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Copyright © 2010 Open Geospatial Consortium, Inc.
Listing 6: CAP encoded notification generated by ESS
cap:alert xmlns:cap=urn:oasis:names:tc:emergency:cap:1.1
cap:identifierurn:uuid:885e061e-b6dd-4a4b-ad15-8131e61c512acap:identifier cap:sendergeosynccubewerx.comcap:sender
cap:sent2010-06-03T20:56:41-05:00cap:sent cap:statusActualcap:status
cap:msgTypeAlertcap:msgType cap:sourcehttp:www.cubewerx.comows7cubeservcubeserv.cgi?service=GSSamp;request=Ge
tCapabilitiescap:source cap:scopePubliccap:scope
cap:info cap:categoryOthercap:category
cap:eventNEW REPLICATIONFEED ENTRYcap:event cap:responseTypeNonecap:responseType
cap:urgencyFuturecap:urgency cap:severityUnknowncap:severity
cap:certaintyObservedcap:certainty cap:eventCode
cap:valueNameactioncap:valueName cap:valueINSERTcap:value
cap:eventCode cap:effective2010-06-03T20:56:41-05:00cap:effective
cap:senderNameCuebWerx Inc.cap:senderName cap:headlineNew Feature Availablecap:headline
cap:descriptionA new feature with identifier CWFID.BUILDINGGEOSURFACE.0.326 has been processed by the GSS and is now available.cap:description
cap:instructionThe new feature can be retrieved by following the uri for the Feature Type resource. The WFS transaction that created the feature can be obtained by
following the uri for the ATOM entry resource and reading the content of the entry.cap:instruction
cap:resource cap:resourceDescATOM entrycap:resourceDesc
cap:mimeTypeapplicationatom+xmlcap:mimeType cap:urihttp:www.cubewerx.comows7cubeservcubeserv.cgi?service=GSSamp;request=GetEn
triedamp;id=urn:uuid:8084a1cd-50c6-49b1-9641-96241ad5dd1ecap:uri cap:resource
cap:resource cap:resourceDescFeature Typecap:resourceDesc
cap:mimeTypeapplicationgml+xml; version-3.1.1cap:mimeType cap:urihttp:www.pvretano.comngacubeserv.cgi?service=WFSamp;CONFIG=plugweekamp;DAT
ASTORE=tdsamp;request=GetFeatureamp;typeName=BUILDINGGEOSURFACEamp;featureId=CWFID.BUI LDINGGEOSURFACE.0.326cap:uri
cap:resource cap:area
cap:polygon18.5778097 -72.2787128 18.5778097 -72.2787692 18.5778911 - 72.2787692 18.5778936 -72.2788604 18.5777792 -72.2788631 18.5777741 -72.2787128
18.5778097 -72.2787128cap:polygon cap:area
cap:info cap:alert
12.2.9.9 Filtering CAP messages
As illustrated in Listing 6 and section 12.2.9.8, a CAP message is composed of values that are encoded in-line in the alert, info and area segments and of values that may be
remotely references in the resource segment.
Filtering CAP messages using FES to constrain in-line values is straight forward and does not present any technical challenges. In fact, CAP and FES work quite well together
especially because CAP messages are spatio-temporally enabled thus allowing the spatial and temporal operators defined in FES to be used in query predicates when geometric
location tagging is used. Of course, there is the issue of converting the CAP geometry to GML see 12.2.9.3 but this is more a nuisance than a show stopper.
Copyright © 2010 Open Geospatial Consortium, Inc.
123 Filtering on referenced values presents more of a challenge. Filtering on referenced
values is not a function of FES but of the service within which FES is embedded – see
section 9.1.3. If the service is capable of resolving referenced values then filtering is possible.
Perhaps the best analogy to use here is the Web Feature Service 2.0 implementation specification. The WFS 2.0 standard defines a set of request parameters called the
Standard Resolve Parameters. The following XML Schema fragment from the WFS 2.0 schemas defines these parameters:
xsd:attributeGroup name=StandardResolveParameters xsd:attribute name=resolve type=wfs:ResolveValueType default=none
xsd:attribute name=resolveDepth type=wfs:positiveIntegerWithStar default=
xsd:attribute name=resolveTimeout type=xsd:positiveInteger default=300
xsd:attributeGroup xsd:simpleType name=ResolveValueType
xsd:restriction base=xsd:string xsd:enumeration value=local
xsd:enumeration value=remote xsd:enumeration value=all
xsd:enumeration value=none xsd:restriction
xsd:simpleType xsd:simpleType name=positiveIntegerWithStar
xsd:union memberTypes=xsd:positiveInteger wfs:StarStringType xsd:simpleType
xsd:simpleType name=StarStringType xsd:restriction base=xsd:string
xsd:enumeration value= xsd:restriction
xsd:simpleType
The resolve parameters appear on requests and direct the service how to handle referenced values. The resolve parameter tells the service which referenced values to
resolve; local, remote, all or none. The resolveDepth and resolveTimeout parameters control the number of nested levels to which referenced values should be resolved and
how long to wait to resolve a remote value reference. When processing a predicate and the service encounters a remote value reference, it uses these parameters to control how it
resolves that reference in order to obtain a value to test in the predicate. If the resolution is successful and a testable value is obtained, filter processing continues as normal. If
value resolution fails, then filter processing fails and an exception is raised.
12.2.9.10 EDXL-DE
EDXL-DE Emergency Data Exchange Language Distribution Element was not used in the GSS experiment and so it is discussed only briefly here.
The purpose of EDXL-DE is to facilitate the routing of any XML emergency message to recipients. An EDXL-DE message may be thought of as a container. An EDXL-DE
message provides the information to route payload message sets such as Alerts or Resource Messages, by including key routing information such as distribution type,
geography, incident, and senderrecipient IDs.
