ENUM WG J. Peterson
Internet-Draft NeuStar
Expires: November 18, 2004 May 20, 2004
Enumservice Registration for Presence Services
draft-ietf-enum-pres-01
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 November 18, 2004.
Copyright Notice
Copyright (C) The Internet Society (2004). All Rights Reserved.
Abstract
This document registers an ENUM service for presence. Specifically,
this document focuses on provisioning pres URIs in ENUM.
Peterson Expires November 18, 2004 [Page 1]
Internet-Draft pres enumservice May 2004
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 . . . . . . . . . . . . . . . . . . . . . . 6
8. IPR Considerations . . . . . . . . . . . . . . . . . . . . . . . 6
Normative References . . . . . . . . . . . . . . . . . . . . . . 6
Informative References . . . . . . . . . . . . . . . . . . . . . 7
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 7
Full Copyright Statement . . . . . . . . . . . . . . . . . . . . 8
Peterson Expires November 18, 2004 [Page 2]
Internet-Draft pres enumservice May 2004
1. Introduction
ENUM (E.164 Number Mapping, RFC3761 [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 identify resources.
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 IETF has 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 November 18, 2004 [Page 3]
Internet-Draft pres enumservice May 2004
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 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
[12]) 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 SHOULD be the 'pres' URI
scheme. Other URI schemes appropriate to presence services MAY be
used; however, the use of the 'pres' URI scheme ensures a greater
level of compatibility than the use of any URI specific to a
particular presence protocol. The purpose of a pres URI is to
provide a generic way of locating a presence service. Techniques for
Peterson Expires November 18, 2004 [Page 4]
Internet-Draft pres enumservice May 2004
dereferencing the pres URI scheme to locate a presence service are
given in [5].
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.
The use of anonymous URIs mitigates that risk. 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.
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.
Peterson Expires November 18, 2004 [Page 5]
Internet-Draft pres enumservice May 2004
7. IANA Considerations
This document registers the 'E2U+pres' enumservice under the
enumservice registry described in the IANA considerations in RFC3761.
Details of the registration are given in Section 2.
8. IPR Considerations
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.
Normative References
[1] Faltstrom, P. and M. Mealling, "The E.164 to URI DDDS
Application", RFC 3761, April 2004.
[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.
Peterson Expires November 18, 2004 [Page 6]
Internet-Draft pres enumservice May 2004
Informative References
[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, <http://www.itu.int>.
[11] Vaha-Sipila, A., "URLs for Telephone Calls", RFC 2806, April
2000.
[12] Mealling, M., "Dynamic Delegation Discovery System (DDDS) Part
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 November 18, 2004 [Page 7]
Internet-Draft pres enumservice May 2004
Full Copyright Statement
Copyright (C) The Internet Society (2004). 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. However, this
document itself may not be modified in any way, such as by removing
the copyright notice or references to the Internet Society or other
Internet organizations, except as needed for the purpose of
developing Internet standards in which case the procedures for
copyrights defined in the Internet Standards process must be
followed, or as required to translate it into languages other than
English.
The limited permissions granted above are perpetual and will not be
revoked by the Internet Society or its successors or assigns.
This document and the information contained herein is provided on an
"AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
TASK FORCE DISCLAIMS 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.
Acknowledgement
Funding for the RFC Editor function is currently provided by the
Internet Society.
Peterson Expires November 18, 2004 [Page 8]
