Network Working Group H. Schulzrinne
Internet-Draft V. Singh
Intended status: Experimental Columbia University
Expires: December 24, 2009 H. Tschofenig
Nokia Siemens Networks
M. Thomson
Andrew Corporation
June 22, 2009
Dynamic Extensions to the Presence Information Data Format Location
Object (PIDF-LO)
draft-singh-geopriv-pidf-lo-dynamic-06
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Copyright Notice
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Copyright (c) 2009 IETF Trust and the persons identified as the
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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 that are intended to convey
information about moving objects. Elements are defined that enable
expression of spatial orientation, speed, heading, and acceleration
of the presentity.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Dynamic Elements . . . . . . . . . . . . . . . . . . . . . . . 4
3.1. Angular Measures and Coordinate Reference Systems . . . . 5
4. Dynamic Feature XML Schema . . . . . . . . . . . . . . . . . . 7
5. Security Considerations . . . . . . . . . . . . . . . . . . . 8
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8
6.1. Dynamic Feature Extensions Namespace Registration . . . . 8
6.2. Dynamic Feature Extensions Schema Registration . . . . . . 8
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 9
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 9
8.1. Normative References . . . . . . . . . . . . . . . . . . . 9
8.2. Informative References . . . . . . . . . . . . . . . . . . 9
Appendix A. Earth Centered, Earth Fixed Direction Vectors . . . . 9
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 10
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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.
With the extensions defined in [RFC5491] more guidelines to
implementers are being provided with respect to the expression
location information in PIDF-LO.
The addition of rate of change information to the PIDF-LO enables a
range of use cases. These use cases either directly use dynamic
information, or use that information 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 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].
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. Sse
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Section 3.1 for details.
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 directional component of velocity. Sse Section 3.1 for
details.
acceleration:
Acceleration is the time rate of change of velocity. This element
contains the scalar component of velocity, measured in meters per
second per second.
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:
<dyn:Dynamic xmlns:dyn="urn:ietf:params:xml:ns:pidf:dynamic">
<dyn:orientation>-3 12</dyn:orientation>
<dyn:speed>24</dyn:speed>
<dyn:heading>278</dyn:heading>
</dyn:Dynamic>
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 two-dimensional (latitude,
longitude, altitude) CRS identified by "urn:ogc:def:crs:EPSG::4979".
Dynamic locations similarly assume that either of these coordinate
reference systems are used.
The <orientation> and <heading> establish a direction. Both measures
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 MAY be negative. If two
measures are present, the values are separated by whitespace.
The first measure specifies the horizontal direction from the current
position of the presentity to a point that it either pointing towards
or travelling towards. Horizontal angles are measured from Northing
to Easting. Horizontal angles start from zero when pointing to or
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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 and the speed measure MAY be assumed to only contain the
horizontal component of speed.
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4. Dynamic Feature XML Schema
<?xml version="1.0"?>
<xs:schema
targetNamespace="urn:ietf:params:xml:ns:pidf:dynamic"
xmlns:dyn="urn:ietf:params:xml:ns:pidf: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:element name="acceleration" minOccurs="0"
type="xs:double"/>
<xs:any namespace="##other" processContents="lax"
minOccurs="0" maxOccurs="unbounded"/>
</xs:sequence>
<xs:anyAttribute namespace="##other" processContents="lax"/>
</xs:restriction>
</xs:complexContent>
</xs:complexType>
<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>
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5. Security Considerations
This document defines additional location elements carried by
PIDF-LO. No additional security considerations beyond those
described in RFC 4119 [RFC4119] are applicable to this document.
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:dynamic"
Registrant Contact: IETF Geopriv Working Group, Hannes Tschofenig
(hannes.tschofenig@nsn.com).
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:dynamic</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
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@nsn.com).
XML: The XML schema to be registered is contained in Section 4. Its
first line is
<?xml version="1.0"?>
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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.
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
[GeoShape]
Thomson, M. and C. Reed, "GML 3.1.1 PIDF-LO Shape
Application Schema for use by the Internet Engineering
Task Force (IETF)", Candidate OpenGIS Implementation
Specification 06-142, Version: 0.0.9, December 2006.
[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.
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.
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The direction of North as a unit vector in 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) ]
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/
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Martin Thomson
Andrew Corporation
Wollongong
NSW Australia
Email: martin.thomson@andrew.com
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