GEOPRIV R. Mahy
Internet-Draft Plantronics
Intended status: Standards Track B. Rosen, Ed.
Expires: January 14, 2010 NeuStar
H. Tschofenig
Nokia Siemens Networks
July 13, 2009
A Document Format for Filtering and Reporting Location Notications in
the Presence Information Document Format Location Object (PIDF-LO)
draft-ietf-geopriv-loc-filters-04.txt
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Abstract
This document describes filters that limit asynchronous location
notifications to compelling events, designed as an extension to RFC
4661 "An XML-Based Format for Event Notification Filtering". The
resulting location information is conveyed in existing location
formats wrapped in the Presence Information Document Format
(PIDF-LO).
Table of Contents
1. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Filter Definitions . . . . . . . . . . . . . . . . . . . . . . 5
3.1. Horizontal and Vertical Movement . . . . . . . . . . . . . 5
3.2. Changes in Speed . . . . . . . . . . . . . . . . . . . . . 5
3.3. Changes in Value . . . . . . . . . . . . . . . . . . . . . 6
3.4. Enter or Exit a Region . . . . . . . . . . . . . . . . . . 7
4. Rate Control . . . . . . . . . . . . . . . . . . . . . . . . . 9
5. XML Schema . . . . . . . . . . . . . . . . . . . . . . . . . . 10
6. Security Considerations . . . . . . . . . . . . . . . . . . . 11
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12
7.1. Content-type registration for
'application/location-delta-filter+xml' . . . . . . . . . 12
7.2. URN Sub-Namespace Registration for
urn:ietf:params:xml:ns:location-filter . . . . . . . . . . 13
7.3. Schema Registration For location-filter . . . . . . . . . 14
8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 15
9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 16
9.1. Normative References . . . . . . . . . . . . . . . . . . . 16
9.2. Informational References . . . . . . . . . . . . . . . . . 17
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 18
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1. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
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2. Introduction
Conveying location in PIDF-LO [RFC4119] bodies is described in
[I-D.ietf-sip-location-conveyance]. Asynchronous notification of
location information is unfortunately more complex since many forms
of location are measured as a continuous gradient. Unlike
notifications using discret quantities, it is difficult to know when
a change in location is large enough to warrant a notification. The
mechanism described in this document defines filters as an extension
to RFC 4661 [RFC4661], which limits location notification to events
that are of relevance to the subscriber. These filters persist until
they are changed with a replacement filter.
The frequency of notifications necessary for various geographic
location applications varies dramatically. The subscriber should be
able to get asynchronous notifications with appropriate frequency and
granularity, without having to issue a large number of notifications
that are not important to the application. This section of this
document defines an extension to [RFC4661]'s TriggerType element to
describe interesting conditions or events. The terminal elements in
this format are utilizing Geographic Markup Language (GML) [GML] data
types and civic address elements.
This document also defines a MIME type for this location filter
format, namely 'application/location-delta-filter+xml'.
This document defines the following as an initial list of events that
could be interesting to a subscriber:
1. the Target moves more than a specified distance horizontally or
vertically since the last notification
2. the Target exceeds a specified speed
3. the Target enters or exits one or more GML objects (for example,
a set of 2-dimensional or 3-dimensional regions) included or
referenced in the filter.
4. one or more of the values of the specified address labels has
changed for the location of the Target (for example, the value of
the <A1> civic address element has changed from 'California' to
'Nevada')
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3. Filter Definitions
3.1. Horizontal and Vertical Movement
Changes in the position of the Target require extensions to the
functionality of RFC 4661 and a simplying assumption. The former
aspect refers to the need to enhance the capability to extract a
value from inside an XML element, in our example from the <pos>
element, which describes the user's location. Regarding the latter
aspect we assume that the user's location information of any shape
and uncertainty is converted into a point before the comparison
regarding the movement with the previously notified location takes
place.
The example shown in Figure 1 references the latitude value (using
the "gml:pos[1]" notation) and the 'by' attribute of the <changed>
element indicates the desired change that triggers a notification to
be sent.
<?xml version="1.0" encoding="UTF-8"?>
<filter-set xmlns="urn:ietf:params:xml:ns:simple-filter">
<ns-bindings>
<ns-binding prefix="pidf"
urn="urn:ietf:params:xml:ns:pidf"/>
<ns-binding prefix="gp"
urn="urn:ietf:params:xml:ns:pidf:geopriv10"/>
<ns-binding prefix="dyn"
urn="http://www.opengis.net/gml"/>
</ns-bindings>
<filter id="123" uri="sip:presentity@example.com">
<trigger>
<changed by="100">
/pidf:presence/pidf:device/gp:geopriv/
gp:location-info/gml:Point/gml:pos[1]
</changed>
</trigger>
</filter>
</filter-set>
Figure 1: Movement Filter Example
3.2. Changes in Speed
Speed changes can be filtered with the help of RFC 4661 and the
functionality provided in [I-D.singh-geopriv-pidf-lo-dynamic], which
extends the PIDF-LO with support for spatial orientation, speed,
heading, and acceleration.
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Figure 2 shows an example for a trigger that fires when the speed of
the Target changes by 20 meters per second.
<?xml version="1.0" encoding="UTF-8"?>
<filter-set xmlns="urn:ietf:params:xml:ns:simple-filter">
<ns-bindings>
<ns-binding prefix="pidf"
urn="urn:ietf:params:xml:ns:pidf"/>
<ns-binding prefix="gp"
urn="urn:ietf:params:xml:ns:pidf:geopriv10"/>
<ns-binding prefix="dyn"
urn="urn:ietf:params:xml:schema:pidf:dynamic"/>
</ns-bindings>
<filter id="123" uri="sip:presentity@example.com">
<trigger>
<changed by="3">
/pidf:presence/pidf:tuple/pidf:status/
gp:geopriv/gp:location-info/dyn:Dynamic/dyn:speed
</changed>
</trigger>
</filter>
</filter-set>
Figure 2: Speed Change Example
3.3. Changes in Value
Changes in values, for example related to civic location information,
can be provided by the base functionality offered with RFC 4661.
Figure 3 shows an example where a notification is sent when the civic
address tokens A1, A2, A3, or PC change.
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<?xml version="1.0" encoding="UTF-8"?>
<filter-set xmlns="urn:ietf:params:xml:ns:simple-filter">
<ns-bindings>
<ns-binding prefix="pidf"
urn="urn:ietf:params:xml:ns:pidf"/>
<ns-binding prefix="gp"
urn="urn:ietf:params:xml:ns:pidf:geopriv10"/>
<ns-binding prefix="cl"
urn="urn:ietf:params:xml:ns:pidf:geopriv10:civilLoc"/>
</ns-bindings>
<filter id="123" uri="sip:presentity@example.com">
<trigger>
<changed>
/pidf:presence/pidf:tuple/pidf:status/gp:geopriv/
gp:location-info/cl:civilAddress/cl:A1
</changed>
<changed>
/pidf:presence/pidf:tuple/pidf:status/gp:geopriv/
gp:location-info/cl:civilAddress/cl:A2
</changed>
<changed>
/pidf:presence/pidf:tuple/pidf:status/gp:geopriv/
gp:location-info/cl:civilAddress/cl:A3
</changed>
<changed>
/pidf:presence/pidf:tuple/pidf:status/gp:geopriv/
gp:location-info/cl:civilAddress/cl:PC
</changed>
</trigger>
</filter>
</filter-set>
Figure 3: Speed Change Example
3.4. Enter or Exit a Region
The <enterOrExit> condition is satisfied when the Target enters or
exits a named 2-dimensional or 3-dimensional region described by a
polygon (as defined in Section 5.2.2 of [RFC5491]), or a circle (as
defined in Section 5.2.3 of [RFC5491]).
Figure 4 and Figure 5 shows filter examples whereby a notification is
sent when the Target enters or exits an area described by a circle
and by a 3d polygon.
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<?xml version="1.0" encoding="UTF-8"?>
<filter-set
xmlns="urn:ietf:params:xml:ns:simple-filter"
xmlns:con="urn:ietf:params:xml:ns:pidf:geopriv10:containment"
xmlns:gml="http://www.opengis.net/gml"
xmlns:gs="http://www.opengis.net/pidflo/1.0">
<filter id="123" uri="sip:presentity@example.com">
<con:enterOrExit>
<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">
850.24
</gs:radius>
</gs:Circle>
</con:enterOrExit>
</filter>
</filter-set>
Figure 4: <enterOrExit> (2D) Filter Example
<?xml version="1.0" encoding="UTF-8"?>
<filter-set xmlns="urn:ietf:params:xml:ns:simple-filter"
xmlns:con="urn:ietf:params:xml:ns:pidf:geopriv10:containment"
xmlns:gml="http://www.opengis.net/gml">
<filter id="123" uri="sip:presentity@example.com">
<con:enterOrExit>
<gml:Polygon srsName="urn:ogc:def:crs:EPSG::4326">
<gml:exterior>
<gml:LinearRing>
<gml:posList>
43.311 -73.422 43.111 -73.322
43.111 -73.222 43.311 -73.122
43.411 -73.222 43.411 -73.322
43.311 -73.422
</gml:posList>
</gml:LinearRing>
</gml:exterior>
</gml:Polygon>
</con:enterOrExit>
</filter>
</filter-set>
Figure 5: <enterOrExit> (3D) Filter Example
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4. Rate Control
The throttle mechanisms [I-D.ietf-sipcore-event-rate-control] can be
used to control the rate of notifications. The "throttle", "force"
and "average" settings can filter notications by time.
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5. XML Schema
<?xml version="1.0" encoding="UTF-8"?>
<xs:schema
targetNamespace="urn:ietf:params:xml:ns:location-filter"
xmlns:xs="http://www.w3.org/2001/XMLSchema"
xmlns:gml="http://www.opengis.net/gml">
<!-- This element is an child element of the RFC 4661
<filter> element.
-->
<xs:element name="enterOrExit" type="gml:FeaturePropertyType"/>
</xs:schema>
Figure 6: XML Schema
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6. Security Considerations
Location information is typically very privacy sensitive. As such,
notifications MUST be encrypted and integrity protected.
Additional privacy and security considerations are discussed in
detail in [RFC5491].
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7. IANA Considerations
7.1. Content-type registration for 'application/
location-delta-filter+xml'
This specification requests the registration of a new MIME type
according to the procedures of RFC 4288 [RFC4288] and guidelines in
RFC 3023 [RFC3023].
MIME media type name: application
MIME subtype name: location-delta-filter+xml
Mandatory parameters: none
Optional parameters: charset; Indicates the character encoding of
enclosed XML.
Encoding considerations: Uses XML, which can employ 8-bit
characters, depending on the character encoding used. See RFC
3023 [RFC3023], Section 3.2.
Security considerations: See the "Security Considerations" section
in this document.
Interoperability considerations: None
Published specification: RFCXXXX [NOTE TO IANA/RFC-EDITOR: Please
replace XXXX with the RFC number of this specification.]
Applications which use this media type: This content type supports
the exchange of filters to throttle asynchronous notifications of
location information.
Additional information:
Magic Number: N/A
File Extension: N/A
Macintosh file type code: N/A
Personal and email address for further information: Brian Rosen,
br@brianrosen.net
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Intended usage: LIMITED USE
Author:
This specification is a work item of the IETF GEOPRIV working
group, with mailing list address <geopriv@ietf.org>.
Change controller:
The IESG <iesg@ietf.org>
7.2. URN Sub-Namespace Registration for
urn:ietf:params:xml:ns:location-filter
This section registers a new XML namespace, as per the guidelines in
[RFC3688].
URI: The URI for this namespace is
urn:ietf:params:xml:ns:location-filter.
Registrant Contact: IETF, GEOPRIV working group, <geopriv@ietf.org>,
as delegated by the IESG <iesg@ietf.org>.
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>
<meta http-equiv="content-type"
content="text/html;charset=iso-8859-1"/>
<title>Location Filter Namespace</title>
</head>
<body>
<h1>Namespace for PIDF-LO Location Filters</h1>
<h2>urn:ietf:params:xml:ns:location-filter</h2>
<p>See <a href="[[[URL of published RFC]]]">RFCXXXX</a>.</p>
</body>
</html>
END
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7.3. Schema Registration For location-filter
This specification registers a schema, as per the guidelines in
[RFC3688].
URI: please assign.
Registrant Contact: IETF, GEOPRIV Working Group
(geopriv@ietf.org), as delegated by the IESG (iesg@ietf.org).
XML: The XML can be found as the sole content of Section 5.
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8. Acknowledgments
Thanks to Allan Thompson, James Winterbottom, and Martin Thomson for
their comments.
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9. References
9.1. Normative References
[GML] OpenGIS, "Open Geography Markup Language (GML)
Implementation Specification", OpenGIS OGC 02-023r4,
January 2003,
<http://www.opengis.org/techno/implementation.htm>.
[I-D.ietf-sipcore-event-rate-control]
Niemi, A., Kiss, K., and S. Loreto, "Session Initiation
Protocol (SIP) Event Notification Extension for
Notification Rate Control",
draft-ietf-sipcore-event-rate-control-00 (work in
progress), May 2009.
[I-D.singh-geopriv-pidf-lo-dynamic]
Schulzrinne, H., Singh, V., Tschofenig, H., and M.
Thomson, "Dynamic Extensions to the Presence Information
Data Format Location Object (PIDF-LO)",
draft-singh-geopriv-pidf-lo-dynamic-06 (work in progress),
June 2009.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3023] Murata, M., St. Laurent, S., and D. Kohn, "XML Media
Types", RFC 3023, January 2001.
[RFC4119] Peterson, J., "A Presence-based GEOPRIV Location Object
Format", RFC 4119, December 2005.
[RFC4288] Freed, N. and J. Klensin, "Media Type Specifications and
Registration Procedures", BCP 13, RFC 4288, December 2005.
[RFC4661] Khartabil, H., Leppanen, E., Lonnfors, M., and J. Costa-
Requena, "An Extensible Markup Language (XML)-Based Format
for Event Notification Filtering", RFC 4661,
September 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.
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9.2. Informational References
[I-D.ietf-sip-location-conveyance]
Polk, J. and B. Rosen, "Location Conveyance for the
Session Initiation Protocol",
draft-ietf-sip-location-conveyance-13 (work in progress),
March 2009.
[RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
January 2004.
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Authors' Addresses
Rohan Mahy
Plantronics
345 Encincal Street
Santa Cruz, CA
USA
Email: rohan@ekabal.com
Brian Rosen (editor)
NeuStar
470 Conrad Dr.
Mars, PA 16046
US
Phone: +1 724 382 1051
Email: br@brianrosen.net
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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