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 (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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