INTERNET-DRAFT                                      Kurt D. Zeilenga
Intended Category: Experimental                     OpenLDAP Foundation
Expires: 20 May 2002                                20 November 2001

                           LDAPv3 Transactions

Status of 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 an Experimental document.
  Distribution of this memo is unlimited.  Technical discussion of this
  document will take place on the IETF LDAP Extension Working Group
  mailing list <>.  Please send editorial
  comments directly to the author <>.

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  Copyright 2001, The Internet Society.  All Rights Reserved.

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


  LDAP update operations have atomic properties upon individual entries.
  However, it is often desirable to update two or more entries as one
  atomic action, a transaction.  Transactions are necessary to support a
  number of applications including resource provisioning and information
  replication.  This document defines an LDAP extension to support

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  The key words "SHALL", "SHALL NOT", "MUST", "MUST NOT", "SHOULD",
  "SHOULD NOT", "MAY" and "MAY NOT" used 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. Overview

  This document extends LDAP [RFC2251] to allow clients to group a
  number of related update operations and have them preformed as one
  atomic action, a transaction.   The mechanism uses the grouping
  mechanism provided by [GROUP] to relate operations of the transaction.
  The createGrouping operation is used to obtain a group cookie which is
  used to identify operations which are apart of the transaction.  The
  group cookie can be viewed as a transaction identifier.  The
  endGrouping operation is used to settle (commit or abort) the

  This document is a ''work in progress.''  This specification will
  likely be significantly enhanced before it progressed.  In particular,
  clarification of transaction semantics and better error handling will
  likely be added.  A ''prepare'' capability may also be added.

2. Specification of a Transaction

  Servers implementing this specification SHOULD publish the
  transactionGroupingType as a value of the supportedGroupingTypes
  attribute contained within the Root DSE.

      transactionGroupingType ::= 1.1.1 ;; fictious

  A client wishing to preform a transaction MUST issue a
  createGroupingRequest with a createGroupType of
  transactionGroupingType and no createGroupValue.  A server which is
  willing and able to support transactions SHALL return a
  createGroupingResponse with a success result code, a
  createGroupCookie, and no createGroupValue.  Otherwise the server
  SHALL return a non-success result code, no createGroupCookie, and no

  The client MAY then attach a GroupingControl to subsequent update

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  operations (modify or moddn) to indicate that they are to be processed
  as part of the transaction per [GROUP], Section 3.5.  If the server is
  willing and able to attempt to process operation as part of the
  transaction, the server SHALL return success.  If the server is
  unwilling or unable to attempt to process the operation as part of the
  transaction, the server SHALL return a non-successful result code.

  If the server becomes unwilling or unable to continue the
  specification of a transaction, the server SHOULD issue a
  endGroupNotice.  Any future use of cookie by the client SHALL result
  in a response containing a non-success result code.

  Upon receipt of a endGroupingNotice, the client SHOULD discontinue all
  use of the grouping cookie.  The client SHOULD NOT issue an
  endGroupingRequest for the grouping cookie as the transaction is null
  and void.

  A client requests settling of transaction by issuing an
  endGroupingRequest where the groupingCookie is the group cookie
  identify the transaction.  The absence of any endGroupingValue
  indicates a commit request.  The presence of an empty endGroupValue
  indicates an abort request.  The endGroupValue MUST be empty if

  The endGroupingResponse of success indicates the settle action was
  successfully.  No endGroupingValue is provided with the

3. Transaction Semantics

  Upon request to commit the transaction, the server perform the
  operations as one atomic action.  Operations belonging to the
  transaction are applied in the request order.  If any operation fails,
  the contents of target objects is left unchanged and a non-success
  result code is returned indicating the nature of the failure.

  There is no requirement that a server serialize transactions.  That
  is, a server MAY process multiple transactions commit requests (from
  one or more clients) acting upon different sets of entries
  concurrently.  A server MUST ensure concurrent processing of
  transactions provides the atomic properties described above.  A server
  MUST avoid deadlock.

4. Distributed Directory Considerations

  The LDAP/X.500 models provide for distributed directory operations

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  including server-side chaining and client-side chasing of operations.

  This document does not disallow servers from chaining operations which
  are part of a transaction.  However, if a server does allow such
  chaining, it MUST ensure that transaction semantics detailed above are

  This mechanism defined by this document does not support client-side
  chasing.  Grouping cookies used to identify the transaction are
  specific to a particular client/server session.

  The LDAP/X.500 models provide for a single-master/multiple-slave
  replication architecture.  This document states no requirement that
  changes made to the directory based upon processing a transaction be
  replicated as one atomic action.  That is, the client SHOULD NOT
  assume tight data consistency nor fast data convergence at slave
  servers unless they have a priori knowledge that such is provided.
  Though this mechanism could be used to support replication, such use
  is not described in this document.

  The LDAP/X.500 models do not currently support a multi-master
  replication architecture and, hence, not considered by this

5. Security Considerations

  Transactions mechanisms and related grouping operations may be the
  target of denial of service attacks.  Implementors should provide
  safeguards to ensure these mechanisms are not abused.

6. Acknowledgments

  The author gratefully acknowledges the contributions made by members
  of the Internet Engineering Task Force.

7. Author's Address

  The author may be contacted as follows:
      Kurt D. Zeilenga
      OpenLDAP Foundation

8. Normative References

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

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

  [GROUP]   K. Zeilenga, "LDAPv3: Grouping of Related Operations",
            draft-zeilenga-ldap-grouping-xx.txt, a work in progress.

  [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.

9. Informative References

  [X.500]   ITU-T, "The Directory: Overview of Concepts, Models, and
            Services", X.500, 1993.

  [X.501]   ITU-T, "The Directory: Models", X.501, 1993.

Copyright 2001, The Internet Society.  All Rights Reserved.

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