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Versions: (draft-hardie-ecrit-lost) 00 01 02 03 04 05 06 07 08 09 10 RFC 5222

Network Working Group                                          T. Hardie
Internet-Draft                                            Qualcomm, Inc.
Intended status: Standards Track                               A. Newton
Expires: March 8, 2007                                         SunRocket
                                                          H. Schulzrinne
                                                             Columbia U.
                                                           H. Tschofenig
                                                                 Siemens
                                                       September 4, 2006


            LoST: A Location-to-Service Translation Protocol
                      draft-ietf-ecrit-lost-01.txt

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   This Internet-Draft will expire on March 8, 2007.

Copyright Notice

   Copyright (C) The Internet Society (2006).









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Abstract

   This document describes an XML-based protocol for mapping service
   identifiers and geospatial or civic location information to service
   contact URIs.  In particular, it can be used to determine the
   location-appropriate PSAP for emergency services.


Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  4
   2.  Requirements Notation  . . . . . . . . . . . . . . . . . . . .  6
   3.  Usage  . . . . . . . . . . . . . . . . . . . . . . . . . . . .  7
   4.  Resolving Service URNs Using LoST  . . . . . . . . . . . . . .  8
   5.  Query  . . . . . . . . . . . . . . . . . . . . . . . . . . . .  9
     5.1.  Location Information Element . . . . . . . . . . . . . . .  9
     5.2.  Service Element  . . . . . . . . . . . . . . . . . . . . .  9
     5.3.  Validate Attribute . . . . . . . . . . . . . . . . . . . .  9
     5.4.  Query Message Examples . . . . . . . . . . . . . . . . . .  9
   6.  Response . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
     6.1.  Uniform Resource Identifiers (URI) Element . . . . . . . . 11
     6.2.  Display Name Element . . . . . . . . . . . . . . . . . . . 11
     6.3.  Service Element  . . . . . . . . . . . . . . . . . . . . . 11
     6.4.  ServiceBoundary Element  . . . . . . . . . . . . . . . . . 12
     6.5.  ServiceNumber Element  . . . . . . . . . . . . . . . . . . 12
     6.6.  TimeToLive Attribute . . . . . . . . . . . . . . . . . . . 12
     6.7.  Validation Element . . . . . . . . . . . . . . . . . . . . 12
     6.8.  Response Message Examples  . . . . . . . . . . . . . . . . 12
   7.  List Services Query and Response . . . . . . . . . . . . . . . 15
     7.1.  List Service Query . . . . . . . . . . . . . . . . . . . . 15
     7.2.  List Service Response  . . . . . . . . . . . . . . . . . . 15
   8.  Status Code Definitions  . . . . . . . . . . . . . . . . . . . 17
     8.1.  Informational 1xx  . . . . . . . . . . . . . . . . . . . . 17
     8.2.  Successful 2xx . . . . . . . . . . . . . . . . . . . . . . 17
       8.2.1.  200 OK . . . . . . . . . . . . . . . . . . . . . . . . 17
       8.2.2.  201 Service Substitution . . . . . . . . . . . . . . . 17
     8.3.  Redirection 3xx  . . . . . . . . . . . . . . . . . . . . . 17
       8.3.1.  301 Move Permanently . . . . . . . . . . . . . . . . . 17
       8.3.2.  302 Moved Temporarily  . . . . . . . . . . . . . . . . 18
       8.3.3.  Example  . . . . . . . . . . . . . . . . . . . . . . . 18
     8.4.  Client Error 4xx . . . . . . . . . . . . . . . . . . . . . 18
       8.4.1.  400 Bad Request  . . . . . . . . . . . . . . . . . . . 18
       8.4.2.  403 Forbidden  . . . . . . . . . . . . . . . . . . . . 18
       8.4.3.  404 Not Found  . . . . . . . . . . . . . . . . . . . . 18
       8.4.4.  414 Location Error . . . . . . . . . . . . . . . . . . 18
       8.4.5.  Example  . . . . . . . . . . . . . . . . . . . . . . . 18
     8.5.  Server Error 5xx . . . . . . . . . . . . . . . . . . . . . 20
       8.5.1.  500 Server Internal Error  . . . . . . . . . . . . . . 20



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       8.5.2.  501 Service Not Implemented  . . . . . . . . . . . . . 20
       8.5.3.  504 Server Time-Out  . . . . . . . . . . . . . . . . . 21
       8.5.4.  Example  . . . . . . . . . . . . . . . . . . . . . . . 21
   9.  LoST Transport . . . . . . . . . . . . . . . . . . . . . . . . 22
   10. LoST Uniform Resource Locators . . . . . . . . . . . . . . . . 23
   11. Example  . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
   12. Deployment Methods . . . . . . . . . . . . . . . . . . . . . . 26
   13. Relax NG Schema  . . . . . . . . . . . . . . . . . . . . . . . 28
   14. Internationalization Considerations  . . . . . . . . . . . . . 33
   15. IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 34
     15.1. Content-type registration for 'application/lost+xml' . . . 34
     15.2. LoST Relax NG Schema Registration  . . . . . . . . . . . . 35
     15.3. LoST Namespace Registration  . . . . . . . . . . . . . . . 36
     15.4. Registration Template  . . . . . . . . . . . . . . . . . . 36
   16. Security Considerations  . . . . . . . . . . . . . . . . . . . 38
   17. Acknowledgments  . . . . . . . . . . . . . . . . . . . . . . . 39
   18. Open Issues  . . . . . . . . . . . . . . . . . . . . . . . . . 40
   19. References . . . . . . . . . . . . . . . . . . . . . . . . . . 41
     19.1. Normative References . . . . . . . . . . . . . . . . . . . 41
     19.2. Informative References . . . . . . . . . . . . . . . . . . 42
   Appendix A.  Non-Normative RELAX NG Schema in XML Syntax . . . . . 43
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 51
   Intellectual Property and Copyright Statements . . . . . . . . . . 52




























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1.  Introduction

   This document describes a protocol for mapping a service identifier
   [6] and location information compatible with PIDF-LO [11] to one or
   more service contact URIs.  Example contact URI schemes include sip,
   xmpp, and tel.  While the initial focus is on providing mapping
   functions for emergency services, it is likely that the protocol is
   applicable to any service URN.  For example, in the United States,
   the "2-1-1" and "3-1-1" services follow a similar location-to-service
   behavior as emergency services.

   This document names this protocol usage "LoST" for Location-to-
   Service Translation Protocol.  The features of LoST are:

   o  Supports queries using civic as well as geospatial location
      information.

   o  Support for recursive and iterative resolution.

   o  Support for address validation.

   o  A hierarchical deployment of mapping servers is independent of
      civic location labels.

   o  Indication of errors in the location data to facilitate debugging
      and proper user feedback while simultaneously providing best-
      effort answers.

   o  Mapping can be based on either civic or geospatial location
      information, with uniform protocol treatment of both.

   o  Support for overlapping service regions.

   o  Satisfies the requirements [5] for mapping protocols.

   o  Minimizes round trips by caching individual mappings and by
      supporting return of coverage regions ("hinting").

   o  Facilitates reuse of Transport Layer Security (TLS).

   This document focuses on the description of the protocol between the
   mapping client (seeker or resolver) and the mapping server (resolver
   or other servers).  The relationship between other functions, such as
   discovery of mapping servers, data replication and the overall
   mapping server architecture in general, will be described in a
   separate document. [20] is a first attempt to describe such a mapping
   server architecture.




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   The high-level protocol operation can be described as follows:



       Location
       Info      +----------+
       --------> |          |
       Service   |  LoST    |
       URN       |  Server  |
       --------> |          |
                 +----------+

        Query


            URI +----------+
       <------- |          |
       Optional |  LoST    |
    Info (hints)|  Server  |
       <------- |          |
                +----------+

        Response

                            Figure 1: Overview

   The query message carries location information and a service
   identifier encoded as a Uniform Resource Name (URN) (see [6]) from
   the LoST client to the LoST server.  The LoST server uses its
   database to map the input values to a Uniform Resource Identifiers
   (URI) and returns it including optional information such as hints
   about the service boundary in a response message back to the LoST
   client.


















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2.  Requirements Notation

   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 [3].














































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3.  Usage

   The client queries a server, indicating the desired service and
   location information.  If the query succeeds, the server returns a
   result that includes one or more URIs for reaching the appropriate
   service for the location indicated.  Depending on the query, the
   result may contain a service boundary where the same mapping would
   apply, a reference to another server to which the client should send
   a query, or an error messages indicating problems.  The combination
   of these components are left to the needs and policy of the
   jurisdiction where the server is being operated.

   The client may perform the mapping at any time.  Among the common
   triggers for mapping are:

   1.  When the client starts up and/or attaches to a new network
       location.

   2.  When the client detects that its location has changed
       sufficiently that it is outside the bounds of the region returned
       in an earlier query.

   3.  When cached mapping information has expired.

   4.  When calling for a particular service.  During such calls, a
       client may want to request a short response that contains only
       the mapping data, omitting service boundary information.

   Cached answers are expected to be used by clients only after failing
   to accomplish a location-to-URI mapping at call time.  Cache entries
   may expire according to their time-to-live value, or they may become
   invalid if the location of the caller's device moves outside the
   boundary limits of the cache entry.  Boundaries for cache entries may
   be set in both geospatial and civic terms.

















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4.  Resolving Service URNs Using LoST

   If a LoST URL contains a host name rather than an IP address, clients
   need to perform an U-NAPTR [17] lookup to obtain a DNS A record and
   IP address.  These records map the 'host' part of the LoST URL to one
   or more URLs indicating the protocol to carry the LoST request.  In
   this document, only the HTTP and HTTPS URL schemes are defined.  Note
   that the HTTP URL can be any valid HTTP URL, including those
   containing path elements.

   Here is an example:

   example.com.

   IN NAPTR 100  10   "u"    "LoST:https"
        "!*.!https://lostserver.example.com/secure!"  ""

   IN NAPTR 200  10   "u"    "LoST:http"
        "!*.!http://lostserver.example.com!"  ""
































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5.  Query

   LoST provides the ability to use civic or geospatial location
   information in the query message.  In addition to location
   information the query also contains a service identifier.  An
   optional parameter might furthermore request the LoST server to
   validate location information.

5.1.  Location Information Element

   LoST supports a query using geospatial and civic location information
   using the <findServiceByLocation> query.  Geospatial location
   information uses GML format [10] and civic location information
   utilizes the format defined in [16].  This document does not define
   location formats.

5.2.  Service Element

   The type of service desired is specified by the <service> element.
   The (emergency) service identifiers listed in the registry
   established with [6] will be used in this document.

   The <service> element is a mandatory element.  In case the database
   at the LoST server does not provided service for the specific
   geographical region the LoST server has various choices with regard
   to the response:

   o  It can send an error response.

   o  It can map one service to another one, if appropriate, and return
      a different service identifier as described in Section 6.3.

   o  It can populate the URIs of one service to another service.

   The operation of the LoST server is largely a policy issue.  No
   behavior is mandated in this document.  Guidelines for operating a
   LoST server for emergency services is provided in [21].

5.3.  Validate Attribute

   The 'validate' attribute implements the validation behavior described
   in [5].

5.4.  Query Message Examples

   This section shows an example of a query message providing geospatial
   and civic location information.




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   <?xml version="1.0" encoding="UTF-8"?>
   <findServiceByLocation
     xmlns="urn:ietf:params:xml:ns:lost1"
     xmlns:p2="http://www.opengis.net/gml"
     validate="false" operation="recursive">
     <locationInfo>
       <p2:Point id="point1" srsName="epsg:4326">
         <p2:coordinates>37:46:30N 122:25:10W</p2:coordinates>
       </p2:Point>
     </locationInfo>
     <service>urn:service:sos.police</service>
   </findServiceByLocation>

   Figure 3: Query Message Example using Geospatial Location Information

   The example above shows a query using geospatial location information
   with no validation required and asking for the
   'urn:service:sos.police' service.



   <?xml version="1.0" encoding="UTF-8"?>
   <findServiceByLocation xmlns="urn:ietf:params:xml:ns:lost1"
                          validate="false" operation="recursive">
     <locationInfo>
       <civicLocation>
         <country>Germany</country>
         <A1>Bavaria</A1>
         <A3>Munich</A3>
         <A6>Neu Perlach</A6>
         <HNO>96</HNO>
         <PC>81675</PC>
       </civicLocation>
     </locationInfo>
     <service>urn:service:sos.police</service>
   </findServiceByLocation>

     Figure 4: Query Message Example using Civic Location Information

   The example above shows a query using a civic location in Munich
   asking for the 'urn:service:sos.police' service.  The query indicates
   that validation is not desired and the query has to be executed
   recursively.








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6.  Response

   A response message might either contain civic or geospatial location
   information depending on the type of the query.  If the
   findServiceByLocation query message contained civic location
   information then the <serviceBoundary> element of the response
   message will also contain civic information.  If the
   findServiceByLocation query message contained geospatial location
   information then the <serviceBoundary> element of the response
   message will contain a GML polygon.  More information about the
   <serviceBoundary> element can be found at Section 6.4.

6.1.  Uniform Resource Identifiers (URI) Element

   Each <uri> element contains an appropriate contact URI for the
   service for which mapping was requested. <uri> elements are of type
   xs:anyURI.  In the emergency service context operators are strongly
   discouraged from using relative URIs, even though these are permitted
   by the type.

6.2.  Display Name Element

   Each <displayName> element contains a string that is suitable for
   display. <displayName> elements are of type "text" that is suitable
   for internationalized human-readable text.

6.3.  Service Element

   The <service> element is an optional element in the response message.
   The (emergency) service identifiers listed in the registry
   established with [6] will be used in this document.  If the service
   that was requested by the LoST client is not available for a
   particular location then the server MAY return an alternate service.
   If it does so, it MUST indicate the actual service returned (i.e.,
   its service URN).  Alternatively, the LoST server MAY return an error
   response indicating that the requested service is not available.

   The following example illustrates the main idea.  If there is a
   region that only understands the 'urn:service:sos' service and not
   'urn:service:sos.fire', 'urn:service:sos.ambulance', and
   'urn:service:sos.police'.  If a LoST client asks for the
   'urn:service:sos.fire' service then the LoST server could, depending
   on the local policy at the LoST server, return:

   1.  'urn:service:sos', or

   2.  'urn:service:sos.fire' with the values of 'urn:service:sos' being
       populated to 'urn:service:sos.fire', or



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   3.  an error message

   In case of (1) the <service> element carries the value of
   'urn:service:sos'.

6.4.  ServiceBoundary Element

   Each <serviceBoundary> element contains either one or more civic
   location elements derived from the GeoPriv civic address schema or a
   GML-based polygon.

   The <serviceBoundary> element indicates where the same query would
   yield to the same response, i.e., it provides information about the
   service boundary.

6.5.  ServiceNumber Element

   TBD: This element contains the (emergency) service number, which is a
   string of digits used to reach the (emergency) service.

6.6.  TimeToLive Attribute

   Each timeToLive attribute is a positive integer, expressing the
   validity period of the response in seconds.  The LoST client MUST NOT
   consider the returned location current after the expiration of the
   validity period.

6.7.  Validation Element

   The <validation> element contains a string that is composed of
   concatenated tokens separated by a whitespace.  These tokens refer to
   the civic location labels used in child elements of the
   <civicAddress> element from the request that have been recognized as
   valid by the server.

   The following code snippet indicates that the civic address labels
   'country', 'A1', 'A3', 'A6, 'PC' have been valided by the LoST
   server.


            <validation>country A1 A3 A6 PC</validation>

6.8.  Response Message Examples

   This section shows an example of a query message providing geospatial
   and civic location information.





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   <?xml version="1.0" encoding="UTF-8"?>
   <response
     xmlns="urn:ietf:params:xml:ns:lost1"
     xmlns:p2="http://www.opengis.net/gml"  >
     <result status="200" message="OK" xml:lang="en" timeToLive="1000">
       <displayName xml:lang="en">
         New York City Police Department
       </displayName>
       <service>urn:service:sos.police</service>
       <serviceBoundary>
         <p2:Polygon srsName="urn:ogc:def::crs:EPSG::4326">
           <p2:exterior>
             <p2:LinearRing>
               <p2:pos>37.775 -122.4194</p2:pos>
               <p2:pos>37.555 -122.4194</p2:pos>
               <p2:pos>37.555 -122.4264</p2:pos>
               <p2:pos>37.775 -122.4264</p2:pos>
               <p2:pos>37.775 -122.4194</p2:pos>
             </p2:LinearRing>
           </p2:exterior>
         </p2:Polygon>
       </serviceBoundary>
       <uri>sip:nypd@example.com</uri>
       <uri>xmpp:nypd@example.com</uri>
       <serviceNumber>911</serviceNumber>
     </result>
   </response>

   Figure 6: Response Message Example using Geospatial Location Service
                              Boundary Hints

   This example shows a response with two URIs for the previously
   queried service URN.  Information about the service boundary is
   provided by a GML polygon.  The <serviceNumber> element indicates the
   valid service number for the expressed location and service URN.
















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   <?xml version="1.0" encoding="UTF-8"?>
   <response xmlns="urn:ietf:params:xml:ns:lost1">
     <result status="200" timeToLive="10000">
       <displayName xml:lang="de">Munich Police Department</displayName>
       <service>urn:service:sos.police</service>
       <serviceBoundary>
         <civicLocation>
           <country>Germany</country>
           <A1>Bavaria</A1>
           <A3>Munich</A3>
           <PC>81675</PC>
         </civicLocation>
       </serviceBoundary>
       <uri>sip:munich-police@example.com</uri>
       <uri>xmpp:munich-police@example.com</uri>
       <service-number>110</service-number>
     </result>
   </response>

    Figure 7: Response Message Example providing Civic Location Service
                              Boundary Hints

   This example shows a response that returns two URIs (one for SIP and
   another one for XMPP), a distring that indicates the valid distring
   for the location provided in the query, a hint about the service
   boundary in the <serviceBoundary> element and information about the
   validated civic address fields.  The timeToLive attribute indicates
   that the returned information can be cached for 10000 seconds and
   provides a *<displayName> element with additional, textual
   information about the returned information.





















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7.  List Services Query and Response

7.1.  List Service Query

   This subsection describes a mechanism that offers the LoST client to
   query for available service identifiers supported by the LoST server.
   The listServices query MUST carry the <locationInfo> and the
   <service> element.  The LoST server MUST return only immediate child
   elements of the service identifier specified in the <service> element
   of the listServices query available for the provided location
   information.



   <?xml version="1.0" encoding="UTF-8"?>
   <listServices
     xmlns="urn:ietf:params:xml:ns:lost1"
     xmlns:p2="http://www.opengis.net/gml"
     operation="false">

     <locationInfo>
       <p2:Point id="point1" srsName="epsg:4326">
         <p2:coordinates>37:46:30N 122:25:10W</p2:coordinates>
       </p2:Point>
     </locationInfo>
     <service>urn:service:sos</service>
   </listServices>

                Figure 8: Example for a List Service Query

   This listService query aims to query the immediate child elements of
   the 'urn:service:sos' URN.

7.2.  List Service Response

   This subsection describes the response message that provides the LoST
   client with the list of immediate child service identifiers based on
   the service identifier provided by LoST client with respect to the
   location information provided in the listService query.

   The following example shows the response to the listServices query
   example of Figure 8 listing the available services offered by the
   LoST server starting with 'urn:service:sos.ambulance' and finishing
   with 'urn:service:sos.suicide'.







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   <?xml version="1.0" encoding="UTF-8"?>
   <response xmlns="urn:ietf:params:xml:ns:lost1">
       <serviceList status="200" message="OK" xml:lang="en">
         urn:service:sos.ambulance
         urn:service:sos.animal-control
         urn:service:sos.fire
         urn:service:sos.gas
         urn:service:sos.mountain
         urn:service:sos.marine
         urn:service:sos.physician
         urn:service:sos.poison
         urn:service:sos.police
         urn:service:sos.suicide
       </serviceList>
   </response>

        Figure 9: Example for the Response to a List Service Query


































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8.  Status Code Definitions

   Each response contains a <status> element that conveys a numeric
   status code and a reason phrase indicating the success or failure of
   the response.  The appearance of other elements in the response
   depends on the status code.  Hence, different elements are used for
   groups of status codes.

   Status codes always have three digits; the list of status codes is
   meant to be extensible by IANA registration and follows the general
   pattern of the Session Initiation Protocol (SIP) [22] and HTTP [14].
   The first digit indicates the type of response, with '2' signaling a
   successful request, '3' a redirection, '4' a request failure due to
   client behavior, and '5' a server failure.

   If used within HTTP, LoST also utilizes the normal HTTP status codes.
   However, the HTTP request can succeed, while the LoST request caused
   an error.  All LoST status codes appear in HTTP 200 (OK) responses.
   For example, a LoST 404, 414 or 500 status would occur in an HTTP 200
   response.

   Temporary unavailability of the service should be indicated by an
   HTTP 505 (Service Unavailable) status code.

   [Editor's Note: Does this make any sense or should all or some LoST
   errors occur in a non-200 HTTP response?]

8.1.  Informational 1xx

   This document does not define informational status codes.

8.2.  Successful 2xx

8.2.1.  200 OK

   The query completed successfully.

8.2.2.  201 Service Substitution

   The service requested is not available for the location requested,
   but the server is configured to provide a replacement service.

8.3.  Redirection 3xx

8.3.1.  301 Move Permanently

   The requested location is being mapped by a different server and all
   future requests for that location (and locations in the service area)



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   should be directed to that server.

8.3.2.  302 Moved Temporarily

   The requested location is being mapped by a different server, but
   future requests should continue to use this server.

8.3.3.  Example

   This is an example of an error message with a 302 status code:


   <?xml version="1.0" encoding="UTF-8"?>
   <response xmlns="urn:ietf:params:xml:ns:lost1">
     <redirect status="302"
       message="County-level routing"
       xml:lang="en"
       redirect="lost:co.lancaster.pa.us"
   </response>

8.4.  Client Error 4xx

8.4.1.  400 Bad Request

   The request could not be understood due to malformed syntax.

8.4.2.  403 Forbidden

   The server understood the request, but is refusing to fulfill it.
   Authorization will not help, and the request SHOULD NOT be repeated.

8.4.3.  404 Not Found

   The server has definitive information that there is no service
   mapping for the location specified.

8.4.4.  414 Location Error

   The location provided does not exist or fields within the location
   information are contradictory.

8.4.5.  Example

   The first example shows an error message with a 414 status code that
   is attached to the response message indicating that there was a
   problem with the postal code:





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   <?xml version="1.0" encoding="UTF-8"?>
   <response xmlns="urn:ietf:params:xml:ns:lost1">
     <result status="250" message="Default Route"
                          xml:lang="en" timeToLive="10000">
       <displayName xml:lang="en">
         New York City Police Department
       </displayName>
       <service>unknown</service>
       <serviceBoundary>
         <civicLocation>
           <country>US</country>
           <A1>New York</A1>
           <A3>New York</A3>
         </civicLocation>
       </serviceBoundary>
       <uri>sip:nypd@example.com</uri>
       <uri>xmpp:nypd@example.com</uri>
       <service-number>911</service-number>
     </result>
     <failure status="414" message="Address error" xml:lang="en">
       <cause name="PC"
         message="postal code is outside of service boundary"
         xml:lang="en" />
     </failure>
   </response>

   The second example shows an error message with a 414 status code that
   is attached to the response message indicating that there was a
   problem with the provided geospatial location information:






















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   <?xml version="1.0" encoding="UTF-8"?>
   <response
     xmlns="urn:ietf:params:xml:ns:lost1"
     xmlns:p2="http://www.opengis.net/gml"  >
     <result status="250" message="Default PSAP"
             xml:lang="en" timeToLive="1000">
       <displayName xml:lang="en">
         New York City Police Department
       </displayName>
       <service>urn:service:sos.police</service>
       <serviceBoundary>
         <p2:Polygon srsName="urn:ogc:def::crs:EPSG::4326">
           <p2:exterior>
             <p2:LinearRing>
               <p2:pos>37.775 -122.4194</p2:pos>
               <p2:pos>37.555 -122.4194</p2:pos>
               <p2:pos>37.555 -122.4264</p2:pos>
               <p2:pos>37.775 -122.4264</p2:pos>
               <p2:pos>37.775 -122.4194</p2:pos>
             </p2:LinearRing>
           </p2:exterior>
         </p2:Polygon>
       </serviceBoundary>
       <uri>sip:nypd@example.com</uri>
       <uri>xmpp:nypd@example.com</uri>
       <serviceNumber>911</serviceNumber>
     </result>
     <failure status="414"
        message="Invalide Goegraphic Location" xml:lang="en">
       <cause name="p2:coordinates"
         message="invalid latitude" xml:lang="en" />
     </failure>
   </response>

8.5.  Server Error 5xx

8.5.1.  500 Server Internal Error

   The server encountered an unexpected condition that prevented it from
   fulfilling the request.  The client MAY retry the request after
   several seconds.

8.5.2.  501 Service Not Implemented

   The server does not implement mapping for the service requested and
   cannot provide an alternate service.





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8.5.3.  504 Server Time-Out

   A server time-out occurs if the server contacted tries to recursively
   resolve the query, but cannot get an answer within the time limit set
   for the query.

8.5.4.  Example

   This is an example of an error message with a 500 status code:


   <?xml version="1.0" encoding="UTF-8"?>
   <response xmlns="urn:ietf:params:xml:ns:lost1">
     <status code="500">Server failure</status>
   </response>




































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9.  LoST Transport

   LoST needs an underlying protocol transport mechanisms to carry
   requests and responses.  This document defines the use of LoST over
   HTTP and HTTP-over-TLS; other mechanisms are left to future
   documents.  The available transport mechanisms are indicated in the
   LoST U-NAPTR DNS resource record.  In protocols that support content
   type indication, LoST uses the media type application/lost+xml.

   When using HTTP [14] and HTTP-over-TLS [15], LoST requests use the
   HTTP POST method.  All HTTP responses are applicable.  The HTTP URL
   is derived from the LoST URL via U-NAPTR translation, as discussed in
   Section 4.






































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10.  LoST Uniform Resource Locators

   LoST Uniform Resource Locators (URLs) follow the format of URLs
   defined in RFC 3986 [9], with the following ABNF:

      LoST-URI = "lost:" host

   'host' is defined in Section 3.2.2 of RFC 3986 [9].

   An example is 'lost:lostserver.example.com'









































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11.  Example

   After performing link layer attachment and end host performs stateful
   address autoconfiguration (in our example) using DHCP.  Then, DHCP
   provides the end host with civic location as described in [19].



      +--------+---------------+
      | CAtype | CAvalue       |
      +--------+---------------+
      | 0      | US            |
      | 1      | New York      |
      | 3      | New York      |
      | 6      | Broadway      |
      | 22     | Suite 75      |
      | 24     | 10027-0401    |
      +--------+---------------+

                 Figure 14: DHCP Civic Information Example

   Additionally, DHCP may provide information about the LoST server that
   can be contacted.  Alternatively, an additional step of indirection
   is possible, for example by having DHCP return a domain name that has
   to be resolved to one or more IP addresses hosting LoST servers.

   Both at attachment time and call time, the client places a LoST
   request, including its civic location and the desired service.  The
   request is shown below:


   <?xml version="1.0" encoding="UTF-8"?>
   <findServiceByLocation xmlns="urn:ietf:params:xml:ns:lost1"
                          validate="false" operation="recursive">
     <locationInfo>
       <civicLocation>
         <country>US</country>
         <A1>New York</A1>
         <A3>New York</A3>
         <A6>Broadway</A6>
         <LOC>Suite 75</LOC>
         <PC>10027-0401</PC>
       </civicLocation>
     </locationInfo>
     <service>urn:service:sos.police</service>
   </findServiceByLocation>

                              Mapping Request



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   Since the contacted LoST server has the requested information
   available the following response is returned.  The <displayName>
   element indicates, as a human readable display string, that the 'New
   York City Police Department' is responsible for the given
   geographical area.  The indicated URI allows the user to start
   communication using SIP or XMPP.  The <validation> element indicates
   which parts of the civic address were matched successfully against a
   database and represent a known address.  Other parts of the address,
   here, the suite number, were ignored and not validated.  The
   <serviceBoundary> element indicates that all of New York City would
   result in the same response.  The <serviceNumber> element indicates
   that the service can be reached via the emergency service number 911.


   <?xml version="1.0" encoding="UTF-8"?>
   <response xmlns="urn:ietf:params:xml:ns:lost1">
     <result status="200" message="OK" xml:lang="en" timeToLive="10000">
       <displayName xml:lang="en">
         New York City Police Department
       </displayName>
       <service>unknown</service>
       <serviceBoundary>
         <civicLocation>
           <country>US</country>
           <A1>New York</A1>
           <A3>New York</A3>
         </civicLocation>
       </serviceBoundary>
       <uri>sip:nypd@example.com</uri>
       <uri>xmpp:nypd@example.com</uri>
       <service-number>911</service-number>
     </result>
   </response>

                             Mapping Response
















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12.  Deployment Methods

   Because services for emergency contact resolution may differ
   depending on local or service needs, this document only specifies the
   "wire format" for LoST services and explicitly leaves open the
   possibility for many different types of deployment.

   For instance:

      During discovery, a client may be directed to issue all queries to
      an LoST service completely authoritative for a given jurisdiction.

      A client may be directed to issue queries to an LoST server that
      acts as a reflector.  In such a case, the LoST server analyzes the
      query to determine the best server to which to refer the client.

      Or the client may be directed to a server that performs further
      resolution on behalf of the client.

   A LoST service may also be represented by multiple LoST servers,
   either grouped together or at multiple network locations.  Using
   S-NAPTR [24], clients may be given a list of multiple servers to
   which queries can be sent for a single service.

   For instance, the service at emergency.example.com may advertise LoST
   service at local1.emergency.example.com,
   local2.emergency.example.com, and master.emergency.example.com.  Each
   server may given a different preference.  In this case, 'local-1' and
   'local-2' may be given a lower preference (more preferred) than
   'master', which might be a busier server or located further away.



   +-----------+             pref 10 +-----------+
   |           |-------------------->+           |
   |  client   |------               |  local-1  |
   |           |---   \              |           |
   +-----------+   \   \             +-----------+
                    \   \
                     \   \           +-----------+
                      \   \  pref 10 |           |
                       \   --------->|  local-2  |
                        \            |           |
                         \           +-----------+
                          \
                           \                           +-----------+
                            \                  pref 20 |           |
                             ------------------------->|  master   |



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                                                       |           |
                                                       +-----------+

















































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13.  Relax NG Schema

   This section provides the Relax NG schema used by LoST protocol in
   the compact form.  The verbose form is included in Appendix A.


 default namespace = "urn:ietf:params:xml:ns:lost1"
 namespace a = "http://relaxng.org/ns/compatibility/annotations/1.0"
 namespace ns1 = "urn:ietf:params:xml:ns:pidf:geopriv10:civicAddr"
 namespace ns2 = "http://www.opengis.net/gml"


 ##
 ##       Location-to-Service Translation Protocol (LoST)
 ##
 ##       A LoST XML instance has three "root" types:
 ##       the findServiceByLocation query, the listServices query,
 ##       and the response to these queries.
 ##
 start = findServiceByLocation | listServices | response

 ##
 ##       The queries.
 ##
 div {
   findServiceByLocation =
     element findServiceByLocation {
       query,
       attribute validate { xsd:boolean >> a:defaultValue [ "false" ] }?
     }
   listServices = element listServices { query }
 }

 ##
 ##       The response.
 ##
 div {
   response =
     element response {

       ##
       ##               2xx responses.
       ##
       (result
        | element serviceList {
            list { xsd:anyURI* },
            status
          })?,



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       ##
       ##             3xx, 4xx, and 4xx responses.
       ##
       ((error | redirect | failure)?),
       extensionPoint
     }
 }

 ##
 ##       Query pattern.
 ##
 div {
   query =
     element locationInfo { anyElement* },
     element service { xsd:anyURI },
     extensionPoint,
     [ a:defaultValue [ "recursive" ] ] attribute operation { text }?
 }

 ##
 ##       A result.
 ##
 div {

   ##
   ##         2xx response.
   ##
   result =
     element result {
       element displayName {
         xsd:string,
         attribute xml:lang { xsd:language }
       }?,
       element service { xsd:anyURI },
       element serviceBoundary {
         (civicLocation, polygon?) | (civicLocation?, polygon)
       }?,
       element uri { xsd:anyURI }+,
       element serviceNumber {
         xsd:string { pattern = "[0-9]+" }
       }?,
       element validation {
         list { xsd:QName* }
       }?,
       extensionPoint,
       attribute timeToLive { xsd:positiveInteger },
       status
     }



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 }

 ##
 ##       Non-result responses.
 ##
 div {

   ##
   ##         5xx response.
   ##
   error = element error { status, extensionPoint }

   ##
   ##         3xx response.
   ##
   redirect =
     element redirect {
       status,
       attribute redirect { xsd:anyURI },
       extensionPoint
     }

   ##
   ##         4xx response.
   ##
   failure =
     element failure {
       status,
       element cause {
         attribute name { xsd:QName },
         attribute message { xsd:string },
         attribute xml:lang { xsd:language }
       }*,
       extensionPoint
     }
 }

 ##
 ##       Status pattern.
 ##
 div {
   status =
     attribute status { xsd:positiveInteger },
     attribute extendedStatus { xsd:positiveInteger }?,
     (attribute message { xsd:string },
      attribute xml:lang { xsd:language })?
 }




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 ##
 ##       Patterns for inclusion of elements from schemas in
 ##       other namespaces.
 ##
 div {

   ##
   ##         A wildcard pattern for including any element
   ##         from any other namespace.
   ##
   anyElement =
     element * {
       (attribute * { text }
        | text
        | anyElement)*
     }

   ##
   ##         A point where future extensions
   ##         (elements from other namesapces)
   ##         can be added.
   ##
   extensionPoint = anyElement*

   ##
   ##         A pattern to include the GEOPRIV civil location elements.
   ##
   civicAddress =
     element ns1:* {
       (attribute * { text }
        | text
        | anyElement)*
     }

   ##
   ##         A definition of civic location from GEOPRIV.
   ##
   civicLocation = element civicLocation { civicAddress*, anyElement* }

   ##
   ##         A pattern to include GML elements.
   ##
   GML =
     element ns2:* {
       (attribute * { text }
        | text
        | anyElement)*
     }



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   polygon =
     element ns2:Polygon {
       attribute * { text }*,
       GML
     }
 }













































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14.  Internationalization Considerations

   This mechanism is largely for passing protocol information from one
   subsystem to another; as such, most of its elements are tokens not
   meant for direct human consumption.  If these tokens are presented to
   the end user, some localization may need to occur.  The content of
   the <displayName> element may be displayed to the end user, and it is
   thus a complex type designed for this purpose.











































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15.  IANA Considerations

15.1.  Content-type registration for 'application/lost+xml'

   This specification requests the registration of a new MIME type
   according to the procedures of RFC 4288 [13] and guidelines in RFC
   3023 [12].

   MIME media type name:  application


   MIME subtype name:  lost+xml


   Mandatory parameters:  none


   Optional parameters:  charset

      Indicates the character encoding of enclosed XML.


   Encoding considerations:

      Uses XML, which can employ 8-bit characters, depending on the
      character encoding used.  See RFC 3023 [12], Section 3.2.


   Security considerations:

      This content type is designed to carry LoST protocol payloads.


   Interoperability considerations:  None


   Published specification:  RFCXXXX [NOTE TO IANA/RFC-EDITOR: Please
      replace XXXX with the RFC number of this specification.] this
      document


   Applications which use this media type:

      Emergency and Location-based Systems







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   Additional information:

      Magic Number:  None


      File Extension:  .lostxml


      Macintosh file type code:  'TEXT'


   Personal and email address for further information:  Hannes
      Tschofenig, Hannes.Tschofenig@siemens.com


   Intended usage:  LIMITED USE


   Author:

      This specification is a work item of the IETF ECRIT working group,
      with mailing list address <ecrit@ietf.org>.


   Change controller:

      The IESG <iesg@ietf.org>

15.2.  LoST Relax NG Schema Registration

   URI:  urn:ietf:params:xml:ns:lost

   Registrant Contact:  IETF ECRIT Working Group, Hannes Tschofenig
      (Hannes.Tschofenig@siemens.com).

   Relax NG Schema:  The Relax NG schema to be registered is contained
      in Section 13.  Its first line is

   default namespace = "urn:ietf:params:xml:ns:lost1"

      and its last line is

   }








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15.3.  LoST Namespace Registration

   URI:  urn:ietf:params:xml:ns:lost

   Registrant Contact:  IETF ECRIT Working Group, Hannes Tschofenig
      (Hannes.Tschofenig@siemens.com).

   XML:

   BEGIN
   <?xml version="1.0"?>
   <!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 Namespace</title>
   </head>
   <body>
     <h1>Namespace for LoST</h1>
     <h2>urn:ietf:params:xml:ns:lost</h2>
   <p>See <a href="[URL of published RFC]">RFCXXXX
       [NOTE TO IANA/RFC-EDITOR:
        Please replace XXXX with the RFC number of this
       specification.]</a>.</p>
   </body>
   </html>
   END

15.4.  Registration Template

   This registration template is in accordance with [8].

   URL scheme name:

      lost


   URL scheme syntax:

      See Section 10


   Character encoding considerations:

      See Section 10




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   Intended Use:

      The intended usage is described in this document.


   Application and protocols which use this scheme:

      The usage of the LoST URL scheme is targeted for this document and
      hence for location-based services that make use of the mapping
      protocol specified in this document.


   Interoperability considerations:

      None


   Security considerations:

      See Section 16


   Relevant publications:

      This document provides the relevant context for this URL scheme.


   Contact:

      Hannes Tschofenig, Hannes.Tschofenig@siemens.com


   Author/Change controller:

      The IESG <iesg@ietf.org>
















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16.  Security Considerations

   There are multiple threats to the overall system of which service
   mapping forms a part.  An attacker that can obtain service contact
   URIs can use those URIs to attempt to disrupt those services.  An
   attacker that can prevent the lookup of contact URIs can impair the
   reachability of such services.  An attacker that can eavesdrop on the
   communication requesting this lookup can surmise the existence of an
   emergency and possibly its nature, and may be able to use this to
   launch a physical attack on the caller.

   To avoid that an attacker can modify the query or its result, the
   authors RECOMMEND the use of channel security, such as TLS, with
   LoST.

   A more detailed description of threats and security requirements are
   provided in [4].


































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17.  Acknowledgments

   [Editor's Note: Names need to be added here.  Forgot it...Sorry.]
















































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18.  Open Issues

   Please find open issues at: http://www.ietf-ecrit.org:8080/lost/
















































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19.  References

19.1.  Normative References

   [1]   World Wide Web Consortium, "XML Schema Part 2: Datatypes",
         W3C XML Schema, October 2000,
         <http://www.w3.org/TR/2001/REC-xmlschema-2-20010502/>.

   [2]   World Wide Web Consortium, "XML Schema Part 1: Structures",
         W3C XML Schema, October 2000,
         <http://www.w3.org/TR/2001/REC-xmlschema-1-20010502/>.

   [3]   Bradner, S., "Key words for use in RFCs to Indicate Requirement
         Levels", BCP 14, RFC 2119, March 1997.

   [4]   Taylor, T., "Security Threats and Requirements for Emergency
         Call Marking and Mapping", draft-ietf-ecrit-security-threats-03
         (work in progress), July 2006.

   [5]   Schulzrinne, H. and R. Marshall, "Requirements for Emergency
         Context Resolution with Internet Technologies",
         draft-ietf-ecrit-requirements-12 (work in progress),
         August 2006.

   [6]   Schulzrinne, H., "A Uniform Resource Name (URN) for Services",
         draft-ietf-ecrit-service-urn-05 (work in progress),
         August 2006.

   [7]   Mealling, M., "The IETF XML Registry",
         draft-mealling-iana-xmlns-registry-05 (work in progress),
         June 2003.

   [8]   Petke, R. and I. King, "Registration Procedures for URL Scheme
         Names", BCP 35, RFC 2717, November 1999.

   [9]   Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
         Resource Identifier (URI): Generic Syntax", STD 66, RFC 3986,
         January 2005.

   [10]  OpenGIS, "Open Geography Markup Language (GML) Implementation
         Specification", OGC OGC 02-023r4, January 2003.

   [11]  Peterson, J., "A Presence-based GEOPRIV Location Object
         Format", RFC 4119, December 2005.

   [12]  Murata, M., St. Laurent, S., and D. Kohn, "XML Media Types",
         RFC 3023, January 2001.




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   [13]  Freed, N. and J. Klensin, "Media Type Specifications and
         Registration Procedures", BCP 13, RFC 4288, December 2005.

   [14]  Fielding, R., Gettys, J., Mogul, J., Frystyk, H., Masinter, L.,
         Leach, P., and T. Berners-Lee, "Hypertext Transfer Protocol --
         HTTP/1.1", RFC 2616, June 1999.

   [15]  Rescorla, E., "HTTP Over TLS", RFC 2818, May 2000.

   [16]  Thomson, M. and J. Winterbottom, "Revised Civic Location Format
         for PIDF-LO", draft-ietf-geopriv-revised-civic-lo-02 (work in
         progress), April 2006.

   [17]  Daigle, L., "Domain-based Application Service Location Using
         URIs and the Dynamic  Delegation Discovery Service (DDDS)",
         draft-daigle-unaptr-00 (work in progress), June 2006.

19.2.  Informative References

   [18]  Schulzrinne, H., "The tel URI for Telephone Numbers", RFC 3966,
         December 2004.

   [19]  Schulzrinne, H., "Dynamic Host Configuration Protocol (DHCPv4
         and DHCPv6) Option for Civic  Addresses Configuration
         Information", draft-ietf-geopriv-dhcp-civil-09 (work in
         progress), January 2006.

   [20]  Schulzrinne, H., "Location-to-URL Mapping Architecture and
         Framework", draft-ietf-ecrit-mapping-arch-00 (work in
         progress), August 2006.

   [21]  Rosen, B. and J. Polk, "Best Current Practice for
         Communications Services in support of Emergency  Calling",
         draft-rosen-sos-phonebcp-01 (work in progress), June 2006.

   [22]  Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, A.,
         Peterson, J., Sparks, R., Handley, M., and E. Schooler, "SIP:
         Session Initiation Protocol", RFC 3261, June 2002.

   [23]  Rosenberg, J., "Interactive Connectivity Establishment (ICE): A
         Methodology for Network  Address Translator (NAT) Traversal for
         Offer/Answer Protocols", draft-ietf-mmusic-ice-10 (work in
         progress), August 2006.

   [24]  Daigle, L. and A. Newton, "Domain-Based Application Service
         Location Using SRV RRs and the Dynamic Delegation Discovery
         Service (DDDS)", RFC 3958, January 2005.




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Appendix A.  Non-Normative RELAX NG Schema in XML Syntax


  <?xml version="1.0" encoding="UTF-8"?>
  <grammar ns="urn:ietf:params:xml:ns:lost1"
          xmlns="http://relaxng.org/ns/structure/1.0"
          xmlns:a="http://relaxng.org/ns/compatibility/annotations/1.0"
          datatypeLibrary="http://www.w3.org/2001/XMLSchema-datatypes">

          <start>
      <a:documentation>
        Location-to-Service Translation Protocol (LoST)

        A LoST XML instance has three "root" types:
        the findServiceByLocation query, the listServices query,
        and the response to these queries.
      </a:documentation>
      <choice>
        <ref name="findServiceByLocation" />
        <ref name="listServices" />
        <ref name="response" />
      </choice>
          </start>

    <div>
      <a:documentation>
        The queries.
      </a:documentation>

      <define name="findServiceByLocation">
        <element name="findServiceByLocation">
          <ref name="query" />
          <optional>
            <attribute name="validate">
              <data type="boolean" />
              <a:defaultValue>false</a:defaultValue>
            </attribute>
          </optional>
        </element>
      </define>

      <define name="listServices">
        <element name="listServices">
          <ref name="query" />
        </element>
      </define>

    </div>



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    <div>
      <a:documentation>
        The response.
      </a:documentation>

      <define name="response">
        <element name="response">
          <optional>
            <choice>
              <a:documentation>
                2xx responses.
              </a:documentation>
              <ref name="result" />
              <element name="serviceList">
                <list>
                  <zeroOrMore>
                    <data type="anyURI" />
                  </zeroOrMore>
                </list>
                <ref name="status" />
              </element>
            </choice>
          </optional>
          <optional>
            <a:documentation>
              3xx, 4xx, and 4xx responses.
            </a:documentation>
            <choice>
              <ref name="error" />
              <ref name="redirect" />
              <ref name="failure" />
            </choice>
          </optional>
          <ref name="extensionPoint" />
        </element>
      </define>

    </div>

    <div>
      <a:documentation>
        Query pattern.
      </a:documentation>

      <define name="query">
        <element name="locationInfo">
          <zeroOrMore>
            <ref name="anyElement"/>



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          </zeroOrMore>
        </element>
        <element name="service">
          <data type="anyURI"/>
        </element>
        <ref name="extensionPoint" />
        <optional>
          <attribute name="operation">
            <a:defaultValue>recursive</a:defaultValue>
          </attribute>
        </optional>
      </define>

    </div>

    <div>
      <a:documentation>
        A result.
      </a:documentation>

      <define name="result">
        <a:documentation>
          2xx response.
        </a:documentation>
        <element name="result">
          <optional>
            <element name="displayName">
              <data type="string"/>
              <attribute name="xml:lang">
                <data type="language" />
              </attribute>
            </element>
          </optional>
          <element name="service">
            <data type="anyURI"/>
          </element>
          <optional>
            <element name="serviceBoundary">
              <choice>
                <group>
                  <ref name="civicLocation" />
                  <optional>
                    <ref name="polygon" />
                  </optional>
                </group>
                <group>
                  <optional>
                    <ref name="civicLocation" />



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                  </optional>
                  <ref name="polygon" />
                </group>
              </choice>
            </element>
          </optional>
          <oneOrMore>
            <element name="uri">
              <data type="anyURI"/>
            </element>
          </oneOrMore>
          <optional>
            <element name="serviceNumber">
              <data type="string">
                <param name="pattern">[0-9]+</param>
              </data>
            </element>
          </optional>
          <optional>
            <element name="validation">
              <list>
                <zeroOrMore>
                  <data type="QName"/>
                </zeroOrMore>
              </list>
            </element>
          </optional>
          <ref name="extensionPoint" />
          <attribute name="timeToLive">
            <data type="positiveInteger"/>
          </attribute>
          <ref name="status" />
        </element>
      </define>

    </div>

    <div>
      <a:documentation>
        Non-result responses.
      </a:documentation>

      <define name="error">
        <a:documentation>
          5xx response.
        </a:documentation>
        <element name="error">
          <ref name="status"/>



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          <ref name="extensionPoint" />
        </element>
      </define>

      <define name="redirect">
        <a:documentation>
          3xx response.
        </a:documentation>
        <element name="redirect">
          <ref name="status"/>
          <attribute name="redirect">
            <data type="anyURI"/>
          </attribute>
          <ref name="extensionPoint" />
        </element>
      </define>

      <define name="failure">
        <a:documentation>
          4xx response.
        </a:documentation>
        <element name="failure">
          <ref name="status"/>
          <zeroOrMore>
            <element name="cause">
              <attribute name="name">
                <data type="QName"/>
              </attribute>
              <attribute name="message">
                <data type="string"/>
              </attribute>
              <attribute name="xml:lang">
                <data type="language"/>
              </attribute>
            </element>
          </zeroOrMore>
          <ref name="extensionPoint" />
        </element>
      </define>

    </div>

    <div>
      <a:documentation>
        Status pattern.
      </a:documentation>

      <define name="status">



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        <attribute name="status">
          <data type="positiveInteger"/>
        </attribute>
        <optional>
          <attribute name="extendedStatus">
            <data type="positiveInteger"/>
          </attribute>
        </optional>
        <optional>
          <group>
            <attribute name="message">
              <data type="string"/>
            </attribute>
            <attribute name="xml:lang">
              <data type="language"/>
            </attribute>
          </group>
        </optional>
      </define>

    </div>

    <div>
      <a:documentation>
        Patterns for inclusion of elements from schemas in
        other namespaces.
      </a:documentation>

      <define name="anyElement">
        <a:documentation>
          A wildcard pattern for including any
          element from any other namespace.
        </a:documentation>
        <element>
          <anyName/>
          <zeroOrMore>
            <choice>
              <attribute>
                <anyName/>
              </attribute>
              <text/>
              <ref name="anyElement"/>
            </choice>
          </zeroOrMore>
        </element>
      </define>

      <define name="extensionPoint">



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        <a:documentation>
          A point where future extensions
          (elements from other namespaces)
          can be added.
        </a:documentation>
        <zeroOrMore>
          <ref name="anyElement" />
        </zeroOrMore>
      </define>

      <define name="civicAddress">
        <a:documentation>
          A pattern to include the GEOPRIV civil location elements.
        </a:documentation>
        <element>
          <nsName ns="urn:ietf:params:xml:ns:pidf:geopriv10:civicAddr"/>
          <zeroOrMore>
            <choice>
              <attribute>
                <anyName/>
              </attribute>
              <text/>
              <ref name="anyElement"/>
            </choice>
          </zeroOrMore>
        </element>
      </define>

      <define name="civicLocation">
        <a:documentation>
          A definition of civic location from GEOPRIV.
        </a:documentation>
        <element name="civicLocation">
          <zeroOrMore>
            <ref name="civicAddress"/>
          </zeroOrMore>
          <zeroOrMore>
            <ref name="anyElement" />
          </zeroOrMore>
        </element>
      </define>

      <define name="GML">
        <a:documentation>
          A pattern to include GML elements.
        </a:documentation>
        <element>
          <nsName ns="http://www.opengis.net/gml" />



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          <zeroOrMore>
            <choice>
              <attribute>
                <anyName/>
              </attribute>
              <text/>
              <ref name="anyElement" />
            </choice>
          </zeroOrMore>
        </element>
      </define>

      <define name="polygon">
        <element name="Polygon" ns="http://www.opengis.net/gml">
          <zeroOrMore>
            <attribute>
              <anyName/>
            </attribute>
          </zeroOrMore>
          <ref name="GML"/>
        </element>
      </define>

    </div>

  </grammar>

























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Authors' Addresses

   Ted Hardie
   Qualcomm, Inc.

   Email: hardie@qualcomm.com


   Andrew Newton
   SunRocket
   8045 Leesburg Pike, Suite 300
   Vienna, VA  22182
   US

   Phone: +1 703 636 0852
   Email: andy@hxr.us


   Henning Schulzrinne
   Columbia University
   Department of Computer Science
   450 Computer Science Building
   New York, NY  10027
   US

   Phone: +1 212 939 7004
   Email: hgs+ecrit@cs.columbia.edu
   URI:   http://www.cs.columbia.edu


   Hannes Tschofenig
   Siemens
   Otto-Hahn-Ring 6
   Munich, Bavaria  81739
   Germany

   Phone: +49 89 636 40390
   Email: Hannes.Tschofenig@siemens.com
   URI:   http://www.tschofenig.com












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Full Copyright Statement

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