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'3' == Outdated reference: A later version (-05) exists of draft-ietf-sip-content-indirect-mech-02 Summary: 5 errors (**), 0 flaws (~~), 5 warnings (==), 3 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 SIMPLE WG M. Lonnfors 3 Internet-Draft Nokia Research Center 4 Expires: April 2, 2004 J. Costa-Requena 5 E. Leppanen 6 H. Khartabil 7 Nokia 8 October 3, 2003 10 Requirements for Efficient Delivery of Presence Information 11 draft-ietf-simple-presinfo-deliv-reg-01 13 Status of this Memo 15 This document is an Internet-Draft and is in full conformance with 16 all provisions of Section 10 of RFC2026. 18 Internet-Drafts are working documents of the Internet Engineering 19 Task Force (IETF), its areas, and its working groups. Note that other 20 groups may also distribute working documents as Internet-Drafts. 22 Internet-Drafts are draft documents valid for a maximum of six months 23 and may be updated, replaced, or obsoleted by other documents at any 24 time. It is inappropriate to use Internet-Drafts as reference 25 material or to cite them other than as "work in progress." 27 The list of current Internet-Drafts can be accessed at http:// 28 www.ietf.org/ietf/1id-abstracts.txt. 30 The list of Internet-Draft Shadow Directories can be accessed at 31 http://www.ietf.org/shadow.html. 33 This Internet-Draft will expire on April 2, 2004. 35 Copyright Notice 37 Copyright (C) The Internet Society (2003). All Rights Reserved. 39 Abstract 41 A Presence service implemented using SIMPLE has some constraints for 42 delivering presence information to devices with low data processing 43 capabilities, small display, and limited battery power. Other 44 limitations can be caused by the interface between the terminal and 45 the network, i.e. if presence information is delivered over radio 46 links with high latency and low bandwidth. This memo presents 47 requirements for a solution that can aid to reduce the impacts of 48 these constrains and helps to increase efficiency. 50 Table of Contents 52 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 53 2. Conventions . . . . . . . . . . . . . . . . . . . . . . . . . 3 54 3. Requirements . . . . . . . . . . . . . . . . . . . . . . . . . 4 55 3.1 General requirements . . . . . . . . . . . . . . . . . . . . . 4 56 3.2 Performance requirements . . . . . . . . . . . . . . . . . . . 4 57 3.3 Client and server requirements . . . . . . . . . . . . . . . . 4 58 4. Example use cases . . . . . . . . . . . . . . . . . . . . . . 5 59 4.1 Case 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 60 4.2 Case 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 61 4.3 Case 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 62 5. Security Considerations . . . . . . . . . . . . . . . . . . . 5 63 6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 5 64 References . . . . . . . . . . . . . . . . . . . . . . . . . . 6 65 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 6 66 Intellectual Property and Copyright Statements . . . . . . . . 8 68 1. Introduction 70 SIP extensions for presence [6] allow users ('watchers') to subscribe 71 to other users ('presentities') presence information. The presence 72 information is composed of multiple pieces of data (tuples) that are 73 delivered to the watcher. Model for presence information delivery 74 that is defined in [2] and in [6] specify that watchers always 75 receive all presence data related to a presentity. The size of the 76 presence information can potentially become large (i.e. presence 77 document may contain an arbitrary number of elements called tuples 78 that may convey data). It may not be reasonable to send complete 79 presence information over low bandwidth and high latency links when 80 only part of that information has changed. This may end up in 81 degrading the presence service and causing bad perception at the 82 watcher side. Thus, it is necessary to provide solutions to overcome 83 this problem. 85 Presence based applications in wireless terminals have certain 86 processing and bandwidth limitations. It is foreseen that the 87 presence information may have a considerable size, especially if 88 non-ACSII content (for example a picture) is included in presence 89 information. Requirements of wireless environments are addressed in 90 [3]. 92 There are some mechanisms, which might be used to help the problem, 93 such as signaling compression [4] and content indirection [5]. 94 However, none of the existing solutions are optimal because they may 95 set additional requirements on basic network functionalities such as 96 security and cause difficulties in implementing some charging models. 97 SIGCOMP helps to reduce the transported data size if data can be 98 compressed. However, if data cannot be compressed (for example 99 pictures in jpeg format) use of SIGCOMP doesn't provide much help. 100 Some of the existing solutions (e.g. content indirection) require 101 having a specific server to store the requested presence information 102 until the terminal fetches it using another protocol (e.g. HTTP) and 103 therefore increases possible security concerns. 105 This memo discusses the requirements for an approach where the 106 Presence Server (PS) can deliver to the watchers only the part of the 107 presence information that has changed compared to the previous 108 notification. This mechanism is called partial notification. The 109 partial notification is already identified as a potential approach by 110 the SIP Extensions for Presence document [6]. . 112 2. Conventions 114 In this document, the key words "MUST", "MUST NOT", "REQUIRED", 115 "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", 116 and "OPTIONAL" are to be interpreted as described in RFC 2119 [1] 117 and indicate requirement levels for compliant implementations. 119 3. Requirements 121 3.1 General requirements 123 REG1: The subscriber MUST have a mechanism to limit the overall 124 content size delivered in the notifications. 126 REQ2: The presence service MUST allow mechanisms for efficient 127 handling of large contents of presence documents. 129 RE3: The mechanism MUST allow the subscriber to get information about 130 presence information changes (modifications, removals, and additions) 131 compared to last notification. 133 REQ4: The mechanism MUST NOT affect the requirements of basic network 134 functionalities such as security. 136 3.2 Performance requirements 138 REQ5: The presence service MUST allow efficient utilization of the 139 network resources (radio links). The presence service MUST be able to 140 avoid additional or unnecessary round-trips for receiving changed 141 presence information. 143 REQ6: The presence service MUST be able to avoid transmission of 144 unnecessary information (over radio links) when notifying the 145 presence information change to watcher. 147 REQ7: The presence service MUST be able to be utilized by devices 148 with low data processing capabilities, small display, limited memory 149 size and limited battery power. 151 3.3 Client and server requirements 153 REQ8: The subscriber MUST be able to negotiate, during the 154 subscription phase, to receive only changes of the presence document. 156 REQ9: The subscriber MUST be able to indicate support to receive only 157 changes of the presence information. 159 REQ10: The subscriber SHOULD be able to request, during the 160 subscription phase, that the Presence Agent sends only changes to the 161 presence document. 163 REQ11: The subscriber capable of receiving only changes to presence 164 documents MUST be able to use the presence service with full state 165 notifications. 167 4. Example use cases 169 4.1 Case 1 171 Presence service charging for a subscriber is based on the received 172 data volume. Thus the subscriber requires from the presence server 173 that only the changed content is delivered after the first 174 notification. 176 4.2 Case 2 178 The watcher and the presentity have network subscriptions for 179 different operators. Presentity's presence information contains 180 non-ASCII data like pictures. One option to deliver pictures could be 181 implemented by using content indirection mechanism [5] but 182 presentity's operator may not be willing to store content that will 183 be delivered to customer of some other operator. To enable efficient 184 handling of non-ACSII data and to limit the network load operator can 185 support partial notifications instead. 187 4.3 Case 3 189 The presentity's presence data is composed of the normal status 190 information and it also contains a picture. The watcher using a 191 wireless terminal subscribes to presentity's presence information. 192 Due to limitations in wireless environment the watcher would like to 193 limit the amount of transferred data over wireless links. Using the 194 partial notifications presence server can send only changed presence 195 information thus limiting the amount of data transferred over 196 wireless links. 198 5. Security Considerations 200 This document provides requirements for efficient delivery of 201 Presence information. Because of this no security consideration apply 202 directly to this document. However, solution is likely to build on 203 top of presence delivery mechanisms defined in IMPP and in SIMPLE 204 working group all security considerations defined in PIDF [2] and in 205 [6] will apply to the solution. 207 6. Acknowledgements 209 The authors would like to thank Juha Kalliokulju for his valuable 210 comments. 212 References 214 [1] Bradner, S., "Key words for use in RFCs to Indicate Requirement 215 Levels", BCP 14, RFC 2119, March 1997. 217 [2] Day, M., Rosenberg, J. and H. Sugano, "A Model for Presence and 218 Instant Messaging", RFC 2778, February 2000. 220 [3] Kiss, K., "Requirements for Presence Service based on 3GPP 221 specifications and wireless environment characteristics", 222 draft-kiss-simple-presence-wireless-reqs-02 (work in progress), 223 Febryary 2003. 225 [4] Price, R., "Signaling Compression (SigComp)", RFC 3320, January 226 2003. 228 [5] Olson, S., "A Mechanism for Content Indirection in Session 229 Initiation Protocol (SIP) Messages", 230 draft-ietf-sip-content-indirect-mech-02, November 2002. 232 [6] Rosenberg, J., "Session Initiation Protocol (SIP) Extensions for 233 Presence", draft-ietf-simple-presence-10.txt, May 2002. 235 Authors' Addresses 237 Mikko Lonnfors 238 Nokia Research Center 239 Itamerenkatu 00180 240 Helsinki 241 Finland 243 Phone: + 358 71 8008000 244 EMail: mikko.lonnfors@nokia.com 246 Jose Costa-Requena 247 Nokia 248 Valimotie 9 00380 249 Helsinki 250 Finland 252 Phone: +358 71 8008000 253 EMail: jose.costa-requena@nokia.com 254 Eva Leppanen 255 Nokia 256 P.O BOX 785 257 Tampere 258 Finland 260 Phone: +358 7180 77066 261 EMail: eva-maria.leppanen@nokia.com 263 Hisham Khartabil 264 Nokia 265 P.O. 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