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Copyright © 2013 Open Geospatial Consortium.
Advanced Filtering functionality: Event Service Update Interval, Stored Filters, AIXM Features as Geometry Operands, Spatial Filtering of Non-spatial Features,
Simple Altitude Queries and Selective Metadata Retrieval.
The following sections provide implementation descriptions of selected features.
6.2.4.3 Stored Filters
The IDS ES implements “CreateStoredFilters”, “ListStoredFilters” and “DescribedStoredFilters” methods that are exposed via the NotificationBroker service
end point. Clients can use Simple Object Access Protocol SOAP messaging to create a stored filter, get a list of all available stored filters, or get a detailed description of a
stored filter such as title, filter and required parameters.
A client can subscribe to a stored filter via the normal ES’ Subscribe operation, using the new filter dialect, i.e. StoredFilterSubscription.
6.2.4.4 Update Intervals
This feature was implemented as an add-on component instead of modifying the filtering component, since WS-N’s “Subscription Policy” has been utilized to define this feature
capability. Hence, the filtering component was not impacted by this feature.
The client needs to specify the interval how often the notifications will be sent out, dissemination method all notifications since the last time, or only the latest, and
treatment matched subscription only, or any notifications. An experimental schema has been created for this purpose.
The following figure shows how the new update interval component fit into the existing event service.
Copyright © 2013 Open Geospatial Consortium.
33 .
Figure 8 -
Update Interval Framework
.
6.2.4.5 Simple Altitude Queries
Upon receiving a producer’s notification, the Event Service performed additional checks to determine if a particular subscription included altitude information as part of its
filtering message. For OWS-9, this was embedded in the route segment. A separate thread was created to perform a WFS GetFeature request. That query performed a logical
“AND” operation on the notification’s feature identifier and the subscription’s route segment filtering. If the WFS query returned a non-empty result that meant the
notification matches the given subscription. In that case, it was disseminated to the subscriber.
6.2.5 IfGI Event Service
