Network Working Group
Request for Comments: 3909
Category: Standards Track
K. Zeilenga
OpenLDAP Foundation
October 2004

Lightweight Directory Access Protocol (LDAP)

Cancel Operation

Status of this Memo

This document specifies an Internet standards track protocol for the Internet community, and requests discussion and suggestions for improvements. Please refer to the current edition of the "Internet Official Protocol Standards" (STD 1) for the standardization state and status of this protocol. Distribution of this memo is unlimited.

Copyright Notice

Copyright © The Internet Society (2004).


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.

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 requires no response from the abandoned operation. These semantics provide the client with no clear indication of the outcome of the Abandon operation.

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

The LDAP 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.

Protocol elements are described using ASN.1 [X.680] with implicit tags. 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].

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

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. Cancel Operation

The Cancel operation is defined as an LDAP Extended Operation [RFC2251, Section 4.12] identified by the object identifier This section details the syntax of the Cancel request and response messages and defines additional LDAP resultCodes.

2.1. Cancel Request

The Cancel request is an ExtendedRequest with the requestName field containing and a requestValue field which contains a BER-encoded cancelRequestValue value.

      cancelRequestValue ::= SEQUENCE {
          cancelID        MessageID
                          -- MessageID is as defined in [RFC2251]

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        (118)
      noSuchOperation (119)
      tooLate         (120)
      cannotCancel    (121)

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 set to the message ID of the outstanding operation. The Cancel Request itself has a distinct message ID. Clients SHOULD NOT request the 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 an 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 for cancelation.

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:

  • operations which have no response,
   -  operations which create, alter, or destroy authentication and/or
      authorization associations,
  • operations which establish, alter, 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 Cancel operation cannot be abandoned.

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 has already committed updates to the underlying data store.

Servers SHOULD indicate their support for this extended operation by providing 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 it.

4. Security Considerations

This operation is intended to allow a user to cancel operations they previously issued during the current LDAP association. In certain cases, such as when the Proxy Authorization Control is in use, different outstanding operations may be processed under different LDAP associations. Servers MUST NOT allow a user to cancel an operation belonging to another user.

Some operations should not be cancelable for security reasons. This specification disallows the cancelation of the 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

The following values [RFC3383] have been registered by the IANA.

5.1. Object Identifier

The IANA has registered upon Standards Action the LDAP Object Identifier to identify the LDAP Cancel Operation as defined in this document.

      Subject: Request for LDAP Object Identifier Registration
      Person & email address to contact for further information:
           Kurt Zeilenga <>
      Specification: RFC 3909
      Author/Change Controller: IESG
           Identifies the LDAP Cancel Operation

5.2. LDAP Protocol Mechanism

The IANA has registered upon Standards Action the LDAP Protocol Mechanism described in this document.

      Subject: LDAP Protocol Mechanism Registration
      Object Identifier:
      Description: LDAP Cancel Operation
      Person & email address to contact for further information:
           Kurt Zeilenga <>
      Usage: Extended Operation
      Specification: RFC 3909
      Author/Change Controller: IESG
      Comments: none

5.3. LDAP Result Codes

The IANA has registered 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 <>
      Result Code Name: canceled (118)
      Result Code Name: noSuchOperation (119)
      Result Code Name: tooLate (120)
      Result Code Name: cannotCancel (121)
      Specification: RFC 3909
      Author/Change Controller: IESG

6. Acknowledgment

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

7. References

7.1. Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.
   [RFC2251]  Wahl, M., Howes, T., and S. Kille, "Lightweight Directory
              Access Protocol (v3)", RFC 2251, December 1997.
   [RFC2830]  Hodges, J., Morgan, R., and M. Wahl, "Lightweight
              Directory Access Protocol (v3): Extension for Transport
              Layer Security", RFC 2830, May 2000.
   [RFC3377]  Hodges, J. and R. Morgan, "Lightweight Directory Access
              Protocol (v3): Technical Specification", RFC 3377,
              September 2002.
   [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).
   [X.690]    International Telecommunication Union - Telecommunication
              Standardization Sector, "Specification of ASN.1 encoding
              rules: Basic Encoding Rules (BER), Canonical Encoding
              Rules (CER), and Distinguished Encoding Rules (DER)",
              X.690(1997) (also ISO/IEC 8825-1:1998).

7.2. Informative References

   [RFC3383]  Zeilenga, K., "Internet Assigned Numbers Authority (IANA)
              Considerations for the Lightweight Directory Access
              Protocol (LDAP)", BCP 64, RFC 3383, September 2002.
   [X.511]    International Telecommunication Union - Telecommunication
              Standardization Sector, "The Directory: Abstract Service
              Definition", X.511(1993).

8. Author's Address

Kurt D. Zeilenga
OpenLDAP Foundation


9. Full Copyright Statement

Copyright © The Internet Society (2004).

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


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