Network Working Group A. Niemi Internet-Draft E. Leppanen Expires: April 19, 2004 Nokia October 20, 2003 An Extension for Watcher Information History draft-niemi-simple-winfo-history-00 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 19, 2004. Copyright Notice Copyright (C) The Internet Society (2003). All Rights Reserved. Abstract This document defines an extension to the Session Initiation Protocol (SIP) watcher information template-package. This extension enables a subscriber to request for a list of past watcher information events over some time period. This document defines a mechanism for requesting watcher information history in subscriptions to the watcherinfo template-package. It also defines an extension to the watcher information data format for representing this history information. Niemi & Leppanen Expires April 19, 2004 [Page 1] Internet-Draft Watcherinfo History October 2003 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Requirements . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. Document Conventions . . . . . . . . . . . . . . . . . . . . . 4 4. Overview of Operation . . . . . . . . . . . . . . . . . . . . 4 5. Using and Collecting Watcher Information History . . . . . . . 4 6. Subscriber Behavior . . . . . . . . . . . . . . . . . . . . . 5 7. Notifier Behavior . . . . . . . . . . . . . . . . . . . . . . 5 8. Example Watcher Information with History . . . . . . . . . . . 6 9. Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 9.1 "winfo-history" Header Parameter . . . . . . . . . . . . . . . 7 9.2 Augmented BNF Definitions . . . . . . . . . . . . . . . . . . 7 9.3 XML Schema Definitions . . . . . . . . . . . . . . . . . . . . 7 10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9 11. Security Considerations . . . . . . . . . . . . . . . . . . . 9 12. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 9 13. Open Issues . . . . . . . . . . . . . . . . . . . . . . . . . 9 Normative References . . . . . . . . . . . . . . . . . . . . . 10 Informative References . . . . . . . . . . . . . . . . . . . . 10 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 10 Intellectual Property and Copyright Statements . . . . . . . . 12 Niemi & Leppanen Expires April 19, 2004 [Page 2] Internet-Draft Watcherinfo History October 2003 1. Introduction The SIP events framework [1] defines a generic framework for subscriptions to and notifications of events related to SIP systems. This framework defines the methods SUBSCRIBE and NOTIFY, and introduces the concepts of an event package and a template-package. A package is a concrete application of the SIP events framework to a particular class of events. A template-package is a special event package in that it is always associated with some other event package. It can be applied to any event package, including itself. The watcher information [3] event template-package defines a facility for tracking the state of subscriptions to a resource in another event package. For instance, when applied to the presence event package [6], it would generate notifications of the state of presence subscriptions for that presentity. The main motivating application for watcher information has been presence authorization. By being subscribed to its own presence watcher information, a UA can be made aware of watchers who have requested subscription but are in "pending" state, i.e., they have not yet received authorization for presence. The user can then take action to reactively authorize such watchers. However, the client may not be able to subscribe to watcher information all the time, e.g., when being outside of network coverage. Any watcher information events that occur during that time would therefore not be seen by the user. For such cases, a watcher information history feature is utilized, similar to a "Missed Calls" log in a telephony application. This provides the user information about watcher information events in the past, allowing the user to take action to retroactively authorize watchers, or simply see the status of subscriptions while being un-subscribed. This document defines an Event header parameter and an extension to the watcherinfo data format [4] for requesting and representing watcherinfo history. 2. Requirements The 3GPP presence requirements [7] contain a requirement for watcherinfo history: "WATCHINF-REQ3: Watcher history It must be possible for the presentity to fetch the list of the watchers who have accessed (by subscription or fetch) his presence Niemi & Leppanen Expires April 19, 2004 [Page 3] Internet-Draft Watcherinfo History October 2003 information during a well-defined time- period (e.g. last 7 days). Additionally to the list of watchers, the details of the presence information provided to different watchers should be available for the presentity when fetching the watcher history." 3. Document 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 RFC 2119 [5] and indicate requirement levels for compliant implementations. 4. Overview of Operation The subscriber's desire to receive a past history of watcher information events is indicated as part of the SUBSCRIBE message in the subscription to the watcherinfo event package. Namely, the subscriber indicates the preferred watcherinfo history period as an Event header parameter of the SUBSCRIBE request. The notifier is not required to abide by or even understand this indication for watcherinfo history. Instead, the notifier can safely accept the subscription and ignore any Event header parameters it does not understand, or is unwilling to comply with. If the notifier understands and supports watcherinfo history, it can accept the subscriber's preferred history period, or choose a shorter period based on any local policy. The notifier then adds a element into the of the first NOTIFY request. This list includes elements pertaining to watcherinfo events in the past, over a certain history period. 5. Using and Collecting Watcher Information History By definition, watcherinfo deals with the set of current subscriptions to a resource - it delivers the set of active subscriptions, and notifies of state changes therein. Consequently, watcherinfo history deals with the past subscriptions to a resource - it delivers the set of past subscriptions that are no longer in active state. In other words, it delivers the set of those subscriptions that entered the terminated state within the given history period. By default, all watchers in will have "terminated" state. Each will also list the event that caused the watcher to transition to the terminated state, along with a timestamp indicating the time of this transition. Niemi & Leppanen Expires April 19, 2004 [Page 4] Internet-Draft Watcherinfo History October 2003 6. Subscriber Behavior In general, the way in which a subscriber generates SUBSCRIBE requests and receives NOTIFY requests is according to RFC 3265 [1]. Subscriptions specifically to watcherinfo events are created according to the watcherinfo package [3]. A UA that wants to receive watcherinfo history MAY include a "winfo-history" Event header parameter in the SUBSCRIBE request, indicating in seconds the preferred period over which the history information is to be included. The value of this parameter is an integral number of seconds (in decimal) between 0 and (2**32)-1. Typically, the resulting watcherinfo history is contained in the first NOTIFY request received in the subscription. However, a subscriber MUST always accept notifications without watcher information history. If no watcher information history is present in the NOTIFY, this means that the notifier is either unwilling, or unable to provide such information. The is completely independent of any element(s) present in the NOTIFY. Therefore, implementations MUST treat the data in a watcher-list and watcher-history separate. For example, the "id" attributes of watchers can not be assumed to be unique across watcher-list and watcher-history. 7. Notifier Behavior In general, the way in which a notifier processes SUBSCRIBE requests and generates NOTIFY requests is according to RFC 3265 [1]. Subscriptions specifically to watcherinfo events are handled according to the watcherinfo package [3]. A notifier that supports watcherinfo history SHOULD have tools available for maintaining a list of past watcher information events of a particular resource. The time period over which this event log extends is solely an implementation issue. A notifier that is able to support watcher information history extracts the value of the "winfo-history" Event header parameter (if present), and uses it as the proposed time period for watcherinfo history. Implementations MAY treat values larger than (2**32)-1 as equivalent to (2**32)-1. The notifier MAY choose any value lower than the proposed history period, based on its local policy. The notifier MUST NOT choose a time period greater than the proposed history period. The chosen history period is then used as a search key to retrieve Niemi & Leppanen Expires April 19, 2004 [Page 5] Internet-Draft Watcherinfo History October 2003 events related to past subscriptions to the resource. These events are then inserted into the watcher information [4] in the form of a element. Watcher-history includes a collection of elements The notifier SHOULD only send watcherinfo history in the first NOFIFY request of a subscription, or in a NOTIFY resulting from a fetch (i.e., a SUBSCRIBE with Expires: 0) of watcherinfo. Watcherinfo history SHOULD be sent only as part of that contains full watcherinfo state, i.e., has the "state" attribute set to "full". A notifier SHOULD NOT send history information unless the subscriber indicated a desire to receiving it in the SUBSCRibe. A NOTIFY MUST NOT contain a "history-period" Event header parameter. If the NOTIFY contains watcherinfo history, its history period is indicated in the "period" attribute of the element. 8. Example Watcher Information with History The following represents an example watcher information, including history. sip:userA@example.com sip:userB@example.com sip:userC@example.com sip:userA@example.org sip:userX@example.net 9. Syntax This section describes the syntax extensions required for watcherinfo history. Note that the formal syntax definitions described in this section are expressed in the Augmented BNF format used in SIP [2], and contain references to elements defined therein. 9.1 "winfo-history" Header Parameter TBD: May potentially need to add this parameter to the SIP header parameter registry, if available. The maximum value of this parameter is (2**32) - 1. 9.2 Augmented BNF Definitions This section describes the Augmented BNF definitions for the new syntax element. The notation is as used in SIP [2] and the documents to which is refers. generic-param = history-param / token [ EQUAL gen-value ] history-param = "winfo-history" EQUAL delta-seconds 9.3 XML Schema Definitions This section describes the XL Schema definitions for watcherinfpo history. Niemi & Leppanen Expires April 19, 2004 [Page 7] Internet-Draft Watcherinfo History October 2003 Niemi & Leppanen Expires April 19, 2004 [Page 8] Internet-Draft Watcherinfo History October 2003 10. IANA Considerations TBD: Register the XML namespace(s) and possibly the event header parameter. 11. Security Considerations Overall, the security considerations of [3], [4], and [1] apply to watcher information history. In addition, since watcher information history may be sensitive information, care should be taken to authenticate and authorize the subscriptions. The notifier MUST use additional care in authorizing watcherinfo history subscriptions, so that information that normally would not be delivered as part of watcherinfo do not become visible in the watcherinfo history. 12. Acknowledgements Thanks to Jose Costa-Requena for providing the XML schema and for comments, and for Mikko Lonnfors, Pekka Pessi for comments and suggestions on the draft. 13. Open Issues This chapter discusses some open items and issues. o The mechanism described in this document can be easily applied to other events as well. For example, the reg-event could make use of similar features very easily. Should we try to generalize the history mechanism to be applicable to other event packages as well? Niemi & Leppanen Expires April 19, 2004 [Page 9] Internet-Draft Watcherinfo History October 2003 Normative References [1] Roach, A., "Session Initiation Protocol (SIP)-Specific Event Notification", RFC 3265, June 2002. [2] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, A., Peterson, J., Sparks, R., Handley, M. and E. Schooler, "SIP: Session Initiation Protocol", RFC 3261, June 2002. [3] Rosenberg, J., "A Watcher Information Event Template-Package for the Session Initiation Protocol (SIP)", draft-ietf-simple-winfo-package-05 (work in progress), January 2003. [4] Rosenberg, J., "An Extensible Markup Language (XML) Based Format for Watcher Information", draft-ietf-simple-winfo-format-04 (work in progress), January 2003. [5] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. Informative References [6] Rosenberg, J., "A Presence Event Package for the Session Initiation Protocol (SIP)", draft-ietf-simple-presence-10 (work in progress), January 2003. [7] Kiss, K., "Requirements for Presence Service in 3GPP Wireless Systems", draft-kiss-simple-presence-wireless-reqs-02 (work in progress), March 2003. Authors' Addresses Aki Niemi Nokia P.O. Box 321 NOKIA GROUP, FIN 00045 Finland Phone: +358 50 389 1644 EMail: aki.niemi@nokia.com Niemi & Leppanen Expires April 19, 2004 [Page 10] Internet-Draft Watcherinfo History October 2003 Eva Leppanen Nokia P.O. Box 785 NOKIA GROUP, FIN 00045 Finland Phone: +358 EMail: eva-maria.leppanen@nokia.com Niemi & Leppanen Expires April 19, 2004 [Page 11] Internet-Draft Watcherinfo History 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. 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