GENWiki

Premier IT Outsourcing and Support Services within the UK

User Tools

Site Tools


rfc:rfc5962

Internet Engineering Task Force (IETF) H. Schulzrinne Request for Comments: 5962 V. Singh Category: Standards Track Columbia University ISSN: 2070-1721 H. Tschofenig

                                                Nokia Siemens Networks
                                                            M. Thomson
                                                    Andrew Corporation
                                                        September 2010
     Dynamic Extensions to the Presence Information Data Format
                     Location Object (PIDF-LO)

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 defines PIDF-LO extensions to convey information about
 moving objects.  Elements are defined that enable expression of
 spatial orientation, speed, and heading of the presentity.

Status of This Memo

 This is an Internet Standards Track document.
 This document is a product of the Internet Engineering Task Force
 (IETF).  It represents the consensus of the IETF community.  It has
 received public review and has been approved for publication by the
 Internet Engineering Steering Group (IESG).  Further information on
 Internet Standards is available in Section 2 of RFC 5741.
 Information about the current status of this document, any errata,
 and how to provide feedback on it may be obtained at
 http://www.rfc-editor.org/info/rfc5962.

Schulzrinne, et al. Standards Track [Page 1] RFC 5962 Dynamic Extensions to PIDF-LO September 2010

Copyright Notice

 Copyright (c) 2010 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.

Table of Contents

 1. Introduction ....................................................2
 2. Terminology .....................................................3
 3. Dynamic Elements ................................................3
    3.1. Angular Measures and Coordinate Reference Systems ..........5
 4. Dynamic Feature XML Schema ......................................6
 5. Security Considerations .........................................7
 6. IANA Considerations .............................................7
    6.1. Dynamic Feature Extensions Namespace Registration ..........7
    6.2. Dynamic Feature Extensions Schema Registration .............8
 7. Acknowledgements ................................................8
 8. References ......................................................9
    8.1. Normative References .......................................9
    8.2. Informative References .....................................9
 Appendix A.  Earth Centered, Earth Fixed Direction Vectors ........10

1. Introduction

 The Presence Information Data Format - Location Object (PIDF-LO) (see
 RFC 4119 [RFC4119]) provides geographical location of a presentity.
 This corresponds to a physical location at a given instance of time.
 RFC 5491 [RFC5491] extends PIDF-LO and provides additional guidelines
 to implementers.
 This document extends PIDF-LO to convey spatial orientation, speed,
 and heading of a presentity.  The addition of rate-of-change
 information to the PIDF-LO enables a range of use cases.  These use
 cases either use dynamic information directly or use that information

Schulzrinne, et al. Standards Track [Page 2] RFC 5962 Dynamic Extensions to PIDF-LO September 2010

 for smoother tracking of a position over time.  For example, an
 application that continuously tracks a presentity could use velocity
 information to extrapolate positions in between times that location
 information is measured.  A shipping company could directly use speed
 to monitor delivery truck speed to ensure speed limits are observed.

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
 [RFC2119].
 This document uses the term "presentity", as defined in RFC 2778
 [RFC2778], to refer to the device subject to location determination.
 The similarity to presence concepts and the abstract location privacy
 architecture, as described in RFC 4079 [RFC4079], led to re-use of
 the Presence Information Data Format (PIDF) (see RFC 3863 [RFC3863]),
 and its enhancement for location information (see RFC 4119
 [RFC4119]).  Note that this document does not differentiate between
 human and non-human objects, and hence both are in scope.

3. Dynamic Elements

 This document defines a new element, <Dynamic>, for the conveyance of
 dynamic information.
 Dynamic information MAY be included without any other location
 information being present.  When dynamic information is associated
 with information about the instantaneous position of the presentity,
 the <Dynamic> element MUST be included in the same <location-info>
 element as the corresponding geodetic (or civic) location
 information.
 Dynamic information can be safely ignored by a recipient that does
 not support this specification.  The <Dynamic> element contains the
 following components:
 orientation:
    The <orientation> element describes the spatial orientation of the
    presentity -- the direction that the object is pointing.  For a
    device, this orientation might depend on the type of device.  See
    Section 3.1 for details.

Schulzrinne, et al. Standards Track [Page 3] RFC 5962 Dynamic Extensions to PIDF-LO September 2010

 speed:
    Speed is the time rate of change in position of a presentity
    without regard for direction: the scalar component of velocity.
    The value for the <speed> element is a measure that is defined in
    meters per second.
 heading:
    Heading is the directional component of velocity.  See Section 3.1
    for details.
 Each element can be omitted if no information is available.  In the
 following example, the presentity is approximately oriented to the
 North at a slightly elevated angle.  The presentity is travelling
 24 meters per second to the West:
 <?xml version="1.0" encoding="UTF-8"?>
 <presence
     xmlns="urn:ietf:params:xml:ns:pidf"
     xmlns:dm="urn:ietf:params:xml:ns:pidf:data-model"
     xmlns:gp="urn:ietf:params:xml:ns:pidf:geopriv10"
     xmlns:dyn="urn:ietf:params:xml:ns:pidf:geopriv10:dynamic"
     xmlns:gml="http://www.opengis.net/gml"
     entity="pres:alice@example.com">
     <dm:device id="abc123">
         <gp:geopriv>
             <gp:location-info>
                 <dyn:Dynamic>
                     <dyn:orientation>-3 12</dyn:orientation>
                     <dyn:speed>24</dyn:speed>
                     <dyn:heading>278</dyn:heading>
                 </dyn:Dynamic>
             </gp:location-info>
             <gp:usage-rules/>
             <method>gps</method>
         </gp:geopriv>
         <timestamp>2009-06-22T20:57:29Z</timestamp>
         <dm:deviceID>mac:1234567890ab</dm:deviceID>
     </dm:device>
 </presence>

Schulzrinne, et al. Standards Track [Page 4] RFC 5962 Dynamic Extensions to PIDF-LO September 2010

 Another example shows a PIDF-LO document of the presentity
 alice@example.com on a bike travelling 12 meters per second.  Her
 position is indicated as a circle.  The values for speed may be used
 by a receiver to adjust the uncertainty over time.
 <?xml version="1.0" encoding="UTF-8"?>
 <presence
     xmlns="urn:ietf:params:xml:ns:pidf"
     xmlns:dm="urn:ietf:params:xml:ns:pidf:data-model"
     xmlns:gp="urn:ietf:params:xml:ns:pidf:geopriv10"
     xmlns:dyn="urn:ietf:params:xml:ns:pidf:geopriv10:dynamic"
     xmlns:gml="http://www.opengis.net/gml"
     xmlns:gs="http://www.opengis.net/pidflo/1.0"
     entity="pres:alice@example.com">
     <dm:device id="abc123">
         <gp:geopriv>
             <gp:location-info>
                 <gs:Circle srsName="urn:ogc:def:crs:EPSG::4326">
                     <gml:pos>42.5463 -73.2512</gml:pos>
                     <gs:radius uom="urn:ogc:def:uom:EPSG::9001">
                         100
                     </gs:radius>
                 </gs:Circle>
                 <dyn:Dynamic>
                     <dyn:speed>12</dyn:speed>
                 </dyn:Dynamic>
             </gp:location-info>
             <gp:usage-rules/>
             <method>gps</method>
         </gp:geopriv>
         <timestamp>2009-06-22T20:57:29Z</timestamp>
         <dm:deviceID>mac:1234567890ab</dm:deviceID>
     </dm:device>
 </presence>

3.1. Angular Measures and Coordinate Reference Systems

 [RFC5491] constrains the coordinate reference system (CRS) used in
 PIDF-LO to World Geodetic System 1984 (WGS 84), using either the two-
 dimensional (latitude, longitude) CRS identified by
 "urn:ogc:def:crs:EPSG::4326" or the three-dimensional (latitude,
 longitude, altitude) CRS identified by "urn:ogc:def:crs:EPSG::4979".
 Dynamic locations similarly assume that either of these coordinate
 reference systems will be used.
 The <orientation> and <heading> elements both describe a direction.
 The <orientation> element describes the "direction of facing"; the
 <heading> element describes the "direction of travel".  Both measures

Schulzrinne, et al. Standards Track [Page 5] RFC 5962 Dynamic Extensions to PIDF-LO September 2010

 contain one or two angular values that are expressed relative to the
 current position of the presentity (see Appendix A).  Angular
 measures are expressed in degrees, and values can be negative.  If
 two measures are present, the values MUST be separated by whitespace.
 The first measure specifies the horizontal direction from the current
 position of the presentity to a point that it is pointing towards
 (for <orientation>) or travelling towards (for <heading>).
 Horizontal angles are measured from Northing to Easting.  Horizontal
 angles start from zero when pointing to or travelling towards the
 North and increase towards the East.
 The second measure, if present, specifies the vertical component of
 this angle.  This angle is the elevation from the local horizontal
 plane.  If the second angle value is omitted, the vertical component
 is unknown.  If only one angle is present, <orientation> describes
 only the horizontal component.  For <heading>, the associated <speed>
 measure contains only the horizontal component of speed.

4. Dynamic Feature XML Schema

 <?xml version="1.0"?>
 <xs:schema
     targetNamespace="urn:ietf:params:xml:ns:pidf:geopriv10:dynamic"
     xmlns:dyn="urn:ietf:params:xml:ns:pidf:geopriv10:dynamic"
     xmlns:xs="http://www.w3.org/2001/XMLSchema"
     elementFormDefault="qualified"
     attributeFormDefault="unqualified">
   <xs:element name="Dynamic" type="dyn:dynamicType"/>
   <xs:complexType name="dynamicType">
     <xs:complexContent>
       <xs:restriction base="xs:anyType">
         <xs:sequence>
           <xs:element name="orientation" minOccurs="0"
                       type="dyn:directionType"/>
           <xs:element name="speed" minOccurs="0"
                       type="xs:double"/>
           <xs:element name="heading" minOccurs="0"
                       type="dyn:directionType"/>
           <xs:any namespace="##other" processContents="lax"
                   minOccurs="0" maxOccurs="unbounded"/>
         </xs:sequence>
         <xs:anyAttribute namespace="##other" processContents="lax"/>
       </xs:restriction>
     </xs:complexContent>
   </xs:complexType>

Schulzrinne, et al. Standards Track [Page 6] RFC 5962 Dynamic Extensions to PIDF-LO September 2010

   <xs:simpleType name="directionType">
     <xs:restriction base="dyn:doubleListType">
       <xs:minLength value="1"/>
       <xs:maxLength value="2"/>
     </xs:restriction>
   </xs:simpleType>
   <xs:simpleType name="doubleListType">
     <xs:list itemType="xs:double"/>
   </xs:simpleType>
 </xs:schema>

5. Security Considerations

 This document defines additional location elements carried by
 PIDF-LO.  These additional elements provide greater reason to observe
 the privacy and security considerations described in RFC 4119
 [RFC4119].  No further privacy or security measures are necessary.
 RFC 4119 points back to RFC 3694 [RFC3694] and RFC 3693 [RFC3693] to
 describe the threat model and the security requirements imposed on
 the GEOPRIV architecture for sharing location information as a result
 of the threat model.  It is important to note that these two
 documents often refer to threats related to the current location
 information of a presentity, while this document introduces dynamic
 information that may be used by attackers to anticipate the future
 location of a presentity.  While already a series of location
 snapshots is likely to offer information for guessing the future
 location of a presentity, it has to be said that including more
 information in a PIDF-LO does increase the severity of an information
 leak.  Those who deploy location-based services are in general
 strongly advised to provide their users with ways to control the
 distribution of location information to those who have been
 authorized to see it.

6. IANA Considerations

 This section registers a new XML namespace (as described in
 [RFC3688]) and a new XML schema.

6.1. Dynamic Feature Extensions Namespace Registration

 URI: urn:ietf:params:xml:ns:pidf:geopriv10:dynamic
 Registrant Contact: IETF Geopriv Working Group, Hannes Tschofenig
    (hannes.tschofenig@gmx.net).

Schulzrinne, et al. Standards Track [Page 7] RFC 5962 Dynamic Extensions to PIDF-LO September 2010

 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>
      <title>Dynamic Feature Extensions Namespace</title>
    </head>
    <body>
      <h1>Namespace for Dynamic Feature Extensions to PIDF-LO</h1>
      <h2>urn:ietf:params:xml:ns:pidf:geopriv10:dynamic</h2>
    <p>See <a href=
      "http://www.rfc-editor.org/rfc/rfc5962.txt"> RFC5962</a>.</p>
    </body>
    </html>
    END

6.2. Dynamic Feature Extensions Schema Registration

 URI: urn:ietf:params:xml:schema:pidf:dynamic
 Registrant Contact: IETF Geopriv Working Group, Hannes Tschofenig
    (hannes.tschofenig@gmx.net)
 XML: The XML schema registered is contained in Section 4.  Its first
    line is
 <?xml version="1.0"?>
 and its last line is
 </xs:schema>

7. Acknowledgements

 We would like to thank Klaus Darilion, Cullen Jennings, Rohan Mahy,
 Carl Reed, and Brian Rosen for their comments.  Furthermore, we would
 like to thank Alexey Melnikov, Adrian Farrel, Tim Polk, Dan Romascanu
 for his IESG review comments, Avshalom Houri for his GenArt review,
 Hilarie Orman for her SECDIR review, and Joel Jaeggli for his
 Operations Directorate review.

Schulzrinne, et al. Standards Track [Page 8] RFC 5962 Dynamic Extensions to PIDF-LO September 2010

8. References

8.1. Normative References

 [RFC2119]   Bradner, S., "Key words for use in RFCs to Indicate
             Requirement Levels", BCP 14, RFC 2119, March 1997.
 [RFC3688]   Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
             January 2004.
 [RFC4119]   Peterson, J., "A Presence-based GEOPRIV Location Object
             Format", RFC 4119, December 2005.

8.2. Informative References

 [RFC2778]   Day, M., Rosenberg, J., and H. Sugano, "A Model for
             Presence and Instant Messaging", RFC 2778, February 2000.
 [RFC3693]   Cuellar, J., Morris, J., Mulligan, D., Peterson, J., and
             J. Polk, "Geopriv Requirements", RFC 3693, February 2004.
 [RFC3694]   Danley, M., Mulligan, D., Morris, J., and J. Peterson,
             "Threat Analysis of the Geopriv Protocol", RFC 3694,
             February 2004.
 [RFC3863]   Sugano, H., Fujimoto, S., Klyne, G., Bateman, A., Carr,
             W., and J. Peterson, "Presence Information Data Format
             (PIDF)", RFC 3863, August 2004.
 [RFC4079]   Peterson, J., "A Presence Architecture for the
             Distribution of GEOPRIV Location Objects", RFC 4079,
             July 2005.
 [RFC5491]   Winterbottom, J., Thomson, M., and H. Tschofenig,
             "GEOPRIV Presence Information Data Format Location Object
             (PIDF-LO) Usage Clarification, Considerations, and
             Recommendations", RFC 5491, March 2009.

Schulzrinne, et al. Standards Track [Page 9] RFC 5962 Dynamic Extensions to PIDF-LO September 2010

Appendix A. Earth Centered, Earth Fixed Direction Vectors

 The absolute orientation or heading of a presentity depends on its
 latitude and longitude.  The following vectors can be used to
 determine the absolute direction in the WGS 84 Earth Centered, Earth
 Fixed (X, Y, Z) coordinate space.
 The direction of North as a unit vector in Earth Centered, Earth
 Fixed (ECEF) coordinates is:
    North = [ -1 * sin(latitude) * cos(longitude),
              -1 * sin(latitude) * sin(longitude),
              cos(latitude) ]
 The direction of "up" (the upward normal of the horizontal plane) as
 a unit vector in ECEF coordinates is:
    Up = [ cos(latitude) * cos(longitude),
           cos(latitude) * sin(longitude),
           sin(latitude) ]

Schulzrinne, et al. Standards Track [Page 10] RFC 5962 Dynamic Extensions to PIDF-LO September 2010

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@cs.columbia.edu
 URI:   http://www.cs.columbia.edu/
 Vishal Singh
 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
 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/
 Martin Thomson
 Andrew Corporation
 Wollongong
 NSW Australia
 EMail: martin.thomson@andrew.com

Schulzrinne, et al. Standards Track [Page 11]

/data/webs/external/dokuwiki/data/pages/rfc/rfc5962.txt · Last modified: 2010/09/13 16:32 (external edit)