< draft-ietf-ecrit-service-urn-03.txt   draft-ietf-ecrit-service-urn-04.txt >
ECRIT H. Schulzrinne ECRIT H. Schulzrinne
Internet-Draft Columbia U. Internet-Draft Columbia U.
Expires: November 20, 2006 May 19, 2006 Expires: February 7, 2007 August 6, 2006
A Uniform Resource Name (URN) for Services A Uniform Resource Name (URN) for Services
draft-ietf-ecrit-service-urn-03 draft-ietf-ecrit-service-urn-04
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 Internet Society (2006).
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 register such 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. Finding the Mapping Server . . . . . . . . . . . . . . . . . . 7 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8 4.1 New Service-Identifying Labels . . . . . . . . . . . . . . 7
5.1 New Service-Identifying Labels . . . . . . . . . . . . . . 8 4.2 Sub-Services for the 'sos' Service . . . . . . . . . . . . 7
5.2 S-NAPTR Application Service Tag . . . . . . . . . . . . . 8 4.3 Sub-Services for the 'counseling' Service . . . . . . . . 8
5.3 Sub-Services for the 'sos' Service . . . . . . . . . . . . 8 4.4 Initial IANA Registration . . . . . . . . . . . . . . . . 9
5.4 Sub-Services for the 'counseling' Service . . . . . . . . 9 5. Internationalization Considerations . . . . . . . . . . . . . 9
6. International Considerations . . . . . . . . . . . . . . . . . 10 6. Security Considerations . . . . . . . . . . . . . . . . . . . 10
7. Security Considerations . . . . . . . . . . . . . . . . . . . 10 7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 10
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 10 7.1 Normative References . . . . . . . . . . . . . . . . . . . 10
8.1 Normative References . . . . . . . . . . . . . . . . . . . 10 7.2 Informative References . . . . . . . . . . . . . . . . . . 10
8.2 Informative References . . . . . . . . . . . . . . . . . . 11
Author's Address . . . . . . . . . . . . . . . . . . . . . . . 12 Author's Address . . . . . . . . . . . . . . . . . . . . . . . 12
A. Alternative Approaches Considered . . . . . . . . . . . . . . 12 A. Alternative Approaches Considered . . . . . . . . . . . . . . 12
B. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 13 B. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 13
Intellectual Property and Copyright Statements . . . . . . . . 15 Intellectual Property and Copyright Statements . . . . . . . . 14
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 911 in North
America, 112 in Europe), community services and volunteer America, 112 in Europe), community services and volunteer
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assistance (automobile clubs) and pizza delivery services. 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 mechanism. (For example, there service and a well-defined resolution or mapping mechanism. For
is no national coordination or call center for "9-1-1" in the United example, there is no national coordination or call center for "9-1-1"
States; rather, various local government organizations cooperate to in the United States; rather, various local government organizations
provide this service, based on jurisdictions.) cooperate to provide this service, based on jurisdictions. We use
the terms resolution and mapping interchangeably.
In this document, we propose a URN namespace that, together with In this document, we propose a URN namespace that, together with
resolution protocols beyond the scope of this document, allows us to resolution protocols beyond the scope of this document, allows us to
define such global, well-known services, while distributing the define such global, well-known services, while distributing the
actual implementation across a large number of service-providing actual implementation across a large number of service-providing
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 directory providers that in turn manage how geographic different mapping service providers that in turn manage how
locations are mapped to service providers. geographic locations are mapped to service providers.
Availability of such service identifiers simplifies end system Availability of such service identifiers simplifies end system
configuration. For example, an IP phone could have a special set of configuration. For example, an IP phone could have a special set of
short cuts or buttons that invoke emergency services, as it would not short cuts, address book entries or buttons that invoke emergency
be practical to manually re-configure the device with local emergency services, as it would not be practical to manually re-configure the
contacts for each city or town a user visits with his or her mobile device with local emergency contacts for each city or town a user
device. Also, such identifiers make it possible to delegate routing visits with his or her mobile device. Also, such identifiers make it
decisions to third parties and to mark certain requests as having possible to delegate routing decisions to third parties and to mark
special characteristics while preventing these characteristics to be certain requests as having special characteristics while preventing
accidentally invoked on inappropriate requests. these characteristics to be accidentally invoked on inappropriate
requests.
This URN identifies services independent of a particular protocol to This URN identifies services independent of the particular protocol
deliver the services. It may appear in protocols that allow general that is used to request or deliver the service. The URN may appear
URIs, such as the Session Initiation Protocol (SIP) [5] request URIs, in protocols that allow general URIs, such as the Session Initiation
web pages or mapping protocols. Protocol (SIP) [5] request URIs, web pages or mapping protocols.
The service URN is generally not expected to be visible to humans. The service URN is a protocol element and generally not expected to
For example, it is expected that callers will still dial '9-1-1' in be visible to humans. For example, it is expected that callers will
the United States to reach emergency services. In some other cases, still dial '9-1-1' in the United States to reach emergency services.
speed dial buttons might identify the service, as is common practice In some other cases, speed dial buttons might identify the service,
on hotel phones today. (Speed dial buttons for summoning emergency as is common practice on hotel phones today. (Speed dial buttons for
help are considered inappropriate by most emergency services summoning emergency help are considered inappropriate by most
professionals, at least for mobile devices, as they are too prone to emergency services professionals, at least for mobile devices, as
being triggered accidentally.) Rather, protocol elements would carry they are too prone to being triggered accidentally.) Rather,
the service URN described here, allowing universal identification. protocols would carry the service URN described here, allowing
The translation of dial strings to service URNs is beyond the scope universal identification. The translation of dial strings or service
of this document; it is likely to depend on the location of the numbers to service URNs is beyond the scope of this document; it is
caller and may be many-to-one. For example, a phone for a traveler likely to depend on the location of the caller and may be many-to-
could recognize the emergency dial string for both the traveler's one. For example, a phone for a traveler could recognize the
home location and the traveler's visited location, translating both emergency number for both the traveler's home location and the
to the same universal service URN, urn:service:sos. traveler's visited location, translating both to the same universal
service URN, urn:service:sos.
Since service URNs are not routable, a proxy or user agent has to Since service URNs are not routable, a SIP proxy or user agent has to
translate the service URN into a routable URI for a location- translate the service URN into a routable URI for a location-
appropriate service provider, such as a SIP URL. LoST [21] is one appropriate service provider, such as a SIP URL. LoST [19] is one
resolution system for mapping service URNs to URLs based on resolution system for mapping service URNs to URLs based on
geographic location. It is anticipated that there will be several geographic location. It is anticipated that there will be several
such systems, possibly with different systems for different services. such systems, possibly with different systems for different services.
Services are described by top-level service type, and may contain a Services are described by top-level service type, and may contain a
hierarchy of sub-services further describing the service, as outlined hierarchy of sub-services further describing the service, as outlined
in Section 3. Mapping protocols SHOULD always provide a mapping just in Section 3. Mapping protocols SHOULD always provide a mapping just
for the top-level service even if sub-services are in use. This for the top-level service even if sub-services are in use. This
mapping for the top-level service MAY also be used if an entity is mapping for the top-level service MAY also be used if an entity is
presented with an invalid sub-service and presenting an error presented with an invalid sub-service and presenting an error
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We discuss alternative approaches for creating service identifiers, We discuss alternative approaches for creating service identifiers,
and why they are unsatisfactory, in Appendix A. and why they are unsatisfactory, in Appendix A.
2. Terminology 2. Terminology
In this document, the key words "MUST", "MUST NOT", "REQUIRED", In this document, the key words "MUST", "MUST NOT", "REQUIRED",
"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 [23]. Terminology specific to emergency services is defined in [21].
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 [15]. according to RFC 3406 [13].
Namespace ID: service Namespace ID: service
Registration Information: Registration version: 1; registration date: Registration Information: Registration version: 1; registration date:
2006-04-02 2006-04-02
Declared registrant of the namespace: TBD Declared registrant of the namespace: TBD
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
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to a large cross-section of Internet users, including both to a large cross-section of Internet users, including both
technical and non-technical users, on a variety of devices, but technical and non-technical users, on a variety of devices, but
particularly for mobile and nomadic users. The service URN will particularly for mobile and nomadic users. The service URN will
allow Internet users needing services to identify the service by allow Internet users needing services to identify the service by
kind, without having to determine manually who provides the kind, without having to determine manually who provides the
particular service in the user's current context, e.g., at the particular service in the user's current context, e.g., at the
user's current location. For example, travelers will be able to user's current location. For example, travelers will be able to
use their mobile devices to request emergency services without use their mobile devices to request emergency services without
having to know the emergency dial string of the visited country. having to know the emergency dial string of the visited country.
The assignment of identifiers is described in the IANA The assignment of identifiers is described in the IANA
Considerations (Section 5). The service URN does not prescribe a Considerations (Section 4). The service URN does not prescribe a
particular resolution mechanism, but it is assumed that a number particular resolution mechanism, but it is assumed that a number
of different entities could operate and offer such mechanisms. of different entities could operate and offer such mechanisms.
Namespace considerations: There do not appear to be other URN Namespace considerations: There do not appear to be other URN
namespaces that serve the same need of uniquely identifying namespaces that serve the same need of uniquely identifying
widely-available communication and information services. Unlike widely-available communication and information services. Unlike
most other currently registered URN namespaces, the service URN most other currently registered URN namespaces, the service URN
does not identify documents and protocol objects (e.g., [13], does not identify documents and protocol objects (e.g., [10],
[14], [18], [19]), types of telecommunications equipment [17], [11], [16], [17]), types of telecommunications equipment [15],
people or organizations [12]. tel URIs [16] identify telephone people or organizations [9]. tel URIs [14] identify telephone
numbers, but numbers commonly identifying services, such as 911 or numbers, but numbers commonly identifying services, such as 911 or
112, are specific to a particular region or country. 112, are specific to a particular region or country.
Identifier uniqueness considerations: A service URN identifies a Identifier uniqueness considerations: A service URN identifies a
logical service, specified in the service registration (see IANA logical service, specified in the service registration (see IANA
considerations). Resolution of the URN, if successful, will Considerations (Section 4)). Resolution of the URN, if
return a particular instance of the service, and this instance may successful, will return a particular instance of the service, and
be different even for two users making the same request in the this instance may be different even for two users making the same
same place at the same time; the logical service identified by the request in the same place at the same time; the logical service
URN, however, is persistent and unique. Service URNs MUST be identified by the URN, however, is persistent and unique. Service
unique for each unique service; this is guaranteed through the URNs MUST be unique for each unique service; this is guaranteed
registration of each service within this namespace, described in through the registration of each service within this namespace,
Section 5. described in Section 4.
Identifier persistence considerations: The 'service' URN for the same Identifier persistence considerations: The 'service' URN for the same
service is expected to be persistent, although there naturally service is expected to be persistent, although there naturally
cannot be a guarantee that a particular service will continue to cannot be a guarantee that a particular service will continue to
be available globally or at all times. 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 5). assignment is described in the IANA Considerations (Section 4).
Process for identifier resolution: 'service' identifiers are resolved Process for identifier resolution: 'service' identifiers are resolved
by the mapping protocols, an instance of a Resolution Discovery by mapping protocols, based on the service and the location of the
System (RDS) as described in RFC 2276 [3]. Each top-level service person or entity desiring the use of the service. Each top-level
can provide its own distinct set of mapping protocols. Within service can provide its own distinct set of mapping protocols.
each top-level service, all mapping protocols MUST return the same Within each top-level service, all mapping protocols MUST return
set of mappings. Section 4 describes how the S-NAPTR mechanism is the same set of mappings. A resolution service is specified in a
used to find an instance of a mapping service. separate document.
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 syntactic
structure' above constrains the syntax for this URN scheme. 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 is
currently a validly-assigned URN [15]. The S-NAPTR mechanism also currently a validly-assigned URN [13]. Due to the distributed
allows to determine if a mapping protocol for a particular top- nature of the mapping mechanism and since not all services are
level service exists. The mapping protocol itself would then available everywhere and not all mapping servers may be configured
answer the question whether the service identifier exists. (The with all current service registrations, validation in this sense
issue of whether a particular combination of service and location is not possible. Also, the discovery mechanism for the mapping
yields a usable answer is beyond the scope of this specification.) mechanism may not be configured with all current top-level
services.
Scope: The scope for this URN is public and global. Scope: The scope for this URN is public and global.
4. Finding the Mapping Server 4. IANA Considerations
When a network entity receives a service URN, it uses the S-NAPTR [6]
mechanism to determine how to map the service URN, possibly using
other information such as geographic location, to a routable URI.
Each top-level service may define one or more such mapping protocols
and mapping protocol servers may be operated by a range of providers.
Thus, the network entity that needs to resolve the service URN
queries an appropriate domain, typically its home or service provider
domain, for NAPTR records and then selects records that match the
service and the mapping protocols it supports. The application
service for this URN is registered in IANA Considerations (Section 5)
of this document; the application protocols are registered in the
appropriate protocol document.
try until a working server has been found DNS name provided by DHCP
(option X) reverse DNS lookup for all ICE derived addresses [20]
application service provider
The S-NAPTR entry MAY contain the "s" flag if the resolving client
needs to perform an SRV resolution on the replacement string.
The first entry in the following example indicates that 'sos' service
URNs should be mapped to URIs using the LoST [21] protocol server at
lost.example.com, a DNS A record. The second entry is for an
imaginary top-level service 'pizza', using the equally imagined
'Pizza Location Protocol', offered by the pizzahouse.example.net
server, which should be queried for the appropriate DNS SRV record.
Note that these NAPTR records are maintained by example.com, i.e.,
example.com does not actually provide the mapping service itself.
example.com.
; order pref flags service regexp
IN NAPTR 50 50 "a" "SURN.sos:LoST" ""
; replacement
lost.example.org
IN NAPTR 10 50 "s" "SURN.pizza:PLP" "" 4.1 New Service-Identifying Labels
_plp._tcp.pizzahouse.example.net
5. IANA Considerations Services and sub-services are identified by labels managed by IANA,
according to the processes outlined in [4] in a new registry called
"Service URN Labels". Thus, creating a new service requires IANA
action. The policy for adding top-level service labels is 'Standards
Action'. (This document defines the top-level service 'sos' and
'counseling'.) The policy for assigning labels to sub-services may
differ for each top-level service designation and MUST be defined by
the document describing the top-level service.
5.1 New Service-Identifying Labels Entries in the registration table have the following format
New service-identifying labels and sub-services are to be managed by Service Reference Description
IANA, according to the processes outlined in [4]. The policy for --------------------------------------------------------------------
top-level service names is 'IETF Consensus'. The policy for foo RFCxyz Brief description of the 'foo' top-level service
assigning labels to sub-services may differ for each top-level foo.bar RFCabc Description of the 'foo.bar' service
service designation and MUST be defined by the document describing
the top-level service.
To allow use within the constraints of S-NAPTR [6], all top-level To allow use within the constraints of S-NAPTR [6], all top-level
service names MUST NOT exceed 27 characters. service names MUST NOT exceed 27 characters.
5.2 S-NAPTR Application Service Tag 4.2 Sub-Services for the 'sos' Service
Since each top-level service could use one or more different
resolution protocols, we need to indicate the top-level service in
the S-NAPTR application service tag. To indicate the URN-to-service
mapping service, all such services start with the string "SURN." (for
"service URN"), followed by the top-level service identifier. Note
that application service tags are case-insensitive and rendered here
in mixed case purely for readability.
This document effectively creates a sub-registry of labels under
SURN, but the contents of that registry are exactly the same as those
defined in Section 5.1 and thus no separate IANA action is needed.
This document registers the label "SURN.sos" as the S-NAPTR
application service tag according to [6] for emergency services and
defines the intended usage, interoperability considerations and
security considerations (Section 7).
5.3 Sub-Services for the 'sos' Service This section defines the first service registration within the IANA
registry defined in Section 4.1, using the top-level service label
'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 should 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 review should take and have a similar emergency nature. The expert is designated by the
into account whether these emergency services are offered widely and ECRIT working group, its successor, or, in their absence, the IESG.
in different countries, with approximately the same caller The expert review should only approve emergency services that are
expectation in terms of services rendered. The 'sos' service is not offered widely and in different countries, with approximately the
meant to invoke general government, public information or social same caller expectation in terms of services rendered. The 'sos'
services. service is not meant to invoke general government, public
information, counseling or social services.
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 natural
gas (and other flammable gas) leaks or other natural gas gas (and other flammable gas) leaks or other natural gas
emergencies. emergencies.
urn:service:sos.marine The 'marine' service refers to maritime search
and rescue services such as those offered by the coast 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.marine The 'marine' service refers to maritime search
and rescue services such as those offered by the coast guard,
lifeboat or surf lifesavers.
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.
urn:service:sos.suicide The 'suicide' service refers to the suicide urn:service:sos.suicide The 'suicide' service refers to the suicide
prevention hotline. prevention hotline.
5.4 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 review should and should be of general public interest. The expert is chosen in
take into account whether these services are offered widely and in the same manner as describe for the 'sos' service. The expert review
different countries, with approximately the same caller expectation should take into account whether these services are offered widely
in terms of services rendered. and in different countries, with approximately the same caller
expectation in terms of services rendered.
urn:service:counseling The generic 'counseling' service reaches a urn:service:counseling The generic 'counseling' service reaches a
call center that transfers the caller based on his or her specific call center that transfers the caller based on his or her specific
needs. needs.
urn:service:counseling.children The 'children' service refers to
counseling and support services that are specifically tailored to
the needs of children. Such services may, for example, provide
advice to run-aways or victims of child abuse.
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.children The 'children' service refers to 4.4 Initial IANA Registration
counseling and support services that are specifically tailored to
the needs of children. Such services may, for example, provide
advice to run-aways or victims of child abuse.
6. International Considerations The following table contains the initial IANA registration for
emergency and counseling services.
The service labels are protocol elements and not normally seen by Service Reference Description
users. Thus, the character set for these elements is restricted, as --------------------------------------------------------------------
described in Section 3. counseling RFC XYZ Counseling services
counseling.children RFC XYZ Counseling for children
counseling.mental-health RFC XYZ Mental health counseling
7. Security Considerations sos RFC XYZ Emergency services
sos.animal-control RFC XYZ Animal control
sos.fire RFC XYZ Fire service
sos.gas RFC XYZ Gas leaks and gas emergencies
sos.marine RFC XYZ Maritime search and rescue
sos.mountain RFC XYZ Mountain rescue
sos.physician RFC XYZ Physician referral service
sos.poison RFC XYZ Poison control center
sos.police RFC XYZ Police, law enforcement
sos.suicide RFC XYZ Suicide prevention hotline
5. Internationalization Considerations
The service labels are protocol elements [12] and not normally seen
by users. Thus, the character set for these elements is restricted,
as described in Section 3.
6. Security Considerations
As an identifier, the service URN does not appear to raise any As an identifier, the service URN does not appear to raise any
particular security issues. The services described by the URN are particular security issues. The services described by the URN are
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 [22]. detailed in [20].
8. References 7. References
8.1 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] Sollins, K., "Architectural Principles of Uniform Resource Name [3] Sollins, K., "Architectural Principles of Uniform Resource Name
Resolution", RFC 2276, January 1998. Resolution", RFC 2276, January 1998.
skipping to change at page 11, line 14 skipping to change at page 10, line 45
Considerations Section in RFCs", BCP 26, RFC 2434, October 1998. Considerations Section in RFCs", BCP 26, RFC 2434, October 1998.
[5] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, A., [5] 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.
[6] Daigle, L. and A. Newton, "Domain-Based Application Service [6] 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.
8.2 Informative References 7.2 Informative References
[7] Droms, R., "Dynamic Host Configuration Protocol", RFC 2131,
March 1997.
[8] Crocker, D., "MAILBOX NAMES FOR COMMON SERVICES, ROLES AND [7] Crocker, D., "MAILBOX NAMES FOR COMMON SERVICES, ROLES AND
FUNCTIONS", RFC 2142, May 1997. FUNCTIONS", RFC 2142, May 1997.
[9] Gulbrandsen, A., Vixie, P., and L. Esibov, "A DNS RR for [8] Resnick, P., "Internet Message Format", RFC 2822, April 2001.
specifying the location of services (DNS SRV)", RFC 2782,
February 2000.
[10] Resnick, P., "Internet Message Format", RFC 2822, April 2001.
[11] Mealling, M. and R. Daniel, "The Naming Authority Pointer
(NAPTR) DNS Resource Record", RFC 2915, September 2000.
[12] Mealling, M., "The Network Solutions Personal Internet Name [9] 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.
[13] Rozenfeld, S., "Using The ISSN (International Serial Standard [10] Rozenfeld, S., "Using The ISSN (International Serial Standard
Number) as URN (Uniform Resource Names) within an ISSN-URN Number) as URN (Uniform Resource Names) within an ISSN-URN
Namespace", RFC 3044, January 2001. Namespace", RFC 3044, January 2001.
[14] Hakala, J. and H. Walravens, "Using International Standard Book [11] Hakala, J. and H. Walravens, "Using International Standard Book
Numbers as Uniform Resource Names", RFC 3187, October 2001. Numbers as Uniform Resource Names", RFC 3187, October 2001.
[15] Daigle, L., van Gulik, D., Iannella, R., and P. Faltstrom, [12] Hoffman, P., "Terminology Used in Internationalization in the
IETF", RFC 3536, May 2003.
[13] Daigle, L., van Gulik, D., Iannella, R., and P. Faltstrom,
"Uniform Resource Names (URN) Namespace Definition Mechanisms", "Uniform Resource Names (URN) Namespace Definition Mechanisms",
BCP 66, RFC 3406, October 2002. BCP 66, RFC 3406, October 2002.
[16] Schulzrinne, H., "The tel URI for Telephone Numbers", RFC 3966, [14] Schulzrinne, H., "The tel URI for Telephone Numbers", RFC 3966,
December 2004. December 2004.
[17] Tesink, K. and R. Fox, "A Uniform Resource Name (URN) Namespace [15] Tesink, K. and R. Fox, "A Uniform Resource Name (URN) Namespace
for the Common Language Equipment Identifier (CLEI) Code", for the Common Language Equipment Identifier (CLEI) Code",
RFC 4152, August 2005. RFC 4152, August 2005.
[18] Kang, S., "Using Universal Content Identifier (UCI) as Uniform [16] Kang, S., "Using Universal Content Identifier (UCI) as Uniform
Resource Names (URN)", RFC 4179, October 2005. Resource Names (URN)", RFC 4179, October 2005.
[19] Kameyama, W., "A Uniform Resource Name (URN) Namespace for the [17] Kameyama, W., "A Uniform Resource Name (URN) Namespace for the
TV-Anytime Forum", RFC 4195, October 2005. TV-Anytime Forum", RFC 4195, October 2005.
[20] Rosenberg, J., "Interactive Connectivity Establishment (ICE): A [18] Rosenberg, J., "Interactive Connectivity Establishment (ICE): A
Methodology for Network Address Translator (NAT) Traversal for Methodology for Network Address Translator (NAT) Traversal for
Offer/Answer Protocols", draft-ietf-mmusic-ice-08 (work in Offer/Answer Protocols", draft-ietf-mmusic-ice-09 (work in
progress), March 2006. progress), June 2006.
[21] Hardie, T., "LoST: A Location-to-Service Translation Protocol", [19] Hardie, T., "LoST: A Location-to-Service Translation Protocol",
draft-hardie-ecrit-lost-00 (work in progress), March 2006. draft-hardie-ecrit-lost-00 (work in progress), March 2006.
[22] Taylor, T., "Security Threats and Requirements for Emergency [20] Taylor, T., "Security Threats and Requirements for Emergency
Call Marking and Mapping", draft-ietf-ecrit-security-threats-01 Call Marking and Mapping", draft-ietf-ecrit-security-threats-03
(work in progress), April 2006. (work in progress), July 2006.
[23] Schulzrinne, H. and R. Marshall, "Requirements for Emergency [21] Schulzrinne, H. and R. Marshall, "Requirements for Emergency
Context Resolution with Internet Technologies", Context Resolution with Internet Technologies",
draft-ietf-ecrit-requirements-09 (work in progress), May 2006. draft-ietf-ecrit-requirements-10 (work in progress), June 2006.
Author's Address Author's Address
Henning Schulzrinne Henning Schulzrinne
Columbia University Columbia University
Department of Computer Science Department of Computer Science
450 Computer Science Building 450 Computer Science Building
New York, NY 10027 New York, NY 10027
US US
Phone: +1 212 939 7004 Phone: +1 212 939 7004
Email: hgs+ecrit@cs.columbia.edu Email: hgs+ecrit@cs.columbia.edu
URI: http://www.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 [16]. Here, NNN is tel:NNN;context=+C This approach uses tel URIs [14]. 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 "tel"
[16] URI. It also only works if every outbound proxy knows how to [14] URI. It also only works if every outbound proxy knows how to
route requests to a proxy that can reach emergency services since route requests to a proxy that can reach emergency services since
tel URIs. The SIP URI proposed here only requires a user's home tel URIs. The SIP URI proposed here only requires a user's home
domain to be appropriately configured. 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 [8] and the "postmaster" convention convention of RFC 2142 [7] and the "postmaster" convention
documented in RFC 2822 [10]. This approach had the advantage that documented in RFC 2822 [8]. 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 "aor-
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