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Internet Engineering Task Force P. Spacek
Internet-Draft Red Hat, Inc.
Intended status: Standards Track November 18, 2015
Expires: May 21, 2016


The Lightweight Directory Access Protocol (LDAP) Content Synchronization
Operation with Transactions
draft-spacek-ldapext-syncrepl-transaction-01

Abstract

This document specifies LDAP Control which extends the persist stage
of the Content Synchronization Operation with information about LDAP
transaction boundaries. This information can be used to support
application-level transactions or for application-level
optimizations.

Status of This Memo

This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.

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This Internet-Draft will expire on May 21, 2016.

Copyright Notice

Copyright (c) 2015 IETF Trust and the persons identified as the
document authors. All rights reserved.












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Table of Contents

1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Document Conventions . . . . . . . . . . . . . . . . . . . . 3
3. Elements of the LDAP Content Synchronization with
Transactions . . . . . . . . . . . . . . . . . . . . . . . . 3
3.1. Transaction Notification Control . . . . . . . . . . . . 3
3.2. Start Transaction Notification Message . . . . . . . . . 3
3.3. End Transaction Notification Message . . . . . . . . . . 3
4. Interaction with the Content Synchronization Operation . . . 3
4.1. Refresh stage . . . . . . . . . . . . . . . . . . . . . . 4
4.2. Persist stage . . . . . . . . . . . . . . . . . . . . . . 4
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4
6. Security Considerations . . . . . . . . . . . . . . . . . . . 4
7. Normative References . . . . . . . . . . . . . . . . . . . . 5
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 5

1. Introduction

The LDAP Content Synchronization Operation [RFC4533] and LDAP
Transactions [RFC5805] are not integrated, which makes the Content
Synchronization Operation less useful.

The client using the Content Synchronization Operation has no
information of which changes were part of a single transaction. As a
result, the client cannot replicate transaction semantics reliably,
especially when a connection to an LDAP server is interrupted in the
middle of the persist stage of the Content Synchronization Operation.

Some clients could use the information where an LDAP transaction
started and ended for transactions at application level to guarantee
consistency of application data. Altenatively, some applications can
use transaction boundaries for optimizations when further processing
of the data is triggered by the end of a transaction. This might
allow the application to save some overhead by processing changes in
groups.





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2. Document Conventions

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 [RFC2119].

Term "transaction identifier" has the same definition as in
[RFC5805].

3. Elements of the LDAP Content Synchronization with Transactions

Existing protocol messages and semantics defined by [RFC4533] are not
changed. The protocol flow is only extended with Transaction
Notification Control, Start, and End Transaction Notification
Messages.

3.1. Transaction Notification Control

The Transaction Notification Control is an LDAPControl [RFC4511]
where the controlType is "TBD1" and the controlValue is absent. The
criticality may be TRUE or FALSE.

3.2. Start Transaction Notification Message

The Start Transaction Notification message is an IntermediateResponse
[RFC4511] where the responseName is "TBD2" and the responseValue is
absent.

3.3. End Transaction Notification Message

The End Transaction Notification message is an IntermediateResponse
[RFC4511] where the responseName is "TBD3" and the responseValue is
absent.

4. Interaction with the Content Synchronization Operation

The client requests information about LDAP Transaction to be added to
the Content Synchronization Operation by sending Transaction
Notification Control along with a SearchRequest Message that contains
a Sync Request Control [RFC4533]. All attempts to use Transaction
Notification Control without Sync Request Control MUST be denied with
the unwillingToPerform [RFC4511] result code.

TODO: THIS SHOULD BE CLARIFIED BY FURTHER UPDATES TO TRANSACTION RFCs

Please note that [RFC5805] defined that LDAP Transactions have
atomic, consistency, isolation, durability (ACID) properties without
further specification of the "isolation" level. This extension



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assumes that an isolation property guarantees that uncommited changes
are generaly not visible to LDAP clients and thus not returned in the
Content Synchronization Operation results.

4.1. Refresh stage

The refresh stage of the Content Synchronization Operation is
unaffected by Transaction Notification Control. The control affects
neither Content Determination nor protocol messages sent during the
refresh stage.

Transaction-aware clients MUST treat the refresh stage as a single
transaction. Messages that mark end of the refresh stage are defined
in [RFC4533].

4.2. Persist stage

Existing protocol messages and semantics defined by [RFC4533] are not
changed. The protocol flow in the persist stage is extended only
with Start and End Transaction Notification Messages.

A Start Transaction Notification Message MUST be sent to a client
when a transaction is successfully commited but before any of the
changes contained in the transaction are sent to the client.

The Start Transaction Notification Message MUST be followed by all
Change notification messages as defined in the persist stage of
[RFC4533]. A server MUST NOT interleave changes made in multiple
transactions to ensure that Start and End messages unambiguously
identify one transaction.

An End Transaction Notification Message MUST be sent immediatelly
after all Change notifications for given transaction were sent to the
client. This message signalizes to the client that the transaction
marked by the Start Transaction Notification Message is complete and
all changes can be commited.

5. IANA Considerations

TBD

6. Security Considerations

This document merely adds information about transaction boundaries to
the existing Content Synchronization Operation. This is believed not
to add any security risk.





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7. Normative References

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

[RFC4511] Sermersheim, J., "Lightweight Directory Access Protocol
(LDAP): The Protocol", RFC 4511, June 2006.

[RFC4533] Zeilenga, K. and J. Choi, "The Lightweight Directory
Access Protocol (LDAP) Content Synchronization Operation",
RFC 4533, June 2006.

[RFC5805] Zeilenga, K., "Lightweight Directory Access Protocol
(LDAP) Transactions", RFC 5805, March 2010.

Author's Address

Petr Spacek
Red Hat, Inc.

Email: pspacek@redhat.com






























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