draft-ietf-ecrit-service-urn-05.txt   draft-ietf-ecrit-service-urn-06.txt 
ECRIT H. Schulzrinne ECRIT H. Schulzrinne
Internet-Draft Columbia U. Internet-Draft Columbia U.
Expires: February 28, 2007 August 27, 2006 Intended status: Standards Track March 4, 2007
Expires: September 5, 2007
A Uniform Resource Name (URN) for Services A Uniform Resource Name (URN) for Services
draft-ietf-ecrit-service-urn-05 draft-ietf-ecrit-service-urn-06
Status of this Memo Status of this Memo
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Copyright Notice Copyright Notice
Copyright (C) The Internet Society (2006). Copyright (C) The IETF Trust (2007).
Abstract Abstract
The content of many communication services depends on the context, The content of many communication services depends on the context,
such as the user's location. We describe a 'service' URN that allows such as the user's location. We describe a 'service' URN that allows
to identify context-dependent services that can be resolved in a to identify context-dependent services that can be resolved in a
distributed manner. distributed manner.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Registration Template . . . . . . . . . . . . . . . . . . . . 5 3. Registration Template . . . . . . . . . . . . . . . . . . . . 5
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
4.1 New Service-Identifying Labels . . . . . . . . . . . . . . 7 4.1. New Service-Identifying Labels . . . . . . . . . . . . . . 7
4.2 Sub-Services for the 'sos' Service . . . . . . . . . . . . 7 4.2. Sub-Services for the 'sos' Service . . . . . . . . . . . . 8
4.3 Sub-Services for the 'counseling' Service . . . . . . . . 8 4.3. Sub-Services for the 'counseling' Service . . . . . . . . 9
4.4 Initial IANA Registration . . . . . . . . . . . . . . . . 9 4.4. Initial IANA Registration . . . . . . . . . . . . . . . . 9
5. Internationalization Considerations . . . . . . . . . . . . . 9 5. Internationalization Considerations . . . . . . . . . . . . . 10
6. Security Considerations . . . . . . . . . . . . . . . . . . . 10 6. Security Considerations . . . . . . . . . . . . . . . . . . . 10
7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 10 7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 11
7.1 Normative References . . . . . . . . . . . . . . . . . . . 10 7.1. Normative References . . . . . . . . . . . . . . . . . . . 11
7.2 Informative References . . . . . . . . . . . . . . . . . . 10 7.2. Informative References . . . . . . . . . . . . . . . . . . 11
Author's Address . . . . . . . . . . . . . . . . . . . . . . . 12 Appendix A. Alternative Approaches Considered . . . . . . . . . . 12
A. Alternative Approaches Considered . . . . . . . . . . . . . . 12 Appendix B. Acknowledgments . . . . . . . . . . . . . . . . . . . 13
B. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 13 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 13
Intellectual Property and Copyright Statements . . . . . . . . 14 Intellectual Property and Copyright Statements . . . . . . . . . . 15
1. Introduction 1. Introduction
In existing telecommunications systems, there are many well-known In existing telecommunications systems, there are many well-known
communication and information services that are offered by loosely communication and information services that are offered by loosely
coordinated entities across a large geographic region, with well- coordinated entities across a large geographic region, with well-
known identifiers. Some of the services are operated by governments known identifiers. Some of the services are operated by governments
or regulated monopolies, others by competing commercial enterprises. or regulated monopolies, others by competing commercial enterprises.
Examples include emergency services (reached by dialing 911 in North Examples include emergency services (reached by dialing 9-1-1 in
America, 112 in Europe), community services and volunteer North America, 1-1-2 in Europe), community services and volunteer
opportunities (211 in some regions of the United States), telephone opportunities (2-1-1 in some regions of the United States), telephone
directory and repair services (411 and 611 in the United States and directory and repair services (4-1-1 and 6-1-1 in the United States
Canada), government information services (311 in some cities in the and Canada), government information services (3-1-1 in some cities in
United States), lawyer referral services (1-800-LAWYER), car roadside the United States), lawyer referral services (1-800-LAWYER), car
assistance (automobile clubs) and pizza delivery services. roadside assistance (automobile clubs) and pizza delivery services.
Unfortunately, almost all of them are limited in scope to a single Unfortunately, almost all of them are limited in scope to a single
country or possibly a group of countries, such as those belonging to country or possibly a group of countries, such as those belonging to
the North American Numbering Plan or the European Union. The same the North American Numbering Plan or the European Union. The same
identifiers are often used for other purposes outside that region, identifiers are often used for other purposes outside that region,
making accessing such services difficult when users travel or use making accessing such services difficult when users travel or use
devices produced outside their home country. devices produced outside their home country.
These services are characterized by long-term stability of user- These services are characterized by long-term stability of user-
visible identifiers, decentralized administration of the underlying visible identifiers, decentralized administration of the underlying
service and a well-defined resolution or mapping mechanism. For service and a well-defined resolution or mapping mechanism. For
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entities. There are many ways to divide provision of such services, entities. There are many ways to divide provision of such services,
such as dividing responsibility by geographic region or by the such as dividing responsibility by geographic region or by the
service provider a user chooses. In addition, users can choose service provider a user chooses. In addition, users can choose
different mapping service providers that in turn manage how different mapping service providers that in turn manage how
geographic locations are mapped to service providers. geographic locations are mapped to service providers.
Availability of such service identifiers allows end systems to convey Availability of such service identifiers allows end systems to convey
information about the desired service to other network entities. For information about the desired service to other network entities. For
example, an IP phone could have a special set of short cuts, address example, an IP phone could have a special set of short cuts, address
book entries or buttons that invoke emergency services. When such a book entries or buttons that invoke emergency services. When such a
service identifier is put into the outgoing SIP message, it allows service identifier is put into the outgoing Session Initiation
SIP proxies to unambiguously take actions, as it would not be Protocol (SIP) [4] message, it allows SIP proxies to unambiguously
practical to configure them with dial strings and emergency numbers take actions, as it would not be practical to configure them with
used throughout the world. Hence, such service identifiers make it dial strings and emergency numbers used throughout the world. Hence,
possible to delegate routing decisions to third parties and to mark such service identifiers make it possible to delegate routing
certain requests as having special characteristics while preventing decisions to third parties and to mark certain requests as having
these characteristics from being accidentally invoked. special characteristics while preventing these characteristics from
being accidentally invoked.
This URN identifies services independent of the particular protocol This URN identifies services independent of the particular protocol
that is used to request or deliver the service. The URN may appear that is used to request or deliver the service. The URN may appear
in protocols that allow general URIs, such as the Session Initiation in protocols that allow general URIs, such as the SIP [4] request
Protocol (SIP) [4] request URIs, web pages or mapping protocols. URIs, web pages or mapping protocols.
The service URN is a protocol element and generally not expected to The service URN is a protocol element and generally not expected to
be visible to humans. For example, it is expected that callers will be visible to humans. For example, it is expected that callers will
still dial the emergency number '9-1-1' in the United States to reach still dial the emergency number '9-1-1' in the United States to reach
emergency services. In some other cases, speed dial buttons might emergency services. In some other cases, speed dial buttons might
identify the service, as is common practice on hotel phones today. identify the service, as is common practice on hotel phones today.
(Speed dial buttons for summoning emergency help are considered (Speed dial buttons for summoning emergency help are considered
inappropriate by most emergency services professionals, at least for inappropriate by most emergency services professionals, at least for
mobile devices, as they are too prone to being triggered mobile devices, as they are too prone to being triggered
accidentally.) Rather, protocols would carry the service URN accidentally.)
described here, allowing universal identification.
The translation of service dial strings or service numbers to service The translation of service dial strings or service numbers to service
URNs in the end host is beyond the scope of this document. These URNs in the end host is beyond the scope of this document. These
translations likely depend on the location of the caller and may be translations likely depend on the location of the caller and may be
many-to-one, i.e., several service numbers may map to one service many-to-one, i.e., several service numbers may map to one service
URN. For example, a phone for a traveler could recognize the URN. For example, a phone for a traveler could recognize the
emergency service number for both the traveler's home location and emergency service number for both the traveler's home location and
the traveler's visited location, mapping both to the same universal the traveler's visited location, mapping both to the same universal
service URN, urn:service:sos. service URN, urn:service:sos.
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"SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY",
and "OPTIONAL" are to be interpreted as described in RFC 2119 [2]. and "OPTIONAL" are to be interpreted as described in RFC 2119 [2].
Terminology specific to emergency services is defined in [19]. Terminology specific to emergency services is defined in [19].
3. Registration Template 3. Registration Template
Below, we include the registration template for the URN scheme Below, we include the registration template for the URN scheme
according to RFC 3406 [12]. according to RFC 3406 [12].
Namespace ID: service Namespace ID: service
Registration Information: Registration version: 1; registration date: Registration Information: Registration version: 1; registration
2006-04-02 date: 2006-04-02
Declared registrant of the namespace: TBD Declared registrant of the namespace:
Registering organization: IETF ECRIT Working Group
Designated contact: Henning Schulzrinne
Designated contact email: hgs@cs.columbia.edu
Declaration of syntactic structure: The URN consists of a Declaration of syntactic structure: The URN consists of a
hierarchical service identifier, with a sequence of labels hierarchical service identifier, with a sequence of labels
separated by periods. The left-most label is the most significant separated by periods. The left-most label is the most significant
one and is called 'top-level service', while names to the right one and is called 'top-level service', while names to the right
are called 'sub-services'. The set of allowable characters is the are called 'sub-services'. The set of allowable characters is the
same as that for domain names [1] and a subset of the labels same as that for domain names [1] and a subset of the labels
allowed in [5]. Labels are case-insensitive and MUST be specified allowed in [5]. Labels are case-insensitive and MUST be specified
in all lower-case. For any given service URN, service-identifiers in all lower-case. For any given service URN, service-identifiers
can be removed right-to-left and the resulting URN is still valid, can be removed right-to-left and the resulting URN is still valid,
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logical service, specified in the service registration (see IANA logical service, specified in the service registration (see IANA
Considerations (Section 4)). Resolution of the URN, if Considerations (Section 4)). Resolution of the URN, if
successful, will return a particular instance of the service, and successful, will return a particular instance of the service, and
this instance may be different even for two users making the same this instance may be different even for two users making the same
request in the same place at the same time; the logical service request in the same place at the same time; the logical service
identified by the URN, however, is persistent and unique. Service identified by the URN, however, is persistent and unique. Service
URNs MUST be unique for each unique service; this is guaranteed URNs MUST be unique for each unique service; this is guaranteed
through the registration of each service within this namespace, through the registration of each service within this namespace,
described in Section 4. described in Section 4.
Identifier persistence considerations: The 'service' URN for the same Identifier persistence considerations: The 'service' URN for the
service is expected to be persistent, although there naturally same service is expected to be persistent, although there
cannot be a guarantee that a particular service will continue to naturally cannot be a guarantee that a particular service will
be available globally or at all times. continue to be available globally or at all times.
Process of identifier assignment: The process of identifier Process of identifier assignment: The process of identifier
assignment is described in the IANA Considerations (Section 4). assignment is described in the IANA Considerations (Section 4).
Process for identifier resolution: There is no single global Process for identifier resolution: There is no single global
resolution service for 'service' URNs. However, each top-level resolution service for 'service' URNs. However, each top-level
service can provide a set of mapping protocols to be used with service can provide a set of mapping protocols to be used with
'service' URNs of that service. 'service' URNs of that service.
Rules for Lexical Equivalence: 'service' identifiers are compared Rules for Lexical Equivalence: 'service' identifiers are compared
according to case-insensitive string equality. according to case-insensitive string equality.
Conformance with URN Syntax: The BNF in the 'Declaration of syntactic Conformance with URN Syntax: The BNF in the 'Declaration of
structure' above constrains the syntax for this URN scheme. syntactic structure' above constrains the syntax for this URN
scheme.
Validation mechanism: Validation determines whether a given string is Validation mechanism: Validation determines whether a given string
currently a validly-assigned URN [12]. Due to the distributed is currently a validly-assigned URN [12]. Due to the distributed
nature of the mapping mechanism and since not all services are nature of the mapping mechanism and since not all services are
available everywhere and not all mapping servers may be configured available everywhere and not all mapping servers may be configured
with all current service registrations, validation in this sense with all current service registrations, validation in this sense
is not possible. Also, the discovery mechanism for the mapping is not possible. Also, the discovery mechanism for the mapping
mechanism may not be configured with all current top-level mechanism may not be configured with all current top-level
services. services.
Scope: The scope for this URN is public and global. Scope: The scope for this URN is public and global.
4. IANA Considerations 4. IANA Considerations
4.1 New Service-Identifying Labels This section registers a new URN scheme with the registration
template provided in Section 3.
Below, Section 4.1 details how to register new service-identifying
labels. Descriptions of sub-services for the first two services to
be registered, sos and counseling, are given in Section 4.2 and
Section 4.3, respectively. Finally, Section 4.4 contains the initial
registration table.
4.1. New Service-Identifying Labels
Services and sub-services are identified by labels managed by IANA, Services and sub-services are identified by labels managed by IANA,
according to the processes outlined in [3] in a new registry called according to the processes outlined in [3] in a new registry called
"Service URN Labels". Thus, creating a new service requires IANA "Service URN Labels". Thus, creating a new service requires IANA
action. The policy for adding top-level service labels is 'Standards action. The policy for adding top-level service labels is 'Standards
Action'. (This document defines the top-level service 'sos' and Action'. (This document defines the top-level service 'sos' and
'counseling'.) The policy for assigning labels to sub-services may 'counseling'.) The policy for assigning labels to sub-services may
differ for each top-level service designation and MUST be defined by differ for each top-level service designation and MUST be defined by
the document describing the top-level service. the document describing the top-level service.
Entries in the registration table have the following format Entries in the registration table have the following format
Service Reference Description Service Reference Description
-------------------------------------------------------------------- --------------------------------------------------------------------
foo RFCxyz Brief description of the 'foo' top-level service foo RFCxyz Brief description of the 'foo' top-level service
foo.bar RFCabc Description of the 'foo.bar' service foo.bar RFCabc Description of the 'foo.bar' service
To allow use within the constraints of S-NAPTR [5], all top-level To allow use within the constraints of S-NAPTR [5], all top-level
service names MUST NOT exceed 27 characters. service names MUST NOT exceed 27 characters.
4.2 Sub-Services for the 'sos' Service 4.2. Sub-Services for the 'sos' Service
This section defines the first service registration within the IANA This section defines the first service registration within the IANA
registry defined in Section 4.1, using the top-level service label registry defined in Section 4.1, using the top-level service label
'sos'. 'sos'.
The 'sos' service type describes emergency services requiring an The 'sos' service type describes emergency services requiring an
immediate response, typically offered by various branches of the immediate response, typically offered by various branches of the
government or other public institutions. Additional sub-services can government or other public institutions. Additional sub-services can
be added after expert review and must be of general public interest be added after expert review and must be of general public interest
and have a similar emergency nature. The expert is designated by the and have a similar emergency nature. The expert is designated by the
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urn:service:sos The generic 'sos' service reaches a public safety urn:service:sos The generic 'sos' service reaches a public safety
answering point (PSAP) which in turn dispatches aid appropriate to answering point (PSAP) which in turn dispatches aid appropriate to
the emergency. It encompasses all of the services listed below. the emergency. It encompasses all of the services listed below.
urn:service:sos.ambulance This service identifier reaches an urn:service:sos.ambulance This service identifier reaches an
ambulance service that provides emergency medical assistance and ambulance service that provides emergency medical assistance and
transportation. transportation.
urn:service:sos.animal-control Animal control is defined as control urn:service:sos.animal-control Animal control is defined as control
of dogs, cats, and domesticated or undomesticated animals. of dogs, cats, and domesticated or undomesticated animals.
urn:service:sos.fire The 'fire' service identifier summons the fire urn:service:sos.fire The 'fire' service identifier summons the fire
service, also known as the fire brigade or fire department. service, also known as the fire brigade or fire department.
urn:service:sos.gas The 'gas' service allows the reporting of natural urn:service:sos.gas The 'gas' service allows the reporting of
gas (and other flammable gas) leaks or other natural gas natural gas (and other flammable gas) leaks or other natural gas
emergencies. emergencies.
urn:service:sos.marine The 'marine' service refers to maritime search urn:service:sos.marine The 'marine' service refers to maritime
and rescue services such as those offered by the coast guard, search and rescue services such as those offered by the coast
lifeboat or surf lifesavers. guard, lifeboat or surf lifesavers.
urn:service:sos.mountain The 'mountain' service refers to mountain urn:service:sos.mountain The 'mountain' service refers to mountain
rescue services, i.e., search and rescue activities that occur in rescue services, i.e., search and rescue activities that occur in
a mountainous environment, although the term is sometimes also a mountainous environment, although the term is sometimes also
used to apply to search and rescue in other wilderness used to apply to search and rescue in other wilderness
environments. environments.
urn:service:sos.physician The 'physician' emergency service connects urn:service:sos.physician The 'physician' emergency service connects
the caller to a physician referral service. the caller to a physician referral service.
urn:service:sos.poison The 'poison' service refers to special urn:service:sos.poison The 'poison' service refers to special
information centers set up to inform citizens about how to respond information centers set up to inform citizens about how to respond
to potential poisoning. These poison control centers maintain a to potential poisoning. These poison control centers maintain a
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rescue services, i.e., search and rescue activities that occur in rescue services, i.e., search and rescue activities that occur in
a mountainous environment, although the term is sometimes also a mountainous environment, although the term is sometimes also
used to apply to search and rescue in other wilderness used to apply to search and rescue in other wilderness
environments. environments.
urn:service:sos.physician The 'physician' emergency service connects urn:service:sos.physician The 'physician' emergency service connects
the caller to a physician referral service. the caller to a physician referral service.
urn:service:sos.poison The 'poison' service refers to special urn:service:sos.poison The 'poison' service refers to special
information centers set up to inform citizens about how to respond information centers set up to inform citizens about how to respond
to potential poisoning. These poison control centers maintain a to potential poisoning. These poison control centers maintain a
database of poisons and appropriate emergency treatment. database of poisons and appropriate emergency treatment.
urn:service:sos.police The 'police' service refers to the police urn:service:sos.police The 'police' service refers to the police
department or other law enforcement authorities. department or other law enforcement authorities.
4.3 Sub-Services for the 'counseling' Service 4.3. Sub-Services for the 'counseling' Service
The 'counseling' service type describes services where callers can The 'counseling' service type describes services where callers can
receive advice and support, often anonymous, but not requiring an receive advice and support, often anonymous, but not requiring an
emergency response. (Naturally, such services may transfer callers emergency response. (Naturally, such services may transfer callers
to an emergency service or summon such services if the situation to an emergency service or summon such services if the situation
warrants.) Additional sub-services can be added after expert review warrants.) Additional sub-services can be added after expert review
and should be of general public interest. The expert is chosen in and should be of general public interest. The expert is chosen in
the same manner as describe for the 'sos' service. The expert review the same manner as describe for the 'sos' service. The expert review
should take into account whether these services are offered widely should take into account whether these services are offered widely
and in different countries, with approximately the same caller and in different countries, with approximately the same caller
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urn:service:counseling.mental-health The 'mental-health' service urn:service:counseling.mental-health The 'mental-health' service
refers to the "diagnostic, treatment, and preventive care that refers to the "diagnostic, treatment, and preventive care that
helps improve how persons with mental illness feel both physically helps improve how persons with mental illness feel both physically
and emotionally as well as how they interact with other persons." and emotionally as well as how they interact with other persons."
(U.S. Department of Health and Human Services) (U.S. Department of Health and Human Services)
urn:service:counseling.suicide The 'suicide' service refers to the urn:service:counseling.suicide The 'suicide' service refers to the
suicide prevention hotline. suicide prevention hotline.
4.4 Initial IANA Registration 4.4. Initial IANA Registration
The following table contains the initial IANA registration for The following table contains the initial IANA registration for
emergency and counseling services. emergency and counseling services.
Service Reference Description Service Reference Description
-------------------------------------------------------------------- --------------------------------------------------------------------
counseling RFC XYZ Counseling services counseling RFC XYZ Counseling services
counseling.children RFC XYZ Counseling for children counseling.children RFC XYZ Counseling for children
counseling.mental-health RFC XYZ Mental health counseling counseling.mental-health RFC XYZ Mental health counseling
counseling.suicide RFC XYZ Suicide prevention hotline counseling.suicide RFC XYZ Suicide prevention hotline
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meant to be well-known, even if the particular service instance is meant to be well-known, even if the particular service instance is
access-controlled, so privacy considerations do not apply to the URN. access-controlled, so privacy considerations do not apply to the URN.
There are likely no specific privacy issues when including a service There are likely no specific privacy issues when including a service
URN on a web page, for example. On the other hand, ferrying the URN URN on a web page, for example. On the other hand, ferrying the URN
in a signaling protocol can give attackers information on the kind of in a signaling protocol can give attackers information on the kind of
service desired by the caller. For example, this makes it easier for service desired by the caller. For example, this makes it easier for
the attacker to automatically find all calls for emergency services the attacker to automatically find all calls for emergency services
or directory assistance. Appropriate, protocol-specific security or directory assistance. Appropriate, protocol-specific security
mechanisms need to be implemented for protocols carrying service mechanisms need to be implemented for protocols carrying service
URNs. The mapping protocol needs to address a number of threats, as URNs. The mapping protocol needs to address a number of threats, as
detailed in [18]. detailed in [18]. That document also discusses the security
considerations related to the use of the service URN for emergency
services.
7. References 7. References
7.1 Normative References 7.1. Normative References
[1] Braden, R., "Requirements for Internet Hosts - Application and [1] Braden, R., "Requirements for Internet Hosts - Application and
Support", STD 3, RFC 1123, October 1989. Support", STD 3, RFC 1123, October 1989.
[2] Bradner, S., "Key words for use in RFCs to Indicate Requirement [2] Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", BCP 14, RFC 2119, March 1997. Levels", BCP 14, RFC 2119, March 1997.
[3] Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA [3] Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA
Considerations Section in RFCs", BCP 26, RFC 2434, October 1998. Considerations Section in RFCs", BCP 26, RFC 2434,
October 1998.
[4] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, A., [4] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, A.,
Peterson, J., Sparks, R., Handley, M., and E. Schooler, "SIP: Peterson, J., Sparks, R., Handley, M., and E. Schooler, "SIP:
Session Initiation Protocol", RFC 3261, June 2002. Session Initiation Protocol", RFC 3261, June 2002.
[5] Daigle, L. and A. Newton, "Domain-Based Application Service [5] Daigle, L. and A. Newton, "Domain-Based Application Service
Location Using SRV RRs and the Dynamic Delegation Discovery Location Using SRV RRs and the Dynamic Delegation Discovery
Service (DDDS)", RFC 3958, January 2005. Service (DDDS)", RFC 3958, January 2005.
7.2 Informative References 7.2. Informative References
[6] Crocker, D., "MAILBOX NAMES FOR COMMON SERVICES, ROLES AND [6] Crocker, D., "MAILBOX NAMES FOR COMMON SERVICES, ROLES AND
FUNCTIONS", RFC 2142, May 1997. FUNCTIONS", RFC 2142, May 1997.
[7] Resnick, P., "Internet Message Format", RFC 2822, April 2001. [7] Resnick, P., "Internet Message Format", RFC 2822, April 2001.
[8] Mealling, M., "The Network Solutions Personal Internet Name [8] Mealling, M., "The Network Solutions Personal Internet Name
(PIN): A URN Namespace for People and Organizations", RFC 3043, (PIN): A URN Namespace for People and Organizations", RFC 3043,
January 2001. January 2001.
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for the Common Language Equipment Identifier (CLEI) Code", for the Common Language Equipment Identifier (CLEI) Code",
RFC 4152, August 2005. RFC 4152, August 2005.
[15] Kang, S., "Using Universal Content Identifier (UCI) as Uniform [15] Kang, S., "Using Universal Content Identifier (UCI) as Uniform
Resource Names (URN)", RFC 4179, October 2005. Resource Names (URN)", RFC 4179, October 2005.
[16] Kameyama, W., "A Uniform Resource Name (URN) Namespace for the [16] Kameyama, W., "A Uniform Resource Name (URN) Namespace for the
TV-Anytime Forum", RFC 4195, October 2005. TV-Anytime Forum", RFC 4195, October 2005.
[17] Hardie, T., "LoST: A Location-to-Service Translation Protocol", [17] Hardie, T., "LoST: A Location-to-Service Translation Protocol",
draft-ietf-ecrit-lost-00 (work in progress), June 2006. draft-ietf-ecrit-lost-04 (work in progress), February 2007.
[18] Taylor, T., "Security Threats and Requirements for Emergency [18] Taylor, T., "Security Threats and Requirements for Emergency
Call Marking and Mapping", draft-ietf-ecrit-security-threats-03 Call Marking and Mapping", draft-ietf-ecrit-security-threats-03
(work in progress), July 2006. (work in progress), July 2006.
[19] Schulzrinne, H. and R. Marshall, "Requirements for Emergency [19] Schulzrinne, H. and R. Marshall, "Requirements for Emergency
Context Resolution with Internet Technologies", Context Resolution with Internet Technologies",
draft-ietf-ecrit-requirements-11 (work in progress), draft-ietf-ecrit-requirements-12 (work in progress),
August 2006. August 2006.
Author's Address
Henning Schulzrinne
Columbia University
Department of Computer Science
450 Computer Science Building
New York, NY 10027
US
Phone: +1 212 939 7004
Email: hgs+ecrit@cs.columbia.edu
URI: http://www.cs.columbia.edu
Appendix A. Alternative Approaches Considered Appendix A. Alternative Approaches Considered
The discussions of ways to identify emergency calls has yielded a The discussions of ways to identify emergency calls has yielded a
number of proposals. Since these are occasionally brought up during number of proposals. Since these are occasionally brought up during
discussions, we briefly summarize why this document chose not to discussions, we briefly summarize why this document chose not to
pursue these solutions. pursue these solutions.
tel:NNN;context=+C This approach uses tel URIs [13]. Here, NNN is tel:NNN;context=+C This approach uses tel URIs [13]. Here, NNN is
the national emergency number, where the country is identified by the national emergency number, where the country is identified by
the context C. This approach is easy for user agents to implement, the context C. This approach is easy for user agents to implement,
but hard for proxies and other SIP elements to recognize, as it but hard for proxies and other SIP elements to recognize, as it
would have to know about all number-context combinations in the would have to know about all number-context combinations in the
world and track occasional changes. In addition, many of these world and track occasional changes. In addition, many of these
numbers are being used for other services. For example, the numbers are being used for other services. For example, the
emergency number in Paraguay (00) is also used to call the emergency number in Paraguay (00) is also used to call the
international operator in the United States. As another example, international operator in the United States. As another example,
A number of countries, such as Italy, use 118 as an emergency A number of countries, such as Italy, use 118 as an emergency
number, but it also connects to directory assistance in Finland. number, but it also connects to directory assistance in Finland.
tel:sos This solution avoids name conflicts, but is not a valid "tel" tel:sos This solution avoids name conflicts, but is not a valid
[13] URI. It also only works if every outbound proxy knows how to "tel" [13] URI. It also only works if every outbound proxy knows
route requests to a proxy that can reach emergency services since how to route requests to a proxy that can reach emergency services
tel URIs. The SIP URI proposed here only requires a user's home since tel URIs. The SIP URI proposed here only requires a user's
domain to be appropriately configured. home domain to be appropriately configured.
sip:sos@domain Earlier work had defined a special user identifier, sip:sos@domain Earlier work had defined a special user identifier,
sos, within the caller's home domain in a SIP URI, for example, sos, within the caller's home domain in a SIP URI, for example,
sip:sos@example.com. Such a user identifier follows the sip:sos@example.com. Such a user identifier follows the
convention of RFC 2142 [6] and the "postmaster" convention convention of RFC 2142 [6] and the "postmaster" convention
documented in RFC 2822 [7]. This approach had the advantage that documented in RFC 2822 [7]. This approach had the advantage that
dial plans in existing user agents could probably be converted to dial plans in existing user agents could probably be converted to
generate such a URI and that only the home proxy for the domain generate such a URI and that only the home proxy for the domain
has to understand the user naming convention. However, it has to understand the user naming convention. However, it
overloads the user part of the URI with specific semantics rather overloads the user part of the URI with specific semantics rather
than being opaque, makes routing by the outbound proxy a special than being opaque, makes routing by the outbound proxy a special
case that does not conform to normal SIP request-URI handling case that does not conform to normal SIP request-URI handling
rules and is SIP-specific. The mechanism also does not extend rules and is SIP-specific. The mechanism also does not extend
readily to other services. readily to other services.
SIP URI user parameter: One could create a special URI, such as "aor- SIP URI user parameter: One could create a special URI, such as
domain;user=sos". This avoids the name conflict problem, but "aor-domain;user=sos". This avoids the name conflict problem, but
requires mechanism-aware user agents that are capable of emitting requires mechanism-aware user agents that are capable of emitting
this special URI. Also, the 'user' parameter is meant to describe this special URI. Also, the 'user' parameter is meant to describe
the format of the user part of the SIP URI, which this usage does the format of the user part of the SIP URI, which this usage does
not do. Adding other parameters still leaves unclear what, if not do. Adding other parameters still leaves unclear what, if
any, conventions should be used for the user and domain part of any, conventions should be used for the user and domain part of
the URL. Neither solution is likely to be backward-compatible the URL. Neither solution is likely to be backward-compatible
with existing clients. with existing clients.
Special domain: A special domain, such as "sip:fire@sos.int" could be Special domain: A special domain, such as "sip:fire@sos.int" could
used to identify emergency calls. This has similar properties as be used to identify emergency calls. This has similar properties
the "tel:sos" URI, except that it is indeed a valid URI. To make as the "tel:sos" URI, except that it is indeed a valid URI. To
this usable, the special domain would have to be operational and make this usable, the special domain would have to be operational
point to an appropriate emergency services proxy. Having a and point to an appropriate emergency services proxy. Having a
single, if logical, emergency services proxy for the whole world single, if logical, emergency services proxy for the whole world
seems to have undesirable scaling and administrative properties. seems to have undesirable scaling and administrative properties.
Appendix B. Acknowledgments Appendix B. Acknowledgments
This document is based on discussions with Jonathan Rosenberg and This document is based on discussions with Jonathan Rosenberg and
benefited from the comments of Leslie Daigle, Keith Drage, Benja benefited from the comments of Leslie Daigle, Keith Drage, Benja
Fallenstein, Paul Kyzivat, Andrew Newton, Brian Rosen, Jonathan Fallenstein, Paul Kyzivat, Andrew Newton, Brian Rosen, Jonathan
Rosenberg, Martin Thomson and Hannes Tschofenig. Rosenberg, Martin Thomson and Hannes Tschofenig.
Intellectual Property Statement Author's Address
Henning Schulzrinne
Columbia University
Department of Computer Science
450 Computer Science Building
New York, NY 10027
US
Phone: +1 212 939 7004
Email: hgs+ecrit@cs.columbia.edu
URI: http://www.cs.columbia.edu
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
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skipping to change at page 14, line 29 skipping to change at page 15, line 45
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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 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.
Copyright Statement
Copyright (C) The Internet Society (2006). 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.
Acknowledgment Acknowledgment
Funding for the RFC Editor function is currently provided by the Funding for the RFC Editor function is provided by the IETF
Internet Society. Administrative Support Activity (IASA).
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