SIMPLE WG M. Lonnfors Internet-Draft Nokia Research Center Expires: April 2, 2004 J. Costa-Requena E. Leppanen H. Khartabil Nokia October 3, 2003 Requirements for Efficient Delivery of Presence Information draft-ietf-simple-presinfo-deliv-reg-01 Status of this Memo This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of RFC2026. 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. This Internet-Draft will expire on April 2, 2004. Copyright Notice Copyright (C) The Internet Society (2003). All Rights Reserved. Abstract A Presence service implemented using SIMPLE has some constraints for delivering presence information to devices with low data processing capabilities, small display, and limited battery power. Other limitations can be caused by the interface between the terminal and the network, i.e. if presence information is delivered over radio links with high latency and low bandwidth. This memo presents requirements for a solution that can aid to reduce the impacts of these constrains and helps to increase efficiency. Lonnfors, et al. Expires April 2, 2004 [Page 1] Internet-Draft Efficient presence delivery requirements October 2003 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Conventions . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. Requirements . . . . . . . . . . . . . . . . . . . . . . . . . 4 3.1 General requirements . . . . . . . . . . . . . . . . . . . . . 4 3.2 Performance requirements . . . . . . . . . . . . . . . . . . . 4 3.3 Client and server requirements . . . . . . . . . . . . . . . . 4 4. Example use cases . . . . . . . . . . . . . . . . . . . . . . 5 4.1 Case 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 4.2 Case 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 4.3 Case 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 5. Security Considerations . . . . . . . . . . . . . . . . . . . 5 6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 5 References . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 6 Intellectual Property and Copyright Statements . . . . . . . . 8 Lonnfors, et al. Expires April 2, 2004 [Page 2] Internet-Draft Efficient presence delivery requirements October 2003 1. Introduction SIP extensions for presence [6] allow users ('watchers') to subscribe to other users ('presentities') presence information. The presence information is composed of multiple pieces of data (tuples) that are delivered to the watcher. Model for presence information delivery that is defined in [2] and in [6] specify that watchers always receive all presence data related to a presentity. The size of the presence information can potentially become large (i.e. presence document may contain an arbitrary number of elements called tuples that may convey data). It may not be reasonable to send complete presence information over low bandwidth and high latency links when only part of that information has changed. This may end up in degrading the presence service and causing bad perception at the watcher side. Thus, it is necessary to provide solutions to overcome this problem. Presence based applications in wireless terminals have certain processing and bandwidth limitations. It is foreseen that the presence information may have a considerable size, especially if non-ACSII content (for example a picture) is included in presence information. Requirements of wireless environments are addressed in [3]. There are some mechanisms, which might be used to help the problem, such as signaling compression [4] and content indirection [5]. However, none of the existing solutions are optimal because they may set additional requirements on basic network functionalities such as security and cause difficulties in implementing some charging models. SIGCOMP helps to reduce the transported data size if data can be compressed. However, if data cannot be compressed (for example pictures in jpeg format) use of SIGCOMP doesn't provide much help. Some of the existing solutions (e.g. content indirection) require having a specific server to store the requested presence information until the terminal fetches it using another protocol (e.g. HTTP) and therefore increases possible security concerns. This memo discusses the requirements for an approach where the Presence Server (PS) can deliver to the watchers only the part of the presence information that has changed compared to the previous notification. This mechanism is called partial notification. The partial notification is already identified as a potential approach by the SIP Extensions for Presence document [6]. . 2. Conventions In this document, the key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", Lonnfors, et al. Expires April 2, 2004 [Page 3] Internet-Draft Efficient presence delivery requirements October 2003 and "OPTIONAL" are to be interpreted as described in RFC 2119 [1] and indicate requirement levels for compliant implementations. 3. Requirements 3.1 General requirements REG1: The subscriber MUST have a mechanism to limit the overall content size delivered in the notifications. REQ2: The presence service MUST allow mechanisms for efficient handling of large contents of presence documents. RE3: The mechanism MUST allow the subscriber to get information about presence information changes (modifications, removals, and additions) compared to last notification. REQ4: The mechanism MUST NOT affect the requirements of basic network functionalities such as security. 3.2 Performance requirements REQ5: The presence service MUST allow efficient utilization of the network resources (radio links). The presence service MUST be able to avoid additional or unnecessary round-trips for receiving changed presence information. REQ6: The presence service MUST be able to avoid transmission of unnecessary information (over radio links) when notifying the presence information change to watcher. REQ7: The presence service MUST be able to be utilized by devices with low data processing capabilities, small display, limited memory size and limited battery power. 3.3 Client and server requirements REQ8: The subscriber MUST be able to negotiate, during the subscription phase, to receive only changes of the presence document. REQ9: The subscriber MUST be able to indicate support to receive only changes of the presence information. REQ10: The subscriber SHOULD be able to request, during the subscription phase, that the Presence Agent sends only changes to the presence document. REQ11: The subscriber capable of receiving only changes to presence Lonnfors, et al. Expires April 2, 2004 [Page 4] Internet-Draft Efficient presence delivery requirements October 2003 documents MUST be able to use the presence service with full state notifications. 4. Example use cases 4.1 Case 1 Presence service charging for a subscriber is based on the received data volume. Thus the subscriber requires from the presence server that only the changed content is delivered after the first notification. 4.2 Case 2 The watcher and the presentity have network subscriptions for different operators. Presentity's presence information contains non-ASCII data like pictures. One option to deliver pictures could be implemented by using content indirection mechanism [5] but presentity's operator may not be willing to store content that will be delivered to customer of some other operator. To enable efficient handling of non-ACSII data and to limit the network load operator can support partial notifications instead. 4.3 Case 3 The presentity's presence data is composed of the normal status information and it also contains a picture. The watcher using a wireless terminal subscribes to presentity's presence information. Due to limitations in wireless environment the watcher would like to limit the amount of transferred data over wireless links. Using the partial notifications presence server can send only changed presence information thus limiting the amount of data transferred over wireless links. 5. Security Considerations This document provides requirements for efficient delivery of Presence information. Because of this no security consideration apply directly to this document. However, solution is likely to build on top of presence delivery mechanisms defined in IMPP and in SIMPLE working group all security considerations defined in PIDF [2] and in [6] will apply to the solution. 6. Acknowledgements The authors would like to thank Juha Kalliokulju for his valuable comments. Lonnfors, et al. Expires April 2, 2004 [Page 5] Internet-Draft Efficient presence delivery requirements October 2003 References [1] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [2] Day, M., Rosenberg, J. and H. Sugano, "A Model for Presence and Instant Messaging", RFC 2778, February 2000. [3] Kiss, K., "Requirements for Presence Service based on 3GPP specifications and wireless environment characteristics", draft-kiss-simple-presence-wireless-reqs-02 (work in progress), Febryary 2003. [4] Price, R., "Signaling Compression (SigComp)", RFC 3320, January 2003. [5] Olson, S., "A Mechanism for Content Indirection in Session Initiation Protocol (SIP) Messages", draft-ietf-sip-content-indirect-mech-02, November 2002. [6] Rosenberg, J., "Session Initiation Protocol (SIP) Extensions for Presence", draft-ietf-simple-presence-10.txt, May 2002. Authors' Addresses Mikko Lonnfors Nokia Research Center Itamerenkatu 00180 Helsinki Finland Phone: + 358 71 8008000 EMail: mikko.lonnfors@nokia.com Jose Costa-Requena Nokia Valimotie 9 00380 Helsinki Finland Phone: +358 71 8008000 EMail: jose.costa-requena@nokia.com Lonnfors, et al. Expires April 2, 2004 [Page 6] Internet-Draft Efficient presence delivery requirements October 2003 Eva Leppanen Nokia P.O BOX 785 Tampere Finland Phone: +358 7180 77066 EMail: eva-maria.leppanen@nokia.com Hisham Khartabil Nokia P.O. Box 321 Helsinki Finland Phone: +358 7180 76161 EMail: hisham.khartabil@nokia.com Lonnfors, et al. Expires April 2, 2004 [Page 7] Internet-Draft Efficient presence delivery requirements October 2003 Intellectual Property Statement The IETF takes no position regarding the validity or scope of any 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. 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Expires April 2, 2004 [Page 8] Internet-Draft Efficient presence delivery requirements October 2003 HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Acknowledgement Funding for the RFC Editor function is currently provided by the Internet Society. Lonnfors, et al. Expires April 2, 2004 [Page 9]