ECRIT                                                     H. Schulzrinne
Internet-Draft                                               Columbia U.
Intended status: Standards Track                       November 26, 2006
Expires: May 30, 2007


      Synchronizing Location-to-Service Translation (LoST) Servers
                draft-schulzrinne-ecrit-lost-sync-00.txt

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Copyright Notice

   Copyright (C) The Internet Society (2006).

Abstract

   The LoST (Location-to-Service Translation) protocol is used to map
   locations to service URLs.  This document defines a set of LoST
   extensions that allow LoST servers to synchronize their lists of
   mappings.







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Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Terminology  . . . . . . . . . . . . . . . . . . . . . . . . .  3
   3.  Distributing Mappings via <pushMappingsRequest>  . . . . . . .  3
   4.  Synchronizing Mapping Stores via <getMappingsRequest> and
       <getMappingsResponse>  . . . . . . . . . . . . . . . . . . . .  6
   5.  Security Considerations  . . . . . . . . . . . . . . . . . . .  7
   6.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . .  8
     6.1.  LoST Synchronization Namespace Registration  . . . . . . .  8
   7.  Acknowledgments  . . . . . . . . . . . . . . . . . . . . . . .  8
   8.  RelaxNG  . . . . . . . . . . . . . . . . . . . . . . . . . . .  8
   9.  References . . . . . . . . . . . . . . . . . . . . . . . . . .  9
     9.1.  Normative References . . . . . . . . . . . . . . . . . . .  9
     9.2.  Informative References . . . . . . . . . . . . . . . . . .  9
   Author's Address . . . . . . . . . . . . . . . . . . . . . . . . .  9
   Intellectual Property and Copyright Statements . . . . . . . . . . 10


































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1.  Introduction

   The LoST (Location-to-Service Translation) protocol [2] maps
   geographic locations to service URLs.  As specified in the LoST
   architecture description [3], there are a variety of LoST servers
   that cooperate to provide a global, scalable and resilient mapping
   service.  The LoST protocol specification only describes the protocol
   used for individual seeker-originated queries.  This document adds
   LoST operations that allow forest guides, resolver clusters and
   authoritative servers to synchronize their database of mappings.

   In the LoST architecture, servers can peer, i.e., have an on-going
   data exchange relationship.  Peering relationships are set up
   manually, based on local policies.  A server can peer with any number
   of other servers.  Forest guides peer with other forest guides;
   resolvers peer with forest guides and other resolvers (in the same
   cluster); authoritative mapping servers peer with forest guides and
   other authoritative servers, either in the same cluster or above or
   below them in the tree.  If the type of LoST role does not matter, we
   refer to LoST protocol participants as LoST nodes.

   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.  The service URL
   contains the LoST URL of the child node.

   This extension defines two new requests, <pushMappingsRequest> and
   <getMappingsRequest>, that allow peering servers to exchange
   mappings.  These requests are used for all peering relationships and
   always contain mapping entries, but naturally the content of the data
   exchanged differs.


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 [1].

   This document reuses terminology introduced by the mapping
   architecture document [3].


3.  Distributing Mappings via <pushMappingsRequest>

   When a LoST node obtains new information that is of interest to its
   peers, it pushes the new mappings to its peers.  This information
   might arrive through non-LoST means, such as a manual addition to the



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   local mappings database, or through another LoST node, via a
   <pushMappings> request or a <getMappingsResponse> described later.
   Mappings in that request replace existing mappings with the same 'id'
   parameter and a more recent 'created' parameter.  (Enforcing the
   latter avoids that a node that wakes up injects outdated information
   into the system.)

   Each peer keeps track of which peer it has exchanged which mapping
   elements with.  Mapping elements are identified by the 'id' and 'tag'
   parameters.  A mapping is considered the same if these two attributes
   match.  Nodes never push the same information to the same peer twice.

   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
   mapping is identified only by the 'sourceId' and 'source' parameters;
   the other parameters are ignored if present.  In other words, the
   delete operation affects all versions of a mapping.

   The response to <pushMappingsRequest> is <pushMappingsResponse>.  It
   only contains <errors> elements if there is an error condition.  Only
   the .... errors are defined (TBD).

   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, giving the relatively low volume of data.)

   An example is shown in Figure 1.  In the example, the last mapping,
   with source lost:nj.us.example and mapping ID 'englewood', is being
   removed.


   <?xml version="1.0" encoding="UTF-8"?>
   <pushMappingsRequest xmlns="urn:ietf:params:xml:ns:lost1:sync">
   <mappings>
     <mapping sourceId="lost:leonia.nj.us.example"
       version="1" lastUpdated="2006-11-26T01:00:00Z"
       timeToLive="2007-12-26T01:00:00Z">
       <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



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           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="2007-01-01T01:44:33Z"
       lastUpdated="2006-11-01T01:00:00Z"
       source="lost:authoritative.example"
       sourceId="abc123" version="1">
       <displayName xml:lang="en">
         New York City Police Department
       </displayName>
       <service>urn:service:sos.police</service>
       <serviceBoundary profile="geodetic-2d">
         <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>
     </mapping>

     <mapping source="lost:nj.us.example" sourceId="englewood"/>

   </mappings>
   </pushMappingsRequest>

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





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      Figure 1: Example pushMappingsRequest and pushMappingsResponse


4.  Synchronizing Mapping Stores via <getMappingsRequest> and
    <getMappingsResponse>

   While the <pushMappingsRequest> request allows new mappings to
   propagate, it does not allow a newly-arriving node to acquire all
   mappings maintained by another node.  Thus, <getMappingsRequest> and
   <getMappingsResponse> are used to synchronize two mapping stores.  A
   LoST node wanting to synchronize its mapping store with another node
   issues a <getMappingsRequest>, containing an enumeration of the
   current mapping source identifiers, tags and versions.  The recipient
   of the request compares that list to its own list of mappings.  It
   then returns an unordered set of mappings that are more recent than
   the ones identified in the <getMappingsRequest>.  It also returns any
   mappings that it knows about that are not contained in the list at
   all.  Thus, a querier can get the complete listing of mappings by
   omitting 'm' elements altogether.

   An example request and response is shown in Figure 2






























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   <?xml version="1.0" encoding="UTF-8"?>
   <getMappingsRequest xmlns="urn:ietf:params:xml:ns:lost1:sync">
     <m sourceId="lost:authoritative.example"
       sourceId="abc123" version="1" />
   </getMappingsRequest>

   <?xml version="1.0" encoding="UTF-8"?>
   <getMappingsResponse xmlns="urn:ietf:params:xml:ns:lost1:sync"
     xmlns:p2="http://www.opengis.net/gml">
     <mappings>
       <mapping
        expires="2007-01-26T01:44:33Z"
        lastUpdated="2006-11-26T01:00:00Z"
        source="lost:authoritative.example"
         sourceId="abc123" version="2">
         <displayName xml:lang="en">
           New York City Police Department
         </displayName>
         <service>urn:service:sos.police</service>
         <serviceBoundary profile="geodetic-2d">
           <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@ny.example.com</uri>
         <uri>xmpp:nypd@example.com</uri>
         <serviceNumber>911</serviceNumber>
       </mapping>
     </mappings>
   </getMappingsResponse>

       Figure 2: Example getMappingsRequest and getMappingsResponse


5.  Security Considerations

   The LoST security considerations are discussed in [2].  The
   operations described in this document involve mutually-trusting LoST
   nodes.  These nodes need to authenticate each other, using mechanisms
   such as HTTP Digest, HTTP Basic over TLS or TLS client and server



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   certificates.  Nodes implementing LoST MUST implement HTTP Basic
   authentication over TLS and MAY implement other authentication
   mechanisms.


6.  IANA Considerations

6.1.  LoST Synchronization Namespace Registration

   URI:  urn:ietf:params:xml:ns:lost1:sync
   Registrant Contact:  IETF ECRIT Working Group, Henning Schulzrinne
      (hgs@cs.columbia.edu).
   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 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


7.  Acknowledgments

   Your name here.


8.  RelaxNG

   TBD


9.  References




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9.1.  Normative References

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

   [2]  Hardie, T., "LoST: A Location-to-Service Translation Protocol",
        draft-ietf-ecrit-lost-02 (work in progress), October 2006.

9.2.  Informative References

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


Author's Address

   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
























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