INTERNET-DRAFT Kurt D. Zeilenga Intended Category: Experimental OpenLDAP Foundation Expires in six months 3 May 2003 LDAP Transactions 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 an Experimental document. Distribution of this memo is unlimited. Technical discussion of this document will take place on the IETF LDAP Extension Working Group mailing list . Please send editorial comments directly to the author . 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 . The list of Internet-Draft Shadow Directories can be accessed at . Copyright 2003, The Internet Society. All Rights Reserved. Please see the Copyright section near the end of this document for more information. Abstract Lightweight Directory Access Protocol (LDAP) update operations acting upon entries have atomic, consistency, isolation, durability (ACID) properties. However, it is often desirable to update two or more entries as one unit of interaction, a transaction. Transactions are necessary to support a number of applications including resource provisioning and information replication. This document defines an Zeilenga LDAP Transactions [Page 1] INTERNET-DRAFT draft-zeilenga-ldap-txn-06 3 May 2003 LDAP extension to support transactions. 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 BCP 14 [RFC2119]. 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]. 1. Overview This document extends the Lightweight Directory Access Protocol (LDAP) [RFC3377] to allow clients to group a number of related update operations [RFC2251] and have them preformed as one unit of interaction, a transaction. As with distinct update operations, each transaction has atomic, consistency, isolation, and durability ([ACID]) properties. This extension uses the grouping mechanism provided by [GROUP] to relate operations of the transaction. The createGrouping operation is used to obtain a group cookie which is used to identify operations which are apart of the transaction. The group cookie can be viewed as a transaction identifier. The endGrouping operation is used to settle (commit or abort) the transaction. 2. Specification of a Transaction Servers implementing this specification SHOULD publish the transactionGroupingType as a value of the 'supportedGroupingTypes' attribute contained within the Root DSE. transactionGroupingType ::= IANA-ASSIGNED-OID A client wishing to preform a transaction issues a createGroupingRequest with a createGroupType of transactionGroupingType and no createGroupValue. A server which is willing and able to support transactions returns a createGroupingResponse with a success result code, a createGroupCookie, and no createGroupValue. Otherwise the server returns a non-success result code, no createGroupCookie, and no createGroupValue. Zeilenga LDAP Transactions [Page 2] INTERNET-DRAFT draft-zeilenga-ldap-txn-06 3 May 2003 The client then issues may issue one or more update (add, delete, modify, rename) requests, each with a GroupingControl indicating they are to processed as part of the transaction grouping. If the server is willing and able to attempt to process operation as part of the transaction, the server returns success. As further processing of the operation is be deferred until settlement, the operation is considered still outstanding and its messageID cannot to be reused until after settlement. If the server is unwilling or unable to attempt to process the operation as part of the transaction, the server returns a non-successful result code. If the server becomes unwilling or unable to continue the specification of a transaction, the server return the canceled resultCode for each deferred operation and then issue a endGroupNotice with a non-success resultCode. Any future use of cookie by the client will result in a response containing a non-success result code. Upon receipt of a endGroupingNotice, the client is to discontinue all use of the grouping cookie as the transaction is null and void. A client requests settling of transaction by issuing an endGroupingRequest where the groupingCookie is the group cookie identify the transaction. The absence of any endGroupingValue indicates a commit request. The presence of an empty endGroupValue indicates an abort request. The endGroupValue MUST be empty if provided. If the commit response indicates failure, the server may return an endGroupingValue with the endGroupingResponse. If so, it contains the BER-encoding of a MessageID [RFC2251] of the update operation associated with the failure. 3. Settling of the Transaction Upon receipt of a request to abort the transaction, the server is to abort the transaction and then return an endGroupingResponse indicating success. Upon receipt of a request to commit the transaction, the server processes the group of update operations as one atomic, isolated action with each update request being processed in turn. Either all of the requested updates SHALL be successfully applied or none of the requested SHALL be applied. If all are applied, the server returns an endGroupingResponse indicating success. Otherwise, the server returns an endGroupingResponse indicating the nature of the failure. If the failure is associated with a particular update operation, the message ID is returned an attached endGroupingValue. If the failure was not associated with any particular update operation, no endGroupingValue Zeilenga LDAP Transactions [Page 3] INTERNET-DRAFT draft-zeilenga-ldap-txn-06 3 May 2003 is to be provided. There is no requirement that a server serialize transactions. That is, a server MAY process multiple transactions commit requests (from one or more clients) acting upon different sets of entries concurrently. A server MUST avoid deadlock. 4. Distributed Directory Considerations The LDAP/X.500 models provide for distributed directory operations including server-side chaining and client-side chasing of operations. This document does not disallow servers from chaining operations which are part of a transaction. However, if a server does allow such chaining, it MUST ensure that transaction semantics detailed above are provided. This mechanism defined by this document does not support client-side chasing. Grouping cookies used to identify the transaction are specific to a particular client/server session. The LDAP/X.500 models provide for a single-master/multiple-slave replication architecture. This document states no requirement that changes made to the directory based upon processing a transaction be replicated as one atomic action. That is, the client SHOULD NOT assume tight data consistency nor fast data convergence at slave servers unless they have prior knowledge that such is provided. Though this mechanism could be used to support replication, such use is not described in this document. The LDAP/X.500 models do not currently support a multi-master replication architecture and, hence, not considered by this specification. 5. Security Considerations Transactions mechanisms and related grouping operations may be the target of denial of service attacks. Implementors should provide safeguards to ensure these mechanisms are not abused. 6. IANA Considerations In accordance with [RFC3383], it is requested that Internet Assigned Numbers Authority (IANA) make the following assignments. Zeilenga LDAP Transactions [Page 4] INTERNET-DRAFT draft-zeilenga-ldap-txn-06 3 May 2003 6.1. Object Identifier An LDAP Object Identifier to identify the grouping type defined in this document is requested. The following registration template is suggested: Subject: Request for LDAP Object Identifier Registration Person & email address to contact for further information: Kurt Zeilenga Specification: RFCXXXX Author/Change Controller: IESG Comments: Identifies the LDAP Transactions Grouping Type 6.2. LDAP Protocol Mechanism Registration of the protocol mechanisms defined in this document is requested. Subject: Request for LDAP Protocol Mechansism Registration Object Identifier: IANA-ASSIGNED-OID Description: LDAP Transaction Grouping Type Person & email address to contact for further information: Kurt Zeilenga Usage: Grouping Specification: RFCxxxx Author/Change Controller: IESG Comments: none 7. Acknowledgments The author gratefully acknowledges the contributions made by members of the Internet Engineering Task Force. 8. Author's Address Kurt D. Zeilenga OpenLDAP Foundation 9. Normative References Zeilenga LDAP Transactions [Page 5] INTERNET-DRAFT draft-zeilenga-ldap-txn-06 3 May 2003 [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. [RFC3377] J. Hodges, R. Morgan, "Lightweight Directory Access Protocol (v3): Technical Specification", RFC 3377, September 2002. [GROUP] K. Zeilenga, "LDAP: Grouping of Related Operations", draft-zeilenga-ldap-grouping-xx.txt, a work in progress. [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. Informative References [ACID] Section 4 of ISO/IEC 10026-1:1992. [RFC3383] K. Zeilenga, "IANA Considerations for LDAP", BCP 64 (also RFC 3383), September 2002. [X.500] ITU-T, "The Directory: Overview of Concepts, Models, and Services", X.500, 1993. [X.501] ITU-T, "The Directory: Models", X.501, 1993. Copyright 2003, The Internet Society. 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 implementation 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. The limited permissions granted above are perpetual and will not Zeilenga LDAP Transactions [Page 6] INTERNET-DRAFT draft-zeilenga-ldap-txn-06 3 May 2003 be revoked by the Internet Society or its successors or assigns. This document and the information contained herein is provided on an "AS IS" basis and THE AUTHORS, THE INTERNET SOCIETY, AND THE INTERNET ENGINEERING TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Zeilenga LDAP Transactions [Page 7]