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Versions: (draft-schulzrinne-ecrit-lost-sync) 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 RFC 6739

ECRIT                                                     H. Schulzrinne
Internet-Draft                                       Columbia University
Intended status: Experimental                              H. Tschofenig
Expires: February 18, 2012                        Nokia Siemens Networks
                                                         August 17, 2011


  Synchronizing Location-to-Service Translation (LoST) Protocol based
                Service Boundaries and Mapping Elements
                   draft-ietf-ecrit-lost-sync-12.txt

Abstract

   The Location-to-Service Translation (LoST) protocol is an XML-based
   protocol for mapping service identifiers and geodetic or civic
   location information to service URIs and service boundaries.  In
   particular, it can be used to determine the location-appropriate
   Public Safety Answering Point (PSAP) for emergency services.

   The main data structure, the <mapping> element, used for
   encapsulating information about service boundaries is defined in the
   LoST protocol specification and circumscribes the region within which
   all locations map to the same service Uniform Resource Identifier
   (URI) or set of URIs for a given service.

   This document defines an XML protocol to exchange these mappings
   between two nodes.  This mechanism is designed for the exchange of
   authoritative <mapping> elements between two entities.  Exchanging
   cached <mapping> elements, i.e. non-authoritative elements, is
   possible but not envisioned.  In any case, this document can also be
   used without the LoST protocol even though the format of the
   <mapping> element is re-used from the LoST specification.

Status of this Memo

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

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

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




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   This Internet-Draft will expire on February 18, 2012.

Copyright Notice

   Copyright (c) 2011 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

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



































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Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  4
   2.  Terminology  . . . . . . . . . . . . . . . . . . . . . . . . . 10
   3.  Querying for Mappings with a <getMappingsRequest> /
       <getMappingsResponse> Exchange . . . . . . . . . . . . . . . . 11
     3.1.  Behavior of the LoST Sync Destination  . . . . . . . . . . 11
     3.2.  Behavior of the LoST Sync Source . . . . . . . . . . . . . 11
     3.3.  Examples . . . . . . . . . . . . . . . . . . . . . . . . . 12
   4.  Pushing Mappings via <pushMappings> and
       <pushMappingsResponse> . . . . . . . . . . . . . . . . . . . . 14
     4.1.  Behavior of the LoST Sync Source . . . . . . . . . . . . . 14
     4.2.  Behavior of the LoST Sync Destination  . . . . . . . . . . 14
     4.3.  Example  . . . . . . . . . . . . . . . . . . . . . . . . . 15
   5.  Transport  . . . . . . . . . . . . . . . . . . . . . . . . . . 18
   6.  RelaxNG  . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
   7.  Operational Considerations . . . . . . . . . . . . . . . . . . 21
   8.  Security Considerations  . . . . . . . . . . . . . . . . . . . 22
   9.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 23
     9.1.  Content-type registration for
           'application/lostsync+xml' . . . . . . . . . . . . . . . . 23
     9.2.  LoST Sync Relax NG Schema Registration . . . . . . . . . . 24
     9.3.  LoST Synchronization Namespace Registration  . . . . . . . 24
   10. Acknowledgments  . . . . . . . . . . . . . . . . . . . . . . . 26
   11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 27
     11.1. Normative References . . . . . . . . . . . . . . . . . . . 27
     11.2. Informative References . . . . . . . . . . . . . . . . . . 27
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 28























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1.  Introduction

   The LoST (Location-to-Service Translation) protocol [RFC5222] maps
   service identifiers and geodetic or civic location information to
   service URIs.  The main data structure, the <mapping> element, used
   for encapsulating information about service boundaries is defined in
   the LoST protocol specification and circumscribes the region within
   which all locations map to the same service Uniform Resource
   Identifier (URI) or set of URIs for a given service.

   This mechanism is designed for the exchange of authoritative
   <mapping> elements between two entities (the LoST Sync source and the
   LoST Sync destination).

   The LoST Sync mechanism can, for example, be used in the LoST
   architecture, as specified in the [RFC5582].  There, LoST servers act
   in different roles that cooperate to provide an ubiquitous, globally
   scalable and resilient mapping service.  In the LoST mapping
   architecture, LoST servers can peer, i.e., have an on-going data
   exchange relationship.  Peering relationships are set up manually,
   based on local policies.  A LoST server may peer with any number of
   other LoST servers.  Forest guides peer with other forest guides;
   authoritative mapping servers peer with forest guides and other
   authoritative servers, either in the same cluster or above or below
   them in the tree.  Authoritative mapping servers push coverage
   regions "up" the tree, i.e., from child nodes to parent nodes.  The
   child informs the parent of the geospatial or civic region that it
   covers for a specific service.

   Consider a hypothetical deployent of LoST in two countries, we call
   them Austria and Finland.  Austria, in our example, runs three
   authoritative LoST servers labeled as 'East', 'West' and 'Vienna'
   whereby the former two cover the entire country expect for Vienna,
   which is covered by a separate LoST server.  There may be other
   caching LoST servers run by ISPs, universities, and VSPs but they are
   not relevant for this illustration.  Finland, on the other hand,
   decided to only deploy a single LoST server that also acts as a
   Forest Guide.  For this simplistic illustration we assume that only
   one service is available, namely 'urn:service:sos' since otherwise
   the number of stored mappings would have to be multiplied by the
   number of used services.

   Figure 1 shows the example deployment.








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                      +---LoST-Sync-->\\     //<--LoST-Sync----+
                      |                 -----                  |
                      |                                        |
                      \/                                       \/
                    -----                                     -----
                  //     \\                                 //     \\
                 /         \                               /         \
                |  Forest   |                             |   Forest  |
                |  Guide    |                             |   Guide   |
                |  Austria  |                             |   Finland
                 \         /                               \         /
       +--------->\\     //<--------+                       \\     //
       |            -----           |                         -----
       |             /\             |                           |
     LoST            |             LoST                     //------\\
     Sync           LoST           Sync                    |Co-Located|
       |            Sync            |                      |   LoST   |
       \/            |              \/                     | Server   |
    //----\\         \/          //----\\                   \\------//
   |  LoST  |     //----\\      |  LoST  |
   | Server |    |  LoST  |     | Server |
   | (East) |    | Server |     |(Vienna)|
    \\----//     | (West) |      \\----//
                  \\----//

                     Figure 1: LoST Deployment Example

   The configuration of these nodes would therefore be as follows:

   Forest Guide Austria:  This forest guide would contain mappings for
      the three authoritative LoST servers (East, West and Vienna)
      describing what area they are responsible for.  Note that each
      mapping would contain a service URN and these mappings point to
      LoST servers rather than to PSAPs or ESRPs.

   LoST Server 'East':  This LoST server would contain all the mappings
      to PSAPs covering one half of the country.

      Additionally, the LoST server aggregates all the information it
      has and provides an abstracted view towards the Forest Guide
      indicating that it is responsible for a certain area (for a given
      service, and for a given location profile).  Such a mapping would
      have the following structure:








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   <?xml version="1.0" encoding="UTF-8"?>
   <mapping
       xmlns="urn:ietf:params:xml:ns:lost1"
       xmlns:gml="http://www.opengis.net/gml"
       expires="2009-01-01T01:44:33Z"
       lastUpdated="2009-12-01T01:00:00Z"
       source="east-austria.lost-example.com"
       sourceId="e8b05a41d8d1415b80f2cdbb96ccf109">
       <displayName xml:lang="en">LoST Server 'East' </displayName>
       <service>urn:service:sos</service>
       <serviceBoundary profile="geodetic-2d">
           <gml:Polygon srsName="urn:ogc:def::crs:EPSG::4326">
               <gml:exterior>
                   <gml:LinearRing>
                       <gml:pos> ... </gml:pos>
                       ..... list of coordinates for
                       boundary of LoST server 'East'
                       <gml:pos> ... </gml:pos>
                   </gml:LinearRing>
               </gml:exterior>
           </gml:Polygon>
       </serviceBoundary>
       <uri/>
   </mapping>

                Figure 2: Forest Guide Austria Mapping Example

      As it can be seen in this example there the <uri> element is left
      empty and the 'source' attribute is used to indicate the identity
      of the LoST server, namely "east-austria.lost-example.com".

      The above-shown mapping is what is the LoST server "east-
      austria.lost-example.com" provides to the Austrian Forest Guide.

   LoST Server 'West':  This LoST server would contain all the mappings
      to PSAPs covering the other half of the country.

   LoST Server 'Vienna':  This LoST server would contain all the
      mappings to PSAPs in the area of Vienna.

   Forest Guide Finland:  In our example we assume that Finland would
      deploy a single ESRP for the entire country as their IP-based
      emergency services solution.  There is only a single LoST server
      and it is co-located with the Forest Guide, as shown in Figure 1.
      The mapping data this FG would distribute via LoST sync is shown
      in Figure 3.





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   <?xml version="1.0" encoding="UTF-8"?>
   <mapping xmlns="urn:ietf:params:xml:ns:lost1"
       expires="2007-01-01T01:44:33Z"
       lastUpdated="2006-11-01T01:00:00Z"
       source="finland.lost-example.com"
       sourceId="7e3f40b098c711dbb6060800200c9a66">
       <displayName xml:lang="en"> Finland ESRP </displayName>
       <service>urn:service:sos</service>
       <serviceBoundary profile="civic">
           <civicAddress
               xmlns="urn:ietf:params:xml:ns:pidf:geopriv10:civicAddr">
               <country>FI</country>
           </civicAddress>
       </serviceBoundary>
       <uri/>
   </mapping>

                Figure 3: Forest Guide Finland Mapping Example

      An example mapping stored at the co-located LoST server is shown
      in Figure 4.

   <?xml version="1.0" encoding="UTF-8"?>
   <mapping xmlns="urn:ietf:params:xml:ns:lost1"
       expires="2007-01-01T01:44:33Z"
       lastUpdated="2006-11-01T01:00:00Z"
       source="finland.lost-example.com"
       sourceId="7e3f40b098c711dbb6060800200c9a66">
       <displayName xml:lang="en"> Finland ESRP </displayName>
       <service>urn:service:sos</service>
       <serviceBoundary profile="civic">
           <civicAddress
               xmlns="urn:ietf:params:xml:ns:pidf:geopriv10:civicAddr">
               <country>FI</country>
           </civicAddress>
       </serviceBoundary>
       <uri>sip:esrp@finland-example.com</uri>
       <uri>xmpp:esrp@finland-example.com</uri>
       <serviceNumber>112</serviceNumber>
   </mapping>

       Figure 4: Forest Guide Finland / Co-Located LoST Server Mapping
                                   Example

   The LoST sync mechanism described in this document could be run
   between the two Forest Guides.  Thereby, the three mappings stored in
   the Austria FG are sent to the FG Finland and a single mapping in the
   FG Finland is sent to the FG Austria.  Additionally, the three



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   Austrian LoST servers could utilize LoST sync to inform the Austrian
   FG about their boundaries.  These three authoritative LoST servers in
   Austria would be responsible to maintain their own mapping
   information.  Since the amount of data being exchanged is small and
   the expected rate of change is low the nodes are configured to always
   exchange all their mapping information whenever a change happens.

   This document defines two types of exchanges and those are best
   described by the exchange between two nodes as shown in Figure 5 and
   Figure 6.  The protocol exchange always runs between a LoST Sync
   source and a LoST Sync destination.  Node A in the examples of
   Figure 5 and Figure 6 has mappings that Node B is going to retrieve.
   Node A acts as the source for the data and Node B is the destination.

   The <getMappingsRequest> request allows a LoST Sync source to request
   mappings from a LoST Sync destination.

      +---------+                   +---------+
      | Node B  |                   | Node A  |
      | acting  |                   | acting  |
      | as      |                   | as      |
      | LoST    |                   | LoST    |
      | Sync    |                   | Sync    |
      | Dest.   |                   | Source  |
      +---------+                   +---------+
          |                              |
          |                              |
          |                              |
          | <getMappingsRequest>         |
          |----------------------------->|
          |                              |
          | <getMappingsResponse>        |
          |<-----------------------------|
          |                              |
          |                              |
          |                              |

    Figure 5: Querying for Mappings with a <getMappingsRequest> Message

   Note that in the exchange illustrated in Figure 5 Node B issuing the
   first request and plays the role of the HTTP/HTTPS client (with HTTP
   as selected transport) and Node A plays the role of the HTTP/HTTPS
   server.

   The <pushMappingsRequest> exchange allows a LoST Sync source to push
   mappings to LoST Sync destination.  The assumption is being made that
   Node A and B have previously been configured in a way that they push
   mappings in such a fashion and that Node A maintains state about the



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   mappings have to be pushed to Node B. No subscribe mechanism is
   defined in this document that would allow Node B to tell Node A about
   what mappings it is interested nor a mechanism for learning to which
   entities mappings have to be pushed.

       +---------+                   +---------+
       | Node A  |                   | Node B  |
       | acting  |                   | acting  |
       | as      |                   | as      |
       | LoST    |                   | LoST    |
       | Sync    |                   | Sync    |
       | Source  |                   | Dest.   |
       +---------+                   +---------+
           |                              |
           |                              |
           |                              |
           | <pushMappingsRequest>        |
           |----------------------------->|
           |                              |
           | <pushMappingsResponse>       |
           |<-----------------------------|
           |                              |
           |                              |
           |                              |

      Figure 6: Pushing Mappings with a <pushMappingsRequest> Message

   Note that in the exchange illustrated in Figure 6 Node A issuing the
   first request and plays the role of the HTTP/HTTPS client (with HTTP
   as selected transport) and Node B plays the role of the HTTP/HTTPS
   server.




















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2.  Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC 2119 [RFC2119].

   This document reuses terminology introduced by the mapping
   architecture document [RFC5582].

   Throughout this document we use the term LoST Sync source and LoST
   Sync destination to denote the protocol end points of the exchange.
   The protocol is referred as LoST Sync within the text.







































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3.  Querying for Mappings with a <getMappingsRequest> /
    <getMappingsResponse> Exchange

3.1.  Behavior of the LoST Sync Destination

   A LoST Sync destination has two ways to retrieve mapping elements
   from a LoST Sync source.

   1.  A mechanisms that is suitable when no mappings are available on
       the LoST Sync destination is to submit an empty
       <getMappingsRequest> message, as shown in Figure 7.  The intent
       by the LoST Sync destination thereby is to retrieve all mappings
       from the LoST Sync source.  Note that the request does not
       propagate further to other nodes.

   2.  In case a LoST Sync destination node has already obtained
       mappings in previous exchanges then it may want to check whether
       these mappings have been updated in the meanwhile.  The policy
       when to poll for updated mapping information is outside the scope
       of this document.  The <getMappingsRequest> message with one or
       multiple <exists> child element(s) allows to reduce the number of
       returned mappings to those that have been updated and also to
       those that are missing.

   In response to the <getMappingsRequest> message the LoST Sync
   destination waits for the <getMappingsResponse> message.  In case of
   a successful response the LoST Sync destination stores the received
   mappings and determines which mappings to replace.

3.2.  Behavior of the LoST Sync Source

   When a LoST Sync source receives an empty <getMappingsRequest>
   message then all locally available mappings MUST be returned.

   When a LoST Sync source receives a <getMappingsRequest> message with
   one or multiple <exists> child element(s) then it MUST consult with
   the local mapping database to determine whether any of the mappings
   of the client is stale and whether there are mappings locally that
   the client does not yet have.  The former can be determined by
   finding mappings corresponding to the 'source' and 'sourceID'
   attribut where a mapping with a more recent lastUpdated date exists.

   Processing a <getMappingsRequest> message MAY lead to a successful
   response in the form of a <getMappingsResponse> or an <errors>
   message.  Only the <badRequest>, <forbidden>, <internalError>,
   <serverTimeout> errors, defined in [RFC5222], are utilized by this
   specification.  Neither the <redirect> nor the <warnings> messages
   are reused by this message.



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3.3.  Examples

   The first example shows an empty <getMappingsRequest> message that
   would retrieve all locally stored mappings at the LoST Sync source.

   <?xml version="1.0" encoding="UTF-8"?>
   <getMappingsRequest xmlns="urn:ietf:params:xml:ns:lostsync1"/>

          Figure 7: Example of empty <getMappingsRequest> message

   A further example request is shown in Figure 8 and the corresponding
   response is depicted in Figure 9.  In this example a request is made
   for a specific mapping (with source="authoritative.bar.example" and
   sourceId="7e3f40b098c711dbb6060800200c9a66") that is more recent than
   "2006-11-01T01:00:00Z" as well as any missing mapping.


   <?xml version="1.0" encoding="UTF-8"?>
   <getMappingsRequest xmlns="urn:ietf:params:xml:ns:lostsync1">
       <exists>
           <mapping-fingerprint source="authoritative.bar.example"
           sourceId="7e3f40b098c711dbb6060800200c9a66"
           lastUpdated="2006-11-01T01:00:00Z">
           </mapping-fingerprint>
       </exists>
   </getMappingsRequest>


              Figure 8: Example <getMappingsRequest> Message

   The response to the above request is shown in Figure 9.  A more
   recent mapping was available with the identification of
   source="authoritative.bar.example" and
   sourceId="7e3f40b098c711dbb6060800200c9a66".  Only one mapping that
   matched source="authoritative.foo.example" was found and returned.


   <?xml version="1.0" encoding="UTF-8"?>
   <sync:getMappingsResponse
       xmlns:sync="urn:ietf:params:xml:ns:lostsync1"
       xmlns="urn:ietf:params:xml:ns:lost1"
       xmlns:gml="http://www.opengis.net/gml">

           <mapping source="authoritative.bar.example"
               sourceId="7e3f40b098c711dbb6060800200c9a66"
               lastUpdated="2008-11-26T01:00:00Z"
               expires="2009-12-26T01:00:00Z">
               <displayName xml:lang="en">



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                   Leonia Police Department
               </displayName>
               <service>urn:service:sos.police</service>
               <serviceBoundary
   profile="urn:ietf:params:lost:location-profile:basic-civic">
                   <civicAddress
   xmlns="urn:ietf:params:xml:ns:pidf:geopriv10:civicAddr">
                       <country>US</country>
                       <A1>NJ</A1>
                       <A3>Leonia</A3>
                       <PC>07605</PC>
                   </civicAddress>
               </serviceBoundary>
               <uri>sip:police@leonianj2.example.org</uri>
               <serviceNumber>911</serviceNumber>
           </mapping>

           <mapping expires="2009-01-01T01:44:33Z"
               lastUpdated="2008-11-01T01:00:00Z"
               source="authoritative.foo.example"
               sourceId="7e3f40b098c711dbb606011111111111">
               <displayName xml:lang="en">
                   New York City Police Department
               </displayName>
               <service>urn:service:sos.police</service>
               <serviceBoundary profile="geodetic-2d">
                   <gml:Polygon srsName="urn:ogc:def::crs:EPSG::4326">
                       <gml:exterior>
                           <gml:LinearRing>
                               <gml:pos>37.775 -122.4194</gml:pos>
                               <gml:pos>37.555 -122.4194</gml:pos>
                               <gml:pos>37.555 -122.4264</gml:pos>
                               <gml:pos>37.775 -122.4264</gml:pos>
                               <gml:pos>37.775 -122.4194</gml:pos>
                           </gml:LinearRing>
                       </gml:exterior>
                   </gml:Polygon>
               </serviceBoundary>
               <uri>sip:nypd@example.com</uri>
               <uri>xmpp:nypd@example.com</uri>
               <serviceNumber>911</serviceNumber>
           </mapping>

   </sync:getMappingsResponse>

              Figure 9: Example <getMappingsResponse> Message





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4.  Pushing Mappings via <pushMappings> and <pushMappingsResponse>

4.1.  Behavior of the LoST Sync Source

   When a LoST Sync source obtains new information that is of interest
   to its peers, it may push the new mappings to its peers.
   Configuration settings at both peers decide whether this
   functionality is used and what mappings are pushed to which other
   peers.  New mappings may arrive through various means, such as a
   manual addition to the local mapping database, or through the
   interaction with other entities.  Deleting mappings may also trigger
   a protocol interaction.

   The LoST Sync source SHOULD keep track to which LoST Sync destination
   it has pushed mapping elements.  If it does not keep state
   information then it always has to push the complete data set.  As
   discussed in Section 5.1 of [RFC5222], mapping elements are
   identified by the 'source', 'sourceID' and 'lastUpdated' attributes.
   A mapping is considered the same if these three attributes match.  It
   is RECOMMENDED not to push the same information to the same peer more
   than once.

   A <pushMappings> request sent by a LoST Sync source MUST containing
   one or more <mapping> elements.

   To delete a mapping, the content of the mapping is left empty.  The
   node can delete the mapping from its internal mapping database, but
   has to remember which peers it has distributed this update to.  The
   'expires' attribute is required, but ignored.  If an attempt is made
   to delete a non-existent mapping, the request is silently ignored.

4.2.  Behavior of the LoST Sync Destination

   When a LoST Sync destination receives a <pushMappingsRequest> message
   then a newly received mapping M' MUST replace an existing mapping M
   if all of the following conditions hold:

   1.  M'.source equals M.source

   2.  M'.sourceID' equals M.sourceID

   3.  M'.lastUpdated is greater than M.lastUpdated

   If the received mapping M' does not update any existing mapping M
   then it MUST be added to the local cache as an independent mapping.

   If a <pushMappingsRequest> message with an empty <mapping> element is
   received then a corresponding mapping has to be determined based on



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   the 'source', 'sourceID' and 'lastUpdated' attributes.  If a mapping
   has been found then it MUST be deleted.  If no mapping can be
   identified then an <errors> response MUST be returned that contains
   the <notDeleted> child element.  The <notDeleted> element MAY carry a
   <message> element and MUST contain the <mapping> element(s) that
   caused the error.

   The response to a <pushMappingsRequest> request is a
   <pushMappingsResponse> message.  With this specification, a
   successful response message returns no additional elements, whereas
   an <errors> response is returned in the response message, if the
   request failed.  Only the <badRequest>, <forbidden>, <internalError>
   or <serverTimeout> errors defined in Section 13.1 of [RFC5222], are
   used.  The <redirect> and <warnings> messages are not used for this
   query/response.

   If the set of nodes that are synchronizing their data does not form a
   tree, it is possible that the same information arrives through
   several other nodes.  This is unavoidable, but generally only imposes
   a modest overhead.  (It would be possible to create a spanning tree
   in the same fashion as IP multicast, but the complexity does not seem
   warranted, given the relatively low volume of data.)

4.3.  Example

   An example is shown in Figure 10.  Image a LoST node that obtained
   two new mappings identified as follows:

   o  source="authoritative.example"
      sourceId="7e3f40b098c711dbb6060800200c9a66" lastUpdated="2008-11-
      26T01:00:00Z"

   o  source="authoritative.example"
      sourceId="7e3f40b098c711dbb606011111111111" lastUpdated="2008-11-
      01T01:00:00Z"

   These two mappings have to be added to the peer's mapping database.

   Additionally, the following mapping has to be deleted:

   o  source="nj.us.example" sourceId="123" lastUpdated="2008-11-
      01T01:00:00Z"


   <?xml version="1.0" encoding="UTF-8"?>
   <sync:pushMappings
       xmlns:sync="urn:ietf:params:xml:ns:lostsync1"
       xmlns="urn:ietf:params:xml:ns:lost1"



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       xmlns:gml="http://www.opengis.net/gml">

           <mapping source="authoritative.example"
               sourceId="7e3f40b098c711dbb6060800200c9a66"
               lastUpdated="2008-11-26T01:00:00Z"
               expires="2009-12-26T01:00:00Z">
               <displayName xml:lang="en">
                   Leonia Police Department
               </displayName>
               <service>urn:service:sos.police</service>
               <serviceBoundary
        profile="urn:ietf:params:lost:location-profile:basic-civic">
                   <civicAddress
        xmlns="urn:ietf:params:xml:ns:pidf:geopriv10:civicAddr">
                       <country>US</country>
                       <A1>NJ</A1>
                       <A3>Leonia</A3>
                       <PC>07605</PC>
                   </civicAddress>
               </serviceBoundary>
               <uri>sip:police@leonianj.example.org</uri>
               <serviceNumber>911</serviceNumber>
           </mapping>

           <mapping expires="2009-01-01T01:44:33Z"
               lastUpdated="2008-11-01T01:00:00Z"
               source="authoritative.example"
               sourceId="7e3f40b098c711dbb606011111111111">
               <displayName xml:lang="en">
                   New York City Police Department
               </displayName>
               <service>urn:service:sos.police</service>
               <serviceBoundary profile="geodetic-2d">
                   <gml:Polygon srsName="urn:ogc:def::crs:EPSG::4326">
                       <gml:exterior>
                           <gml:LinearRing>
                               <gml:pos>37.775 -122.4194</gml:pos>
                               <gml:pos>37.555 -122.4194</gml:pos>
                               <gml:pos>37.555 -122.4264</gml:pos>
                               <gml:pos>37.775 -122.4264</gml:pos>
                               <gml:pos>37.775 -122.4194</gml:pos>
                           </gml:LinearRing>
                       </gml:exterior>
                   </gml:Polygon>
               </serviceBoundary>
               <uri>sip:nypd@example.com</uri>
               <uri>xmpp:nypd@example.com</uri>
               <serviceNumber>911</serviceNumber>



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           </mapping>

           <mapping source="nj.us.example"
               sourceId="123"
               lastUpdated="2008-11-01T01:00:00Z"
               expires="2008-11-01T01:00:00Z"/>

   </sync:pushMappings>

             Figure 10: Example <pushMappingsRequest> Message

   In response, the peer performs the necessary operation and updates
   its mapping database.  In particular, it will check whether the other
   peer is authorized to perform the update and whether the elements and
   attributes contain values that it understands.  In our example, a
   positive response is returned as shown in Figure 11.


   <?xml version="1.0" encoding="UTF-8"?>
   <pushMappingsResponse xmlns="urn:ietf:params:xml:ns:lostsync1" />

                 Figure 11: Example <pushMappingsResponse>

   In case that a mapping could not be deleted as requested the
   following error response might be returned instead.

   <?xml version="1.0" encoding="UTF-8"?>
   <errors xmlns="urn:ietf:params:xml:ns:lost1"
       xmlns:sync="urn:ietf:params:xml:ns:lostsync1"
       source="nodeA.example.com">

       <sync:notDeleted
           message="Could not delete the indicated mapping."
           xml:lang="en">

           <mapping source="nj.us.example"
               sourceId="123"
               lastUpdated="2008-11-01T01:00:00Z"
               expires="2008-11-01T01:00:00Z"/>
       </sync:notDeleted>
   </errors>

                    Figure 12: Example <errors> Message








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5.  Transport

   LoST Sync needs an underlying protocol transport mechanism to carry
   requests and responses.  This document defines an XML protocol over
   HTTP and over HTTP-over-TLS.  Client and server developers are
   reminded that full support of RFC 2616 HTTP facilities is expected.
   If clients or servers re-implement HTTP, rather than using available
   servers or client code as a base, careful attention must be paid to
   full interoperability.  Other transport mechanisms are left to future
   documents.  The selection of the transport mechanism will in most
   cases be determined through manual configuration although the usage
   of the U-NAPTR application defined in the LoST specification is
   possible.  In protocols that support content type indication, LoST
   Sync uses the media type application/lostsync+xml.

   When using HTTP [RFC2616] and HTTP-over-TLS [RFC2818], LoST Sync
   messages use the HTTP POST method.  The HTTP request MUST use the
   Cache-Control response directive "no-cache" to HTTP-level caching
   even by caches that have been configured to return stale responses to
   client requests.

   All LoST Sync responses, including those indicating a LoST warning or
   error, are carried in 2xx responses, typically 200 (OK).  Other 2xx
   responses, in particular 203 (Non-authoritative information) may be
   returned by HTTP caches that disregard the caching instructions. 3xx,
   4xx and 5xx HTTP response codes indicates that the HTTP request
   itself failed or was redirected; these responses do not contain any
   LoST Sync XML elements.























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6.  RelaxNG


   <?xml version="1.0" encoding="utf-8"?>

        <grammar ns="urn:ietf:params:xml:ns:lostsync1"
        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">

            <include href="lost.rng"/>

            <start combine="choice">

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

                <choice>
                    <ref name="pushMappings"/>
                    <ref name="pushMappingsResponse"/>
                    <ref name="getMappingsRequest"/>
                    <ref name="getMappingsResponse"/>
                </choice>
            </start>


            <define name="pushMappings">
                <element name="pushMappings">
                        <oneOrMore>
                            <ref name="mapping"/>
                        </oneOrMore>

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

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

             <define name="getMappingsRequest">
                  <element name="getMappingsRequest">
                    <choice>
                         <ref name="exists"></ref>
                         <ref name="extensionPoint"/>
                    </choice>



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                </element>
            </define>

             <define name="exists">
                  <element name="exists">
                       <oneOrMore>
                            <element name="mapping-fingerprint">
                                 <attribute name="source">
                                      <data type="token"/>
                                 </attribute>
                                 <attribute name="sourceId">
                                      <data type="token"/>
                                 </attribute>
                                 <attribute name="lastUpdated">
                                      <data type="dateTime"/>
                                 </attribute>
                                 <ref name="extensionPoint"/>
                            </element>
                       </oneOrMore>
                  </element>
             </define>

            <define name="getMappingsResponse">
                <element name="getMappingsResponse">
                        <oneOrMore>
                            <ref name="mapping"/>
                        </oneOrMore>
                    <ref name="extensionPoint"/>
                </element>
            </define>

             <!-- error messages -->

             <define name="notDeleted">
                  <element name="notDeleted">
                       <ref name="basicException"/>
                       <oneOrMore>
                            <ref name="mapping"/>
                       </oneOrMore>
                  </element>
             </define>
        </grammar>









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7.  Operational Considerations

   When different LoST servers use the mechanism described in this
   document to synchronize their mapping data then it is important to
   ensure that loops are avoided.  The example shown in Figure 13 with
   three LoST servers A, B and C (each of them acts as a sync source and
   a sync destination) illustrates the challenge in more detail.  A and
   B synchronize data between each other; the same is true for A and C,
   and B and C, respectively.


        A -------- B
         \        /
          \      /
           \    /
            \  /
             C

             Figure 13: Synchronization Configuration Example

   Now, imagine that server A adds a new mapping.  This mapping is
   uniquely identified by the combination of "source", "sourceid" and
   "last updated".  Assume that A would push this new mapping to B and
   C. When B obtained this new mapping it would find out that it has to
   distribute it to its peer C. C would also want to distribute the
   mapping to B (and vice versa).  If the originally mapping with the
   "source", "sourceid" and "last updated" is not modified by either B
   or C then these two servers would recognize that they already possess
   the mapping and can ignore the update.

   It is important that implementations MUST NOT modify mappings they
   receive.  An entity acting maliciously would, however, intentially
   modify mappings or inject bogus mappings.  To avoid the possibility
   of an untrustworthy member claiming a coverage region that it is not
   authorized for, any node introducing a new service boundary MUST sign
   the object by protecting the data with an XML digital signature
   [W3C.REC-xmldsig-core-20020212].  A recipient MUST verify that the
   signing entity is indeed authorized to speak for that region.
   Determining who can speak for a particular region is inherently
   difficult unless there is a small set of authorizing entities that
   participants in the mapping architecture can trust.  Receiving
   systems should be particularly suspicious if an existing coverage
   region is replaced with a new one with a new mapping address.  With
   this mechanism it is also possible to avoid the distribution of
   mappings that have been modified by servers forwarding mappings as
   part of the synchronization procedure.





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8.  Security Considerations

   This document defines a protocol for exchange of mapping information
   between two entities.  Hence, the operations described in this
   document involve mutually-trusting LoST nodes.  These nodes need to
   authenticate each other, using mechanisms such as HTTP Digest
   [RFC2617], HTTP Basic [RFC2617] over TLS [RFC5246] or TLS client and
   server certificates.  Manual configuration for the setup of the
   peering relationships is required and hence the choice of the
   security mechanisms used between the two entities is a deployment
   specific decision.  In any case, it MUST be ensured that the two end
   points are authenticated and that a secure communication channel
   (i.e., an integrity protected exchange of data with the help of the
   TLS Record Layer) is setup to avoid the possibility of injecting
   bogus mappings.  If an adversary manages to inject false mappings
   then this could lead to denial of service attacks.  If the mapping
   data contains a URL that does not exist then emergency services for
   the indicated area are not reachable.  If all mapping data contains
   URLs that point to a single PSAP (rather than a large number) then
   this PSAP is likely to experience overload conditions.  If the
   mapping data contains a URL that points to a server controlled by the
   adversary itself then it might impersonate PSAPs.





























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9.  IANA Considerations

9.1.  Content-type registration for 'application/lostsync+xml'

   This specification requests the registration of a new MIME type
   according to the procedures of RFC 4288 [RFC4288] and guidelines in
   RFC 3023 [RFC3023].

   MIME media type name:  application


   MIME subtype name:  lostsync+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 [RFC3023], Section 3.2.


   Security considerations:  This content type is designed to carry LoST
      Syncronization protocol payloads.


   Interoperability considerations:  None



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


   Applications which use this media type:  Emergency and Location-based
      Systems


   Additional information:







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      Magic Number:  None


      File Extension:  .lostsyncxml


      Macintosh file type code:  'TEXT'


   Personal and email address for further information:  Hannes
      Tschofenig, Hannes.Tschofenig@nsn.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>

9.2.  LoST Sync Relax NG Schema Registration

   URI:  urn:ietf:params:xml:schema:lostsync1

   Registrant Contact:  IETF ECRIT Working Group, Hannes Tschofenig
      (Hannes.Tschofenig@gmx.net).

   Relax NG Schema:  The Relax NG schema to be registered is contained
      in Section 6.

9.3.  LoST Synchronization Namespace Registration

   URI:  urn:ietf:params:xml:ns:lostsync1

   Registrant Contact:  IETF ECRIT Working Group, Hannes Tschofenig
      (Hannes.Tschofenig@gmx.net).

   XML:







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   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 Synchronization Namespace</title>
   </head>
   <body>
     <h1>Namespace for LoST server synchronization</h1>
     <h2>urn:ietf:params:xml:ns:lost1:sync</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































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10.  Acknowledgments

   Robins George, Cullen Jennings, Karl Heinz Wolf, Richard Barnes,
   Mayutan Arumaithurai, Alexander Mayrhofer, and Andrew Newton provided
   helpful input.  Jari Urpalainen assisted with the Relax NG schema.
   We would also like to thank our PROTO shepherd Roger Marshall for his
   help with the document.

   We would like to particularly thank Andrew Newton for his timely and
   valuable review of the XML-related content.









































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11.  References

11.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC2616]  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.

   [RFC2617]  Franks, J., Hallam-Baker, P., Hostetler, J., Lawrence, S.,
              Leach, P., Luotonen, A., and L. Stewart, "HTTP
              Authentication: Basic and Digest Access Authentication",
              RFC 2617, June 1999.

   [RFC2818]  Rescorla, E., "HTTP Over TLS", RFC 2818, May 2000.

   [RFC3023]  Murata, M., St. Laurent, S., and D. Kohn, "XML Media
              Types", RFC 3023, January 2001.

   [RFC4288]  Freed, N. and J. Klensin, "Media Type Specifications and
              Registration Procedures", BCP 13, RFC 4288, December 2005.

   [RFC5222]  Hardie, T., Newton, A., Schulzrinne, H., and H.
              Tschofenig, "LoST: A Location-to-Service Translation
              Protocol", RFC 5222, August 2008.

   [RFC5246]  Dierks, T. and E. Rescorla, "The Transport Layer Security
              (TLS) Protocol Version 1.2", RFC 5246, August 2008.

   [W3C.REC-xmldsig-core-20020212]
              Solo, D., Eastlake, D., and J. Reagle, "XML-Signature
              Syntax and Processing", World Wide Web Consortium
              FirstEdition REC-xmldsig-core-20020212, February 2002,
              <http://www.w3.org/TR/2002/REC-xmldsig-core-20020212>.

11.2.  Informative References

   [RFC5582]  Schulzrinne, H., "Location-to-URL Mapping Architecture and
              Framework", RFC 5582, September 2009.










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Authors' Addresses

   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
   Nokia Siemens Networks
   Linnoitustie 6
   Espoo  02600
   Finland

   Phone: +358 (50) 4871445
   Email: Hannes.Tschofenig@gmx.net
   URI:   http://www.tschofenig.priv.at




























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