Summary Realization of Publish Subscribe

Copyright © 2010 Open Geospatial Consortium, Inc. 67 7 Event Discovery

7.1 Introduction

An initial model for Event Service Discovery is presented in this chapter. A CSW-ebRIM registry extension package is developed to correspond with the Event Service Discovery model. Example Services are provided along with queries to demonstrate the discovery process. An online registry service is available to test the queries.

7.2 Event Metadata Example

The classes in the Event Metadata package described in section 6.2.1.3 were implemented in XML Schema to support testing of the event discovery functionality in OWS-7. The schema is provided in chapter 16, Annex D – Event Metadata . Event metadata was created for two exemplary services, one from the Sensor Web and one from the Aviation domain. The metadata describes the event types that are published by the services on given event channels in certain encodings. Figure 30 and Figure 31 show the event metadata that was exemplarily created for OWS-7 in UML object diagram notation. Figure 30: Example of Event Metadata for Aviation Service – UML Object Diagram Notation 68 Copyright © 2010 Open Geospatial Consortium, Inc. The figure shows that three different event types are in use at the service. The events are published in AIXM and WXXM encodings more specifically, as dnotam:Event and wx:Forecast wx:Observation on two event channels. Each channel has been assigned a specific name which uniquely identifies the channel semantics for a given domain. Note: the XML implementation of the event metadata shown in Figure 30 can be found in Annex D – Event Metadata XML Implementation , section 16.2. Figure 31: Example of Event Metadata for SFE Service – UML Object Diagram Notation Figure 31 shows that two different event types are in use at the service. The events are published in OM and CAP encodings on two event channels. Each channel has been assigned a specific name which uniquely identifies the channel semantics for a given domain. Note: the XML implementation of the event metadata shown in Figure 31 can be found in Annex D – Event Metadata XML Implementation , section 16.3. The example metadata described in above figures was used to test the event service discovery model, which is discussed in the following sections.