Introduction Document object model

118 Copyright © 2010 Open Geospatial Consortium, Inc. Figure 42: UML for CAP Message The model defines four primary segments: alert , info , resource and area . The alert segment provides basic information about the message: purpose, source, status, etc. The alter segment can be used alone for message acknowledgements, cancellations and other system functions. The info segment encodes the details of the alert. Multiple info segments can be included to express information in multiple languages or across multiple disconnected areas. The resource segment provides an optional reference to additional related resources. The area segment describes the geographic area to which the notification applies.

12.2.9.3 Spatially enabled

CAP is spatially enabled allowing messages to be targeted geographically. Copyright © 2010 Open Geospatial Consortium, Inc. 119 The following XML-Schema fragment shows the declaration of the cap:area element which allows CAP messages to be tagged with location. Listing 5: Extract of CAP XML Schema showing location support element name = area minOccurs = 0 maxOccurs = unbounded complexType sequence element name = areaDesc type = string element name = polygon type = string minOccurs = 0 maxOccurs = unbounded element name = circle type = string minOccurs = 0 maxOccurs = unbounded element name = geocode minOccurs = 0 maxOccurs = unbounded complexType sequence element ref = cap:valueName element ref = cap:value sequence complexType element element name = altitude type = string minOccurs = 0 element name = ceiling type = string minOccurs = 0 sequence complexType Location is expressed textually using the cap:areaDesc element and can be expressed geometrically or using a geo-code such as a postal code. The standard states that geometric tagging is the preferred method. Unfortunately, the geometric tagging is done using a non-standard encoding forcing a conversion to and from a standard encoding like GML.

12.2.9.4 Code lists

The CAP standard defines a number of lists of values for parameters in the model. Here are a couple of examples: element name = category maxOccurs = unbounded simpleType restriction base = string enumeration value = Geo enumeration value = Met enumeration value = Safety enumeration value = Security enumeration value = Rescue enumeration value = Fire enumeration value = Health enumeration value = Env enumeration value = Transport enumeration value = Infra enumeration value = CBRNE enumeration value = Other restriction simpleType element element name=responseType minOccurs=0 maxOccurs=unbounded simpleType restriction base=string enumeration value=Shelter enumeration value=Evacuate enumeration value=Prepare enumeration value=Execute enumeration value=Monitor enumeration value=None restriction simpleType element