A LoST extension to return complete and similar location info
draft-ietf-ecrit-similar-location-11
The information below is for an old version of the document.
| Document | Type | Active Internet-Draft (ecrit WG) | |
|---|---|---|---|
| Authors | Brian Rosen , Roger Marshall , Jeff Martin | ||
| Last updated | 2021-09-29 (Latest revision 2021-09-02) | ||
| Stream | Internet Engineering Task Force (IETF) | ||
| Formats | plain text html xml htmlized pdfized bibtex | ||
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| Document shepherd | Henning Schulzrinne | ||
| IESG | IESG state | AD is watching | |
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| Responsible AD | Murray Kucherawy | ||
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draft-ietf-ecrit-similar-location-11
ECRIT B. Rosen
Internet-Draft
Updates: 5222 (if approved) R. Marshall
Intended status: Standards Track J. Martin
Expires: 2 April 2022 Comtech TCS
29 September 2021
A LoST extension to return complete and similar location info
draft-ietf-ecrit-similar-location-11
Abstract
This document introduces a new way to provide returned location
information in LoST responses that is either of a completed or
similar form to the original input civic location, based on whether
valid or invalid civic address elements are returned within the
<findServiceResponse> message. This document defines a new extension
to the <findServiceResponse> message within the LoST protocol
[RFC5222] that enables the LoST protocol to return in a response a
completed civic address element set for a valid location response,
and one or more suggested sets of similar location information for an
invalid location. These two types of civic addresses are referred to
as either "complete location" or "similar location", and are included
as a compilation of CAtype xml elements within the existing LoST
<findServiceResponse> message structure.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
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."
This Internet-Draft will expire on 2 April 2022.
Copyright Notice
Copyright (c) 2021 IETF Trust and the persons identified as the
document authors. All rights reserved.
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This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents (https://trustee.ietf.org/
license-info) in effect on the date of publication of this document.
Please review these documents carefully, as they describe your rights
and restrictions with respect to this document. Code Components
extracted from this document must include Simplified BSD License text
as described in Section 4.e of the Trust Legal Provisions and are
provided without warranty as described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Overview of Returned Location Information . . . . . . . . . . 4
4. Returned Location Information . . . . . . . . . . . . . . . . 7
5. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . 8
5.1. Complete Location returned for Valid Location response . 8
5.2. Similar Location returned for Invalid Location
response . . . . . . . . . . . . . . . . . . . . . . . . 10
6. XML Schema . . . . . . . . . . . . . . . . . . . . . . . . . 13
7. Security Considerations . . . . . . . . . . . . . . . . . . . 15
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 15
8.1. XML Schema Registration . . . . . . . . . . . . . . . . . 15
8.2. LoST-RLI Namespace Registration . . . . . . . . . . . . . 15
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 16
9.1. Normative References . . . . . . . . . . . . . . . . . . 16
9.2. Informative References . . . . . . . . . . . . . . . . . 16
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 17
1. Introduction
The LoST protcol [RFC5222] supports the validation of civic location
information sent in a <findService> request, by providing a set of
validation result status indicators in the response. The current
usefulness of the supported xml elements <valid>, <invalid>, and
<unchecked> is limited. They each provide an indication of validity
for any one location element as a part of the whole civic address,
but this is insufficient in providing either the complete set of
civic address elements that the LoST server contains, or of providing
alternate suggestions (hints) as to which civic address is intended
for use.
Whether the queried civic location is valid but missing information,
or invalid due to missing or wrong information, this document
provides a mechanism to return a complete set of civic address
elements.
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This enhancement to the validation feature within LoST is required by
systems that rely on accurate location for processing. Use of this
enhancement increases the likelihood that the correct and/or complete
form of a civic location becomes timely known in those cases where it
is incomplete or incorrect. One such use case is that of location
based emergency calling. The use of this protocol extension
facilitates the timely correction of errors, and allows location
servers to be more easily provisioned with complete address
information.
The structure of this document includes terminology, Section 2,
followed by a discussion of the basic elements involved in location
validation. The use of these elements, by way of example, is
discussed in an overview section, Section 3, with accompanying
rationale, and a brief discussion of the impacts to LoST, and its
current schema.
2. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
The following terms are defined in this document:
Location: The term Location can be used to refer to either a civic
location or a geodetic location.
Geodetic Location: a geographic coordinate set of values that
describes a point within a defined geographic datum. For example,
a WGS84 referenced latitude, longitude coordinate pair (2D), or
latitude, longitude, and altitude (3D). Note: geodetic location
is defined here for context, but is not used elsewhere within this
document.
Civic Location: The term Civic Location applies to a set of one or
more Civic Address Elements that are used in conjunction with each
other, and in accordance with a known ruleset to designate a
specific place within a region of geography, or a region of
geography by itself as defined in [RFC5139].
Civic Address: The term Civic Address is used interchangeably with
the term Civic Location within this document.
Civic Address Element: The term Civic Address Element is used within
this document to apply to an individual CAtype data descriptor,
for example, as is described in [RFC4776], [RFC5774], and
[RFC6848].
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Invalid Location: A Civic Location that was included in a LoST
request with 'validateLocation' set and subsequently returned with
one or more Civic Address Elements marked as invalid. Note that
location information may be submitted in the <findService> request
that causes the LoST server to return Civic Address Elements in
the <invalid> list. It is also possible that the location
information submitted is so inaccurate that this extension can not
be used, and the LoST server may return a <notFound> error. In
this document, we use the term Invalid Location only to refer to a
case where the LoST server returns one or more elements in the
<invalid> list.
Valid Location: A Civic Location that was included in a LoST query
with 'validateLocation' set and subsequently returned with all
Civic Address Elements in the <valid> or <unchecked> lists.
Complete Location: An expanded civic location that includes other
Civic Address Elements in addition to the existing validated Civic
Address Elements provided as input to a LoST server.
Similar Location: A suggested civic location that is similar to the
civic location which was input, but which had one or more invalid
civic address elements returned by the LoST server or was missing
Civic Adddress Elements the server has for the location.
Returned Location Information: A set of civic locations returned in
a LoST response.
3. Overview of Returned Location Information
This document describes an extension to LoST [RFC5222] to allow
additional location information to be returned in the
<locationValidation> element of a <findServiceResponse>. This
extension is applicable when the location information in the
<findService> request is in a civic profile as described in RFC5222
or in another profile derived from that civic profile. This
extension has two different use cases: first, when the input location
is incomplete but the LoST server can identify the intended unique
address, and second, when the input location is invalid and the LoST
server can identify one or more likely intended locations.
When a LoST server is asked to validate a civic location, its goal is
to take the set of Civic Address Elements provided as the location
information in the LoST request, and find a unique location in its
database that matches the information in the request. Uniqueness
might not require values for all possible elements in the Civic
Address that the database might hold. Further, the input location
information might not represent the form of location the users of the
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LoST service prefer to have. As an example, there are LoST Civic
Address Elements that could be used to define a postal location,
suitable for delivery of mail as well as a municipal location
suitable for responding to an emergency call. While the LoST server
might be able to determine the location from the postal elements
provided, the emergency services would prefer that the municipal
location be used for any subsequent emergency call. Since validation
is often performed well in advance of an end-user placing an
emergency call, if the LoST server could return the preferred form of
location (or more properly in this example, the municipal elements in
addition to the postal elements), those elements could be stored in a
LIS or client application and used in a later emergency call.
In addition, this document describes the reuse of the same mechanism,
but for a different purpose: to supply similar location information
in the case where a LoST server response includes one or more Civic
Address Elements marked as invalid, constituting an Invalid Location
response. In this case, the response contains one or more suggested
alternative Valid Locations.
In a LoST findServiceResponse indicating a Valid Location -- i.e.,
containing a <locationValidation> element with no elements listed as
invalid -- the LoST server can use this extension to include
additional location information in a <locationValidation> element.
As an example, the query might contain a <HNO> (house number), <RD>
(road name) <A3> (city), <A1> (state/province) and a few more CAtype
elements, but might not contain <A2> (county) or <PC> (Postal Code)
CAtypes. The civic location in the request might contain <HNO>,
<RD>, <STS>, <POD>, <A3> and <A1> Civic Address Elements that are
sufficient enough for the LoST server to uniquely locate the address
specified in the request and thus be considered Valid. Yet, other
entities involved in a subsequent emergency call might find it
helpful to have additional Civic Address Elements such as <A2>
(county), <PC>, (Postal Code) be included as part of a complete civic
location. Since [RFC5222] currently does not have a way for this
additional location information to be returned in the
<findServiceResponse>, this document extends the LoST protocol so
that it can include a <completeLocation> element within the
<locationValidation> element of the <findServiceResponse> message,
allowing for the representation of complete location information.
An example showing complete location information supplied:
Input address: 6000 15th Ave NW Seattle
Complete Location: 6000 15th Ave NW Seattle, WA 98105 US
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The information provided in the request may be enough to identify a
unique location in the LoST server, but that may not be the location
intended by the user. The <completeLocation> information may alert
the user to a mismatch between the provided location information and
the unique location the server interpreted that information to
identify.
The other use case for this extension is when Invalid Location is
received from the LoST server. When a LoST server returns a response
to a <findService> request that contains a set of Civic Address
Elements with one or more labeled as invalid, the location
information in the <findServiceResponse> can be extended to include
one or more locations that might be the location desired.
In the example cited above, policy at the LoST server might deem a
missing <A3> element as invalid, even if the location information in
the request was sufficient to identify a unique address. In that
case, the missing element would be listed in the <invalid> list, and
a <similarLocation> element could be returned in the response showing
a complete civic location that includes the missing <A3> element,
just as in the above example.
As another example of the use of <similarLocation>, consider the
results based on a similar data set as used above, where the <HNO>,
<RD>, <STS>, <A1>, and <A3> Civic Address Elements are not sufficient
to locate a unique address, which leads to an invalid location
result. Because the LoST server typically contains additional civic
address elements which could have resulted in a uniquely identifiable
location if these additional elements had been included in the
location sent in the query. Since [RFC5222] currently does not have
a way for this additional location information to be returned in the
<findServiceResponse>, this document extends [RFC5222] so that the
LoST <locationValidation> element of the <findServiceResponse>
message can include one or more <similarLocation> elements
representing similar civic locations.
To show this, suppose that a slightly modified version of the above
address is sent within a Lost findService request:
Input address: 6000 15th Ave N Seattle, WA.
This time we make the assumption that the address is deemed "invalid"
by the LoST server because there is no such thing as "15th Ave N"
within the LoST server's data for the city of Seattle. However, we
also happen to know for this example that there are two addresses
within the address dataset that are "similar", when all parts of the
address are taken as a whole. These similar addresses that could be
returned to the client are as follows:
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Similar address #1: 6000 15th Ave NW Seattle, WA 98107
Similar address #2: 6000 15th Ave NE Seattle, WA 98105
This extension allows the LoST server to include the above similar
addresses in the response to 'validateLocaton' request. The next
section shows examples of the LoST request and response XML message
fragments for the above valid and invalid scenarios, returning the
complete or similar addresses respectively.
4. Returned Location Information
A LoST server implementing this extension MAY include
<completeLocation> or <similarLocation> elements within the
<locationValidation> portion of the <findServiceResponse>. The
<completeLocation> and <similarLocation> elements contain a list of
Civic Address Elements identical to the elements used in the location
element with the 'civic' profile in [RFC5222] or another profile
derived from the civic profile.
The LoST server MAY include more than one <similarLocation> element
in the response. If there are too many possible locations, the
server MAY return none, or it MAY return a subset considered most
likely. How many to return is left to the implementation of the LoST
server. The server is unable to know what the intended location
information was suppose to be; it is guessing. Therefore the correct
location may or may not be one of the <similarLocation> elements the
server provides, and the client cannot assume that any of them are
the correct location.
Where a LoST server contains additional location information relating
to the Civic Address used in a <findService> request, the
<findServiceResponse> message MAY include a <completeLocation>
element containing additional location information along with the
original validated Civic Address Elements; the additional Civic
Address Elements may be deemed by local policy as necessary to form a
Complete Location. The <completeLocation> element MUST NOT be
returned in response messages where any Civic Address Elements occur
in the invalid list of the response, or where the set of Civic
Address Elements in the request do not identify a unique location.
The Complete Location MUST NOT contain any elements that would be
marked as invalid, or cause an error, if a recipient of that location
performs a subsequent <findService> request using the Complete
Location. However, if a subsequent request includes the Complete
Location, the corresponding response MAY include elements in the
unchecked list.
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Clients can control the return of additional location information by
including the optional 'returnAdditionalLocation' attribute with
possible values 'none', 'similar', 'complete' or 'any'. The value
'none' means to not return additional location information, 'similar'
and 'complete' mean to only return the respective type of additional
location information (if the server could send any) and 'any' means
to include Similar and/or Complete Location (if the server could send
any). If the request includes this attribute, the server MUST NOT
send location information contravening the client's request.
Omitting this attribute in the request is equivalent to including it
with the value 'none'.
The server may determine that there are many possible Similar
Locations and decide not to send them all. The number of Similar
Locations sent is entirely up to the server. The server MAY include
a 'similarLocationsLimited' attribute which contains a non-zero
integer indicating the minimum number of Similar Locations not
included in the response. There may be more than the indicated
similar locations available in the data held by the server.
Clients MAY ignore the location information this extension defines.
The information is optional to send, and optional to use. In the
case where the location information in the request was valid, this
extension does not change the validity. In the case where the
location information in the request is invalid, but alternate
location information is returned, the original location remains
invalid, and the LoST server does not change the mapping response
other than optionally including the information defined by this
extension.
The <completeLocation> and <similarLocation> elements use the
<locationInformation> element from [RFC5222] updated by
[I-D.ietf-ecrit-lost-planned-changes], including the 'profile'
attribute, which is useful if the request contains location
information in a profile derived from the 'civic' profile. The
'profile' attribute MUST be included in both the request and the
response and MUST be the same profile in both.
5. Examples
5.1. Complete Location returned for Valid Location response
Based on the example input request above, Returned Location
Information is provided in a <findServiceResponse> message since the
original input address is considered valid but is missing some
additional data that the LoST server has.
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<!-- =====Request=================================== -->
<findService xmlns="urn:ietf:params:xml:ns:lost1"
xmlns:rli="urn:ietf:params:xml:ns:lost-rli1"
validateLocation="true" rli:returnAdditionalLocation="any">
<location id="587cd3880" profile="civic">
<civicAddress
xmlns="urn:ietf:params:mxl:ns:pidf:geopriv10:civicAddr">
<country>US</country>
<A1>WA</A1>
<A3>Seattle</A3>
<RD>15th</RD>
<STS>Avenue</STS>
<POD>Northwest</POD>
<HNO>6000</HNO>
</civicAddress>
</location>
<service>urn:service:sos</service>
</findService>
<!-- =====Response================================== -->
<findServiceResponse >
xmlns="urn:ietf:params:xml:ns:lost1"
xmlns:rli="urn:ietf:params:xml:ns:lost-rli1">
xmlns:ca="urn:ietf:params:xml:ns:pidf:geopriv10:civicAddr">
<mapping
expires="NO-CACHE"
lastUpdated="2006-11-01T01:00:00Z"
source="authoritative.example"
sourceId="8799e346000098aa3e">
<displayName xml:lang="en">Seattle 911</displayName>
<service>urn:service:sos</service>
<uri>sip:seattle-911@example.com</uri>
<serviceNumber>911</serviceNumber>
</mapping>
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<locationValidation>
<valid>ca:country ca:A1 ca:A3 ca:RD ca:STS ca:POD ca:HNO
</valid>
<invalid></invalid>
<unchecked></unchecked>
<rli:completeLocation profile="civic"><!--completed address-->
<ca:civicAddress>
<ca:country>US</ca:country>
<ca:A1>WA</ca:A1>
<ca:A2>KING COUNTY</ca:A2>
<ca:A3>SEATTLE</ca:A3>
<ca:RD>15TH</ca:RD>
<ca:STS>AVENUE</ca:STS>
<ca:POD>NORTHWEST</ca:POD>
<ca:HNO>6000</ca:HNO>
<ca:PC>98106</ca:PC>
<ca:PCN>SEATTLE</ca:PCN>
</ca:civicAddress>
</rli:completeLocation>
</locationValidation>
<path>
<via source="authoritative.example"/>
</path>
<locationUsed id="587cd3880"/>
</findServiceResponse>
<!-- =============================================== -->
5.2. Similar Location returned for Invalid Location response
The following example shows two returned Similar Locations in a
<findServiceResponse> message when the original input address is
considered invalid, in this example because the LoST server needed
the omitted POD data to match a unique address.
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<!-- =====Request=================================== -->
<findService xmlns="urn:ietf:params:xml:ns:lost1"
xmlns:rli="urn:ietf:params:xml:ns:lost-rli1"
validateLocation="true"
rli:returnAdditionalLocation="any">
<location id="587cd3880" profile="civic">
<civicAddress
xmlns="urn:ietf:params:xml:ns:pidf:geopriv10:civicAddr">
<country>US</country>
<A1>WA</A1>
<A2>KING COUNTY</A2>
<A3>SEATTLE</A3>
<RD>15TH</RD>
<STS>AVENUE</STS>
<HNO>6000</HNO>
<PC>98106</PC>
<PCN>SEATTLE</PCN>
</civicAddress>
</location>
<service>urn:service:sos</service>
</findService>
<!-- =====Response=================================== -->
<findServiceResponse>
xmlns="urn:ietf:params:xml:ns:lost1"
xmlns:rli="urn:ietf:params:xml:ns:lost-rli1">
xmlns:ca="urn:ietf:params:xml:ns:pidf:geopriv10:civicAddr">
<mapping
expires="NO-CACHE"
lastUpdated="2006-11-01T01:00:00Z"
source="authoritative.example"
sourceId="8799e346000098aa3e">
<displayName xml:lang="en">Seattle 911</displayName>
<service>urn:service:sos</service>
<uri>sip:seattle-911@example.com</uri>
<serviceNumber>911</serviceNumber>
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</mapping>
<locationValidation>
<valid>ca:country ca:A1 ca:A3 ca:STS ca:RD</valid>
<invalid>ca:POD</invalid>
<unchecked>ca:HNO</unchecked>
<rli:similarLocation profile="civic"><!--similar location-->
<ca:civicAddress> <!-- similar address #1 -->
<ca:country>US</ca:country>
<ca:A1>WA</ca:A1>
<ca:A2>KING COUNTY</ca:A2>
<ca:A3>SEATTLE</ca:A3>
<ca:RD>15TH</ca:RD>
<ca:STS>AVENUE</ca:STS>
<ca:POD>NORTHWEST</ca:POD>
<ca:HNO>6000</ca:HNO>
<ca:PC>98106</ca:PC>
<ca:PCN>SEATTLE</ca:PCN>
</ca:civicAddress>
</rli:similarLocation>
<rli:similarLocation profile="civic" similarLocationsLimited="5">
<ca:civicAddress> <!-- similar address #2 -->
<ca:country>US</ca:country>
<ca:A1>WA</ca:A1>
<ca:A2>KING COUNTY</ca:A2>
<ca:A3>SEATTLE</ca:A3>
<ca:RD>15TH</ca:RD>
<ca:STS>AVENUE</ca:STS>
<ca:POD>NORTHEAST</ca:POD>
<ca:HNO>6000</ca:HNO>
<ca:PC>98105</ca:PC>
<ca:PCN>SEATTLE</ca:PCN>
</ca:civicAddress>
</rli:similarLocation>
</locationValidation>
<path>
<via source="authoritative.example"/>
</path>
<locationUsed id="587cd3880"/>
</findServiceResponse>
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<!-- =============================================== -->
6. XML Schema
This section provides the schema of the LoST extensions, based on the
schema in [I-D.ietf-ecrit-lost-planned-changes]
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<?xml version="1.0" encoding="UTF-8"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"
xmlns:lost1="urn:ietf:params:xml:ns:lost1"
xmlns="urn:ietf:params:xml:ns:lost-rli1"
targetNamespace="urn:ietf:params:xml:ns:lost-rli1"
elementFormDefault="qualified">
<!-- Import base Lost -->
<xs:import namespace="urn:ietf:params:xml:ns:lost1"/>
<!-- extend findService by placing the following
at the extensionPoint
in the included commonRequestPattern: -->
<xs:attribute name="returnAdditionalLocation" use="optional">
<xs:simpleType>
<xs:restriction base="xs:token">
<xs:enumeration value="none"/>
<xs:enumeration value="similar"/>
<xs:enumeration value="complete"/>
<xs:enumeration value="any"/>
</xs:restriction>
</xs:simpleType>
</xs:attribute>
<!-- extend locationValidation by placing the following
at the extensionPoint -->
<group>
<xs:choice minOccurs="0">
<xs:element name="similarLocation"
type="lost1:locationInformation"
minOccurs="1" maxOccurs="unbounded" />
<xs:element name="completeLocation"
type="lost1:locationInformation"/>
</xs:choice>
</group>
<!-- and also at the locationValidation extensionPoint -->
<xs:attribute name="similarLocationsLimited" use="optional">
<xs:simpleType>
<xs:restriction base="xs:integer">
<xs:minInclusive value="1">
</xs:restriction>
</xs:simpleType>
</xs:attribute>
</xs:schema>
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7. Security Considerations
Whether the input to the LoST server is a Valid or Invalid Location,
the LoST server ultimately determines what it considers to be a Valid
Location. Even in the case where the input location is valid, the
requester still might not actually understand where that location is.
For this kind of Valid Location use case, this extension will
typically return more location information than what the requester
started with, which might reveal to the requester additional
information (additional CAtypes) about the location. While this is
very desirable in some scenarios such as supporting an emergency
call, it might not be as desirable for other services. Individual
LoST server implementations SHOULD consider the risk of releasing
more detail versus the value in doing so. Generally, supplying more
information (CAtypes) is not considered to be a significant problem
because the requester has to already have enough information for the
location to be considered valid, which in most cases is enough to
uniquely locate the address. Providing more CAtypes generally
doesn't actually reveal anything more. When Invalid Locations are
submitted, this extension allows the LoST response to include
locations that are similar to what was input, again resulting in more
information provided in the response than was sent in the request.
LoST server implementations SHOULD evaluate the particular use cases
where this extension is supported, and weigh the risks around its
use. Many services available today via the Internet offer similar
features, such as "did you mean" or address completion, so this
capability is not introducing any fundamentally new threat.
8. IANA Considerations
8.1. XML Schema Registration
URI: urn:ietf:params:xml:schema:lost-rli1
Registrant Contact: IETF ECRIT Working Group, Brian Rosen
(br@brianrosen.net).
XML Schema: The XML schema to be registered is contained
in Section 7.
8.2. LoST-RLI Namespace Registration
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URI: urn:ietf:params:xml:ns:lost-rli1
Registrant Contact: IETF ECRIT Working Group, Brian Rosen
(br@brianrosen.net).
XML:
BEGIN
<?xml version="2.0"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML Basic 1.0//EN"
"http://www.w3.org/TR/xhtml-basic/xhtml-basic10.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="content-type"
content="text/html;charset=iso-8859-1"/>
<title>LoST Returned Location Information Namespace</title>
</head>
<body>
<h1>Namespace for LoST Returned Location Information extension</h1>
<h2>urn:ietf:params:xml:ns:lost-rli1</h2>
<p>See <a href="http://www.rfc-editor.org/rfc/rfc????.txt">
RFC????</a>.</p>
</body>
</html>
END
9. References
9.1. Normative References
[I-D.ietf-ecrit-lost-planned-changes]
Rosen, B., "Validation of Locations Around a Planned
Change", Work in Progress, Internet-Draft, draft-ietf-
ecrit-lost-planned-changes-04, 19 August 2021,
<https://www.ietf.org/archive/id/draft-ietf-ecrit-lost-
planned-changes-04.txt>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC5222] Hardie, T., Newton, A., Schulzrinne, H., and H.
Tschofenig, "LoST: A Location-to-Service Translation
Protocol", RFC 5222, DOI 10.17487/RFC5222, August 2008,
<https://www.rfc-editor.org/info/rfc5222>.
9.2. Informative References
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[RFC4776] Schulzrinne, H., "Dynamic Host Configuration Protocol
(DHCPv4 and DHCPv6) Option for Civic Addresses
Configuration Information", RFC 4776,
DOI 10.17487/RFC4776, November 2006,
<https://www.rfc-editor.org/info/rfc4776>.
[RFC5139] Thomson, M. and J. Winterbottom, "Revised Civic Location
Format for Presence Information Data Format Location
Object (PIDF-LO)", RFC 5139, DOI 10.17487/RFC5139,
February 2008, <https://www.rfc-editor.org/info/rfc5139>.
[RFC5774] Wolf, K. and A. Mayrhofer, "Considerations for Civic
Addresses in the Presence Information Data Format Location
Object (PIDF-LO): Guidelines and IANA Registry
Definition", BCP 154, RFC 5774, DOI 10.17487/RFC5774,
March 2010, <https://www.rfc-editor.org/info/rfc5774>.
[RFC6848] Winterbottom, J., Thomson, M., Barnes, R., Rosen, B., and
R. George, "Specifying Civic Address Extensions in the
Presence Information Data Format Location Object (PIDF-
LO)", RFC 6848, DOI 10.17487/RFC6848, January 2013,
<https://www.rfc-editor.org/info/rfc6848>.
Authors' Addresses
Brian Rosen
470 Conrad Dr
Mars, PA 16046
United States of America
Email: br@brianrosen.net
Roger Marshall
Comtech TCS
2401 Elliott Avenue
2nd Floor
Seattle, WA 98121
United States of America
Email: roger.marshall@comtechtel.com
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Jeff Martin
Comtech TCS
2401 Elliott Avenue
2nd Floor
Seattle, WA 98121
United States of America
Email: jeff.martin@comtechtel.com
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