Network Working Group V. Singh
Internet-Draft
Intended status: Experimental H. Schulzrinne
Expires: May 3, 2009 Columbia University
H. Tschofenig
Nokia Siemens Networks
October 30, 2008
Dynamic Feature Extensions to the Presence Information Data Format
Location Object (PIDF-LO)
draft-singh-geopriv-pidf-lo-dynamic-04.txt
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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.
The PIDF-LO specification made a subset of the functionality offered
by the Geography Markup Language (GML) standard 3.0 mandatory to
implement. This document defines child elements to the <location-
info> element specified in RFC 4119 to carry temporal feature
elements useful for tracking moving objects. It defines five
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elements, namely speed, bearing, acceleration elevation and
directionOfObject.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. XML Extensions . . . . . . . . . . . . . . . . . . . . . . . . 3
4. XML Schema . . . . . . . . . . . . . . . . . . . . . . . . . . 4
5. Example . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
6. Security Considerations . . . . . . . . . . . . . . . . . . . 5
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 6
9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 6
9.1. Normative References . . . . . . . . . . . . . . . . . . . 6
9.2. Informative References . . . . . . . . . . . . . . . . . . 6
Appendix A. Transferring Multiple Location Objects within SIP . . 6
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 9
Intellectual Property and Copyright Statements . . . . . . . . . . 10
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1. Introduction
The Presence Information Data Format - Location Object (PIDF-LO) (see
RFC 4119 [RFC4119]) provides geographical location of the presentity.
This corresponds to a physical location at a given instance of time.
The PIDF-LO specification made a subset of the functionality offered
by the Geography Markup Language (GML) standard 3.0 mandatory to
implement. With the extensions defined in
[I-D.ietf-geopriv-pdif-lo-profile] more guidelines to implementers
are being provided with respect to a number of location shapes that
have to be supported for usage within PIDF-LO. However, a number of
applications 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.
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. XML Extensions
This document defines a location vector by adding child elements to
the <location-info> element described in RFC 4119 [RFC4119], to carry
temporal feature elements. A receiver MAY ignore the temporal
elements defined in this document if it does not understand this
extension.
speed:
Speed is the rate of motion. (The terms speed and velocity are
often used interchangeably, but speed is a scalar, having
magnitude only, while velocity is a vector, 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 and a
further explaination is provided at the end of this section.
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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 mandates applications
using this document to make use of the <DirectionVector> element
only.
acceleration:
This element specifies the rate (usually rapid) at which something
happens. The <acceleration> element also contains a 'uom'
attribute.
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.
GML permits a range of units of measure for the uom attribute. This
document restricts this set to the #m/s (meters per second).
4. XML Schema
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 [RFC4119].
5. Example
The following example shows a PIDF-LO document indicating geospatial
location information using the gml:Point structure. Following 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">
<device id="sg89ae">
<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>
<timestamp>2008-06-22T20:57:29Z</timestamp>
</device>
</presence>
Figure 1: Example of a PIDF-LO with Speed Information
6. Security Considerations
This document defines additional location elements carried by PIDF-LO
(see [RFC4119]). The security considerations of RFC 4119 [RFC4119]
are applicable to this document.
7. IANA Considerations
This document does not require actions by IANA.
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8. Acknowledgements
We would like to thank Klaus Darilion, Cullen Jennings, Rohan Mahy,
Carl Reed, Brian Rosen, and Martin Thomson for their comments.
9. References
9.1. Normative References
[GML] "Geographic information - Geography Markup Language (GML),
OpenGIS 03-105r1, available at:
http://portal.opengeospatial.org/files/?artifact_id=4700",
April 2004.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", RFC 2119, BCP 14, March 1997.
[RFC4119] Peterson, J., "A Presence-based GEOPRIV Location Object
Format", RFC 4119, December 2005.
[RFC4481] 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.
9.2. Informative References
[I-D.ietf-geopriv-pdif-lo-profile]
Winterbottom, J., Thomson, M., and H. Tschofenig, "GEOPRIV
PIDF-LO Usage Clarification, Considerations and
Recommendations", draft-ietf-geopriv-pdif-lo-profile-13
(work in progress), September 2008.
Appendix A. Transferring Multiple Location Objects within SIP
To show the path of an object, it may be useful to deliver multiple
location vector objects in one PIDF-LO document to reduce the number
of notifications. The <timed-presence> element [RFC4481] can contain
multiple location objects, with the structure shown in Figure 2 and
an example in Figure 3.
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<?xml version="1.0" encoding="UTF-8"?>
<presence>
<device>
<gp:geopriv>
..........
</gp:geopriv>
<timestamp>.....</timestamp>
<timed-status from="start-time" until="end-time">
<gp:geopriv>
............
</gp:geopriv>
<gp:geopriv>
...........
</gp:geopriv>
</timed-status>
</device>
<tuple>
.......
</tuple>
<person>
.......
</person>
</presence>
Figure 2: Structure of Handling Multiple Location Objects
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">
<device id="sg89ae">
<gp:geopriv>
<gp:location-info>
<gml:location>
<gml:Point>
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<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>
<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>
</timed-status>
</device>
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</presence>
Figure 3: Example showing multiple Location Vectors transmitted
simultaneously.
Authors' Addresses
Singh Vishal
Email: singh.vishal@gmail.com
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
Linnoitustie 6
Espoo 02600
Finland
Phone: +358 (50) 4871445
Email: Hannes.Tschofenig@gmx.net
URI: http://www.tschofenig.priv.at
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