ECRIT                                                     H. Schulzrinne
Internet-Draft                                               Columbia U.
Intended status: Standards Track                           H. Tschofenig
Expires: May 6, 2009                                                 NSN
                                                        November 2, 2008


      Synchronizing Location-to-Service Translation (LoST) Servers
                     draft-ietf-ecrit-lost-sync-01

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Copyright Notice

   Copyright (C) The IETF Trust (2008).

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 <pushMappings> and
       <pushMappingsResponse> . . . . . . . . . . . . . . . . . . . .  4
   4.  Synchronizing Mapping Stores via <getMappings> and
       <getMappingsResponse>  . . . . . . . . . . . . . . . . . . . .  6
   5.  Security Considerations  . . . . . . . . . . . . . . . . . . .  8
   6.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . .  8
     6.1.  LoST Synchronization Namespace Registration  . . . . . . .  8
   7.  Acknowledgments  . . . . . . . . . . . . . . . . . . . . . . .  9
   8.  RelaxNG  . . . . . . . . . . . . . . . . . . . . . . . . . . .  9
   9.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 11
     9.1.  Normative References . . . . . . . . . . . . . . . . . . . 11
     9.2.  Informative References . . . . . . . . . . . . . . . . . . 12
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 12
   Intellectual Property and Copyright Statements . . . . . . . . . . 13

































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1.  Introduction

   The LoST (Location-to-Service Translation) protocol [RFC5222] maps
   geographic locations to service URLs.  As specified in the LoST
   architecture description [I-D.ietf-ecrit-mapping-arch], 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 coverage regions of different authoritative servers can overlap.
   This should only happen if the authoritative servers are
   misconfigured or if there is a political dispute that involves
   competing claims for the same region.  A server MUST detect such
   colliding claims and implement a policy to resolve the collision,
   either through an automated policy mechanism or manual intervention.

   This extension defines two new requests, <pushMappings> and
   <getMappings>, 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. <pushMappings> allows a peer to send newer
   mappings to another peer; with a <getMappings> query, a node can
   obtain mappings that are newer than those it already has.


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].




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   This document reuses terminology introduced by the mapping
   architecture document [I-D.ietf-ecrit-mapping-arch].


3.  Distributing Mappings via <pushMappings> and <pushMappingsResponse>

   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
   local mappings database, or through another LoST node, via a
   <pushMappings> request or a <getMappingsResponse> described later.

   Each peer keeps track of which peer it has exchanged which mapping
   elements with.  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.  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
   'expires' attribute is required, but ignored.  If the querier
   attempts to remove a non-existent mapping, the query is silently
   ignored.

   The response to a <pushMappings> request is a <pushMappingsResponse>,
   currently without additional elements, if the request was successful
   or an <errors> response if the request failed.  Only the
   <badRequest>, <forbidden>, <internalError> or <serverTimeout> errors
   defined in Section 13.1 of [RFC5222] are used.  Neither the
   <redirect> nor the <warnings> messages are used for this query.

   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.)

   A newly received mapping M' replaces an existing mapping M if all of
   the following conditions hold:
   1.  M'.source equals M.source, ignoring case
   2.  M'.sourceID' equals M.sourceID, ignoring case
   3.  M'.lastUpdated greater or equal to M.lastUpdated

   An example is shown in Figure 1.  In the example, the mappings with
   sourceId 7e3f40b098c711dbb6060800200c9a66 sourceId



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   7e3f40b098c711dbb606011111111111 are added by the recipient.  The
   last mapping, with source 'nj.us.example' and sourceID 'englewood',
   is removed.


   <?xml version="1.0" encoding="UTF-8"?>
   <sync:pushMappings
     xmlns:sync="urn:ietf:params:xml:ns:lost-sync1"
     xmlns:p2="http://www.opengis.net/gml"
     xmlns="urn:ietf:params:xml:ns:lost1:sync">
   <sync:mappings>
     <mapping source="leonia.nj.us.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 source="authoritative.example"
       sourceId="7e3f40b098c711dbb606011111111111"
       expires="2009-01-01T01:44:33Z"
       lastUpdated="2008-11-01T01:00:00Z">
       <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>



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

   </sync:mappings>
   </sync:pushMappings>

                     Figure 1: Example <pushMappings>

   In response, the peer performs the necessary operation and updates
   its mapping database.  In particular, it will check whether the
   querier 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 2.



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


                 Figure 2: Example <pushMappingsResponse>


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

   Instead of pushing mappings to another LoST node, a LoST client can
   declare all the mappings it has, via a sequence of <m> elements in
   the <getMappings>, and then obtain any missing or outdated mappings
   in the <getMappingsResponse>.  Specifying the existing mappings
   avoids retransmitting data that the querier has already stored.

   If the <getMappings> query has no attributes, the
   <getMappingsResponse> contains all mappings that are either newer



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   than the <m> elements or not contained in the sequence of <m>
   elements.  The querier can restrict the mappings returned by adding
   'source' and 'sourceId' attributes to the <getMappings> query.  Only
   the combinations
   o  source
   o  source, sourceID
   are allowed.

   If the 'source' attribute is specified, only mappings with that
   particular source attribute are considered.  Similarly, the
   'sourceId' attribute restricts mappings to those matching the
   attribute from the 'source' named.

   <m> elements MUST only contain the 'source', 'sourceId' and
   'lastUpdated' attributes that are not contained in the <GetMappings>
   element itself.  Extra attributes that do not match the values of the
   <getMappings> attributes are silently ignored.  (This structure
   reduces the query size for the common case that there are many
   mappings from the same source.)

   Processing a <getMappings> message may lead to a successful response
   in the form of a &tl;getMappingsResponse> or an <errors> message.
   Only the <badRequest>, <forbidden>, <internalError>, <serverTimeout>
   errors defined in [RFC5222] are used.  Neither the <redirect> nor the
   <warnings> messages are used for this query.

   An example request is shown in Figure 3, the corresponding response
   in Figure 4.  In the example, the queried node did not have anything
   newer for mapping 7e3f40b098c711dbb606011111111111, but did have a
   mapping with sourceId 7b7c9630-a93b-11dd-ad8b-0800200c9a66 that
   matched the source parameter 'authoritative.example'.


   <?xml version="1.0" encoding="UTF-8"?>
   <getMappings xmlns="urn:ietf:params:xml:ns:lost1:sync"
     source="authoritative.example">
     <m sourceId="7e3f40b098c711dbb606011111111111"
       lastUpdated="2008-11-26T01:00:00Z" />
   </getMappings>

                  Figure 3: Example <getMappings> request










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   <?xml version="1.0" encoding="UTF-8"?>
   <sync:getMappingsResponse
     xmlns="urn:ietf:params:xml:ns:lost1:sync"
     xmlns:sync="urn:ietf:params:xml:ns:lost-sync1">
     <sync:mappings>
       <mapping
          expires="2007-01-01T01:44:33Z"
          lastUpdated="2006-11-01T01:00:00Z"
          source="authoritative.example"
          sourceId="7b7c9630-a93b-11dd-ad8b-0800200c9a66"
          <displayName xml:lang="en">
            Englewood Police Department
          </displayName>
          <service>urn:service:sos.police</service>
          <serviceBoundary profile="civic">
          ...
          </serviceBoundary>
          <uri>sip:police@englewood.example.com</uri>
          <serviceNumber>911</serviceNumber>
        </mapping>
     </sync:mappings>
   </sync:getMappingsResponse>

                  Figure 4: Example <getMappingsResponse>


5.  Security Considerations

   The LoST security considerations are discussed in [RFC5222].  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.  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).







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   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

   Robins George, Cullen Jennings and Andrew Newton provided helpful
   input.  Jari Urpalainen assisted with the Relax NG schema.


8.  RelaxNG

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

   <grammar ns="urn:ietf:params:xml:ns:lost-sync1"
      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"/>



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              <ref name="pushMappingsResponse"/>
              <ref name="getMappings"/>
              <ref name="getMappingsResponse"/>
          </choice>
      </start>


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

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

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

      <define name="getMappings">
          <element name="getMappings">
              <choice>
                 <ref name="ScopeSource"/>
                 <ref name="ScopeSourceId"/>
              </choice>
              <oneOrMore>
                  <element name="m">
                      <choice>
                          <ref name="ScopeSource"/>
                          <ref name="ScopeSourceId"/>
                          <ref name="ScopeLastUpdated"/>
                      </choice>
                  </element>
              </oneOrMore>
              <ref name="extensionPoint"/>
          </element>
      </define>

      <define name="getMappingsResponse">
          <element name="getMappingsResponse">

              <element name="mappings">



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

              <ref name="extensionPoint"/>

          </element>
      </define>

      <define name="ScopeSource">
          <attribute name="source">
              <data type="token"/>
          </attribute>
      </define>

      <define name="ScopeSourceId">
          <attribute name="source">
              <data type="token"/>
          </attribute>
          <attribute name="sourceId">
              <data type="token"/>
          </attribute>
      </define>

      <define name="ScopeLastUpdated">
          <attribute name="source">
              <data type="token"/>
          </attribute>
          <attribute name="sourceId">
              <data type="token"/>
          </attribute>
          <attribute name="lastUpdated">
              <data type="dateTime"/>
          </attribute>
      </define>

   </grammar>


9.  References

9.1.  Normative References

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

   [RFC2617]  Franks, J., Hallam-Baker, P., Hostetler, J., Lawrence, S.,



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              Leach, P., Luotonen, A., and L. Stewart, "HTTP
              Authentication: Basic and Digest Access Authentication",
              RFC 2617, June 1999.

   [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.

9.2.  Informative References

   [I-D.ietf-ecrit-mapping-arch]
              Schulzrinne, H., "Location-to-URL Mapping Architecture and
              Framework", draft-ietf-ecrit-mapping-arch-03 (work in
              progress), September 2007.


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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Full Copyright Statement

   Copyright (C) The IETF Trust (2008).

   This document is subject to the rights, licenses and restrictions
   contained in BCP 78, and except as set forth therein, the authors
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Acknowledgment

   Funding for the RFC Editor function is provided by the IETF
   Administrative Support Activity (IASA).





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