Network Working Group                                           V. Singh
Internet-Draft
Intended status:  Standards Track                         H. Schulzrinne
Expires:  May 22, 2008                               Columbia University
                                                           H. Tschofenig
                                                  Nokia Siemens Networks
                                                       November 19, 2007


   Dynamic Feature Extensions to the Presence Information Data Format
                       Location Object (PIDF-LO)
               draft-singh-geopriv-pidf-lo-dynamic-02.txt

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Copyright Notice

   Copyright (C) The IETF Trust (2007).

Abstract

   The Geopriv Location Object introduced by the Presence Information
   Data Format - Location Object (PIDF-LO), RFC 4119, defines a basic
   XML format for carrying geographical information of a presentity.
   This document extends the <location> element specified in RFC 4119 to



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   carry temporal feature elements useful for tracking moving objects.
   It defines five elements, namely speed, bearing, acceleration
   elevation and directionOfObject.  The document also specifies
   mechanisms to carry multiple moving object's status elements and
   proposes a mechanism to indicate the type of the PIDF-LO content.


Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Terminology  . . . . . . . . . . . . . . . . . . . . . . . . .  4
   3.  Protocol Behavior  . . . . . . . . . . . . . . . . . . . . . .  4
     3.1.  Indicating Use of Dynamic Feature PIDF-LO using SIP  . . .  4
     3.2.  Indicating Use of Dynamic Feature PIDF-LO using HELD . . .  4
     3.3.  Units of Measure . . . . . . . . . . . . . . . . . . . . .  5
     3.4.  GML DynamicFeature Schema Usage  . . . . . . . . . . . . .  5
   4.  Transferring Multiple Location Objects . . . . . . . . . . . .  5
   5.  Example  . . . . . . . . . . . . . . . . . . . . . . . . . . .  6
   6.  Security Considerations  . . . . . . . . . . . . . . . . . . .  9
   7.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . .  9
   8.  Acknowledgements . . . . . . . . . . . . . . . . . . . . . . .  9
   9.  References . . . . . . . . . . . . . . . . . . . . . . . . . .  9
     9.1.  Normative References . . . . . . . . . . . . . . . . . . .  9
     9.2.  Informative References . . . . . . . . . . . . . . . . . . 10
   Appendix A.  Alternatives Considered . . . . . . . . . . . . . . . 10
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 11
   Intellectual Property and Copyright Statements . . . . . . . . . . 13
























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1.  Introduction

   The Presence Information Data Format - Location Object (PIDF-LO) (see
   RFC 4119 [1]) provides geographical location of the presentity.  This
   corresponds to a physical location at a given instance of time.
   However, a number of applications, described below, can benefit from
   having access to information about changes in location.  Location
   change information is likely to be useful for logistics and public
   safety.  For example, shipping companies or dispatch centers can use
   it to track whether vehicles are deviating from an established path
   or exceeding speed limits.

   This document defines a location vector by extending the the
   <location>, introduced by RFC 4119, to carry temporal feature
   elements:

   speed:

      Speed is the rate of motion.  (The terms speed and velocity are
      often used interchangeably, but speed is a scaler, having
      magnitude only, while velocity is a vector quantity, having both
      magnitude and direction.)

      This element contains a 'uom' (Units Of Measure) attribute, which
      is a reference to a reference system for the amount.  The 'uom'
      attribute uses a URI to refer to a unit of measure definition.
      The GML document defines a set of convenience measure types
      described in ISO 19103.  This is further explained in Section 3.3.

   bearing:

      Bearing is defined as the horizontal direction of one terrestrial
      point from another, expressed as the angular distance from a
      reference direction.  It is usually measured from 000 degrees at
      the reference direction clockwise through 360 degrees.

      The <bearing> element is of type gml:DirectionPropertyType and
      contains a gml:DirectionVector, gml:CompassPoint,
      DirectionKeyword, or a DirectionString element.  This document
      profiles the usage of this GML element and suggests the usage of
      the <DirectionVector> element.

   acceleration:

      This element specifies the rate (usually rapid) at which something
      happens.  The <acceleration> element also contains a 'uom'
      attribute.




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   directionOfObject:

      The <directionOfObject> describes the instantaneous horizontal of
      the front of the object relative to true north and the vertical
      angle relative to the earth's spheroid.  It uses the GML
      <directionVector> element.


2.  Terminology

   In this document, the key words "MUST", "MUST NOT", "REQUIRED",
   "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY",
   and "OPTIONAL" are to be interpreted as described in RFC 2119 [2].

   This document uses the terminology from [3].


3.  Protocol Behavior

   The document describes the protocol requirements for dynamic feature
   extensions, so that it can be transmitted by the Location Server or
   the Location Information Server and understood correctly by Location
   Recipients.  Location Recipients should be able to indicate to the
   server that they can handle the dynamic feature elements.  The server
   should also indicate to the clients that the type of location object
   is PIDF-LO including the dynamic feature extension.  Also, the unit
   of measurements should be communicated by server and understood by
   the clients.

3.1.  Indicating Use of Dynamic Feature PIDF-LO using SIP

   The watcher can can indicate its capability using the SIP Accept
   header.  This document proposes to add a 'supported' parameter for
   the application/pidf-xml media type.  It enumerates the non default
   namespaces supported by the UAS.  An example is given below:

   Accept:  application/pidf+xml; supported="geopriv-temporal-features"

   The server can specify the type of content using Content-Type header.
   The specific PIDF-LO type can be obtained by looking inside the XML
   content.

   Content-Type:  application/pidf+xml;

3.2.  Indicating Use of Dynamic Feature PIDF-LO using HELD

   There are two areas where it is useful to provide feature indication;
   the HELD context draft [6]" allows a Target (or an entity acting on



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   behalf of the Target) to constraint the dereferencing procedure.
   Hence, it is useful to indicate whether dynamic features should or
   should not presented to the Location Recipient when a location URI is
   dereferenced.

   Furthermore, when a dereferencing protocol based on HTTP is used then
   the Location Recipient might want to express the desire to receive a
   specific response, for example a PIDF-LO that contains a trace.

   In a future version of this document the above-described
   functionality will be added.

3.3.  Units of Measure

   GML permits a range of units of measure for the uom attribute.  This
   document restricts this set to the #m/s

   [ Editor's Note:  Need to find the URN for #m/s]

3.4.  GML DynamicFeature Schema Usage

   This document does not define a new schema but instead re-uses a
   subset of the dynamicFeature.xsd schema available with GML 3.1.1,
   namely <speed>, <bearing>, <acceleration>, and <directionOfObject>.

   These four elements are conveyed inside the <location-info> element
   defined by RFC 4119 [1].


4.  Transferring Multiple Location Objects

   Multiple location vector objects may be required to be transported
   simultaneously.  This can be achieved using <timed-presence> defined
   in RFC 4481 [4].

   Typically, the watcher applications can reconstruct the path as well
   as dynamic behavior (speed, acceleration etc.) along the path by
   storing the received location vector objects.  However, a new
   Location Recipient may be interested in past location-vectors or may
   choose to receive notifications at a slower rate without losing
   valuable information.  In other words, it can request to receive
   multiple location vector objects together.  For example, it may want
   to get one NOTIFY every 15 minutes with multiple location objects
   aggregated.

   The structure of the document which can be used for tracking moving
   objects using timed-status extension is shown below.  An example is
   given in Section 5.



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      <?xml version="1.0" encoding="UTF-8"?>
      <presence>
            <tuple>
                  <status>
                      <gp:geopriv>
                      ..........
                      </gp:geopriv>
                  </status>

                  <timestamp>.....</timestamp>

                  <timed-status from="start-time" until="end-time">
                       <gp:geopriv>
                       ............
                       </gp:geopriv>

                       <gp:geopriv>
                       ...........
                       </gp:geopriv>

                  </timed-status>
            </tuple>

            <device>
            .......
            </device>

            <person>
            .......
            </person>
      </presence>



5.  Example

   The following example shows a PIDF-LO indicating geospatial location
   information using the gml:Point structure.  Outside the <gml:
   location/> element the additional fields releated to temporal
   characteristics are included.











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   <?xml version="1.0" encoding="UTF-8"?>
   <presence xmlns="urn:ietf:params:xml:ns:pidf"
     xmlns:gp="urn:ietf:params:xml:ns:pidf:geopriv10"
     xmlns:gml="http://www.opengis.net/gml"
     entity="pres:geotarget@example.com">

     <tuple id="sg89ae">
       <status>
         <gp:geopriv>
           <gp:location-info>
             <gml:location>
               <gml:Point srsName="urn:ogc:def:crs:EPSG::4326">
                 <gml:pos>-34.407 150.883</gml:pos>
               </gml:Point>
             </gml:location>
             <gml:speed uom="#m/s">12</gml:speed>
             <gml:bearing>
               <gml:DirectionVector>
                 <gml:vector> 270.0 -60.0</gml:vector>
               </gml:DirectionVector>
             </gml:bearing>
           </gp:location-info>
           <gp:usage-rules>
             <gp:retransmission-allowed>no</gp:retransmission-allowed>
             <gp:retention-expiry>2003-06-23T04:57:29Z
             </gp:retention-expiry>
           </gp:usage-rules>
         </gp:geopriv>
       </status>
       <timestamp>2008-06-22T20:57:29Z</timestamp>
     </tuple>

   </presence>

           Figure 2: Example of a PIDF-LO with Speed Information

   The following example shows multiple PIDF-LO using <timed-status>.


<?xml version="1.0" encoding="UTF-8"?>
<presence xmlns="urn:ietf:params:xml:ns:pidf"
  xmlns:gp="urn:ietf:params:xml:ns:pidf:geopriv10"
  xmlns:gml="urn:opengis:specification:gml:schema-xsd:feature:v3.0"
  entity="pres:geotarget@example.com">
  <tuple id="sg89ae">
       <status>
         <gp:geopriv>
           <gp:location-info>



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               <gml:location>
                  <gml:Point>
                     <gml:pos>140. -35.</gml:pos>
                  </gml:Point>
               </gml:location>
           <gml:speed uom="#m/s">12</gml:speed>
           </gp:location-info>
           <gp:usage-rules>
             <gp:retransmission-allowed>no</gp:retransmission-allowed>
             <gp:retention-expiry>2003-06-23T04:57:29Z
             </gp:retention-expiry>
           </gp:usage-rules>
         </gp:geopriv>
       </status>
       <timestamp>2003-06-22T20:57:29Z</timestamp>

       <timed-statusfrom="2005-08-15T10:20:00.000-05:00"
          until="2005-08-22T19:30:00.000-05:00">>
          <gp:geopriv>
            <gp:location-info>
               <gml:location>
                  <gml:Point>
                     <gml:pos>110. -35.</gml:pos>
                  </gml:Point>
               </gml:location>
               <gml:speed uom="#m/s">10</gml:speed>
           </gp:location-info>
            <gp:usage-rules>
              <gp:retransmission-allowed>yes</gp:retransmission-allowed>
              <gp:retention-expiry>2003-06-23T04:55:29Z
              </gp:retention-expiry>
            </gp:usage-rules>
          </gp:geopriv>
          <gp:geopriv>
            <gp:location-info>
               <gml:location>
                  <gml:Point>
                     <gml:pos>114. -35.</gml:pos>
                  </gml:Point>
               </gml:location>
               <gml:speed uom="#m/s">18</gml:speed>
            </gp:location-info>
           <gp:usage-rules>
             <gp:retransmission-allowed>yes</gp:retransmission-allowed>
             <gp:retention-expiry>2003-06-23T04:53:29Z
             </gp:retention-expiry>
           </gp:usage-rules>
         </gp:geopriv>



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       </timed-status>

     </tuple>
</presence>

      Figure 3: Example showing multiple Location Vectors transmitted
                              simultaneously.


6.  Security Considerations

   This document defines additional location elements carried by PIDF-LO
   (see [1]).  The security considerations of RFC 4119 [1] are
   applicable to this document.


7.  IANA Considerations

   This section needs to register a token for indicating the dynamic
   feature capability, see Section 3.1.


8.  Acknowledgements

   We would like to thank Carl Reed, Rohan Mahy, Cullen Jennings, Martin
   Thomson, Brian Rosen, and Klaus Darilion for their comments.


9.  References

9.1.  Normative References

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

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

   [3]  Cuellar, J., Morris, J., Mulligan, D., Peterson, J., and J.
        Polk, "Geopriv Requirements", RFC 3693, February 2004.

   [4]  Schulzrinne, H., "Timed Presence Extensions to the Presence
        Information Data Format (PIDF) to Indicate Status Information
        for Past and Future Time Intervals", RFC 4481, July 2006.

   [5]  "Geographic information - Geography Markup Language (GML),
        OpenGIS 03-105r1, available at:
        http://portal.opengeospatial.org/files/?artifact_id=4700",



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        April 2004.

9.2.  Informative References

   [6]  Winterbottom, J., Tschofenig, H., and M. Thomson, "HELD Protocol
        Context Management Extensions",
        draft-winterbottom-geopriv-held-context-01 (work in progress),
        October 2007.


Appendix A.  Alternatives Considered

   During the work on this document we encountered alternative
   approaches.  These approaches make use of the MovingObjectStatus or
   its parent element track of dynamicFeature.xsd.  MovingObjectStatus
   contains child elements where no use cases are currently known, e.g.,
   validTime and contains elements that are already defined with
   PIDF-LO, such as <location>.  Since it might not be know whether a
   Location Recipient understands the location extension defined in this
   document a PIDF-LO with a <location> element inside the
   <MovingObjectStatus> will likely create problems.  Including the
   <location> element twice, once as defined with RFC 4119 (PIDF-LO) and
   again in <MovingObjectStatus>, is unnecessary.  The <track> element
   allows multiple <MovingObjectStatus> to be used.  Figure 4 shows such
   an instance document carrying the <track> element.


   <?xml version="1.0" encoding="UTF-8"?>
   <presence xmlns="urn:ietf:params:xml:ns:pidf"
     xmlns:gp="urn:ietf:params:xml:ns:pidf:geopriv10"
     xmlns:gml="http://www.opengis.net/gml"
     entity="pres:geotarget@example.com">
     <tuple id="sg89ae">
       <status>
         <gp:geopriv>
           <gp:location-info>
             <gml:track>
               <gml:MovingObjectStatus>
                 <gml:validTime>
                   <gml:TimeInstant>
                     <gml:timePosition>2005-11-28T13:00:00
                     </gml:timePosition>
                   </gml:TimeInstant>
                 </gml:validTime>
                 <gml:location>
                   <gml:Point>
                     <gml:pos>140. -35.</gml:pos>
                   </gml:Point>



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                 </gml:location>
                 <gml:speed uom="#kph">12</gml:speed>
                 <gml:bearing>
                   <gml:CompassPoint>SE</gml:CompassPoint>
                 </gml:bearing>
               </gml:MovingObjectStatus>
               <gml:MovingObjectStatus>
                 <gml:validTime>
                   <gml:TimeInstant>
                     <gml:timePosition>2005-11-28T14:00:00
                     </gml:timePosition>
                   </gml:TimeInstant>
                 </gml:validTime>
                 <gml:location>
                   <gml:Point>
                     <gml:pos>140.1 -34.9</gml:pos>
                   </gml:Point>
                 </gml:location>
                 <gml:speed uom="#kph">23.</gml:speed>
                 <gml:bearing>
                   <gml:CompassPoint>ESE</gml:CompassPoint>
                 </gml:bearing>
               </gml:MovingObjectStatus>
             </gml:track>
           </gp:location-info>
           <gp:usage-rules>
             <gp:retransmission-allowed>no</gp:retransmission-allowed>
             <gp:retention-expiry>2003-06-23T04:57:29Z
             </gp:retention-expiry>
           </gp:usage-rules>
         </gp:geopriv>
       </status>
       <timestamp>2003-06-22T20:57:29Z</timestamp>
     </tuple>
   </presence>

            Figure 4: Example of a PIDF-LO with a track Element

   The authors decided to pick the simplest version.


Authors' Addresses

   Singh Vishal


   Email:  singh.vishal@gmail.com




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

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


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

   Email:  Hannes.Tschofenig@nsn.com
   URI:    http://www.tschofenig.com
































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