draft-zeilenga-ldap-grouping-xx.txt [plain text]
INTERNET-DRAFT Kurt D. Zeilenga
Intended Category: Standard Track OpenLDAP Foundation
Expires in six months 3 May 2003
LDAP: Grouping of Related Operations
<draft-zeilenga-ldap-grouping-06.txt>
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 a Standard Track document.
Distribution of this memo is unlimited. Technical discussion of this
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Copyright 2003, The Internet Society. All Rights Reserved.
Please see the Copyright section near the end of this document for
more information.
Abstract
This document provides a general mechanism for grouping related
Lightweight Directory Access Protocol (LDAP) operations. Grouping of
operations can be used to support replication, proxies, and
transactions.
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Conventions
Schema definitions are provided using LDAP description formats
[RFC2252]. Definitions provided here are formatted (line wrapped) for
readability.
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].
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].
1. Introduction
This document provides a general mechanism for grouping related
Lightweight Directory Access Protocol (LDAP) [RFC3377] operations.
Grouping of operations can be used to support replication, proxies,
and high level operations such as transactions [TXNGRP].
This document describes a set of LDAP extended operations [RFC2251]
and other protocol and schema elements to support grouping of related
operations. Uses of this grouping mechanism will be detailed in
separate documents.
A group of operations is defined as a set of operations within a
common session identified by a unique cookie. All requests which are
initiated with the same cookie belong to the same grouping. The
cookie is obtained using the create group operation and is normally
valid until the end group operation is completed. A group can end
prematurely as described below.
Operations can be intermixed regardless of their grouping (or lack of
grouping). Groups can be nested.
Each group is of a particular type specified when the group is
created. This type defines the semantics of the group.
2. Protocol Elements
This document describes three extended operations, two unsolicited
notification, and one control. Extended operations and controls are
described by LDAP [RFC2251] and provide here for convenience:
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ExtendedRequest ::= [APPLICATION 23] SEQUENCE {
requestName [0] LDAPOID,
requestValue [1] OCTET STRING OPTIONAL
}
ExtendedResponse ::= [APPLICATION 24] SEQUENCE {
COMPONENTS of LDAPResult,
responseName [10] LDAPOID OPTIONAL,
response [11] OCTET STRING OPTIONAL
}
Control ::= SEQUENCE {
controlType LDAPOID,
criticality BOOLEAN DEFAULT FALSE,
controlValue OCTET STRING OPTIONAL
}
2.1 Common Protocol Elements
groupCookie ::= OCTET STRING
A groupCookie is an octet string used to uniquely identify a grouping
of related operations within the session. A groupCookie is a
notational convenience.
2.2 Create Grouping Operation
The Create Grouping extended operation is used to create or start a
grouping of related operations. The operation consists of the
createGroupingRequest and the createGroupingResponse. The object
identifier createGroupingOID identifies this operation and SHOULD be
listed as a value of supportedExtension in the root DSE of servers
which support this operation.
createGroupingOID ::= "IANA-ASSIGNED-OID.1"
2.2.1 createGroupingRequest
The client initiates this operation by sending a
createGroupingRequest. This request is an ExtendedRequest where the
requestName is the object identifier createGroupOID and requestValue
is BER-encoded createGroupingRequestValue:
createGroupingRequestValue ::= SEQUENCE {
createGroupType [0] LDAPOID,
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createGroupValue [1] OCTET STRING OPTIONAL
}
where createGroupType is an object identifier that describes the
specific type of grouping and createGroupValue contains a type
specific payload.
2.2.2 createGroupingResponse
The createGroupingResponse is sent in response to a
createGroupingRequest. This response is an ExtendedResponse where the
responseName MUST be the value of the requestName provided in the
request and the response is a BER-encoded createGroupingResponseValue:
createGroupingResponseValue ::= SEQUENCE {
createGroupCookie [0] groupCookie OPTIONAL,
createGroupValue [1] OCTET STRING OPTIONAL
}
where createGroupCookie, if present, is a cookie uniquely identifying
the new grouping and createGroupValue is a type specific payload. The
createGroupCookie only when the operation results in the creation of a
group. Otherwise, it is absent.
2.3 End Grouping Operation
The End Grouping extended operation is used to end or stop a grouping
of related operations. The operation consists of the
endGroupingRequest and the endGroupingResponse. The object identifier
endGroupingOID identifies this operation and SHOULD be listed as a
value of supportedExtension in the root DSE of servers which support
this operation.
endGroupingOID ::= "IANA-ASSIGNED-OID.2"
2.3.1 endGroupingRequest
The client initiates this operation by sending an endGroupingRequest.
This request is an ExtendedRequest where the requestName is the object
identifier endGroupOID and requestValue is BER-encoded
endGroupingRequestValue:
endGroupingRequestValue ::= SEQUENCE {
endGroupCookie [0] groupCookie,
endGroupValue [1] OCTET STRING OPTIONAL
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}
where endGroupCookie is a cookie identifying the grouping and
endGroupValue contains a type specific payload.
2.3.2 endGroupingResponse
The endGroupingResponse is sent in response to a endGroupingRequest.
This response is an ExtendedResponse where the responseName MUST be
the value of the requestName provided in request and the response is a
BER-encoded endGroupingResponseValue:
endGroupingResponseValue ::= SEQUENCE {
endGroupValue [1] OCTET STRING OPTIONAL
}
where endGroupValue is a type specific payload.
2.4 endGroupingNotice
The endGroupingNotice is an LDAP unsolicited notification. The
notification may be sent to the client to end a grouping which the
server is unable or unwilling to continue to process. The notice is
an extendedResponse where the responseName is the object identifier
endGroupingNoticeOID and the response is a BER-encoded
endGroupingNoticeValue:
endGroupingNoticeOID ::= "IANA-ASSIGNED-OID.3"
endGroupingNoticeValue ::= SEQUENCE {
endGroupingCookie [0] groupCookie,
endGroupValue [1] OCTET STRING OPTIONAL
}
where endGroupingCookie is a cookie uniquely identifying the grouping
and endGroupValue contains a type specific payload.
2.5 Action Grouping Operation
The Action Grouping extended operation is used to take an action
affecting a grouping of related operations. The operation consists of
the actionGroupingRequest and the actionGroupingResponse. The object
identifier actionGroupingOID identifies this operation and SHOULD be
listed as a value of supportedExtension in the root DSE of servers
which support this operation.
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actionGroupingOID ::= "IANA-ASSIGNED-OID.4"
2.5.1 actionGroupingRequest
The client initiates this operation by sending an
actionGroupingRequest. This request is an ExtendedRequest where the
requestName is the object identifier actionGroupOID and requestValue
is BER-encoded actionGroupingRequestValue:
actionGroupingRequestValue ::= SEQUENCE {
actionGroupCookie [0] groupCookie,
actionGroupValue [1] OCTET STRING OPTIONAL
}
where actionGroupCookie is a cookie identifying the grouping and
actionGroupValue contains a type specific payload.
2.5.2 actionGroupingResponse
The actionGroupingResponse is sent in response to a
actionGroupingRequest. This response is an ExtendedResponse where the
responseName MUST be the value of the requestName provided in request
and the response is a BER-encoded actionGroupingResponseValue:
actionGroupingResponseValue ::= SEQUENCE {
actionGroupValue [1] OCTET STRING OPTIONAL
}
where actionGroupValue is a type specific payload.
2.6 infoGroupingNotice
The infoGroupingNotice is an LDAP unsolicited notification. The
notice may be sent to the client to provide additional grouping type
specific information. The notice is an extendedResponse where the
responseName is the object identifier infoGroupingNoticeOID and the
response is a BER-encoded infoGroupingNoticeValue:
infoGroupingNoticeOID ::= "IANA-ASSIGNED-OID.5"
infoGroupingNoticeValue ::= SEQUENCE {
infoGroupingCookie [0] groupCookie,
infoGroupValue [1] OCTET STRING OPTIONAL
}
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where infoGroupingCookie is a cookie uniquely identifying the grouping
and infoGroupValue contains a type specific payload.
2.7 groupingControl
The groupingControl is used to identify requests and responses as
belonging to a grouping of operations. The groupingControl is a
Control where the controlType is the object identifier
groupingControlOID, the criticality is TRUE, and the controlValue is a
BER-encoded groupingControlValue:
groupingControlOID ::= "IANA-ASSIGNED-OID.6"
groupingControlValue ::= SEQUENCE {
groupingCookie [0] groupCookie,
groupValue [1] OCTET STRING OPTIONAL
}
where groupingCookie is a cookie uniquely identifying the grouping and
groupingValue contains a type specific payload.
The value groupingControlOID SHOULD be listed as a value of
supportedControl in the root DSE by servers which support this
control.
The control SHALL NOT appear multiple times in the same LDAP PDU. If
multiple occurrences of the control are detected, the PDU SHALL be
treated as a protocol error.
3. Schema Elements
The document describes one attribute type.
3.1. supportedGroupingTypes
Servers SHOULD publish grouping types they support listing group type
object identifiers as values of the supportedGroupingTypes attribute
type in the root DSE. The supportedGroupingTypes attribute type is
defined as:
( IANA-ASSIGNED-OID.7 NAME 'supportedGroupingTypes'
DESC 'supported types of groupings of operations'
EQUALITY objectIdentifierMatch
SYNTAX 1.3.6.1.4.1.1466.115.121.1.38 USAGE dSAOperation )
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The objectIdentifierMatch and OBJECT IDENTIFIER
(1.3.6.1.4.1.1466.115.121.1.38) are defined in [RFC2252].
Servers MUST be capable of recognizing this attribute type by the name
'supportedGroupingTypes'. Servers MAY recognize the attribute type by
other names.
4. Operational Semantics
This section details the common semantics of groups of related
operations. Additional semantics may be associated with each
grouping type as described by other documents.
4.1 Grouping Semantics
This subsection details semantics of the protocol elements introduced
in Section 2.
4.1.1 Create Grouping
To group related operations, the client MUST request a groupCookie
from the server by sending a createGroupingRequest as described in
Section 2.2.1. The client SHALL provide type specific payload in
createGroupValue if so required by the grouping type.
The server SHALL respond with a createGroupingResponse as described in
Section 2.2.2. If the server is willing and able to create the
grouping as requested (and per type requirements), it SHALL respond
with success, provide a session-unique groupCookie and, if
appropriate, a type specific payload. Otherwise the server SHALL
respond with a non-successful response containing no groupCookie, but
MAY, if appropriate, provide a type specific payload.
4.1.2 End Grouping
When the client wishes to end the grouping, the client SHALL send a
endGroupingRequest as described in Section 2.3.1. The client SHALL
provide the groupCookie of the grouping to end and MAY provided a type
specific payload. If the grouping to end contains active nested
groupings, these are implicitly ended as well without notice. The
server SHALL respond with an endGroupingResponse as described in
Section 2.3.2.
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4.1.3 End Group Notice
The server MAY end a group without solicitation for any reason. The
server SHALL notify the client of this action by sending a endGrouping
Notice, as described in Section 2.4. The server SHALL provide the
groupCookie of the group it terminated and MAY provide a type specific
payload. The notice SHALL have a non-success resultCode.
If the group contains nested groups, the nested groups are implicitly
ended as well without additional notice.
4.1.4 Action Grouping
To perform an action within a group of related operations, the client
sends to the server actionGroupingRequest as described in Section
2.5.1. The client SHALL provide the groupCookie of the group the
operation is requested upon and, if required by the grouping type, a
type specific payload.
The server SHALL respond with a actionGroupingResponse as described in
Section 2.5.2. The server SHALL, if required by the grouping type,
provide type specific payload.
4.1.5 Info Grouping Notice
As allowed by the grouping type, the server MAY provide to the client
a notice regarding the grouping of related operations in an
infoGroupingNotice as described in Section 2.6. The server SHALL, if
required by the grouping type, provide type specific payload.
4.2 Nested groupings
Groups of the same or different types MAY be nested. A nested group
is instantiated by providing a groupingControl containing the parent
group's cookie with the createGroupingRequest.
Group type specifications MAY restrict the types of groupings which
may be nested. Servers MAY also place additional restrictions upon
nesting. Clients SHOULD NOT assume support for arbitrary nesting.
4.3 Intermixing of unrelated operations
LDAP is designed to allow clients to perform unrelated tasks
concurrently. In keeping with this design, operations which unrelated
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to the grouping are generally allowed be intermixed with grouped
operations. (See Section 4.5 for specific exceptions to this general
rule.) It is noted that undue restrictions often unrelated operation
cause unnecessary serialization of independent tasks, place
unnecessary burden upon implementors, and can limit extensibility.
Group type specifications SHOULD NOT disallow unrelated operations
from being intermixed with grouped operations.
Note: a grouping which disallows unrelated operatoins from being
intermixed with grouped operations can be viewed as providing
"framing" semantics.
4.4 Grouped operations
Interrogation (compare, search) and update (add, delete, modify,
rename) MAY be grouped. Certain extended operations MAY also be
grouped, but those which affect the session as a whole, such as Start
TLS, MUST NOT be grouped.
Requests and Responses associated with grouped operations contain a
groupingControl control as described in Section 2.7.
Group type specifications MAY restrict the kind and/or number of
operations which may be related. Servers MAY place additional
restrictions upon groupings. Clients SHOULD NOT assume support for
arbitrary grouping.
4.5 Other Operations
Upon issuing any grouping operation, the semantics of following
operations listed is modified as described below.
4.5.1 abandon
The abandon operation SHOULD NOT be used to cancel grouped operations.
The Cancel operation is to be used instead (as discussed in 4.5.3).
4.5.2 bind
The client SHOULD end all outstanding groupings before issuing a bind
request. The server SHALL, in addition to the behavior described in
[RFC2251] and [RFC2829], abandon all outstanding groups. No
endGroupingNotice notification is sent upon such abandonment.
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A Bind operation cannot be related to other operations using this
grouping mechanism. The bind messages SHOULD NOT contain
groupingControl controls and, if present, SHALL be treated as a a
protocol error.
4.5.3 cancel
The cancel operation [CANCEL] MAY be used to cancel grouped operations
but SHOULD NOT contain a groupingControl control unless the group type
calls for a type specific payload to be provided. The groupingCookie
in the provided groupingControl control MUST be the same associated
with the operation to be canceled, otherwise the cancel request SHALL
be treated as an error.
4.5.4 Start TLS
The client SHOULD end all outstanding groupings before issuing a Start
TLS [RFC2930] request. If there are any outstanding groupings, the
server MUST return operationsError in response to a StartTLS request.
Start TLS operation cannot be related to other operations using this
grouping mechanism and the Start TLS request and response PDUs SHALL
NOT contain a groupingControl control.
4.5.5 unbind
The server SHALL, in addition to the behavior described in [RFC2251],
abandon all outstanding groups. No endGroupingNotice is sent upon
such abandonment. An unbind operation cannot be related to other
operations using this grouping mechanism. The unbind request SHOULD
NOT contain a groupingControl control and, if present, SHALL be
ignored.
5. Profiling Requirements
Documents detailing extensions using the grouping mechanism MUST
provide a profile of its use of the mechanism.
The profile SHALL specify the object identifier to be used to uniquely
identify each grouping type it defines. Object identifiers used to
identity group types, like other protocol elements, SHALL be delegated
in accordance with BCP 64 [RFC3383] and registered as LDAP Protocol
Mechanisms [RFC3383] as detailed in Section 7.1 of this document.
The profile SHALL state which protocol elements of the mechanism it
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uses.
Each of the grouping protocol elements defined in this document allow
transfer of type specific payloads. For each protocol element used,
the profile SHALL state whether the element is to carry a type
specific payload or not and SHALL fully describe the syntax and
semantics associated with each type specific payload.
The profile MAY define grouping type specific semantics which place
further restrictions upon the grouping related operations.
6. Security Considerations
This mechanism can be used to support complex groupings of related
operations. With such complexity comes inherit risk. Specifications
of uses of this mechanism should take special care to address security
issues. In particular, denial of service and authentication,
authorization, and access-control issues should be addressed in
documents detailing uses of this grouping mechanism.
7. IANA Considerations
7.1. Future Registration of Grouping Types
Future specifications which detail LDAP grouping types are to register
each grouping type as a LDAP Protocol Mechanism per guidance given in
BCP 64 [RFC3383]. A usage of "Grouping Type" in a Protocol Mechanism
registration template indicates that the value to be registered is
associated with an LDAP Grouping Type.
7.2. Object Identifier Registration
It is requested that IANA register upon Standards Action an LDAP
Object Identifier to identify protocol elements defined in this
technical specification. The following registration template is
suggested:
Subject: Request for LDAP OID Registration
Person & email address to contact for further information:
Kurt Zeilenga <kurt@OpenLDAP.org>
Specification: RFCXXXX
Author/Change Controller: IESG
Comments:
Identifies elements of the LDAP Grouping Operation
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7.3. LDAP Protocol Mechanism
It is requested that IANA register upon Standards Action the LDAP
protocol mechanism described in this document. The following
registration template is suggested:
Subject: Request for LDAP Protocol Mechansism Registration
Object Identifier: IANA-ASSIGNED-OID
Description: See comments
Person & email address to contact for further information:
Kurt Zeilenga <kurt@openldap.org>
Usage: Extended Operation
Specification: RFCXXXX
Author/Change Controller: IESG
Comments: none
Object Identifier Type Description
------------------- ---- -------------------------
IANA-ASSIGNED-OID.1 E Create Grouping Operation
IANA-ASSIGNED-OID.2 E End Grouping Operation
IANA-ASSIGNED-OID.4 E Action Grouping Operation
in 2
7.4. supportedGroupingTypes Registration
It is requested that IANA register upon Standards Action the LDAP
'supportedGroupingTypes' descriptor. The following registration
template is suggested:
Subject: Request for LDAP Descriptor Registration
Descriptor (short name): supportedGroupingTypes
Object Identifier: IANA-ASSIGNED-OID.7
Person & email address to contact for further information:
Kurt Zeilenga <kurt@OpenLDAP.org>
Usage: Attribute Type
Specification: RFCXXXX
Author/Change Controller: IESG
8. Acknowledgments
The author gratefully acknowledges the contributions of the IETF
LDAPext and LDUP working groups. In particular, Roger Harrison
provided many useful suggestions. Also, the author notes that this
document builds upon the early works "Extended Operations for Framing
LDAP Operations" by Ellen Stokes, Roger Harrison, and Gordon Good and
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"Profile for Framing LDAPv3 Operations" by Roger Harrison.
9. Author's Address
Kurt D. Zeilenga
OpenLDAP Foundation
<Kurt@OpenLDAP.org>
10. References
10.1 Normative References
[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.
[RFC2252] M. Wahl, A. Coulbeck, T. Howes, S. Kille, "Lightweight
Directory Access Protocol (v3): Attribute Syntax
Definitions", RFC 2252, December 1997.
[RFC2829] M. Wahl, H. Alvestrand, J. Hodges, R. Morgan,
"Authentication Methods for LDAP", RFC 2829, May 2000.
[RFC2830] J. Hodges, R. Morgan, M. Wahl, "Lightweight Directory
Access Protocol (v3): Extension for Transport Layer
Security", RFC 2830, May 2000.
[RFC3377] J. Hodges, R. Morgan, "Lightweight Directory Access
Protocol (v3): Technical Specification", RFC 3377,
September 2002.
[RFC3383] K. Zeilenga, "IANA Considerations for LDAP", BCP 64 (also
RFC 3383), September 2002.
[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.
10.2. Informative References
[TXNGRP] K. Zeilenga, "LDAP Transactions" (a work in progress),
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draft-zeilenga-ldap-txn-xx.txt.
Copyright 2003, The Internet Society. All Rights Reserved.
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