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openldap/doc/drafts/draft-zeilenga-ldap-txn-xx.txt
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INTERNET-DRAFT Kurt D. Zeilenga
Intended Category: Standard Track Isode Limited
Expires in six months 18 November 2007
LDAP Transactions
<draft-zeilenga-ldap-txn-11.txt>
Status of Memo
This document is intended to be, after appropriate review and
revision, submitted to the IESG for consideration as a Proposed
Standard. 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.Zeilenga@Isode.COM>.
By submitting this Internet-Draft, each author represents that any
applicable patent or other IPR claims of which he or she is aware have
been or will be disclosed, and any of which he or she becomes aware
will be disclosed, in accordance with Section 6 of BCP 79.
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/1id-abstracts.html.
The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html.
Copyright (C) The IETF Trust (2007).
Please see the Full Copyright section near the end of this document
for more information.
Zeilenga LDAP Transactions [Page 1]
INTERNET-DRAFT draft-zeilenga-ldap-txn-11 18 November 2007
Abstract
Lightweight Directory Access Protocol (LDAP) update operations, such
as Add, Delete, and Modify operations, have atomic, consistency,
isolation, durability (ACID) properties. Each of these update
operations act upon an entry. It is often desirable to update two or
more entries in a single unit of interaction, a transaction.
Transactions are necessary to support a number of applications
including resource provisioning. This document extends LDAP to
support transactions.
1. Overview
This document extends the Lightweight Directory Access Protocol (LDAP)
[RFC4510] to allow clients to relate a number of update operations
[RFC4511] and have them performed as one unit of interaction, a
transaction. As with distinct update operations, each transaction has
atomic, consistency, isolation, and durability (ACID) properties
[ACID].
This extension consists of two extended operations, one control, and
one unsolicited notification message. The Start Transaction operation
is used to obtain a transaction identifier. This identifier is then
attached to multiple update operations to indicate that they belong to
the transaction using the Transaction Specification control. The End
Transaction is used to settle (commit or abort) the transaction. The
Aborted Transaction Notice is provided by the server to notify the
client that the server is no longer willing or able to process an
outstanding transaction.
1.1. Conventions and 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].
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 [RFC4511].
DSA stands for "Directory System Agent" (a server). DSE stands for
"DSA-specific entry".
2. Elements of an LDAP Transaction
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2.1. Start Transaction Request and Response
A Start Transaction Request is an LDAPMessage of CHOICE extendedReq
where the requestName is IANA-ASSIGNED-OID.1 and the requestValue is
absent.
A Start Transaction Response is an LDAPMessage of CHOICE extendedRes
sent in response to a Start Transaction Request. Its responseName is
absent. When the resultCode is success (0), responseValue is present
and contains a transaction identifier. Otherwise, the responseValue
is absent.
2.2. Transaction Specification Control
A Transaction Specification control is an LDAPControl where the
controlType is IANA-ASSIGNED-OID.2, the criticality is TRUE, and the
controlValue is a transaction identifier. The control is appropriate
for update requests including Add, Delete, Modify, and ModifyDN
(Rename) requests [RFC4511], as well as the Password Modify requests
[RFC3062].
As discussed in Section 4, the Transaction Specification control can
be used in conjunction with request controls appropriate for the
update request.
2.3. End Transactions Request and Response
An End Transaction Request is an LDAPMessage of CHOICE extendedReq
where the requestName is IANA-ASSIGNED-OID.3 and the requestValue is
present and contains a BER-encoded txnEndReq.
txnEndReq ::= SEQUENCE {
commit BOOLEAN DEFAULT TRUE,
identifier OCTET STRING }
A commit value of TRUE indicates a request to commit the transaction
identified by the identifier. A commit value of FALSE indicates a
request to abort the identified transaction.
An End Transaction Response is an LDAPMessage sent in response to a
End Transaction Request. Its response name is absent. The
responseValue when present contains a BER-encoded txnEndRes.
txnEndRes ::= SEQUENCE {
messageID MessageID OPTIONAL,
-- msgid associated with non-success resultCode
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updatesControls SEQUENCE OF updateControls SEQUENCE {
messageID MessageID,
-- msgid associated with controls
controls Controls
} OPTIONAL
}
-- where MessageID and Controls are as specified in RFC 4511
The txnEndRes.messageID provides the message id of the update request
associated with a non-success response. txnEndRes.messageID is absent
when resultCode of the End Transaction Response is success (0).
The txnEndRes.updatesControls provides a facility for returning
response controls that normally (i.e., in absence of transactions)
would be returned in an update response. The updateControls.messageID
provides the message id of the update request associated with the
response controls provided in updateControls.controls.
The txnEndRes.updatesControls is absent when there are no update
response controls to return.
If both txnEndRes.messageID and txnEndRes.updatesControl are absent,
the responseValue of the End Transaction Response is absent.
2.4. Aborted Transaction Notice
The Aborted Transaction Notice is an Unsolicited Notification message
where the responseName is IANA-ASSIGNED-OID.4 and responseValue is
present and contains a transaction identifier.
3. An LDAP Transaction
3.1. Extension Discovery
To allow clients to discover support for this extension, servers
implementing this specification SHOULD publish IANA-ASSIGNED-OID.1 and
IANA-ASSIGNED-OID.3 as values of the 'supportedExtension' attribute
[RFC4512] within the Root DSE, and publish the IANA-ASSIGNED-OID.2 as
a value of the 'supportedControl' attribute [RFC4512] of the Root DSE.
A server MAY choose to advertise this extension only when the client
is authorized to use it.
3.2. Starting a Transaction
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A client wishing to perform a sequence of directory updates as an
transaction issues a Start Transaction Request. A server which is
willing and able to support transactions responds to this request with
a Start Transaction Response providing a transaction identifier and
with a resultCode of success (0). Otherwise, the server responds with
a Start Transaction Response with a result code other than success
indicating the nature of the failure.
The transaction identifier provided upon successful start of a
transaction is used in subsequent protocol messages to identify this
transaction.
3.3. Specification of a Transaction
The client then can issue one or more update requests, each with a
Transaction Specification control containing the transaction
identifier indicating the updates are to processed as part of the
transaction. Each of these update request MUST have a different
MessageID value. If the server is unwilling or unable to attempt to
process the requested update operation as part of the transaction, the
server immediately returns the appropriate response to the request
with a resultCode indicating the nature of the failure. Otherwise,
the server immediately returns success (0) and the defers further
processing of the operation is then deferred until settlement.
If the server becomes unwilling or unable to continue the
specification of a transaction, the server issues an Aborted
Transaction Notice with a non-success resultCode indicating the nature
of the failure. All operations that were to be processed as part of
the transaction are implicitly abandoned. Upon receipt of an Aborted
Transaction Notice, the client is to discontinue all use of the
transaction identifier as the transaction is null and void. Any
future use of identifier by the client will result in a response
containing a non-success resultCode.
3.4. Transaction Settlement
A client requests settlement of transaction by issuing an End
Transaction request for the transaction indicating whether it desires
the transaction to be committed or aborted.
Upon receipt of a request to abort the transaction, the server is to
abort the identified transaction (abandoning all operations which are
part of the transaction) and indicate that it has done so by returning
an End Transaction Response with a resultCode of success (0).
Zeilenga LDAP Transactions [Page 5]
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Upon receipt of a request to commit the transaction, the server
processes all update operations of the transaction as one atomic,
durable, isolated, and consistent action with each requested update
being processed in turn. Either all of the requested updates are to
be successfully applied or none of the requested are to be applied.
The server returns an End Transaction Response with a resultCode of
success (0) and no responseValue to indicate all the requested updates
were applied. Otherwise, the server returns an End Transaction with
an non-success resultCode indicating the nature of the failure. If
the failure is associated with a particular update request, the
txnEndRes.messageID in the responseValue is the messageID of this
update request. If the failure was not associated with any particular
update request, no txnEnd.messageID is provided.
There is no requirement that a server serialize transactions, or
updates requested outside of a transaction. That is, a server MAY
process multiple commit requests (from one or more clients) acting
upon different sets of entries concurrently. A server MUST avoid
deadlock.
3.5. Miscellaneous Issues
Transactions cannot be nested.
Each LDAP transaction should be initiated, specified, and settled
within a stable security context. Between the Start request and the
End response, the peers SHOULD avoid negotiating new security
associations and/or layers.
Upon receipt of a Bind or Unbind request, the server SHALL abort any
and all outstanding transactions without notice and nullify their
identifiers.
4. Interaction with Other Extensions
The LDAP Transaction extension may be used with many but not all LDAP
control extensions designed to extend Update (and possibly other)
operations. The remainder of this subsection discusses interaction
with a number of control extensions. Interaction with other control
extensions may be discussed in other documents, in particular in
control extension specifications.
4.1. Assertion Control
The Assertion [RFC4528] control is appropriate for use with update
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requests specified as part of a transaction. The evaluation of the
assertion is performed as part of the transaction.
The Assertion control is inappropriate for use with either the
Transaction Start or End extended operations.
4.2. ManageDsaIT Control
The ManageDsaIT [RFC3296] control is appropriate for use with update
requests specified as part of a transaction.
The ManageDsaIT control is inappropriate for use with either the
Transaction Start or End extended operations.
4.3. No-Op Control
The No-Op [NO-OP] control is appropriate for use with the Transaction
Start or End extended operations.
The No-Op control is not appropriate for update requests specified as
part of a transaction. A server supporting both the No-Op control
extension and this extension SHALL regard a request containing both
controls as a protocol violation. As both of the No-Op and
Transaction Specification request controls are required to be marked
as critical, a server implementing one of these request controls, or
neither, is expected to return unavailableCriticalExtension as
prescribed by [RFC4511].
4.4. Proxied Authorization Control
The Proxied Authorization [RFC4370] control is appropriate for use
with the Transaction Start extended operation, but not the Transaction
End extended operation or any update request specified as part of a
transaction.
To request that a transaction be performed under a different
authorization, the client provides a Proxied Authorization control
with the Transaction Start request. If the client is not authorized
to assume the requested authorization identity, the server is to
return the authorizationDenied (123) resultCode in its response.
Otherwise, further processing of the request and transaction is
performed under the requested authorization identity.
Any proxied authorization request attached to an update request
specified as part of a transaction, or attached to a Transaction end
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request, is to be regarded as a protocol error.
4.5. Read Entry Controls
The Pre- and Post-Read Entry [RFC4527] request control are appropriate
for use with update requests specified as part of a transaction.
The response control produced in response to a Pre- or Post-Read Entry
request control is returned in the txnEndRes.updatesControls field of
responseValue of the End Transaction Response.
The Pre- and Post-Read Entry controls are inappropriate for use in the
LDAPMessage.controls field of the Transaction Start and End request
and response messages.
4.6. Relax Rules Control
The Relax Rules [RELAX] control is appropriate for use with update
requests specified as part of a transaction.
The Relax Rules control is inappropriate for use with either the
Transaction Start or End extended operations.
5. Distributed Directory Considerations
The LDAP/X.500 models provide for distributed directory operations,
including server-side chaining and client-side chasing of referrals.
This document does not preclude servers from chaining operations which
are part of a transaction. However, if a server does attempt such
chaining, it MUST ensure that transaction semantics are provided.
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-shadow
replication architecture. There is no requirement that changes made
to the directory based upon processing a transaction be replicated as
one atomic action. Hence, clients SHOULD NOT assume tight data
consistency nor fast data convergence of shadow copies unless they
have prior knowledge that these properties are provided. Note that
DontUseCopy control [DONTUSECOPY] control may be used in conjunction
with the LDAP search request to ask for the return of the
authoritative copy of the entry.
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6. Security Considerations
Transactions mechanisms may be the target of denial-of-service
attacks, especially where implementation lock shared resources for the
duration of a transaction.
General security considerations [RFC4510], especially those associated
with update operations [RFC4511], apply to this extension.
7. IANA Considerations
It is requested that Internet Assigned Numbers Authority (IANA) make
the following assignments.
7.1. Object Identifier
Assignment of an LDAP Object Identifier [RFC4520] to identify the
protocol elements specified in this document this document is
requested.
Subject: Request for LDAP Object Identifier Registration
Person & email address to contact for further information:
Kurt Zeilenga <Kurt.Zeilenga@Isode.COM>
Specification: RFC XXXX
Author/Change Controller: IESG
Comments: Identifies protocol elements for LDAP Transactions
7.2. LDAP Protocol Mechanism
Registration of the protocol mechanisms [RFC4520] specified in this
document is requested.
Subject: Request for LDAP Protocol Mechanism Registration
Object Identifier: see table
Description: see table
Person & email address to contact for further information:
Kurt Zeilenga <Kurt.Zeilenga@Isode.COM>
Specification: RFC XXXX
Author/Change Controller: IESG
Comments:
Object Identifier Type Description
------------------- ---- ----------------------------------
IANA-ASSIGNED-OID.1 E Start Transaction Extended Request
IANA-ASSIGNED-OID.2 C Transaction Specification Control
Zeilenga LDAP Transactions [Page 9]
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IANA-ASSIGNED-OID.3 E End Transaction Extended Request
IANA-ASSIGNED-OID.4 N Aborted Transaction Notice
Legend
------------------------
C => supportedControl
E => supportedExtension
N => Unsolicited Notice
8. Acknowledgments
The author gratefully acknowledges the contributions made by Internet
Engineering Task Force participants.
9. Author's Address
Kurt D. Zeilenga
Isode Limited
Email: Kurt.Zeilenga@Isode.COM
10. References
[[Note to the RFC Editor: please replace the citation tags used in
referencing Internet-Drafts with tags of the form RFCnnnn where
possible.]]
10.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14 (also RFC 2119), March 1997.
[RFC3062] Zeilenga, K., "LDAP Password Modify Extended Operation",
RFC 3062, February 2000.
[RFC3296] Zeilenga, K., "Named Subordinate References in
Lightweight Directory Access Protocol (LDAP)
Directories", RFC 3296, July 2002.
[RFC4370] Weltman, R., "LDAP Proxied Authentication Control", RFC
4370, Feb. 2006.
[RFC4510] Zeilenga, K. (editor), "LDAP: Technical Specification
Road Map", RFC 4510, June 2006.
Zeilenga LDAP Transactions [Page 10]
INTERNET-DRAFT draft-zeilenga-ldap-txn-11 18 November 2007
[RFC4511] Sermersheim, J. (editor), "LDAP: The Protocol", RFC
4511, June 2006.
[RFC4512] Zeilenga, K. (editor), "LDAP: Directory Information
Models", RFC 4512, June 2006.
[RFC4527] Zeilenga, K., "LDAP Read Entry Controls", RFC 4527, June
2006.
[RFC4528] Zeilenga, K., "LDAP Assertion Control", RFC 4528, June
2006.
[X.680] International Telecommunication Union -
Telecommunication Standardization Sector, "Abstract
Syntax Notation One (ASN.1) - Specification of Basic
Notation", X.680(2002) (also ISO/IEC 8824-1:2002).
[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(2002) (also ISO/IEC
8825-1:2002).
[NO-OP] Zeilenga, K., "LDAP No-Operation Control", draft-
zeilenga-ldap-noop-xx.txt, a work in progress.
[RELAX] Zeilenga, K., "LDAP Relax Rules Control", draft-
zeilenga-ldap-relax-xx.txt, a work in progress.
10.2. Informative References
[RFC4520] Zeilenga, K., "Internet Assigned Numbers Authority
(IANA) Considerations for the Lightweight Directory
Access Protocol (LDAP)", RFC 4520, BCP 64, June 2006.
[ACID] Section 4 of ISO/IEC 10026-1:1992.
[DONTUSECOPY] Zeilenga, K., "LDAP Don't Use Copy Control", draft-
zeilenga-ldap-dontusecopy-xx.txt, a work in progress.
Intellectual Property
The IETF takes no position regarding the validity or scope of any
Intellectual Property Rights or other rights that might be claimed to
Zeilenga LDAP Transactions [Page 11]
INTERNET-DRAFT draft-zeilenga-ldap-txn-11 18 November 2007
pertain to the implementation or use of the technology described in
this document or the extent to which any license under such rights
might or might not be available; nor does it represent that it has
made any independent effort to identify any such rights. Information
on the procedures with respect to rights in RFC documents can be found
in BCP 78 and BCP 79.
Copies of IPR disclosures made to the IETF Secretariat and any
assurances of licenses to be made available, or the result of an
attempt made to obtain a general license or permission for the use of
such proprietary rights by implementers or users of this specification
can be obtained from the IETF on-line IPR repository at
http://www.ietf.org/ipr.
The IETF invites any interested party to bring to its attention any
copyrights, patents or patent applications, or other proprietary
rights that may cover technology that may be required to implement
this standard. Please address the information to the IETF at
ietf-ipr@ietf.org.
Full Copyright
Copyright (C) The IETF Trust (2007).
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, THE IETF TRUST 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.
Zeilenga LDAP Transactions [Page 12]
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