WG R. Mahy Internet-Draft SIP Edge LLC Expires: January 9, 2008 July 8, 2007 A Location Dereference Event Package using the Session Initiation Protocol (SIP) draft-mahy-geopriv-sip-loc-pkg-02.txt Status of this Memo By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she becomes aware will be disclosed, in accordance with Section 6 of BCP 79. 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 January 9, 2008. Copyright Notice Copyright (C) The IETF Trust (2007). Abstract This document describes a Session Initiation Protocol (SIP) event package to dereference raw location data about named SIP resources (as opposed to presence data with embedded filtered location) as a GEOPRIV Using Protocol. The resulting location information is conveyed in existing location formats wrapped in GEOPRIV privacy extensions to the Presence Information Document Format (PIDF-LO). In the envisioned usage, location disclosure is limited to voluntary disclosure to the target of its own location or to a trusted service Mahy Expires January 9, 2008 [Page 1]
Internet-Draft Location Event Package July 2007 (such as a presence server) which enforces the target's privacy rules on the target's behalf. Table of Contents 1. Conventions . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. Event Package Formal Definition . . . . . . . . . . . . . . . . 3 3.1. Event Package Name . . . . . . . . . . . . . . . . . . . . 3 3.2. Event Package Parameters . . . . . . . . . . . . . . . . . 4 3.3. SUBSCRIBE Bodies . . . . . . . . . . . . . . . . . . . . . 4 3.4. Subscription Duration . . . . . . . . . . . . . . . . . . . 4 3.5. NOTIFY Bodies . . . . . . . . . . . . . . . . . . . . . . . 4 3.6. Subscriber generation of SUBSCRIBE requests . . . . . . . . 4 3.7. Notifier processing of SUBSCRIBE requests . . . . . . . . . 5 3.8. Notifier generation of NOTIFY requests . . . . . . . . . . 5 3.9. Subscriber processing of NOTIFY requests . . . . . . . . . 5 3.10. Handling of Forked Requests . . . . . . . . . . . . . . . . 5 3.11. Rate of notifications . . . . . . . . . . . . . . . . . . . 6 3.12. State Agents and Lists . . . . . . . . . . . . . . . . . . 6 3.13. Behavior of a Proxy Server . . . . . . . . . . . . . . . . 6 4. Security Considerations . . . . . . . . . . . . . . . . . . . . 6 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 6 5.1. SIP Event Package Registration for 'location' . . . . . . . 7 6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . 7 7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 7 7.1. Normative References . . . . . . . . . . . . . . . . . . . 7 7.2. Informational References . . . . . . . . . . . . . . . . . 8 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 8 Intellectual Property and Copyright Statements . . . . . . . . . . 9 Mahy Expires January 9, 2008 [Page 2]
Internet-Draft Location Event Package July 2007 1. 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]. 2. Introduction The GEOPRIV working group has developed a set of requirements [8] for providing raw location by reference in PIDF-LO [3] format. In many of the use cases discussed asynchronous notifications of changes to that location is also a requirement. For example this allows a presence server for a target or other trusted entity to be fetch location about that target from a Location Generator without requiring the target (possibly a battery operated wireless device) to continually poll and republish its location data to the trusted server. This document defines a SIP [1] event package [2] for location data to meet these requirements for nodes that require asynchronous notification, or simply those that already implement SIP. One difficult part about asynchronous notification of location information is that many forms of location are measured as a continous gradient. Unlike notications using discreet quanties, it is difficult to know when a change in location is large enough to warrant notifications. Moreover, different applications require a wide variety of location resolutions. Any optimization made for one application would ultimately result in wasteful polling or a sluggish user interface for other applications. The mechanism described here uses location filters [4] in XML [6] documents which limit location notification to events which are of relevance to the subscriber. These filters are provided in the body of SIP subscription requests and persist for the duration of the subscription or until they are changed in an updated SIP subscription request with a replacement filter. 3. Event Package Formal Definition 3.1. Event Package Name This document defines a SIP Event Package as defined in RFC 3265 [2]. The event-package token name for this package is: "location" Mahy Expires January 9, 2008 [Page 3]
Internet-Draft Location Event Package July 2007 3.2. Event Package Parameters This package does not define any event package parameters. 3.3. SUBSCRIBE Bodies For this package the subscriber SHOULD include an 'application/ location-delta-filter+xml' SUBSCRIBE body in the format defined in [4], which is used to filter notifications. Subscribers normally includes a location filter with at least one filter event in every new subscription request, or when the subscriber wants to modify the current filter. A filter is not necessary, nor desirable in an unsubscription or subscription refresh request. 3.4. Subscription Duration Subscriptions to this event package MAY range from minutes to weeks. Subscriptions in hours or days are more typical and are RECOMMENDED. The default subscription duration for this event package is one hour. 3.5. NOTIFY Bodies Both subscribers and notifiers MUST implement PIDF-LO. Notifiers MAY send location information in any format acceptable to the subscriber (based on the subscriber inclusion of these formats in an Accept header). "application/cpim-pidf+xml" A future extension MAY define other NOTIFY bodies. If no "Accept" header is present in the SUBSCRIBE, the body type defined in this document MUST be assumed. 3.6. Subscriber generation of SUBSCRIBE requests Each new subscribe request establishes a notification filter. Subsequent subscriptions keep the same filter unless a new filter is provided. If a new filter is provided in a subscription, it completely replaces the previous filter. Subscriber User Agents will typically SUBSCRIBE to location information for a period of hours or days, and automatically attempt to re-SUBSCRIBE well before the subscription is completely expired. If re-subscription fails, the Subscriber SHOULD periodically retry again until a subscription is successful, taking care to backoff to avoid network congestion. If a subscription has expired, new re- subscriptions MUST use a new Call-ID. The Subscriber MAY also explicitly fetch the current status at any time. The subscriber SHOULD renew its subscription immediately after Mahy Expires January 9, 2008 [Page 4]
Internet-Draft Location Event Package July 2007 a reboot, or when the subscriber's network connectivity has just been re-established. The Subscriber MUST be prepared to receive and process a NOTIFY with new state immediately after sending a new SUBSCRIBE, a SUBSCRIBE renewal, an unsubscribe, or a fetch; or at any time during the subscription. 3.7. Notifier processing of SUBSCRIBE requests When a Notifier receives SUBSCRIBE messages with the location event- type, it MUST authenticate the subscription request. If authentication is successful, the Notifier SHOULD authorize the subscriber. Note that in some cases, the SIP URI itself may act as a form of "metro pass" or "pawn ticket" authentication. If no location-filter is provided, the Notifier SHOULD reject the subscription with a 403 Forbidden response. The Notifier MAY further limit the duration of the subscription to an administrator defined amount of time as described in SIP Events. For new subscriptions, or anytime the location-filter is updated by the subscriber, the notifier MUST include appropriate containment locations for every feature mentioned in an enterOrExit element in the corresponding filter. If the subscriber is not authorized to receive this information, the notifier MUST either include each these locations with the value of undefined, or alternatively, send a 403 Forbidden response to the subscriber. 3.8. Notifier generation of NOTIFY requests Immediately after a subscription is accepted, the Notifier MUST send a NOTIFY with the current location information as appropriate based on the identity of the subscriber. This allows the Subscriber to resynchronize its state. When the location changes sufficiently to trigger any of the filter events in the current location-filter for the subscription, the notifier sends a notification with the new location information. 3.9. Subscriber processing of NOTIFY requests No special processing is defined here. 3.10. Handling of Forked Requests Forked requests are not allowed for this event type. Mahy Expires January 9, 2008 [Page 5]
Internet-Draft Location Event Package July 2007 3.11. Rate of notifications A Notifier MAY choose to hold NOTIFY requests in "quarantine" for a short administrator-defined period (milliseconds or seconds) when the location is changing rapidly. Requests in the quarantine which become invalid are replaced by newer notifications, thus reducing the total volume of notifications. This behavior is encouraged for implementations with heavy interactive use. Notifiers SHOULD NOT generate NOTIFY requests more frequently than ten per second, nor more frequently than thirty in a thirty-second period of time. 3.12. State Agents and Lists This document does not preclude implementations from building state agents which support this event package. 3.13. Behavior of a Proxy Server There are no additional requirements on a SIP Proxy, other than to transparently forward the SUBSCRIBE and NOTIFY methods as required in SIP. 4. Security Considerations Location information is typically very privacy sensitive. At minimum, subscriptions to this event package MUST be authenticated and SHOULD be properly authorized. Furthermore, GEOPRIV requires that notifications MUST be encrypted and integrity protected using either end-to-end mechanisms, or the hop-by-hop protection afforded messages sent to SIPS URIs. Implementations of this event package MUST implement the sips: scheme, and MUST implement the security requirements described in PIDF-LO [3]. In addition, all SIP implementations are already requried to implement Digest authentication. Additional privacy and security considerations are discussed in detail in [7] and in SIP [1] and SIP Events [2]. 5. IANA Considerations Mahy Expires January 9, 2008 [Page 6]
Internet-Draft Location Event Package July 2007 5.1. SIP Event Package Registration for 'location' Package name: location Type: package Contact: [Mahy] Published Specification: This document. 6. Acknowledgments Thanks to Allan Thompson, James Winterbottom, and Martin Thomson for their comments. 7. References 7.1. Normative References [1] 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. [2] Roach, A., "Session Initiation Protocol (SIP)-Specific Event Notification", RFC 3265, June 2002. [3] Peterson, J., "A Presence-based GEOPRIV Location Object Format", draft-ietf-geopriv-pidf-lo-03 (work in progress), September 2004. [4] Mahy, R., "A Document Format for Filtering and Reporting Location Notications in the Presence Information Document Format Location Object (PIDF-LO)", draft-ietf-geopriv-loc-filters-01 (work in progress), March 2007. [5] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [6] Bray, T., Paoli, J., Sperberg-McQueen, C., and E. Maler, "Extensible Markup Language (XML) 1.0 (2nd ed)", W3C REC-xml, October 2000, <http://www.w3.org/TR/REC-xml>. [7] Winterbottom, J., "GEOPRIV PIDF-LO Usage Clarification, Considerations and Recommendations", draft-winterbottom-geopriv-pdif-lo-profile-00 (work in Mahy Expires January 9, 2008 [Page 7]
Internet-Draft Location Event Package July 2007 progress), February 2005. 7.2. Informational References [8] Marshall, R., "Requirements for a Location-by-Reference Mechanism used in Location Configuration and Conveyance", draft-marshall-geopriv-lbyr-requirements-01 (work in progress), March 2007. Author's Address Rohan Mahy SIP Edge LLC Email: rohan@ekabal.com Mahy Expires January 9, 2008 [Page 8]
Internet-Draft Location Event Package July 2007 Full Copyright Statement Copyright (C) The IETF Trust (2007). This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights. This document and the information contained herein are provided on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM 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. Intellectual Property The IETF takes no position regarding the validity or scope of any Intellectual Property Rights 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; nor does it represent that it has made any independent effort to identify any such rights. Information on the procedures with respect to rights in RFC documents can be found in BCP 78 and BCP 79. Copies of IPR disclosures made to the IETF Secretariat 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 implementers or users of this specification can be obtained from the IETF on-line IPR repository at http://www.ietf.org/ipr. The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights that may cover technology that may be required to implement this standard. Please address the information to the IETF at ietf-ipr@ietf.org. Acknowledgment Funding for the RFC Editor function is provided by the IETF Administrative Support Activity (IASA). Mahy Expires January 9, 2008 [Page 9]