GEOPRIV WG J. Peterson Internet-Draft NeuStar Expires:
January 13,March 9, 2005 July 15,September 8, 2004 A Presence Architecture for the Distribution of GeoprivGEOPRIV Location Objects draft-ietf-geopriv-pres-01draft-ietf-geopriv-pres-02 Status of this Memo By submitting this Internet-Draft, I certify that any applicable patent or other IPR claims of which I am aware have been disclosed, and any of which I become aware will be disclosed, in accordance with RFC 3668. 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 13,March 9, 2005. Copyright Notice Copyright (C) The Internet Society (2004). All Rights Reserved. Abstract GeoprivGEOPRIV defines the concept of a 'using protocol', a protocol that carries GeoprivGEOPRIV location objects. GeoprivGEOPRIV also defines various scenarios for the distribution of location objects that require the concept of subscriptions and asynchronous notifications. This document examines some existing IETF work on the concept of presence, shows how presence architectures map onto GeoprivGEOPRIV architectures, and moreover demonstrates that tools already developed for presence could be reused to simplify the standardization and implementation of Geopriv.GEOPRIV. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Framework Analysis . . . . . . . . . . . . . . . . . . . . . . 3 3. Presence Architecture for GeoprivGEOPRIV . . . . . . . . . . . . . . 4 4. GeoprivGEOPRIV Extensions to PIDF . . . . . . . . . . . . . . . . . . 6 5. Security Considerations . . . . . . . . . . . . . . . . . . . 6 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 Author's Address . . . . . . . . . . . . . . . . . . . . . . . 7 7. Informative References . . . . . . . . . . . . . . . . . . . . 6 Author's AddressA. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 78 Intellectual Property and Copyright Statements . . . . . . . . 89 1. Introduction GeoprivGEOPRIV is a standard for the transmission of location information and privacy policies over the Internet. Location information is a description of a particular spatial location, which may be represented as coordinates (via longitude, latitude, and so on), or as civil addresses (such as postal addresses), or in other ways. GeoprivGEOPRIV focuses on the privacy and security issues, both from a technology perspective and a policy perspective, of sharing location information over the Internet; it essentially defines a secure container class capable of carrying both location information and policy data governing the distribution of this information. GeoprivGEOPRIV also defines the concept of a 'using protocol', a protocol that carries the GeoprivGEOPRIV location object. Presence is a service defined in RFC2778  that allows users of a communications service to monitor one another's availability and disposition in order to make decisions about communicating. Presence information is highly dynamic, and generally characterizes whether a not auser is online or offline, busy or idle, away from communications devices or nearby, and the like. This document shows the applicability of presence to Geopriv,GEOPRIV, and arguesshows that a presence protocol mightcould be a suitable using protocol for Geopriv.GEOPRIV. This document is not intended to demonstrate that presence is the only method by which GeoprivGEOPRIV location objects might be distributed. However, there are numerous applications of GeoprivGEOPRIV that depend on the fundamental subscription/notification architecture that also underlies presence. 2. Framework Analysis The GeoprivGEOPRIV framework  defines four primary network entities: a Location Generator, a Location Server, a Location Recipient, and a Rule Holder. Three interfaces between these entities are defined, including a publication interface and a notification interface. GeoprivGEOPRIV specifies that a 'using protocol' is employed to transport location objects from one place to another. If the publication interface and notification interface are network connections, then a using protocol would be responsible for the transmission of the location object. Location Recipients may request that a Location Server provide them with GeoprivGEOPRIV location information concerning a particular Target. The Location Generator publishes Location Information to a Location Server, which, in coordination with policies set by the Rule Maker, distributes the location information to Location Recipients as necessary. The GeoprivGEOPRIV requirements document shows three scenarios for the use of the GeoprivGEOPRIV protocol. In some of these scenarios (such as the third), a Location Recipient sends some kind of message to the Location Server to request the periodic transmission of location information. The location of a GeoprivGEOPRIV Target is likely to vary over time (if the Target is a person, or something similarly mobile) and consequently the concept of a persistent subscription to the location of a Target resulting in periodic notification is valuable to Geopriv.GEOPRIV. In other scenarios, a Location Recipient may request a one-time notification of the geographical location of the Target. GeoprivGEOPRIV places few requirements on using protocols. However, it is clear from the description above that there must be some mechanism to allow Location Recipients to establish a persistent subscription in order to receive regular notification of the geographical location of a Target as their location changes over time. There must also be a way for Location Generators to publish location information to a Location Server that applies further policies for distribution. This document adopts a model in which the using protocol is responsible for requesting subscriptions, handling publications, and sending notifications. There are other models for GeoprivGEOPRIV in which such operations might be built into location objects themselves. However, there is a significant amount of pre-existing work in the IETF related to managing publications, subscriptions and notifications for data sets that vary over time. In fact, these concepts all correspond exactly to architectures for presence that have been developed in support of real-time communications applications such as instant messaging, voice and video sessions. Note that there are some GeoprivGEOPRIV scenarios in which the Location Recipient does not actively request the location of a Target, but rather it receives an unsolicited notification of Target's location. This document focuses on the use of presence only for those scenarios in which the Location Recipient actively solicits location information. It is however possible that many of these base operations of the subscription/notification framework of presence could be reused in for cases in which the Location Recipient is passive. 3. Presence Architecture for GeoprivGEOPRIV The Common Profile for Presence  (CPP) defines a set of operations for delivery of presence information. These primarily consist of subscription operations and notification operations. A subscription creates a persistent connection between a 'watcher' (which corresponds to the Location Recipient of Geopriv)GEOPRIV) and a 'presentity' (which corresponds roughly to the Location Server).GEOPRIV target). When a watcher subscribes to a presentity, a persistent connection is created; notifications of presence information will henceforth be sent to the watcher as the presence information changes. CPP also supports unsubscriptions (terminating the persistent subscription) and fetches (one-time requests for presence information that result in no persistent subscription). CPP provides a number of attributes of these operations that flesh out the presence system. There is a system for automatically expiring subscriptions if they are not refreshed at user-defined intervals (in order to eliminate stale subscriptions). There are transaction and subscription identifiers used to correlate messages, and a URI scheme ("pres:") is defined to identify watchers and presentities. The IETF IMPP WG has also defined an XML data format for presence information called the Presence Information Data Format  (PIDF). PIDF is a body carried by presence protocols that contains presence information, including the current state of a presentity. PIDF is discussed in more detail in Section 4. At a high-level, then, the presence architecture seems to have considerable applicability to the problem of delivering GeoprivGEOPRIV information. However, the CPP framework is an abstract framework - it doesn't actually specify a protocol, it specifies a framework and a set of requirements to which presence protocols must conform. Also, CPP does not define any concept similar to a Location Server. However, the IETF has standardized protocols that instantiate this framework, such as SIMPLE  and XMPP . XMPP and SIMPLE both have architectural elements comparable to a Location Server: points where presentities register their availability, and where policies for distributing presence can be managed. The presence community has also defined a policy protocol and schema set called XCAP  through which authorization policies can be provisioned in a presence server. In summary, like Geopriv,GEOPRIV, presence requires an architecture for publication, subscription, and notification for a mutable set of data associated with a principal. Presence has already tackled many of the harder issues associated with subscription management, including subscription expiration, development of identifiers for principals, and defining document formats for presence information. Rather than reinventing work that has been done elsewhere in the IETF, Geopriv should if at all possible reuseGEOPRIV has reused this existing work by specifying presence protocols as GeoprivGEOPRIV using protocols. Moreover, the existing foundational presence tools developed in IMPP, such as PIDF, have immediate applicability to the efforts underway in GeoprivGEOPRIV to develop objects for sharing location information. 4. GeoprivGEOPRIV Extensions to PIDF As was mentioned above, the presence architecture developed in the IETF IMPP WG has defined a format for presence information called PIDF. PIDF is an XML format that provides presence information about a presentity - primarily, this consists of status information, but also optionally includes contact addresses (a way of reaching the presentity), timestamps, and textual notes with arbitrary content. PIDF is an extensible format. It defines an XML element for representing the status of a presentity (the status element), and gives some guidance on how this element might be extended. While the authors of PIDF viewed geographical location as a potential category of presence information, baseline PIDF currentlydefines no way to do so.format for location information. PIDF meets the security requirements given in RFC2779  (see especially 5.1, 5.2 and 5.3), which parallel the security requirements of the GeoprivGEOPRIV location object given in the GeoprivGEOPRIV requirements . CPP and PIDF specify mechanisms for mutual authentication of participants in a presence exchange as well as confidentiality and integrity properties for presence information. So in short, many of the requirements of GeoprivGEOPRIV objects map well onto the capabilities of PIDF. 5. Security Considerations GeoprivGEOPRIV information, like presence information, has very sensitive security requirements. The requirements of RFC2779 , which are instantiated by CPP, PIDF and XCAP, in addition to the various derivative concrete presence protocols like XMPP and SIMPLE, map well onto the security requirements of the GeoprivGEOPRIV protocol, as defined in the GeoprivGEOPRIV requirements document and the GeoprivGEOPRIV threat analysis  document. Specifically, the presence security requirements call for authentication of watchers, integrity and confidentiality properties, and similar measures to prevent abuse of presence information. 6. IANA Considerations This document introduces no considerations for the IANA. 7 Informative References  Cuellar, J., Morris, J., Mulligan, D., Peterson, J. and J. Polk, "Geopriv"GEOPRIV requirements", RFC 3693, February 2004.  Day, M., Rosenberg, J. and H. Sugano, "A Model for Presence and Instant Messaging", RFC 2778, February 2000.  Day, M., Aggarwal, S. and J. Vincent, "Instant Messaging / Presence Protocol Requirements", RFC 2779, February 2000.  Peterson, J., "A Model for Presence and Instant Messaging", draft-ietf-impp-pres-04 (work in progress),RFC 3859, August 2003.2004.  Peterson, J., "Address Resolution for Instant Messaging and Presence", draft-ietf-impp-srv-04 (work in progress), September 2003.RFC 3861, August 2004.  Sugano, H., Fujimoto, S., Klyne, G., Bateman, A., Carr, W. and J. Peterson, "CPIM Presence Information Data Format", draft-ietf-impp-cpim-pidf-08 (work in progress), May 2003.RFC 3863, August 2004.  Rosenberg, J., "A Presence Event Package for the Session Initiation Protocol (SIP)", draft-ietf-simple-presence-10 (work in progress), Jan 2003.RFC 3856, August 2004.  Saint-Andre, P., "Extensible Messaging and Presence Protocol (XMPP): Instant Messaging and Presence", draft-ietf-xmpp-im-22 (work in progress), April 2004.  Rosenberg, J., "The Extensible Markup Language (XML) Configuration Access Protocol (XCAP)", draft-ietf-simple-xcap-02 (work in progress), February 2004.  Danley, M., Morris, J., Mulligan, D. and J. Peterson, "Threat Analysis of the geoprivGEOPRIV Protocol", RFC 3694, February 2004.  Berners-Lee, T., Fielding, R. and L. Masinter, "Uniform Resource Identifiers (URI): Generic Syntax", RFC 2396, August 1998. Author's Address Jon Peterson NeuStar, Inc. 1800 Sutter St Suite 570 Concord, CA 94520 USA Phone: +1 925/363-8720 EMail: firstname.lastname@example.org URI: http://www.neustar.biz/ Appendix A. Acknowledgements Thanks to Randall Gellens, John Morris, Hannes Tschofenig, and Behcet Sarikaya for their comments. Intellectual Property Statement 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. 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