Web Feature Service for CAP alerts

[Eliot Christian <echristi@usgs.gov>]

This year, USGS, NOAA, CDC, and all other Federal agencies
to some extent, are required to implement CAP for all public
alerts and notifications. Such CAP alerts will be available
typically as an RSS feed, e.g., http://www.weather.gov/alerts
or http://www.usgs.gov/hazard_alert/alerts/rss.xml

A CAP alert is designed to describe a hazardous event, and
a given CAP message can designate more than one area. For
instance, a CAP message about a tornado might designate
one area as "evacuate" and a larger surrounding area as
"shelter in place". (I suppose the larger one ought to
have a hole corresponding to the smaller one, but that
may be an aside point for now.)

In any case, each feature offered by a Web Feature Service
(WFS) should be associated with one particular area. So, we
need to "flatten" the CAP alert structure and make a set of
place-specific copies. In the tornado example, we should
have one WFS feature for the "evacuate" area and another
WFS feature for the "shelter in place" area.

I posted a CAP Implementors Note about this two years ago
and I am now drafting an update of that Note (my draft is
at http://www.usgs.gov/hazard_alert/ImplementorsNote.doc ).

So, we can have a GML file containing CAP alert messages
that have been converted into featureMember elements within
a WFS featureCollection. My example of such a file is at
http://wwww.usgs.gov/hazard_alert/alerts/capgml.xml .

As I understand the overall OGC architecture for displaying
maps, we need to serve this GML content from a WFS service
that can deliver the CAP alerts as map features on request.

I'd appreciate help on this from anyone who uses the OGC
open standards for getting CAP alerts displayed on maps.

Of course, corrections or comments on any of my text or
example stuff would be greatly appreciated!

Eliot


Eliot Christian, USGS, 590 National Center, Reston VA 20192
cell: 571-212-8294  office: 703-648-7245  fax: 703-648-7112

ImplementorsNote.doc