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2	ecrit                                                           B. Rosen
3	Internet-Draft                                            April 26, 2019
4	Updates: RFC5222 (if approved)
5	Intended status: Standards Track
6	Expires: October 28, 2019

8	            Validation of Locations Around a Planned Change
9	                draft-ietf-ecrit-lost-planned-changes-03

11	Abstract

13	   This document defines an extension to LoST (RFC5222) that allows a
14	   planned change to the data in the LoST server to occur.  Records that
15	   previously were valid will become invalid at a date in the future,
16	   and new locations will become valid after the date.  The extension
17	   adds two elements to the <findservice> request: A URI to be used to
18	   inform the LIS that previously valid locations will be invalid after
19	   the planned change date, and add a date which requests the server to
20	   perform validation as of the date specified.  It also adds an
21	   optional Time-To-Live element to the response, which informs clients
22	   about the current expected lifetime of the validation.  This document
23	   also provides a conventional XML schema for LoST, as backwards
24	   compatible alternative to the RelaxNG schema in RFC5222

26	Status of This Memo

28	   This Internet-Draft is submitted in full conformance with the
29	   provisions of BCP 78 and BCP 79.

31	   Internet-Drafts are working documents of the Internet Engineering
32	   Task Force (IETF).  Note that other groups may also distribute
33	   working documents as Internet-Drafts.  The list of current Internet-
34	   Drafts is at https://datatracker.ietf.org/drafts/current/.

36	   Internet-Drafts are draft documents valid for a maximum of six months
37	   and may be updated, replaced, or obsoleted by other documents at any
38	   time.  It is inappropriate to use Internet-Drafts as reference
39	   material or to cite them other than as "work in progress."

41	   This Internet-Draft will expire on October 28, 2019.

43	Copyright Notice

45	   Copyright (c) 2019 IETF Trust and the persons identified as the
46	   document authors.  All rights reserved.

48	   This document is subject to BCP 78 and the IETF Trust's Legal
49	   Provisions Relating to IETF Documents
50	   (https://trustee.ietf.org/license-info) in effect on the date of
51	   publication of this document.  Please review these documents
52	   carefully, as they describe your rights and restrictions with respect
53	   to this document.  Code Components extracted from this document must
54	   include Simplified BSD License text as described in Section 4.e of
55	   the Trust Legal Provisions and are provided without warranty as
56	   described in the Simplified BSD License.

58	Table of Contents

60	   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
61	   2.  Conventions used in this document . . . . . . . . . . . . . .   4
62	   3.  <plannedChange> element . . . . . . . . . . . . . . . . . . .   4
63	   4.  <locationInvalidated> object  . . . . . . . . . . . . . . . .   4
64	   5.  URI Not Stored Warning  . . . . . . . . . . . . . . . . . . .   5
65	   6.  Time-To-Live (TTL) in Response  . . . . . . . . . . . . . . .   5
66	   7.  Replacement XML schema  . . . . . . . . . . . . . . . . . . .   6
67	   8.  Extension XML Schema  . . . . . . . . . . . . . . . . . . . .  14
68	   9.  Security Considerations . . . . . . . . . . . . . . . . . . .  15
69	   10. IANA Considerations . . . . . . . . . . . . . . . . . . . . .  16
70	     10.1.  Replacement XML Schema Registration  . . . . . . . . . .  16
71	     10.2.  Extension XML Schema Registration  . . . . . . . . . . .  16
72	     10.3.  LoST Namespace Registration  . . . . . . . . . . . . . .  16
73	   11. Normative References  . . . . . . . . . . . . . . . . . . . .  17
74	   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .  17

76	1.  Introduction

78	   This document describes an update to the LoST protocol + which allows
79	   a <findservice> request to optionally add a URI and a date to be used
80	   with planned changes to the underlying location information in the
81	   server.  The URI is retained by the LoST server, associated with the
82	   data record that was validated, and used to notify the LIS (the LoST
83	   client) when a location which was previously valid will become
84	   invalid.  The date is used by the client to ask the server to perform
85	   validation as of a future date.  In addition to this mechanism, the
86	   <findserviceResponse> is also extended to provide a Time-To-Live
87	   (TTL) for validation, after which the client should revalidate the
88	   location.

90	   Validation of civic locations involves dealing with data that changes
91	   over time.  A typical example is a portion of a county or province
92	   that was not part of a municipality is "annexed" to a municipality.
93	   Prior to the change, the content of the PIDF-LO A3 element would be
94	   blank, or represent some other value and after the change would be
95	   the municipality that annexed that part of the county/province.  This
96	   kind of annexation has an effective date and time (typically 00:00 on
97	   the first or last day of a month).

99	   Records in a LIS must change around these kinds of events.  The old
100	   record must be discarded, and a new, validated record must be loaded
101	   into the LIS.  It is often difficult for the LIS operator to know
102	   that records must be changed around such events.  There are other
103	   circumstances where locations that were previously valid become
104	   invalid, such as a street renaming or renumbering event.  As RFC5222
105	   defines validation, the only way for a LIS to discover such changes
106	   was to periodically revalidate its entire database.  Of course, this
107	   would not facilitate timely changes, is not coordinated with the
108	   actual change event, and also adds significant load to the LoST
109	   server.  Even if re-validation is contemplated, the server has no
110	   mechanism to control, or even suggest the time period for
111	   revalidation

113	   This extension allows the client to provide a stable URI that is
114	   retained by the server associated with the location information used
115	   in the request.  In the event of a planned change, or any other
116	   circumstance where the location becomes invalid, the server sends a
117	   notification to the URI informing it of a change.  The notification
118	   contains the date and time when the location becomes invalid.

120	   Ideally, following such a notification, the LIS will prepare a new
121	   record to be inserted in its active database, that becomes active at
122	   the precise planned event date and time, at which point it would also
123	   delete the old record.  However, the new record has to be valid, and
124	   the LIS would like to validate it prior to the planned change event.
125	   If it requests validation before the planned event, the server
126	   (without this extension) would inform the client that the location
127	   was invalid.  This extension includes an optional "as of" date and
128	   time in the request that allows the LoST server to provide validation
129	   as of the date and time specified, as opposed to the "as of now"
130	   implied in the current LoST protocol.

132	   When it is not practical or advisable for the LIS to maintain stable
133	   URIs for all of its records, periodic revalidation can be still used
134	   to maintain the data in the LIS.  However, the server should be able
135	   to control the rate of such revalidation.  For this purpose, a new
136	   TTL element is included in the <findserviceResponse> which provides
137	   advice from the server to the LIS of when validation is suggested.

139	   There are quite a few implementations of LoST.  Experience with these
140	   implementations indicates that the RelaxNG schema is very difficult
141	   to deal with, because the tools that the implementors use don't
142	   support it, and their staff is unfamiliar with it.  Alternative
143	   schemas have been circulated, which is undesirable, as they may not
144	   be in conformance to the RelaxNG schema in [RFC5222].  This document
145	   provides an XML schema that replaces the RelaxNG schema.  It can be
146	   used by any implementation interchangeably with the RelaxNG schema.

148	2.  Conventions used in this document

150	   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
151	   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
152	   document are to be interpreted as described in [RFC2119].

154	   "Server" in this document refers to the LoST server and "Client" is
155	   the LoST client, even when the server is performing an operation on
156	   the client.

158	3.  <plannedChange> element

160	   This document defines a new element to <findService> called
161	   "plannedChange".  This element contains two attributes: 'uri' and
162	   'asOf'.  The 'uri' attribute MUST be a URI with a scheme of HTTPS.
163	   The URI will be stored by the server against the location in the
164	   request for subsequent use with the notification function defined
165	   below.  To minimize storage requirements of at the server, the length
166	   of the URI MUST be 256 bytes or less.  Each client of the server may
167	   only store one URI against a location, where "location" is defined by
168	   policy at the server, since a given unique location may have many
169	   combinations of location elements that resolve to the same location.
170	   If the server receives a 'uri' for the same location from the same
171	   client, the URI in the request replaces the URI it previously
172	   retained.  Policy at the server may limit how many URIs it retains
173	   for a given location.  A new warning is defined below to be used to
174	   indicate that the URI has not been stored.  If the location in the
175	   request is invalid, the URI will not be stored and the warning will
176	   be returned.

178	   The 'asOf' attribute contains a date and time.  The server will
179	   validate the location in the request as of the date specified, taking
180	   into account planned changes.  This allows the client to verify that
181	   it can make changes in the LIS commensurate with changes in the LoST
182	   server by validating locations in advance of a change.

184	4.  <locationInvalidated> object

186	   When the server needs to invalidate a location where the client
187	   provided a URI in <plannedChange>, the server executes an HTTPS POST
188	   containing <locationInvalidated> to the URI previously provided.
189	   This is the notice from the server to the client that the location
190	   may be invalid and should be revalidated.  <locationInvalidated>
191	   contains an 'invalidAsOf' attribute that specifies when the location
192	   may become invalid.  If the date/time in 'invalidAsOf' is earlier
193	   than the time the <locationInvalidated> was sent, the location may
194	   already be invalid and the LIS should take immediate action.  If the
195	   POST operation fails, the server MAY retry the operation immediately,
196	   and if it fails again, retry the operation at a later time.

198	5.  URI Not Stored Warning

200	   A new warning is added to the exceptionContainer, 'uriNotStored'.
201	   This warning MUST NOT be returned unless the <plannedChange> element
202	   was found in the corresponding request.  The warning is returned when
203	   the server decides not to store the URI found in the <plannedChange>
204	   element.  As discussed above, this may occur because, among other
205	   reasons, the policy at the server limits how many URIs will be stored
206	   against a specific location, the URI is not well formed or the policy
207	   at the server has some other restriction on the feature.

209	6.  Time-To-Live (TTL) in Response

211	   A new <ttl> element is added to the <findserviceResponse>.  The <ttl>
212	   element contains a date and time after which the client may wish to
213	   revalidate the location at the server.  This element MAY be added by
214	   the server if validation is requested in the response.  The form of
215	   the element is the 'expires' attribute pattern, which allows explicit
216	   'NO CACHE' and 'NO EXPIRATION' values to be returned in the <ttl>
217	   element.  'NO CACHE' has no meaning and MUST NOT be returned in TTL.
218	   'NO EXPIRATION' means the server does not have any suggested
219	   revalidation period.

221	   Selecting a revalidation interval is a complex balancing of
222	   timeliness, server load, stability of the underlying data, and policy
223	   of the LoST server.  Too short, and load on the server may overwhelm
224	   it.  Too long and invalid data may persist in the server for too
225	   long.  The URI mechanism provides timely notice to coordinate
226	   changes, but even with it, it is often advisable to revalidate data
227	   eventually.

229	   In areas that have little change in data, such as fully built out,
230	   stable communities already part of a municipality, it may be
231	   reasonable to set revalidation periods of 6 months or longer,
232	   especially if the URI mechanism is widely deployed at both the server
233	   and the clients.  In areas that are quickly growing, 20-30 day
234	   revalidation may be more appropriate even though such revalidation
235	   would be the majority of the traffic on the LoST server.

237	   When a planned change is made, typically the TTL value for the
238	   affected records is lowered, so that revalidation is forced soon
239	   after the change is implemented.  It is not advisable to set the
240	   expiration precisely at the planned change time if a large number of
241	   records will be changed, since that would cause a large spike in
242	   traffic at the change time.  Rather, the expiration time should have
243	   a random additional time added to it to spread out the load.

245	7.  Replacement XML schema

247	   The Relax NG schema in [RFC5222] is replaced with the following XML
248	   schema:

250	 <?xml version="1.0" encoding="UTF-8"?>
251	 <xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"
252	            xmlns="urn:ietf:params:xml:ns:lost1"
253	            targetNamespace="urn:ietf:params:xml:ns:lost1"
254	            elementFormDefault="qualified">

256	   <xs:element name="findService">
257	     <xs:complexType>
258	       <xs:sequence>
259	         <xs:group ref="requestLocation"/>
260	         <xs:group ref="commonRequestPattern"/>
261	       </xs:sequence>
262	       <xs:attribute name="validateLocation" type="xs:boolean"/>
263	       <xs:attribute name="serviceBoundary">
264	         <xs:simpleType>
265	           <xs:restriction base="xs:token">
266	             <xs:enumeration value="reference"/>
267	             <xs:enumeration value="value"/>
268	           </xs:restriction>
269	         </xs:simpleType>
270	       </xs:attribute>
271	       <xs:attribute name="recursive" type="xs:boolean"/>
272	     </xs:complexType>
273	   </xs:element>

275	   <xs:element name="listServices">
276	     <xs:complexType>
277	       <xs:group ref="commonRequestPattern"/>
278	     </xs:complexType>
279	   </xs:element>

281	   <xs:element name="listServicesByLocation">
282	     <xs:complexType>
283	       <xs:sequence>
284	         <xs:group ref="requestLocation"/>
285	         <xs:group ref="commonRequestPattern"/>
286	       </xs:sequence>
287	       <xs:attribute name="recursive" type="xs:boolean"/>

289	     </xs:complexType>
290	   </xs:element>

292	   <xs:element name="getServiceBoundary">
293	     <xs:complexType>
294	       <xs:group ref="extensionPoint"/>
295	       <xs:attributeGroup ref="serviceBoundaryKey"/>
296	     </xs:complexType>
297	   </xs:element>

299	   <xs:element name="findServiceResponse">
300	     <xs:complexType>
301	       <xs:sequence>
302	         <xs:element ref="mapping" maxOccurs="unbounded"/>
303	         <xs:element ref="locationValidation" minOccurs="0"/>
304	         <xs:group ref="commonResponsePattern"/>
305	         <xs:group ref="locationUsed"/>
306	       </xs:sequence>
307	     </xs:complexType>
308	   </xs:element>

310	   <xs:element name="listServicesResponse">
311	     <xs:complexType>
312	       <xs:sequence>
313	         <xs:element ref="serviceList"/>
314	         <xs:group ref="commonResponsePattern"/>
315	       </xs:sequence>
316	     </xs:complexType>
317	   </xs:element>

319	   <xs:element name="listServicesByLocationResponse">
320	     <xs:complexType>
321	       <xs:sequence>
322	         <xs:element ref="serviceList"/>
323	         <xs:group ref="commonResponsePattern"/>
324	         <xs:group ref="locationUsed"/>
325	       </xs:sequence>
326	     </xs:complexType>
327	   </xs:element>

329	   <xs:element name="getServiceBoundaryResponse">
330	     <xs:complexType>
331	       <xs:sequence>
332	         <xs:group ref="serviceBoundary"/>
333	         <xs:group ref="commonResponsePattern"/>
334	       </xs:sequence>
335	     </xs:complexType>
336	   </xs:element>
337	   <xs:group name="commonRequestPattern">
338	     <xs:sequence>
339	       <xs:group ref="service"/>
340	       <xs:element ref="path" minOccurs="0"/>
341	       <xs:group ref="extensionPoint"/>
342	     </xs:sequence>
343	   </xs:group>

345	   <xs:group name="commonResponsePattern">
346	     <xs:sequence>
347	       <xs:element ref="warnings" minOccurs="0" maxOccurs="unbounded"/>
348	       <xs:element ref="path"/>
349	       <xs:group ref="extensionPoint"/>
350	     </xs:sequence>
351	   </xs:group>

353	   <xs:group name="requestLocation">
354	     <xs:sequence>
355	       <xs:element ref="location" maxOccurs="unbounded"/>
356	     </xs:sequence>
357	   </xs:group>

359	   <xs:element name="location">
360	     <xs:complexType>
361	       <xs:complexContent>
362	         <xs:extension base="locationInformation">
363	           <xs:attribute name="id" type="xs:token" use="required"/>
364	         </xs:extension>
365	       </xs:complexContent>
366	     </xs:complexType>
367	   </xs:element>

369	   <xs:complexType name="locationInformation">
370	     <xs:group ref="extensionPoint" maxOccurs="unbounded"/>
371	     <xs:attribute name="profile" type="xs:NMTOKEN"/>
372	   </xs:complexType>

374	   <xs:group name="serviceBoundary">
375	     <xs:sequence>
376	       <xs:element ref="serviceBoundary" maxOccurs="unbounded"/>
377	     </xs:sequence>
378	   </xs:group>

380	   <xs:element name="serviceBoundary" type="locationInformation"/>

382	   <xs:element name="serviceBoundaryReference">
383	     <xs:complexType>
384	       <xs:group ref="extensionPoint"/>
385	       <xs:attributeGroup ref="source"/>
386	       <xs:attributeGroup ref="serviceBoundaryKey"/>
387	     </xs:complexType>
388	   </xs:element>

390	   <xs:attributeGroup name="serviceBoundaryKey">
391	     <xs:attribute name="key" type="xs:token" use="required"/>
392	   </xs:attributeGroup>

394	   <xs:element name="path">
395	     <xs:complexType>
396	       <xs:sequence>
397	         <xs:element ref="via" maxOccurs="unbounded"/>
398	       </xs:sequence>
399	     </xs:complexType>
400	   </xs:element>

402	   <xs:element name="via">
403	     <xs:complexType>
404	       <xs:group ref="extensionPoint"/>
405	       <xs:attributeGroup ref="source"/>
406	     </xs:complexType>
407	   </xs:element>

409	   <xs:group name="locationUsed">
410	     <xs:sequence>
411	       <xs:element ref="locationUsed" minOccurs="0"/>
412	     </xs:sequence>
413	   </xs:group>

415	   <xs:element name="locationUsed">
416	     <xs:complexType>
417	       <xs:attribute name="id" type="xs:token" use="required"/>
418	     </xs:complexType>
419	   </xs:element>

421	   <xs:attributeGroup name="expires">
422	     <xs:attribute name="expires" use="required">
423	       <xs:simpleType>
424	         <xs:union memberTypes="xs:dateTime">
425	           <xs:simpleType>
426	             <xs:restriction base="xs:token">
427	               <xs:enumeration value="NO-CACHE"/>
428	             </xs:restriction>
429	           </xs:simpleType>
430	           <xs:simpleType>
431	             <xs:restriction base="xs:token">
432	               <xs:enumeration value="NO-EXPIRATION"/>

434	             </xs:restriction>
435	           </xs:simpleType>
436	         </xs:union>
437	       </xs:simpleType>
438	     </xs:attribute>
439	   </xs:attributeGroup>

441	   <xs:simpleType name="qnameList">
442	     <xs:list itemType="xs:QName"/>
443	   </xs:simpleType>

445	   <xs:element name="mapping">
446	     <xs:complexType>
447	       <xs:sequence>
448	         <xs:element ref="displayName"
449	              minOccurs="0" maxOccurs="unbounded"/>
450	         <xs:group ref="service"/>
451	         <xs:choice minOccurs="0">
452	           <xs:group ref="serviceBoundary"/>
453	           <xs:element ref="serviceBoundaryReference"/>
454	         </xs:choice>
455	         <xs:element ref="uri"
456	              minOccurs="0" maxOccurs="unbounded"/>
457	         <xs:element ref="serviceNumber" minOccurs="0"/>
458	         <xs:group ref="extensionPoint"/>
459	       </xs:sequence>
460	       <xs:attributeGroup ref="expires"/>
461	       <xs:attribute name="lastUpdated" type="xs:dateTime"
462	             use="required"/>
463	       <xs:attributeGroup ref="source"/>
464	       <xs:attribute name="sourceId" type="xs:token"
465	             use="required"/>
466	       <xs:attributeGroup ref="message"/>
467	     </xs:complexType>
468	   </xs:element>

470	   <xs:element name="displayName">
471	     <xs:complexType>
472	       <xs:simpleContent>
473	         <xs:extension base="xs:string">
474	           <xs:attribute ref="xml:lang" use="required"/>
475	         </xs:extension>
476	       </xs:simpleContent>
477	     </xs:complexType>
478	   </xs:element>

480	   <xs:element name="uri" type="xs:anyURI"/>
481	   <xs:element name="serviceNumber">
482	     <xs:simpleType>
483	       <xs:restriction base="xs:token">
484	         <xs:pattern value="[0-9*#]+"/>
485	       </xs:restriction>
486	     </xs:simpleType>
487	   </xs:element>

489	   <xs:element name="locationValidation">
490	     <xs:complexType>
491	       <xs:sequence>
492	         <xs:element ref="valid" minOccurs="0"/>
493	         <xs:element ref="invalid" minOccurs="0"/>
494	         <xs:element ref="unchecked" minOccurs="0"/>
495	         <xs:group ref="extensionPoint"/>
496	       </xs:sequence>
497	     </xs:complexType>
498	   </xs:element>

500	   <xs:element name="valid" type="qnameList"/>

502	   <xs:element name="invalid" type="qnameList"/>

504	   <xs:element name="unchecked" type="qnameList"/>

506	   <xs:complexType name="exceptionContainer">
507	     <xs:sequence>
508	       <xs:choice minOccurs="0" maxOccurs="unbounded">
509	         <xs:element ref="badRequest"/>
510	         <xs:element ref="internalError"/>
511	         <xs:element ref="serviceSubstitution"/>
512	         <xs:element ref="defaultMappingReturned"/>
513	         <xs:element ref="forbidden"/>
514	         <xs:element ref="notFound"/>
515	         <xs:element ref="loop"/>
516	         <xs:element ref="serviceNotImplemented"/>
517	         <xs:element ref="serverTimeout"/>
518	         <xs:element ref="serverError"/>
519	         <xs:element ref="locationInvalid"/>
520	         <xs:element ref="locationProfileUnrecognized"/>
521	       </xs:choice>
522	       <xs:group ref="extensionPoint"/>
523	     </xs:sequence>
524	     <xs:attributeGroup ref="source"/>
525	   </xs:complexType>

527	   <xs:element name="errors" type="exceptionContainer"/>
528	   <xs:element name="warnings" type="exceptionContainer"/>

530	   <xs:complexType name="basicException">
531	     <xs:annotation>
532	       <xs:documentation>
533	         Exception pattern.
534	       </xs:documentation>
535	     </xs:annotation>
536	     <xs:group ref="extensionPoint"/>
537	     <xs:attributeGroup ref="message"/>
538	   </xs:complexType>

540	   <xs:element name="badRequest" type="basicException"/>

542	   <xs:element name="internalError" type="basicException"/>

544	   <xs:element name="serviceSubstitution" type="basicException"/>

546	   <xs:element name="defaultMappingReturned" type="basicException"/>

548	   <xs:element name="forbidden" type="basicException"/>

550	   <xs:element name="notFound" type="basicException"/>

552	   <xs:element name="loop" type="basicException"/>

554	   <xs:element name="serviceNotImplemented" type="basicException"/>

556	   <xs:element name="serverTimeout" type="basicException"/>

558	   <xs:element name="serverError" type="basicException"/>

560	   <xs:element name="locationInvalid" type="basicException"/>

562	   <xs:element name="locationValidationUnavailable"
563	           type="basicException"/>

565	   <xs:element name="locationProfileUnrecognized">
566	     <xs:complexType>
567	       <xs:complexContent>
568	         <xs:extension base="basicException">
569	           <xs:attribute name="unsupportedProfiles"
570	               type="xs:NMTOKENS" use="required"/>
571	         </xs:extension>
572	       </xs:complexContent>
573	     </xs:complexType>
574	   </xs:element>
575	   <xs:element name="redirect">
576	     <xs:complexType>
577	       <xs:group ref="extensionPoint"/>
578	       <xs:attribute name="target" type="appUniqueString"
579	           use="required"/>
580	       <xs:attributeGroup ref="source"/>
581	       <xs:attributeGroup ref="message"/>
582	     </xs:complexType>
583	   </xs:element>

585	   <xs:attributeGroup name="message">
586	     <xs:attribute name="message" type="xs:token"/>
587	     <xs:attribute ref="xml:lang"/>
588	   </xs:attributeGroup>

590	   <xs:group name="service">
591	     <xs:sequence>
592	       <xs:element ref="service" minOccurs="0"/>
593	     </xs:sequence>
594	   </xs:group>

596	   <xs:element name="service" type="xs:anyURI"/>

598	   <xs:simpleType name="appUniqueString">
599	     <xs:restriction base="xs:token">
600	       <xs:pattern value="([a-zA-Z0-9\-]+\.)+[a-zA-Z0-9]+"/>
601	     </xs:restriction>
602	   </xs:simpleType>

604	   <xs:attributeGroup name="source">
605	     <xs:attribute name="source" type="appUniqueString" use="required"/>
606	   </xs:attributeGroup>

608	   <xs:element name="serviceList">
609	     <xs:simpleType>
610	       <xs:list itemType="xs:anyURI"/>
611	     </xs:simpleType>
612	   </xs:element>

614	   <xs:group name="notLost">
615	     <xs:annotation>
616	       <xs:documentation>
617	         Any element not in the LoST namespace.
618	       </xs:documentation>
619	     </xs:annotation>
620	     <xs:choice>
621	       <xs:any namespace="##other" processContents="skip"/>
622	       <xs:any namespace="##local" processContents="skip"/>

624	     </xs:choice>
625	   </xs:group>

627	   <xs:group name="anyElement">
628	     <xs:annotation>
629	       <xs:documentation>
630	         A wildcard pattern for including any element
631	         from any other namespace.
632	       </xs:documentation>
633	     </xs:annotation>
634	     <xs:sequence>
635	       <xs:any processContents="skip"
636	           minOccurs="0" maxOccurs="unbounded"/>
637	     </xs:sequence>
638	   </xs:group>

640	   <xs:attributeGroup name="anyElement">
641	     <xs:annotation>
642	       <xs:documentation>
643	         A wildcard pattern for including any element
644	         from any other namespace.
645	       </xs:documentation>
646	     </xs:annotation>
647	     <xs:anyAttribute processContents="skip"/>
648	   </xs:attributeGroup>

650	   <xs:group name="extensionPoint">
651	     <xs:annotation>
652	       <xs:documentation>
653	         A point where future extensions
654	         (elements from other namespaces)
655	         can be added.
656	       </xs:documentation>
657	     </xs:annotation>
658	     <xs:sequence>
659	       <xs:group ref="notLost"
660	            minOccurs="0" maxOccurs="unbounded"/>
661	     </xs:sequence>
662	   </xs:group>

664	 </xs:schema>

666	8.  Extension XML Schema

668	   This schema provides the extension to the prior section schema for
669	   planned changes:

671	<?xml version="1.0" encoding="UTF-8"?>
672	<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"
673	           xmlns="urn:ietf:params:xml:ns:lostPlannedChange1"
674	           targetNamespace="urn:ietf:params:xml:ns:lostPlannedChange1"
675	           elementFormDefault="qualified">
676	     <!-- Import base Lost -->
677	     <xs:import namespace="urn:ietf:params:xml:ns:lost1"/>
678	<!-- extend the extensionPoint of commonRequestPattern of findService
679	                                                       to include:  -->
680	        xs:group ref="plannedChange" minOccurs="1"/>

682	<!-- where -->
683	       <xs:group name="plannedChange">
684	           <xs:sequence>
685	              <xs:element ref="uri" type="xs:anyURI" />
686	              <xs:element ref="invalidAsOf" type="xs:dateTime" />
687	              <xs:any namespace="##other" processContents="lax"
688	                 minOccurs="0" maxOccurs="unbounded"/>
689	           </xs:sequence>
690	        </xs:group>

692	<!-- extend the extensionPoint of commonResponsePattern in
693	                          findServiceResponse to include: -->
694	           <xs:atttribute name="asOf" type="xs:dateTime" minOccurs="0"/>
695	           <xs:element ref="ttl" type="expires" minOccurs="0" />

697	<!-- extend the extensionPoint of extensionContainer to include: -->
698	           <xs:element ref="uriNotStored"/>
699	<!-- where -->
700	           <xs:element name="uriNotStored" type="basicException"/>

702	</xs:schema>

704	9.  Security Considerations

706	   As an extension to LoST, this document inherits the security issues
707	   raised in [RFC5222].  The server could be tricked into storing a
708	   malicious URI which, when sent the locationInvalidated object could
709	   trigger something untoward.  The server MUST NOT accept any data from
710	   the client in response to POSTing the locationInvalidated.

712	   The server is subject to abuse by clients because it is being asked
713	   to store something and may need to send data to an uncontrolled URI.
714	   Clients could request many URIs for the same location for example.
715	   The server MUST have policy that limits use of this mechanism by a
716	   given client.  If the policy is exceeded, the server returns the
717	   'uriNotStored' warning.  The server MUST validate that the content of
718	   the 'uri' attribute sent is syntactically valid and meets the 256
719	   bytes limit.  When sending the locationInvalidated object to the URI
720	   stored, the server MUST protect itself against common HTTP
721	   vulnerabilities.

723	   The mutual authentication between client and server is RECOMMENDED
724	   for both the initial <findService> operation that requests storing
725	   the URI and the sending of the 'locationInvalidated' object.  The
726	   server should be well known to the client, and its credential should
727	   be learned in a reliable way.  For example, a public safety system
728	   operating the LoST server may have a credential traceable to a well
729	   known Certificate Authority known to provide credentials for public
730	   safety agencies.  Many of the clients will be operated by local ISPs
731	   or other service providers where the server operator can reasonably
732	   obtain a good credential to use for the URI.  Where the server does
733	   not recognize the client, its policy MAY limit the use of this
734	   feature beyond what it would limit a client it recognized.

736	10.  IANA Considerations

738	10.1.  Replacement XML Schema Registration

740	      URI:  urn:ietf:params:xml:schema:lost3
741	      Registrant Contact:  IETF ECRIT Working Group, Brian Rosen
742	         (br@brianrosen.net).

744	   The XML Schema is found in Section 7.

746	10.2.  Extension XML Schema Registration

748	      URI:  urn:ietf:params:xml:schema:lostPlannedChange1
749	      Registrant Contact:  IETF ECRIT Working Group, Brian Rosen
750	         (br@brianrosen.net).

752	   The XML Schema is found in Section 8.

754	10.3.  LoST Namespace Registration
755	      URI:  urn:ietf:params:xml:ns:lost-plannedChange1

757	      Registrant Contact:  IETF ECRIT Working Group, Brian Rosen
758	         (br@brianrosen.net).

760	      XML:

762	   BEGIN
763	   <?xml version="2.0"?>
764	   <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML Basic 1.0//EN"
765	     "http://www.w3.org/TR/xhtml-basic/xhtml-basic10.dtd">
766	   <html xmlns="http://www.w3.org/1999/xhtml">
767	   <head>
768	     <meta http-equiv="content-type"
769	           content="text/html;charset=iso-8859-1"/>
770	     <title>LoST Planned Change Namespace</title>
771	   </head>
772	   <body>
773	     <h1>Namespace for LoST Planned Change extension</h1>
774	     <h2>urn:ietf:params:xml:ns:lost-plannedChange1</h2>
775	   <p>See <a href="http://www.rfc-editor.org/rfc/rfc????.txt">
776	      RFC????</a>.</p>
777	   </body>
778	   </html>
779	   END

781	11.  Normative References

783	   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
784	              Requirement Levels", BCP 14, RFC 2119,
785	              DOI 10.17487/RFC2119, March 1997,
786	              <https://www.rfc-editor.org/info/rfc2119>.

788	   [RFC5222]  Hardie, T., Newton, A., Schulzrinne, H., and H.
789	              Tschofenig, "LoST: A Location-to-Service Translation
790	              Protocol", RFC 5222, DOI 10.17487/RFC5222, August 2008,
791	              <https://www.rfc-editor.org/info/rfc5222>.

793	Author's Address

795	   Brian Rosen
796	   470 Conrad Dr
797	   Mars, PA  16046
798	   US

800	   EMail: br@brianrosen.net