ENUM WG J. Peterson Internet-Draft NeuStar Expires: June 15, 2004 December 16, 2003 Enumservice Registration for Presence Services draft-ietf-enum-pres-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 June 15, 2004. Copyright Notice Copyright (C) The Internet Society (2003). All Rights Reserved. Abstract This document registers an ENUM service for presence services (as described in RFC2778 [2]) pursuant to the guidelines in RFC2916bis [1]. Specifically, this document focuses on provisioning pres URIs in ENUM. Peterson Expires June 15, 2004 [Page 1] Internet-Draft pres enumservice December 2003 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. ENUM Service Registration . . . . . . . . . . . . . . . . . . . 3 3. Presence for E.164 numbers . . . . . . . . . . . . . . . . . . . 3 4. The 'E2U+pres' enumservice . . . . . . . . . . . . . . . . . . . 4 5. Example of E2U+pres enumservice . . . . . . . . . . . . . . . . 5 6. Security Considerations . . . . . . . . . . . . . . . . . . . . 5 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5 References . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 7 Full Copyright Statement . . . . . . . . . . . . . . . . . . . . 8 Peterson Expires June 15, 2004 [Page 2] Internet-Draft pres enumservice December 2003 1. Introduction ENUM (E.164 Number Mapping, RFC2916bis [1]) is a system that uses DNS (Domain Name Service, RFC1034 [8]) to translate telephone numbers, like '+12025332600', into URIs (Uniform Resource Identifiers, RFC2396 [9]), like 'pres:user@host.com'. ENUM exists primarily to facilitate the interconnection of systems that rely on telephone numbers with those that use URIs to route transactions. Presence is a service defined in RFC2778 [2] 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 a user is online or offline, busy or idle, away from communications devices or nearby, and the like. The IMPP WG of the IETF has a defined a generic URI used to identify a presence service for a particular resource: the 'pres' URI scheme (defined in CPP [4]). This document describes an enumservice for advertising presence information associated with an E.164 number. 2. ENUM Service Registration As defined in [1], the following is a template covering information needed for the registration of the enumservice specified in this document. Service Name: "E2U+pres" URI Scheme(s): "pres:" Functional Specification: see Section 4 Security considerations: see Section 6 Intended usage: COMMON Author: Jon Peterson (jon.peterson@neustar.biz) Any other information that the author deems interesting: See Section 3 3. Presence for E.164 numbers This document specifies an enumservice field that allows presence information to be provided for an E.164 number. This may include presence states associated with telephones, or presence of non- Peterson Expires June 15, 2004 [Page 3] Internet-Draft pres enumservice December 2003 telephony communications services advertised by ENUM. Endpoints that participate in a presence architecture are known (following the framework in RFC2778 [2]) as watchers and presentities. Watchers subscribe to the presence of presentities, and are notified when the presence of a presentity changes. Watchers generally monitor the presence of a group of presentities with whom they have an ongoing association. As an example, consider a way that this might apply a telephony service. Most cellular telephones today have an address-book like feature, a small database of names and telephone numbers. Such a telephone might act as a watcher, subscribing to the presence of some or all of the telephone numbers in its address book. The display of the telephone might then show its user, when a presence-enabled telephone number is selected, the availability of the destination. With this information, user might change their calling habits to correspond better to the availability of their associates. The presence information that is shared varies by communications service. The IETF IMPP WG has defined a Presence Information Data Format (or PIDF [6]) for describing the presence data associated with a presentity. The baseline PIDF specification declares only two presence states: OPEN and CLOSED (these terms are defined in RFC2778 [2]); the former suggests that the destination resource is able to accept communication requests, the latter that it is not. These two states provide useful but rudimentary insight into the communications status of a presentity; for that reason, PIDF is an extensible format, and new sorts of status can be defined for specific communications services. For example, a telephony-based presence service might define a status corresponding to 'busy'. Extending PIDF for telephony services is however outside the scope of this document. 4. The 'E2U+pres' enumservice Traditionally, the services field of a NAPTR record (as defined in [13]) contains a string that is composed of two subfields: a 'protocol' subfield and a 'resolution service' subfield. ENUM in particular defines an 'E2U' (E.164 to URI) resolution service. This document defines an 'E2U+pres' enumservice for presence. The scheme of the URI that will appear in the regexp field of a NAPTR record using the 'E2U+pres' enumservice will be the 'pres' URI scheme. There are, however, other URI schemes that can be used to identify presence services. The purpose of a pres URI is to provide a generic way of locating a presence service. Techniques for dereferencing the pres URI scheme to locate a presence service are given in [5]. Peterson Expires June 15, 2004 [Page 4] Internet-Draft pres enumservice December 2003 The 'pres' URI scheme does not identify any particular protocol that will be used to handle presence operations (such as subscriptions and notifications). Rather, the mechanism in [5] details a way to discover whether or not the presence protocol(s) supported by the watcher is/are also supported by the presentity. SIP [7] is one protocol that can be used to convey presence information and manage subscriptions/notifications. 5. Example of E2U+pres enumservice The following is an example of the use of the enumservice registered by this document in a NAPTR resource record. $ORIGIN 0.0.6.2.3.3.5.2.0.2.1.e164.arpa. IN NAPTR 100 10 "u" "E2U+pres" "!^.*$!pres:jon.peterson@neustar.biz!" . 6. Security Considerations DNS does not make policy decisions about the records that it shares with an inquirer. All DNS records must be assumed to be available to all inquirers at all times. The information provided within an ENUM record set must therefore be considered to be open to the public - which is a cause for some privacy considerations. However, revealing a pres URI in and of itself is unlikely to introduce many privacy concerns (although depending on the structure of the URI, it might reveal the full name or employer of the target). There are more serious privacy concerns associated with the unauthorized distribution of presence information. For that reason, presence protocols have a number of security requirements (detailed in RFC2779 [3]) that call for authentication of watchers, integrity and confidentiality properties, and similar measures to prevent abuse of presence information. Any presence protocol that is used in conjunction with the 'pres' URI scheme is required to meet these requirements by the work in the IETF IMPP WG. Unlike a traditional telephone number, the resource identified by a pres URI may require that callers provide cryptographic credentials for authentication and authorization before presence information is returned. In this respect, ENUM in concert with presence protocols can actually provide far greater protection from unwanted callers than the existing PSTN, despite the public availability of ENUM records. 7. IANA Considerations This document registers the 'E2U+pres' enumservice under the Peterson Expires June 15, 2004 [Page 5] Internet-Draft pres enumservice December 2003 enumservice registry described in the IANA considerations in RFC2916bis. Details of the registration are given in Section 2. References [1] Faltstrom, P. and M. Mealling, "The E.164 to URI DDDS Application", draft-ietf-enum-rfc2916bis-07 (work in progress), November 2003. [2] Day, M., Rosenberg, J. and H. Sugano, "A Model for Presence and Instant Messaging", RFC 2778, February 2000. [3] Day, M., Aggarwal, S. and J. Vincent, "Instant Messaging / Presence Protocol Requirements", RFC 2779, February 2000. [4] Peterson, J., "A Model for Presence and Instant Messaging", draft-ietf-impp-pres-04 (work in progress), September 2003. [5] Peterson, J., "Address Resolution for Instant Messaging and Presence", draft-ietf-impp-srv-04 (work in progress), September 2003. [6] 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. [7] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, A., Peterson, J., Sparks, R., Handley, M. and E. Schooler, "SIP: Session Initiation Protocol", RFC 3261, May 2002. [8] Mockapetris, P., "Domain Names - Concepts and Facilities", RFC 1034, November 1987. [9] Berners-Lee, T., Fielding, R. and L. Masinter, "Uniform Resource Identifiers (URI): Generic Syntax", RFC 2396, August 1998. [10] International Telecommunications Union, "Recommendation E.164: The international public telecommunication numbering plan", May 1997, . [11] Vaha-Sipila, A., "URLs for Telephone Calls", RFC 2806, April 2000. [12] Mealling, M. and R. Daniel, "The Naming Authority Pointer (NAPTR) DNS Resource Record", RFC 2915, September 2000. [13] Mealling, M., "Dynamic Delegation Discovery System (DDDS) Part Peterson Expires June 15, 2004 [Page 6] Internet-Draft pres enumservice December 2003 Three: The Domain Name System (DNS) Database", RFC 3403, October 2002. Author's Address Jon Peterson NeuStar, Inc. 1800 Sutter St Suite 570 Concord, CA 94520 USA Phone: +1 925/363-8720 EMail: jon.peterson@neustar.biz URI: http://www.neustar.biz/ Peterson Expires June 15, 2004 [Page 7] Internet-Draft pres enumservice December 2003 Full Copyright Statement Copyright (C) The Internet Society (2003). All Rights Reserved. This document and translations of it may be copied and furnished to others, and derivative works that comment on or otherwise explain it or assist in its implementation may be prepared, copied, published and distributed, in whole or in part, without restriction of any kind, provided that the above copyright notice and this paragraph are included on all such copies and derivative works. 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Acknowledgement Funding for the RFC Editor function is currently provided by the Internet Society. Peterson Expires June 15, 2004 [Page 8]