INTERET-DRAFT J.Costa-Requena draft-lonnfors-simple-presinfo-deliv-reqs-00.txt Eva Leppanen Expires: July 2003 Hisham Khartabil Mikko Lonnfors Nokia January 2003 Requirements for Efficient Delivery of Presence Information 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. 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. over radio links with high latency and low bandwidth. This memo presents requirements for a solution that aids in reducing the impacts of those constrains and increasing efficiency. Table of Contents 1 Introduction....................................................2 2 Conventions used in this document...............................3 3 Requirements....................................................3 3.1 General requirements.......................................3 3.2 Performance requirements...................................3 3.3 Client and server requirements.............................3 Costa-Requena, Leppanen, Khartabil, Lonnfors [Page 1] INTERNET-DRAFT Efficient Delivery of Presence Info January 2003 4 Example use cases...............................................4 5 Security Considerations.........................................4 6 Acknowledgements................................................4 7 References......................................................5 8 Author's Addresses..............................................5 1 Introduction SIP extensions for presence [1] allow users ("watchers") to subscribe to other users ("presentities") presence information. The presence information is composed of multiple pieces of data that is delivered to the watcher. The size of the presence information can be large (i.e. an arbitrary number of elements called ôPresence tuplesö 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 changes. 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 for the sake of success of the presence service. Presence based applications in wireless terminals have certain limitations because it is envisioned that the presence service may demand high bandwidth. It is foreseen that the presence information may have a considerable size, especially if large content is included in presence information. Requirements of wireless environments are also addressed in [2]. There are some mechanisms, which might be used to help the problem, such as signaling compression [3] and content indirection [4, 5]. However, none of the existing solutions are optimal because they set additional requirements on basic network functionalities such as charging and security. Some of the existing solutions enforce certain requirements on the network and terminals for supporting compression mechanism, while other solutions 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 (called ôpartial notificationsö) where the Presence Server (PS) delivers to the watchers only the part of the presence information that has changed compared to the previous notification. The partial notification is already identified as a potential approach by the SIP Extensions for Presence document [1]. Costa-Requena, Leppanen, Khartabil, Lonnfors [Page 2] INTERNET-DRAFT Efficient Delivery of Presence Info January 2003 2 Conventions used in this document 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 RFC 2119 [6]. 3 Requirements 3.1 General requirements REQ1: The subscriber MUST be able 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. REQ3: The mechanism MUST allow the subscriber to get information about state changes (modifications, removals, and additions) of presence information and its structure. REQ4: The mechanism MUST NOT affect the requirements of basic network functionalities such as security, and charging. 3.2 Performance requirements REQ5: The presence service MUST allow efficient utilization of the network resources (radio links). The presence service SHOULD avoid additional or unnecessary round-trips for receiving changed presence information. REQ6: The presence service MUST be able to be utilised by devices with low data processing capabilities, small display and limited battery power. 3.3 Client and server requirements REQ7: The subscriber MUST be able to negotiate, during the subscription phase, to receive only changes of the presence document. REQ8: The subscriber MUST be able to indicate support for partial notification. REQ9: The subscriber SHOULD be able to request, during the subscription phase, that the Presence Agent sends only changes to the presence document. Costa-Requena, Leppanen, Khartabil, Lonnfors [Page 3] INTERNET-DRAFT Efficient Delivery of Presence Info January 2003 REQ10: The subscriber capable of receiving only changes to presence documents MUST be able to use the presence service with full state notifications. REQ11: There MUST NOT be any noticeable delays in getting the presence information available for the end user. 4 Example use cases * 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 delivery. * The subscriber does not have any agreement of using a server for storing data contents in the home network. The subscriber makes a subscription to get contact and availability information of a presentity. The contact and available information includes a photo of the presentity. The subscriber keeps the subscription valid until the presentity becoming available for communication. The subscriber indicates in the subscription about its capability for partial notifications (and thus preference to receive only changed information). * The watcher and the presentity have network subscriptions for different operators. The watcher is abroad and subscribes to presence information consisting a video clip, which is changed once a week. The other subscribed information changes more often based on the status of the presentityÆs devices. Because of a high price of the content transfer to abroad the watcher prefers to minimize costs by subscribing to changes. * The watcher has low memory on his/her mobile device and wants to receive only changes to presence documents. The watcher can switch on the partial notification feature (and consequently get charged for it). 5 Security Considerations This document provides requirements for efficient delivery of Presence information. Because it is based on presence delivery mechanisms defined in IMPP and in SIMPLE working group all security considerations defined in PIDF [7] and in [1] apply. 6 Acknowledgements Costa-Requena, Leppanen, Khartabil, Lonnfors [Page 4] INTERNET-DRAFT Efficient Delivery of Presence Info January 2003 The authors would like to thank Juha Kalliokulju for his valuable comments. 7 References [1] Rosenberg, J., et al, "SIP Extensions for Presence", draft-ietf- simple-presence-07.txt. Internet Draft, May 2002, Work in progress. [2] K.Kiss, ôRequirements for Presence Service based on 3GPP specifications and wireless environment characteristicsö draft-kiss- simple-presence-wireless-reqs-01.txt. Internet Draft, October 2002. Work in progress. [3] Price, R., et al, öSignaling Compression (SigComp)ö, RFC 3320, Internet Engineering Task Force, January 2003. [4] Olson, S.,ö A Mechanism for Content Indirection in Session Initiation Protocol (SIP) Messagesö, draft-ietf-sip-content-indirect- mech-01. Internet Draft, November 2002, Work in progress. [5] Khartabil. H.,ö Congestion safety and Content Indirectionö, draft-khartabil-sip-congestionsafe-ci-01.txt, Internet Draft, October 2002, Work in progress. [6] S. Bradner, "Key words for use in RFCs to indicate requirement levels," RFC 2119, Internet Engineering Task Force, Mar. 1997. [7] H. Sugano, S. Fujimoto, et al, "CPIM presence information data format," draft-ietf-impp-cpim-pidf-05.txt. Internet Draft, May 2002. Work in progress. 8 Author's Addresses Jose Costa-Requena Nokia Valimotie 9 00380 HELSINKI Finland Tel: +358-71-8008000 E-mail: jose.costa-requena@nokia.com Mikko Lonnfors Nokia Research Center P.O. Box 407 FIN-00045 NOKIA GROUP Costa-Requena, Leppanen, Khartabil, Lonnfors [Page 5] INTERNET-DRAFT Efficient Delivery of Presence Info January 2003 Finland Tel: +358 50 4836402 Email: mikko.lonnfors@nokia.com Eva Leppanen Nokia P.O Box 785 FIN-33101 Tampere FINLAND Tel: +358 7180 77066 Email: eva-maria.leppanen@nokia.com Hisham Khartabil Nokia P.O. Box 321 FIN-00045 NOKIA GROUP FINLAND Email: hisham.khartabil@nokia.com Tel: + 358 7180 76161 Costa-Requena, Leppanen, Khartabil, Lonnfors [Page 6]