and furnished to
  others, and derivative works that comment on or otherwise explain it
  or assist in its implementation may be prepared, copied, published and
  distributed, in whole or in part, without restriction of any kind,
  provided that the above copyright notice and this paragraph are



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  included on all such copies and derivative works.  However, this
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