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Copyright Notice
Copyright (C) The Internet Society (2006).
Abstract
This document describes an extension to the Lightweight Directory Access Protocol (LDAP) Modify operation to support an increment capability. This extension is useful in provisioning applications, especially when combined with the assertion control and/or the pre- read or post-read control extension.
The Lightweight Directory Access Protocol (LDAP) [RFC4510] does not currently provide an operation to increment values of an attribute. A client must read the values of the attribute and then modify those values to increment them by the desired amount. As the values may be updated by other clients between this add and modify, the client must
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be careful to construct the modify request so that it fails in this case, and upon failure, to re-read the values and construct a new modify request.
This document extends the LDAP Modify Operation [RFC4511] to support an increment values capability. This feature is intended to be used with either the LDAP pre-read or post-read control extensions [RFC4527]. This feature may also be used with the LDAP assertion control extension [RFC4528] to provide test-and-increment functionality.
In this document key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" are to be interpreted as described in BCP 14 [RFC2119].
This document extends the LDAP Modify request to support a increment values capability. Implementations of this extension SHALL support an additional ModifyRequest operation enumeration value increment (3), as described herein. Implementations not supporting this extension will treat this value as they would an unlisted value, e.g., as a protocol error.
The increment (3) operation value specifies that an increment values modification is requested. All existing values of the modification attribute are to be incremented by the listed value. The modification attribute must be appropriate for the request (e.g., it must have INTEGER or other increment-able values), and the modification must provide one and only one value. If the attribute is not appropriate for the request, a constraintViolation or other appropriate error is to be returned. If multiple values are provided, a protocolError is to be returned.
Servers supporting this feature SHOULD publish the object identifier (OID) 1.3.6.1.1.14 as a value of the 'supportedFeatures' [RFC4512] attribute in the root DSE. Clients supporting this feature SHOULD NOT use the feature unless they know the server supports it.
General LDAP security considerations [RFC4510], as well as those specific to the LDAP Modify [RFC4511], apply to this Modify-Increment extension. Beyond these considerations, it is noted that introduction of this extension should reduce application complexity (by providing one operation for what presently requires multiple operations) and, hence, it may aid in the production of correct and secure implementations.
The IANA has assigned an LDAP Object Identifier to identify the LDAP Modify-Increment feature, as 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 4525 Author/Change Controller: Author Comments: Identifies the LDAP Modify-Increment feature
The following LDAP Protocol Mechanism has been registered.
Subject: Request for LDAP Protocol Mechanism Registration Object Identifier: 1.3.6.1.1.14 Description: Modify-Increment Person & email address to contact for further information: Kurt Zeilenga <kurt@openldap.org>
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[RFC4520] Zeilenga, K., "Internet Assigned Numbers Authority (IANA) Considerations for the Lightweight Directory Access Protocol (LDAP)", BCP 64, RFC 4520, June 2006.
[RFC4527] Zeilenga, K., "Lightweight Directory Access Protocol (LDAP) Read Entry Controls", RFC 4527, June 2006.
[RFC4528] Zeilenga, K., "Lightweight Directory Access Protocol (LDAP) Assertion Control", RFC 4528, June 2006.
Author's Address
Kurt D. Zeilenga OpenLDAP Foundation
EMail: Kurt@OpenLDAP.org
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