INTERNET-DRAFT Kurt D. Zeilenga
Intended Category: Standard Track OpenLDAP Foundation
Expires in six months 10 February 2005
LDAP Read Entry Controls
<draft-zeilenga-ldap-readentry-04.txt>
1. Status of this Memo
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 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.
Internet-Drafts are working documents of the Internet Engineering Task
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Copyright (C) The Internet Society (2005). All Rights Reserved.
Please see the Full Copyright section near the end of this document
for more information.
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Abstract
This document specifies an extension to the Lightweight Directory
Access Protocol (LDAP) to allow the client to read the target entry of
an update operation. The client may request to read the entry before
and/or after the modifications are applied. These reads are done as
an atomic part of the update operation.
1. Background and Intent of Use
This document specifies an extension to the Lightweight Directory
Access Protocol (LDAP) [Roadmap] to allow the client to read the
target entry of an update operation (e.g., Add, Delete, Modify,
ModifyDN). The extension utilizes controls [Protocol] attached to
update requests to request and return copies of the target entry. One
request control, called the Pre-Read request control, indicates that a
copy of the entry before application of update is to be returned.
Another control, called the Post-Read request control, indicates that
a copy of the entry after application of the update is to be returned.
Each request control has a corresponding response control used to
return the entry.
To ensure proper isolation, the controls are processed as an atomic
part of the update operation.
The functionality offered by these controls is based upon similar
functionality in the X.500 Directory Access Protocol (DAP) [X.511].
The Pre-Read controls may be used to obtain replaced or deleted values
of modified attributes or a copy of the entry being deleted.
The Post-Read controls may be used to obtain values of operational
attributes, such as the 'entryUUID' [EntryUUID] and 'modifyTimestamp'
[Models] attributes, updated by the server as part of the update
operation.
2. Terminology
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 5.2 of [Protocol].
DN stands for Distinguished Name.
DSA stands for Directory System Agent (i.e., a directory server).
DSE stands for DSA-specific Entry.
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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].
3. Read Entry Controls
3.1. The Pre-Read Controls
The Pre-Read request and response controls are identified by the
IANA-ASSIGNED-OID.1 object identifier. Servers implementing these
controls SHOULD publish IANA-ASSIGNED-OID.1 as a value of the
'supportedControl' [Models] in their root DSE.
The Pre-Read request control is an LDAP Control [Protocol] whose
controlType is IANA-ASSIGNED-OID.1 and whose controlValue is a
BER-encoded AttributeSelection [Protocol], as extended by [RFC3673].
The criticality may be TRUE or FALSE. This control is appropriate for
the modifyRequest, delRequest, and modDNRequest LDAP messages.
The corresponding response control is a LDAP Control whose controlType
is IANA-ASSIGNED-OID.1 and whose the controlValue, an OCTET STRING,
contains a BER-encoded SearchResultEntry. The criticality may be TRUE
or FALSE. This control is appropriate for the modifyResponse,
delResponse, and modDNResponse LDAP messages with a resultCode of
success (0).
When the request control is attached to an appropriate update LDAP
request, the control requests the return of a copy of target entry
prior to the application of the update. The AttributeSelection
indicates, as discussed in [Protocol][RFC3673] which attributes are
requested to appear in the copy. The server is to return a
SearchResultEntry containing, subject to access controls and other
constraints, values of the requested attributes.
The normal processing of the update operation and the processing of
this control MUST be performed as one atomic action isolated from
other update operations.
If the update operation fails (in either normal or control
processing), no response control is provided.
3.2. The Post-Read Controls
The Post-Read request and response controls are identified by the
IANA-ASSIGNED-OID.2 object identifier. Servers implementing these
controls SHOULD publish IANA-ASSIGNED-OID.2 as a value of the
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'supportedControl' [Models] in their root DSE.
The Post-Read request control is an LDAP Control [Protocol] whose
controlType is IANA-ASSIGNED-OID.2 and whose controlValue, an OCTET
STRING, contains a BER-encoded AttributeSelection [Protocol], as
extended by [RFC3673]. The criticality may be TRUE or FALSE. This
control is appropriate for the addRequest, modifyRequest, and
modDNRequest LDAP messages.
The corresponding response control is a LDAP Control whose controlType
is IANA-ASSIGNED-OID.2 and whose controlValue is a BER-encoded
SearchResultEntry. The criticality may be TRUE or FALSE. This
control is appropriate for the addResponse, modifyResponse, and
modDNResponse LDAP messages with a resultCode of success (0).
When the request control is attached to an appropriate update LDAP
request, the control requests the return of a copy of target entry
after the application of the update. The AttributeSelection
indicates, as discussed in [Protocol][RFC3673], which attributes are
requested to appear in the copy. The server is to return a
SearchResultEntry containing, subject to access controls and other
constraints, values of the requested attributes.
The normal processing of the update operation and the processing of
this control MUST be performed as one atomic action isolated from
other update operations.
If the update operation fails (in either normal or control
processing), no response control is provided.
4. Interaction with other controls
The Pre-Read and Post-Read controls may be combined with each other
and/or with a variety of other controls. When combined with the
assertion control [Assertion] and/or the manageDsaIT control
[RFC3296], the semantics of each control included in the combination
apply. The Pre-Read and Post-Read controls may be combined with other
controls as detailed in other technical specifications.
5. Security Considerations
The controls defined in this document extend update operations to
support read capabilities. Servers MUST ensure that the client is
authorized both for reading of the information provided in this
control in addition to ensuring the client is authorized to perform
the requested directory update.
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Security considerations for the update operations [Protocol] extended
by this control, as well as general LDAP security considerations
[Roadmap], generally apply to implementation and use of this extension
6. IANA Considerations
Registration of the following protocol values [BCP64bis] is requested.
6.1. Object Identifier
It is requested that IANA register an LDAP Object Identifier to
identify LDAP protocol elements defined in this document.
Subject: Request for LDAP Object Identifier Registration
Person & email address to contact for further information:
Kurt Zeilenga <kurt@OpenLDAP.org>
Specification: RFC XXXX
Author/Change Controller: IESG
Comments:
Identifies the LDAP Read Entry Controls
6.2. LDAP Protocol Mechanisms
It is requested that IANA register the LDAP Protocol Mechanism
described in this document.
Subject: Request for LDAP Protocol Mechanism Registration
Object Identifier: IANA-ASSIGNED-OID.1
Description: LDAP Pre-read Control
Person & email address to contact for further information:
Kurt Zeilenga <kurt@openldap.org>
Usage: Control
Specification: RFC XXXX
Author/Change Controller: IESG
Comments: none
in 2
Subject: Request for LDAP Protocol Mechanism Registration
Object Identifier: IANA-ASSIGNED-OID.2
Description: LDAP Post-read Control
Person & email address to contact for further information:
Kurt Zeilenga <kurt@openldap.org>
Usage: Control
Specification: RFC XXXX
Author/Change Controller: IESG
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Comments: none
7. Acknowledgment
The LDAP Pre-Read and Post-Read controls are modeled after similar
capabilities offered in the DAP [X.511].
8. References
[[Note to the RFC Editor: please replace the citation tags used in
referencing Internet-Drafts with tags of the form RFCnnnn where
possible.]]
8.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14 (also RFC 2119), March 1997.
[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.
[Models] Zeilenga, K. (editor), "LDAP: Directory Information
Models", draft-ietf-ldapbis-models-xx.txt, a work in
progress.
[RFC3296] Zeilenga, K., "Named Subordinate References in
Lightweight Directory Access Protocol (LDAP)
Directories", RFC 3296, July 2002.
[RFC3673] Zeilenga, K., "LDAPv3: All Operational Attributes", RFC
3673, December 2003.
[Assertion] Zeilenga, K., "LDAP Assertion Control",
draft-zeilenga-ldap-assert-xx.txt, a work in progress.
[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 -
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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).
8.2. Informative References
[BCP64bis] Zeilenga, K., "IANA Considerations for LDAP",
draft-ietf-ldapbis-bcp64-xx.txt, a work in progress.
[EntryUUID] Zeilenga, K., "The LDAP EntryUUID Operational
Attribute", draft-zeilenga-ldap-uuid-xx.txt, a work in
progress.
[X.511] International Telecommunication Union -
Telecommunication Standardization Sector, "The
Directory: Abstract Service Definition", X.511(1993)
(also ISO/IEC 9594-3:1993).
10. Author's Address
Kurt D. Zeilenga
OpenLDAP Foundation
Email: Kurt@OpenLDAP.org
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