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2 ECRIT B. Rosen
3 Internet-Draft
4 Updates: 5222 (if approved) R. Marshall
5 Intended status: Standards Track J. Martin
6 Expires: 6 March 2022 Comtech TCS
7 2 September 2021
9 A LoST extension to return complete and similar location info
10 draft-ietf-ecrit-similar-location-10
12 Abstract
14 This document introduces a new way to provide returned location
15 information in LoST responses that is either of a completed or
16 similar form to the original input civic location, based on whether
17 valid or invalid civic address elements are returned within the
18 findServiceResponse message. This document defines a new extension
19 to the findServiceResponse message within the LoST protocol [RFC5222]
20 that enables the LoST protocol to return in it's response a completed
21 civic address element set for a valid location response, and one or
22 more suggested sets of similar location information for an invalid
23 location. These two types of civic addresses are referred to as
24 either "complete location" or "similar location", and are included as
25 a compilation of CAtype xml elements within the existing LoST
26 findServiceResponse message structure.
28 Status of This Memo
30 This Internet-Draft is submitted in full conformance with the
31 provisions of BCP 78 and BCP 79.
33 Internet-Drafts are working documents of the Internet Engineering
34 Task Force (IETF). Note that other groups may also distribute
35 working documents as Internet-Drafts. The list of current Internet-
36 Drafts is at https://datatracker.ietf.org/drafts/current/.
38 Internet-Drafts are draft documents valid for a maximum of six months
39 and may be updated, replaced, or obsoleted by other documents at any
40 time. It is inappropriate to use Internet-Drafts as reference
41 material or to cite them other than as "work in progress."
43 This Internet-Draft will expire on 6 March 2022.
45 Copyright Notice
47 Copyright (c) 2021 IETF Trust and the persons identified as the
48 document authors. All rights reserved.
50 This document is subject to BCP 78 and the IETF Trust's Legal
51 Provisions Relating to IETF Documents (https://trustee.ietf.org/
52 license-info) in effect on the date of publication of this document.
53 Please review these documents carefully, as they describe your rights
54 and restrictions with respect to this document. Code Components
55 extracted from this document must include Simplified BSD License text
56 as described in Section 4.e of the Trust Legal Provisions and are
57 provided without warranty as described in the Simplified BSD License.
59 Table of Contents
61 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
62 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
63 3. Overview of Returned Location Information . . . . . . . . . . 4
64 4. Returned Location Information . . . . . . . . . . . . . . . . 7
65 5. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . 8
66 5.1. Complete Location returned for Valid Location response . 8
67 5.2. Similar Location returned for Invalid Location
68 response . . . . . . . . . . . . . . . . . . . . . . . . 10
69 6. XML Schema . . . . . . . . . . . . . . . . . . . . . . . . . 13
70 7. Security Considerations . . . . . . . . . . . . . . . . . . . 15
71 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 15
72 8.1. XML Schema Registration . . . . . . . . . . . . . . . . . 15
73 8.2. LoST-RLI Namespace Registration . . . . . . . . . . . . . 15
74 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 16
75 9.1. Normative References . . . . . . . . . . . . . . . . . . 16
76 9.2. Informative References . . . . . . . . . . . . . . . . . 16
77 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 17
79 1. Introduction
81 The LoST protcol [RFC5222] supports the validation of civic location
82 information sent in a findService request, by providing a set of
83 validation result status indicators in the response. The current
84 usefulness of the supported xml elements, "valid", "invalid", and
85 "unchecked" is limited, because while they each provide an indication
86 of validity for any one location element as a part of the whole civic
87 address, the mechanism is insufficient in providing either the
88 complete set of civic address elements that the LoST server contains,
89 or of providing alternate suggestions (hints) as to which civic
90 address is intended for use.
92 Whether the input civic location is valid but missing information, or
93 invalid due to missing or wrong information, this document provides a
94 mechanism to return a complete set of civic address elements for
95 those valid or invalid cases.
97 This enhancement to the validation feature within LoST is required by
98 systems that rely on accurate location for processing. Use of this
99 enhancement increases the likelihood that the correct and/or complete
100 form of a civic location becomes timely known in those cases where it
101 is incomplete or incorrect. One such use case is that of location
102 based emergency calling. The use of this protocol extension
103 facilitates the timely correction of errors, and allows location
104 servers to be more easily provisioned with complete address
105 information.
107 The structure of this document includes terminology, Section 2,
108 followed by a discussion of the basic elements involved in location
109 validation. The use of these elements, by way of example, is
110 discussed in an overview section, Section 3, with accompanying
111 rationale, and a brief discussion of the impacts to LoST, and its
112 current schema.
114 2. Terminology
116 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
117 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
118 document are to be interpreted as described in RFC 2119 [RFC2119].
120 The following terms are defined in this document:
122 Location: The term Location can be used to refer to either a civic
123 location or a geodetic location.
125 Geodetic Location: a geographic coordinate set of values that
126 describes a point within a defined geographic datum. For example,
127 a WGS84 referenced latitude, longitude coordinate pair (2D), or
128 latitude, longitude, and altitude (3D). Note: geodetic location
129 is defined here for context, but is not used elsewhere within this
130 document.
132 Civic Location: The term Civic Location applies to a set of one or
133 more Civic Address Elements that are used in conjunction with each
134 other, and in accordance with a known ruleset to designate a
135 specific place within a region of geography, or a region of
136 geography by itself as defined in [RFC5139].
138 Civic Address: The term Civic Address is used interchangeably with
139 the term Civic Location within this document.
141 Civic Address Element: The term Civic Address Element is used within
142 this document to apply to an individual CAtype data descriptor,
143 for example, as is described in [RFC4776], [RFC5774], and
144 [RFC6848].
146 Invalid Location: A Civic Location that was included in a LoST
147 validateLocation request and subsequently returned with one or
148 more Civic Address Elements marked as invalid. Note that location
149 information may be submitted in the findRequest that causes the
150 LoST server to return Civic Address Elements in the invalid list.
151 It is also possible that the location information submitted is so
152 inaccurate that this extension can not be used, and the LoST
153 server may return a notFound. In this document, we use the term
154 Invalid Location only to refer to a case where the LoST server
155 returns one or more elements in the invalid list.
157 Valid Location: A Civic Location that was included in a LoST
158 validateLocation request and subsequently returned with all Civic
159 Address Elements in the valid or unchecked lists.
161 Complete Location: An expanded civic location that includes other
162 Civic Address Elements in addition to the existing validated Civic
163 Address Elements provided as input to a LoST server.
165 Similar Location: A suggested civic location that is similar to the
166 civic location which was input, but which had one or more invalid
167 civic address elements returned by the LoST server or was missing
168 Civic Adddress Elements the server has for the location.
170 Returned Location Information: A set of civic locations returned in
171 a LoST response.
173 3. Overview of Returned Location Information
175 This document describes an extension to LoST [RFC5222] to allow
176 additional location information to be returned in the
177 locationValidation element of a findServiceResponse. This extension
178 is applicable when the location information in the findServiceRequest
179 is in a civic profile as described in RFC5222 or in another profile
180 derived from that civic profile. This extension has two different
181 use cases: first, when the input location is incomplete but the LoST
182 server can identify the intended unique address, and second, when the
183 input location is invalid and the LoST server can identify one or
184 more likely intended locations.
186 When a LoST server is asked to validate a civic location, its goal is
187 to take the set of Civic Address Elements provided as the location
188 information in the LoST request, and find a unique location in its
189 database that matches the information in the request. Uniqueness
190 might not require values for all possible elements in the Civic
191 Address that the database might hold. Further, the input location
192 information might not represent the form of location the users of the
193 LoST service prefer to have. As an example, there are LoST Civic
194 Address Elements that could be used to define a postal location,
195 suitable for delivery of mail as well as a municipal location
196 suitable for responding to an emergency call. While the LoST server
197 might be able to determine the location from the postal elements
198 provided, the emergency services would prefer that the municipal
199 location be used for any subsequent emergency call. Since validation
200 is often performed well in advance of an end-user placing an
201 emergency call, if the LoST server could return the preferred form of
202 location (or more properly in this example, the municipal elements in
203 addition to the postal elements), those elements could be stored in a
204 LIS or client application and used in a later emergency call.
206 In addition, this document describes the reuse of the same mechanism,
207 but for a different purpose: to supply similar location information
208 in the case where a LoST server response includes one or more Civic
209 Address Elements marked as invalid, constituting an Invalid Location
210 response. In this case, the response contains one or more suggested
211 alternative Valid Locations.
213 In a LoST findServiceResponse indicating a Valid Location -- i.e.,
214 containing a locationValidation element with no elements listed as
215 invalid -- the LoST server can use this extension to include
216 additional location information in a locationValidation element. As
217 an example, the query might contain a HNO (house number), RD (road
218 name) A3 (city), A1 (state/province) and a few more CAtype elements,
219 but might not contain A2 (county) or PC (Postal Code) CAtypes. The
220 civic location in the request might contain HNO, RD, STS, POD, A3 and
221 A1 Civic Address Elements that are sufficient enough for the LoST
222 server to uniquely locate the address specified in the request and
223 thus be considered Valid. Yet, other entities involved in a
224 subsequent emergency call might find it helpful to have additional
225 Civic Address Elements such as A2 (county), PC, (Postal Code) be
226 included as part of a complete civic location. Since [RFC5222]
227 currently does not have a way for this additional location
228 information to be returned in the findServiceResponse, this document
229 extends the LoST protocol so that it can include a completeLocation
230 element within the locationValidation element of the
231 findServiceResponse message, allowing for the representation of
232 complete location information.
234 An example showing complete location information supplied:
236 Input address: 6000 15th Ave NW Seattle
238 Complete Location: 6000 15th Ave NW Seattle, WA 98105 US
239 The information provided in the request may be enough to identify a
240 unique location in the LoST server, but that may not be the location
241 intended by the user. The completeLocation information may alert the
242 user to a mismatch between the provided location information and the
243 unique location the server interpreted that information to identify.
245 The other use case for this extension is when Invalid Location is
246 received from the LoST server. When a LoST server returns a response
247 to a findService request that contains a set of Civic Address
248 Elements with one or more labeled as invalid, the location
249 information in the findServiceResponse can be extended to include one
250 or more locations that might be the location desired.
252 In the example cited above, policy at the LoST server might deem a
253 missing A3 element as invalid, even if the location information in
254 the request was sufficient to identify a unique address. In that
255 case, the missing element would be listed in the invalid list, and a
256 similarLocation element could be returned in the response showing a
257 complete civic location that includes the missing A3 element, just as
258 in the above example.
260 As another example of the use of similarLocation, consider the
261 results based on a similar data set as used above, where the HNO, RD,
262 STS, A1, and A3 Civic Address Elements are not sufficient to locate a
263 unique address, which leads to an invalid location result. Because
264 the LoST server typically contains additional civic address elements
265 which could have resulted in a uniquely identifiable location if
266 these additional elements had been included in the location sent in
267 the query. Since [RFC5222] currently does not have a way for this
268 additional location information to be returned in the
269 findServiceResponse, this document extends [RFC5222] so that the LoST
270 locationValidation element of the findServiceResponse message can
271 include one or more similarLocation elements representing similar
272 civic locations.
274 To show this, suppose that a slightly modified version of the above
275 address is sent within a Lost findService request:
277 Input address: 6000 15th Ave N Seattle, WA.
279 This time we make the assumption that the address is deemed "invalid"
280 by the LoST server because there is no such thing as "15th Ave N"
281 within the LoST server's data for the city of Seattle. However, we
282 also happen to know for this example that there are two addresses
283 within the address dataset that are "similar", when all parts of the
284 address are taken as a whole. These similar addresses that could be
285 returned to the client are as follows:
287 Similar address #1: 6000 15th Ave NW Seattle, WA 98107
289 Similar address #2: 6000 15th Ave NE Seattle, WA 98105
291 This extension allows the LoST server to include the above similar
292 addresses in the response to locationValidation. The next section
293 shows examples of the LoST request and response XML message fragments
294 for the above valid and invalid scenarios, returning the complete or
295 similar addresses respectively.
297 4. Returned Location Information
299 The LoST server implementing this extension MAY include
300 completeLocation or similarLocation elements within the
301 locationValidation portion of the findService response. The
302 completeLocation and similarLocation elements contain a list of Civic
303 Address Elements identical to the elements used in the location
304 element with the "civic profile" in [RFC5222] or another profile
305 derived from the civic profile.
307 The LoST server MAY include more than one similarLocation element in
308 the response. If there are too many possible locations, the server
309 MAY return none, or it MAY return a subset considered most likely.
310 How many to return is left to the implementation of the LoST server.
311 The server is unable to know what the intended location information
312 was suppose to be; it is guessing. Therefore the correct location
313 may or may not be one of the similarLocation elements the server
314 provides, and the client cannot assume that any of them are the
315 correct location.
317 Where a LoST server contains additional location information relating
318 to the Civic Address used in a findServiceRequest, the
319 findServiceResponse message MAY include a completeLocation element
320 containing additional location information along with the original
321 validated Civic Address Elements; the additional Civic Address
322 Elements may be deemed by local policy as necessary to form a
323 Complete Location. The completeLocation element MUST NOT be returned
324 in response messages where any Civic Address Elements occur in the
325 invalid list of the response, or where the set of Civic Address
326 Elements in the request do not identify a unique location. The
327 Complete Location MUST NOT contain any elements that would be marked
328 as invalid, or cause an error, if a recipient of that location
329 performs a subsequent findService request using the Complete
330 Location. However, if a subsequent request includes the Complete
331 Location, the corresponding request MAY include elements in the
332 unchecked list.
334 Clients can control the return of additional location information by
335 including an optional returnAdditionalLocation attribute with
336 possible values "none", "similar", "complete" or "any". The value
337 "none" means to not return additional location information, "similar"
338 and "complete" mean to only return the respective type of additional
339 location information (if the server could send any) and "any" means
340 to include Similar and/or Complete Location (if the server could send
341 any). If the request includes this attribute, the server MUST NOT
342 send location information contravening the client's request.
343 Omitting this attribute in the request is equivalent to including it
344 with the value "none".
346 The server may determine that there are many possible Similar
347 Locations and decide not to send them all. The number of Similar
348 Locations sent is entirely up to the server. The server MAY include
349 a similarLocationsLimited attribute which contains a non-zero integer
350 indicating the number of Similar Locations not included in the
351 response. The server is NOT obligated to make this number accurate,
352 in that there may be more than the indicated similar locations
353 available in the data held by the server.
355 Clients MAY ignore the location information this extension defines.
356 The information is optional to send, and optional to use. In the
357 case where the location information in the request was valid, this
358 extension does not change the validity. In the case where the
359 location information in the request is invalid, but alternate
360 location information is returned, the original location remains
361 invalid, and the LoST server does not change the mapping response
362 other than optionally including the information defined by this
363 extension.
365 The completeLocation and similarLocation elements use the
366 locationInformation element from [RFC5222] updated by
367 [I-D.ietf-ecrit-lost-planned-changes], including the profile
368 attribute, which is useful if the request contains location
369 information in a profile derived from the civic profile. The profile
370 attribute MUST be included in both the request and the response and
371 MUST be the same profile in both.
373 5. Examples
375 5.1. Complete Location returned for Valid Location response
377 Based on the example input request above, Returned Location
378 Information is provided in a findServiceResponse message since the
379 original input address is considered valid but is missing some
380 additional data that the LoST server has.
382
384
See 673 RFC????.
674 675 676 END 678 9. References 680 9.1. Normative References 682 [I-D.ietf-ecrit-lost-planned-changes] 683 Rosen, B., "Validation of Locations Around a Planned 684 Change", Work in Progress, Internet-Draft, draft-ietf- 685 ecrit-lost-planned-changes-04, 19 August 2021, 686