Karl Wolf's presentation on "Location Information Interoperability of CAP and PIDF-LO for Early Warning Systems" at ISCRAM 2013 in Baden-Baden.
10th International Conference on Information Systems for Crisis Response and Management
12-15 May 2013, Baden-Baden, Germany
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Overview
Location information is the key information for emergency
management
Common Alerting Protocol (CAP) is implemented by several Early
Warning Systems
CAP messages describe the affected area
CAP alert messages can be delivered directly to alert recipients over
various networks
Location-aware receivers can determine, whether the alert is relevant
for the current location
Internet devices are becoming increasingly location-aware
Framework for a unified location system for the Internet was defined by
the Internet Engineering Task Force (IETF)
Internet location services allow devices to acquire their current location
as Presence Information Data Format – Location Object (PIDF-LO)
Location format interoperability of CAP and PIDF-LO is required
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Presence Information Data Format –
Location Object (PIDF-LO)
XML document defined by the IETF
Geodetic and civic location supported
Civic address: predefined types (country, A1-A6, street,
house number, …)
Geodetic location: various shapes (point, polygon, circle,
ellipse, arc band, …)
Central role in the IETF’s framework for Internet
geolocation (e.g. location configuration protocols)
Adopted for next generation emergency calling in
North America by the National Emergency Number
Association (NENA)
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The Common Alerting Protocol (CAP)
CAP 1.2 adopted by Organization for the
Advancement of Structured Information
Standards (OASIS) in 2010
XML data format for all kinds of alerts
Affected area
Textual description
Geodetic shapes: circle and polygon
Geocode: name value pair (no predefined names)
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Geodetic Interoperability
CAP and PIDF-LO are supporting geodetic
location information
Well known algorithms can be used
Example: point-in-polygon query to determine,
whether a point in PIDF-LO lies within our
outside boundaries of a CAP polygon
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Civic Location Interoperability
PIDF-LO is supporting civic addresses
(predefined elements: country, street, etc.)
CAP specification does not mention civic
addresses
CAP has geocode elements (no predefined
elements)
Structure of civic addresses is more complex
How to figure out, whether a civic address lies
inside an area?
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Civic Location Interoperability - Example
<area>
<areaDesc>
Santa Clarita Valley
</areaDesc>
<geocode>
<valueName>UGC</valueName>
<value>CAZ088</value>
</geocode>
</area>
<cl:civicAddress xml:lang="en">
<cl:country>US</cl:country>
<cl:A1>California</cl:A1>
<cl:A2>Los Angeles County</cl:A2>
<cl:A3>Santa Clarita</cl:A3>
<cl:RD>Railroad</cl:RD>
<cl:STS>Ave</cl:STS>
<cl:HNO>24875</cl:HNO>
<cl:PC>CA 91321</cl:PC>
</cl:civicAddress>
Exemplary CAP area representation (left) and PIDF-LO civic address (right)
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Options
Forbid usage of civic addresses in PIDF-LO?
PIDF-LO is typically generated by a different entity than CAP
Civic addresses are also supported in the next generation
emergency calling framework
Civic addresses are suitable for certain scenarios (e.g. location
server serving fixed subscriber line customers)
Convert civic address to geodetic location?
Geocoding service necessary
Error-prone
Include PIDF-LO civic address elements in CAP?
New civic address element or full PIDF-LO inside CAP
Usage of geocode element (used for prototype implementation)
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Example
<area>
<areaDesc>Santa Clarita</areaDesc>
<geocode>
<valueName>PIDF-LO</valueName>
<value>
country="US";A1="California";
A2="Los Angeles County";A3="Santa Clarita“
</value>
</geocode>
</area>
Area representation in CAP with geocode element containing PIDF-LO
civic address elements for interoperability.
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Conclusion
IETF Internet geolocation makes devices location-aware
and allows location-based services to benefit
PIDF-LO was adopted for next generation emergency calling in
North America
Early warning could also benefit when CAP is disseminated to
end devices – only affected people get notified
Dissemination of warnings in geodetic as well as in civic
location format is required
CAP generators have no knowledge about the format the
receivers have configured
Interoperability issue for civic addresses exists
PIDF-LO civic address types would be required in CAP
Further work is required to prevent different
implementations on the Internet