INTERNET-DRAFT Howard Y. Chu Intended Category: Standard Track Symas Corporation Expires in six months 1 December 2004 Change Sequence Numbers for LDAP <draft-chu-ldap-csn-00.txt> Status of this 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 an 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>. 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/ietf/1id-abstracts.txt>. The list of Internet-Draft Shadow Directories can be accessed at <http://www.ietf.org/shadow.html>. Copyright (C) The Internet Society (2004). All Rights Reserved. Please see the Full Copyright section near the end of this document for more information. Abstract This document describes the LDAP/X.500 Change Sequence Number 'CSN' syntax and matching rules and associated attributes. CSNs are used to impose a total ordering upon the sequence of updates applied to a directory. Chu draft-chu-ldap-csn-00 [Page 1]  INTERNET-DRAFT LDAP CSN 1 December 2004 1. Background and Intended Use In X.500 Directory Services [X.501], updates to a directory may need to be distributed to multiple servers. The 'modifyTimeStamp' is already defined for recording the time of an update, but it may be inadequate in an environment where multiple servers with loosely synchronized clocks are interoperating. This document describes the 'CSN' syntax which augments a timestamp with additional information to assist in coordinating updates among multiple directory servers. This document describes the 'entryCSN' operational attribute which carries the CSN of the last update applied to an entry and also the 'contextCSN' operational attribute which carries the greatest CSN of all updates applied to a directory context. Directory clients and servers may use these attributes to assist in synchronizing shadowed copies of directory information. This document describes the 'csnMatch' and 'csnOrderingMatch' matching rules corresponding to the 'CSN' syntax. 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]. Schema definitions are provided using LDAP description formats [RFC2252]. Definitions provided here are formatted (line wrapped) for readability. 2. CSN Schema Elements 2.1 CSN Syntax Values in this syntax are encoded according to the following BNF: CSN = timestamp '#' operation-counter '#' replica-id timestamp = <generalizedTimeString as specified in 6.14 of [RFC2252]> operation-counter = 6hex-digit replica-id = 2hex-digit The timestamp SHALL use GMT and SHALL NOT include fractional seconds. The operation-counter is set to zero at the start of each second, and incremented by one for each update operation that occurs within that second. The replica-id is an identifier that represents a specific Replica in a collection of cooperating servers. The following is a LDAP syntax description [RFC2252] suitable for publication in the subschema. ( IANA-ASSIGNED-OID.1 DESC 'CSN' ) Chu draft-chu-ldap-csn-00 [Page 2]  INTERNET-DRAFT LDAP CSN 1 December 2004 2.2 'csnMatch' Matching Rule The 'csnMatch' matching rule compares an asserted CSN with a stored CSN for equality. Its semantics are same as the octetStringMatch [X.520][RFC2252] matching rule. The following is a LDAP matching rule description [RFC2252] suitable for publication in the subschema. ( IANA-ASSIGNED-OID.2 NAME 'csnMatch' SYNTAX IANA-ASSIGNED-OID.1 ) 2.3 'csnOrderingMatch' Matching Rule The 'csnOrderingMatch' matching rule compares an asserted CSN with a stored CSN for ordering. Its semantics are the same as the octetStringOrderingMatch [X.520][RFC2252] matching rule. The following is a LDAP matching rule description [RFC2252] suitable for publication in the subschema. ( IANA-ASSIGNED-OID.3 NAME 'csnOrderingMatch' SYNTAX IANA-ASSIGNED-OID.1 ) 2.4. 'entryCSN' attribute The 'entryCSN' operational attribute provides the CSN of the last update applied to the entry. The following is a LDAP attribute type description [RFC2252] suitable for publication in the subschema. ( IANA-ASSIGNED-OID.4 NAME 'entryCSN' DESC 'CSN of the entry content' EQUALITY csnMatch ORDERING csnOrderingMatch Chu draft-chu-ldap-csn-00 [Page 3]  INTERNET-DRAFT LDAP CSN 1 December 2004 SYNTAX IANA-ASSIGNED-OID.1 SINGLE-VALUE NO-USER-MODIFICATION USAGE directoryOperation ) Servers SHALL assign a CSN to each entry upon its addition to the directory and provide the entry's CSN as the value of the 'entryCSN' operational attribute. The entryCSN attribute SHOULD be updated upon every update of the entry. 2.5. 'contextCSN' attribute The 'contextCSN' operational attribute provides the greatest CSN of all the updates applied to a context. The following is a LDAP attribute type description [RFC2252] suitable for publication in the subschema. ( IANA-ASSIGNED-OID.5 NAME 'contextCSN' DESC 'the largest committed CSN of a context' EQUALITY csnMatch ORDERING csnOrderingMatch SYNTAX IANA-ASSIGNED-OID.1 SINGLE-VALUE NO-USER-MODIFICATION USAGE directoryOperation ) Servers SHALL record the greatest CSN of all updates applied to a context in the root entry of the context. 3. Security Considerations General LDAP security considerations [RFC3377] apply. 4. IANA Considerations 4.1. Object Identifier Registration It is requested that IANA register upon Standards Action an LDAP Object Identifier for use in this technical specification. Subject: Request for LDAP OID Registration Person & email address to contact for further information: Howard Chu <hyc@symas.com> Specification: RFC XXXX Author/Change Controller: IESG Comments: Identifies the CSN schema elements 4.2. Registration of the csnMatch descriptor It is requested that IANA register upon Standards Action the LDAP 'csnMatch' descriptor. Subject: Request for LDAP Descriptor Registration Descriptor (short name): csnMatch Object Identifier: IANA-ASSIGNED-OID.2 Person & email address to contact for further information: Howard Chu <hyc@symas.com> Usage: Matching Rule Specification: RFC XXXX Author/Change Controller: IESG Chu draft-chu-ldap-csn-00 [Page 4]  INTERNET-DRAFT LDAP CSN 1 December 2004 4.3. Registration of the csnOrderingMatch descriptor It is requested that IANA register upon Standards Action the LDAP 'csnOrderingMatch' descriptor. Subject: Request for LDAP Descriptor Registration Descriptor (short name): csnOrderingMatch Object Identifier: IANA-ASSIGNED-OID.3 Person & email address to contact for further information: Howard Chu <hyc@symas.com> Usage: Matching Rule Specification: RFC XXXX Author/Change Controller: IESG 4.4. Registration of the entryCSN descriptor It is requested that IANA register upon Standards Action the LDAP 'entryCSN' descriptor. Subject: Request for LDAP Descriptor Registration Descriptor (short name): entryCSN Object Identifier: IANA-ASSIGNED-OID.4 Person & email address to contact for further information: Howard Chu <hyc@symas.com> Usage: Attribute Type Specification: RFC XXXX Author/Change Controller: IESG 4.5. Registration of the contextCSN descriptor It is requested that IANA register upon Standards Action the LDAP 'contextCSN' descriptor. Subject: Request for LDAP Descriptor Registration Descriptor (short name): contextCSN Object Identifier: IANA-ASSIGNED-OID.5 Person & email address to contact for further information: Howard Chu <hyc@symas.com> Usage: Attribute Type Specification: RFC XXXX Author/Change Controller: IESG 5. Acknowledgments This document is based on prior work from the IETF LDUP working group including the LDAP Replication Architecture [LDUPMODEL] and the LDAP Content Synchronization Operation [LDUPSYNC]. 6. Author's Addresses Howard Y. Chu Symas Corporation <hyc@symas.com> Kurt D. Zeilenga OpenLDAP Foundation <Kurt@OpenLDAP.org> 7. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14 (also RFC 2119), March 1997. Chu draft-chu-ldap-csn-00 [Page 5]  INTERNET-DRAFT LDAP CSN 1 December 2004 [RFC2252] Wahl, M., A. Coulbeck, T. Howes, and S. Kille, "Lightweight Directory Access Protocol (v3): Attribute Syntax Definitions", RFC 2252, December 1997. [RFC3377] Hodges, J. and R. Morgan, "Lightweight Directory Access Protocol (v3): Technical Specification", RFC 3377, September 2002. [X.501] International Telecommunication Union - Telecommunication Standardization Sector, "The Directory -- Models," X.501(1993) (also ISO/IEC 9594-2:1994). [X.520] International Telecommunication Union - Telecommunication Standardization Sector, "The Directory: Selected Attribute Types", X.520(1993) (also ISO/IEC 9594-6:1994). [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). [LDUPSYNC] Zeilenga, K. and Choi, J-H "LDAP Content Synchronization Operation", draft-zeilenga-ldup-sync-05.txt, a work in progress. 8. Informative References [RFC3383] Zeilenga, K., "IANA Considerations for LDAP", BCP 64 (also RFC 3383), September 2002. [LDUPMODEL] Merrellls, J., Srinivasan, U., and Reed, E., "LDAP Replication Architecture", draft-ietf-ldup-model-09.txt. Intellectual Property Rights The IETF takes no position regarding the validity or scope of any Chu draft-chu-ldap-csn-00 [Page 6]  INTERNET-DRAFT LDAP CSN 1 December 2004 intellectual property or other rights that might be claimed to 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; neither does it represent that it has made any effort to identify any such rights. Information on the IETF's procedures with respect to rights in standards-track and standards-related documentation can be found in BCP-11. Copies of claims of rights made available for publication 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 implementors or users of this specification can be obtained from the IETF Secretariat. The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights which may cover technology that may be required to practice this standard. Please address the information to the IETF Executive Director. Full Copyright Copyright (C) The Internet Society (2004). All Rights Reserved. This document and translations of it may be copied and furnished to others, and derivative works that comment on or otherwise explain it or assist in its implmentation may be prepared, copied, published and distributed, in whole or in part, without restriction of any kind, provided that the above copyright notice and this paragraph are included on all such copies and derivative works. However, this document itself may not be modified in any way, such as by removing the copyright notice or references to the Internet Society or other Internet organizations, except as needed for the purpose of developing Internet standards in which case the procedures for copyrights defined in the Internet Standards process must be followed, or as required to translate it into languages other than English. Chu draft-chu-ldap-csn-00 [Page 7]