Network Working Group                                           V. Singh
Internet-Draft                                            H. Schulzrinne
Intended status:  Standards Track                            Columbia U.
Expires:  August 5, 2007                                   H. Tschofenig
                                                                 Siemens
                                                                Feb 2007


   Dynamic Feature Extensions to the Presence Information Data Format
                       Location Object (PIDF-LO)
               draft-singh-geopriv-pidf-lo-dynamic-01.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
   carry temporal feature elements useful for tracking moving objects.



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


Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Terminology  . . . . . . . . . . . . . . . . . . . . . . . . .  4
   3.  Protocol Behavior  . . . . . . . . . . . . . . . . . . . . . .  5
     3.1.  Indicating Use of Dynamic Feature PIDF-LO  . . . . . . . .  5
     3.2.  Units of Measure . . . . . . . . . . . . . . . . . . . . .  5
   4.  Transferring Multiple Location Objects . . . . . . . . . . . .  6
   5.  XML Schema . . . . . . . . . . . . . . . . . . . . . . . . . .  7
   6.  Example  . . . . . . . . . . . . . . . . . . . . . . . . . . .  7
   7.  Security Considerations  . . . . . . . . . . . . . . . . . . . 10
   8.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 10
   9.  Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 10
   10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 10
     10.1. Normative References . . . . . . . . . . . . . . . . . . . 10
     10.2. Informative References . . . . . . . . . . . . . . . . . . 10
   Appendix A.  Alternatives Considered . . . . . . . . . . . . . . . 11
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 13
   Intellectual Property and Copyright Statements . . . . . . . . . . 14


























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1.  Introduction

   The existing Geopriv location object [5] gives presence information
   which is geographical location of the presentity.  This corresponds
   to a physical location at a given instance of time.  A large number
   of applications, specifically in the transportation industry, fleet
   management applications, goods delivery and postal companies require
   to track not only the geographical location but also the rate of
   change of location of the entities.

   Some of the use case scenarios for such an extension are tracking the
   location of vehicles, monitoring if vehicles are deviating from their
   planned routes or pre-specified speed-limits, reporting the direction
   of movement of ships and airplanes at different instances of time,
   tracking kidnapped/trapped victims for emergency services and
   tracking of culprits by the police.  The applications may be for
   safety and security of personals and vehicles, productivity
   management of mobile crews, monitoring to ensure schedules,
   monitoring to ensure no deviation from scheduled paths.

   This document defines location vector by extending the the <location>
   introduced by the Presence Information Data Format Location Object
   (PIDF-LO), RFC 4119, to carry temporal feature elements.  It defines
   five elements, namely 'speed', 'bearing', 'acceleration', 'elevation'
   and 'directionOfObject'.  The 'speed' and 'accelearation' are used to
   describe the object which is moving.  The 'bearing' is used for the
   direction of travel of the object and describes true bearing rather
   then magnetic bearing.  The 'directionOfObject' is similar to
   'bearing' but it is used to indicate a direction in which an object
   is present from the presentity.  The description of these elements
   except 'directionOfObject' is taken from GML [1] and repeated for
   completeness reasons:

   speed:

      This element points to a measure of the rate of motion.  It
      contains a 'uom' (Units Of Measure) attribute, which is a
      reference to a reference system for the amount, often a ratio or
      interval scale.  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 3.2.

   bearing:

      The <bearing> element is of type gml:DirectionPropertyType and can
      contain a gml:DirectionVector, gml:CompassPoint, DirectionKeyword,
      or a DirectionString element. gml:Directorvectors are specified by



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      providing components of a vector or two angles.  A compass point
      is specified by a simple enumeration string type (e.g., "N",
      "NNE", "NE", ...  "W").  Two elements to contain text-based
      descriptions of direction are provided.  If the direction is
      specified using a term from a list, gml:KeyWord may be used, and
      the list indicated using the value of the codeSpace attribute.  If
      the direction is described in prose, gml:DirectionString may be
      used, allowing the value to be included inline or by reference.

   acceleration:

      This element specifies the rate (usually rapid) at which something
      happens.  Similarly to the <speed> and the <elevation> element the
      <acceleration> element conains a 'uom' (Units Of Measure)
      attribute, which is a reference to a reference system for the
      amount.

   elevation:

      The height of a thing above a reference level; altitude.
      Similarly to the <speed> and the <elevation> element the
      <acceleration> element contains a 'uom' (Units Of Measure)
      attribute, which is a reference to a reference system for the
      amount.  The ability to use the 'elevation' element together with
      geospatial location offers a more compact way of expressing
      composite location information per RFC 3825 [6] location
      information using a civic floor number.

   directionOfObject:  This element is similar to 'bearing' except that
      it defines the direction in which an object is present from the
      point of observer.  It will be relative to a fixed reference
      direction like magnetic north.

   This document therefore allows the existing location formats allowed
   by the GML feature.xsd schema to be extended with dynamic
   characteristics.  The supported shapes are described in detail in
   [7].  This document enhances this functionality and offers support
   for moving objects.


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].




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3.  Protocol Behavior

   The document describes the protocol requirements for dynamic feature
   extensions, so that it can be transmitted by the location server and
   understood correctly by the clients.  The clients 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 + dynamic feature extensions.
   Also, the unit of measurements should be communicated by server and
   understood by the clients.

3.1.  Indicating Use of Dynamic Feature PIDF-LO

   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="urn:ietf:params:xml:ns:temporal1"

   Alternatively, a token can be defined and used, an example is given:

   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.  Units of Measure

   GML permits a range of units of measure for all parameters.  This
   document restricts this set to the following units metre, kilometre
   and mile for distance and seconds for time.  Hence, the acceptable
   units for speed are :  #m/s, #km/h and #mph

   Editor's Note:  Need to find the URN for kph, m/s, km/h need to be
   added here.  Editor's Note:  Need to find the URN for floor, if it
   exists.  It is only valid for the elevation element.

   Only the above-listed units of measurements MUST be used for the uom
   attribute.







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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 watcher
   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 6.



            <tuple>
                  <status>
                      <gp:geopriv>
                      ..........
                      </gp:geopriv>
                  </status>
                  <timestamp>.....</timestamp>

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

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

                  </timed-status>

            </tuple>

            <tuple>
            .......
            </tuple>






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5.  XML Schema

   This section defines the XML schema consisting of five elements that
   are conveyed inside the <location-info> element defined by RFC 4119
   [5].  The data types are taken from GML except the
   'directionOfObject' which may belong to a different namespace.



<?xml version="1.0" encoding="UTF-8"?>
  <schema xmlns="http://www.w3.org/2001/XMLSchema"
    targetNamespace="http://www.opengis.net/gml"
    xmlns:gml="http://www.opengis.net/gml"
    xmlns:xml="http://www.w3.org/XML/1998/namespace"

    elementFormDefault="qualified"
    attributeFormDefault="unqualified">

    <import namespace="http://www.opengis.net/gml" schemaLocation=
    "http://schemas.opengis.net/gml/3.1.1/base/dynamicFeature.xsd"/>

    <element name="speed" type="gml:MeasureType" />
    <element name="bearing" type="gml:DirectionPropertyType"/>
    <element name="acceleration" type="gml:MeasureType"/>
    <element name="elevation" type="gml:MeasureType"/>
    <element name="directionOfObject" type="gml:DirectionPropertyType"/>

  </schema>


                           Figure 2: XML Schema


6.  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="urn:opengis:specification:gml:schema-xsd:feature:v3.0"
     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="#kph">12</temp:speed>
             <gml:bearing>
               <gml:CompassPoint>SE</temp:CompassPoint>
             </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>2003-06-22T20:57:29Z</timestamp>
     </tuple>
   </presence>

           Figure 3: 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>
               <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>
           </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="#kph">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="#kph">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>
       </timed-status>

     </tuple>
</presence>



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      Figure 4: Example showing multiple Location Vectors transmitted
                              simultaneously.


7.  Security Considerations

   This document defines additional location elements carried by PIDF-LO
   (see [5]).  The security considerations of RFC 4119 [5] are
   applicable to this document.


8.  IANA Considerations

   A future version of this document will provide IANA considerations.


9.  Acknowledgements

   Add your name here.


10.  References

10.1.  Normative References

   [1]   "Geographic information - Geography Markup Language (GML),
         OpenGIS 03-105r1, available at:
         http://portal.opengeospatial.org/files/?artifact_id=4700",
         April 2004.

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

10.2.  Informative References

   [6]   Polk, J., Schnizlein, J., and M. Linsner, "Dynamic Host
         Configuration Protocol Option for Coordinate-based Location
         Configuration Information", RFC 3825, July 2004.



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   [7]   Thomson, M., "Geodetic Shapes for the Representation of
         Uncertainty in PIDF-LO", draft-thomson-geopriv-geo-shape-03
         (work in progress), December 2006.

   [8]   Mahy, R., "A Document Format for Filtering and Reporting
         Location Notications in the  Presence Information Document
         Format Location Object (PIDF-LO)",
         draft-ietf-geopriv-loc-filters-01 (work in progress),
         March 2007.

   [9]   Polk, J. and B. Rosen, "Session Initiation Protocol Location
         Conveyance", draft-ietf-sip-location-conveyance-07 (work in
         progress), February 2007.

   [10]  Schulzrinne, H., "Common Policy: A Document Format for
         Expressing Privacy Preferences",
         draft-ietf-geopriv-common-policy-11 (work in progress),
         August 2006.

   [11]  Schulzrinne, H., "Geolocation Policy: A Document Format for
         Expressing Privacy Preferences for  Location Information",
         draft-ietf-geopriv-policy-11 (work in progress), February 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 5 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>



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         <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>
                 </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>



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   </presence>

            Figure 5: Example of a PIDF-LO with a track Element

   The authors decided to pick the simplest version.


Authors' Addresses

   Singh Vishal
   Columbia University
   Department of Computer Science
   450 Computer Science Building
   New York, NY  10027
   US

   Email:  vs2140@cs.columbia.edu
   URI:    http://www.cs.columbia.edu/~vs2140


   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/~hgs


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

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










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Full Copyright Statement

   Copyright (C) The IETF Trust (2007).

   This document is subject to the rights, licenses and restrictions
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Acknowledgment

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





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