The Event Service Discovery Model The Event Service Discovery extension package

70 Copyright © 2010 Open Geospatial Consortium, Inc. Figure 32: Registry Model for Event Service Discovery

7.4 The Event Service Discovery extension package

The components required to support the Event Service Discovery model are listed in the following table. Table 33: Event Service Discovery Model Components Component Description of Component instances Object Types EventChannel, EventType Association Types HasChannel, ChannelBinding Classification Node Sensor event service type, AIM event service type new C- Nodes added to existing ServiceType scheme Classification Schemes Scheme for Filter 2.0.0 Operators and Operands Note: The optional part of the model referring to a Schema object is not implemented in the current OWS project due to time constraints. It is documented in the model so it can be explored in a future OWS project. Copyright © 2010 Open Geospatial Consortium, Inc. 71 The XML representation of the Event Service Discovery extension package is listed in section 15.1.

7.5 Event Serivce Discovery Scenarios

The following discovery scenarios are considered to be representative of typical search patterns that registry clients will follow in order to obtain a reference to a particular Service of interest. The query and expected response are provided in this document with links to a demonstration registry service. This is to enable the interested reader to exercise these scenarios in an interactive manner.

7.5.1 Scenario 1: Find a Service providing Sensor Data that supports Comparison Filters

In this scenario, a complex query is used to demonstrate the discovery of Services of interest based on both Filter capabilities and a specific Event type: Sensor events. The Event Discovery model is utilized as the associations between Services and EventChannels, as well as, between EventChannels and EventTypes, are traversed via multiple filter clauses. The EventDomain property of an EventType is used to identify broad applicability to Sensor events via URN http:www.opengis.netows7sfeevents which is combined with selection of a particular Sensor event type: VideoChangeDetected . 7.5.1.1 Step 1: Formulation of a CSW-ebRIM GetRecords query A query is created using OGC Filter syntax that: selects Services which support Filter comparison operators. offers a channel that provides Sensor related events Listing 1: Registry query to find services providing sensor events and supporting comparison filters ?xml version=1.0 encoding=UTF-8? GetRecords xmlns=http:www.opengis.netcatcsw2.0.2 xmlns:rim=urn:oasis:names:tc:ebxml-regrep:xsd:rim:3.0 xmlns:ogc=http:www.opengis.netogc xmlns:gml=http:www.opengis.netgml xmlns:wrs=http:www.opengis.netcatwrs1.0 outputFormat=applicationxml; charset=UTF-8 service=CSW version=2.0.2 startPosition=1 maxRecords=10 resultType=results -- Find Services which provide Sensor related events -AND- which support the comparison operators -- Query typeNames=Service Classification ExtrinsicObject_channel_event Association_hc_cb ElementSetName typeNames=ServicefullElementSetName Constraint version=1.1.0 ogc:Filter ogc:And -- Service supports Filter Comparison operators -- 72 Copyright © 2010 Open Geospatial Consortium, Inc. ogc:PropertyIsEqualTo ogc:PropertyNameServiceidogc:PropertyName ogc:PropertyNameClassificationclassifiedObjectogc:PropertyName ogc:PropertyIsEqualTo ogc:PropertyIsEqualTo ogc:PropertyNameClassificationclassificationNodeogc:PropertyName ogc:Literalurn:x-ogc:def:rim-scheme:fes-2.0- ops:comparisonogc:Literal ogc:PropertyIsEqualTo -- link Serivce to its Channels -- ogc:PropertyIsEqualTo ogc:PropertyNameServiceidogc:PropertyName ogc:PropertyNamehcsourceObjectogc:PropertyName ogc:PropertyIsEqualTo ogc:PropertyIsEqualTo ogc:PropertyNamehcassociationTypeogc:PropertyName ogc:Literalurn:oasis:names:tc:ebxml- regrep:AssociationType:HasChannelogc:Literal ogc:PropertyIsEqualTo ogc:PropertyIsEqualTo ogc:PropertyNamehctargetObjectogc:PropertyName ogc:PropertyNamechannelidogc:PropertyName ogc:PropertyIsEqualTo ogc:PropertyIsEqualTo ogc:PropertyNamechannelobjectTypeogc:PropertyName ogc:Literalurn:ogc:def:rim-object- type:ows7:EventChannelogc:Literal ogc:PropertyIsEqualTo -- link Channel to its events -- ogc:PropertyIsEqualTo ogc:PropertyNamechannelidogc:PropertyName ogc:PropertyNamecbsourceObjectogc:PropertyName ogc:PropertyIsEqualTo ogc:PropertyIsEqualTo ogc:PropertyNamecbassociationTypeogc:PropertyName ogc:Literalurn:oasis:names:tc:ebxml- regrep:AssociationType:ChannelBindingogc:Literal ogc:PropertyIsEqualTo ogc:PropertyIsEqualTo ogc:PropertyNamecbtargetObjectogc:PropertyName ogc:PropertyNameeventidogc:PropertyName ogc:PropertyIsEqualTo -- Event must be in SFE domain and handle some form of sensor measurement -- ogc:PropertyIsEqualTo ogc:PropertyNameeventSlot[name=EventDomain]ValueListValueogc: PropertyName ogc:Literalhttp:www.opengis.netows7sfeeventsogc:Literal ogc:PropertyIsEqualTo ogc:PropertyIsEqualTo