Enrichment of Thin Events

30 Copyright © 2011 Open Geospatial Consortium, Inc. All Rights Reserved. Figure 5 – Dataflow of Event Notifications

7.4.1.2.2 Dynamic Subscriptions

The dynamic filter functionality as described in section 9.4 has been implemented prototypically within this testbed. Besides the enrichment of events, this is another major change in the ES compared to OWS-7. Using the EML patterns the ES recognizes the subscription as a dynamic one and takes - in addition to the digital NOTAMs - the AircraftPositionUpdates into consideration for internal filtering. The internal representation of the subscription is continuously updated according to the retrieved positions. Thus, only those events matching the remaining flight route are forwarded to the clients.

7.4.2 IDS

The Event Service is provided by IDS Ingegneria dei Sistemi S.p.A. It is being developed in the context of OWS-8. The IDS Event Service allows distributing AIXM messages to interested clients. Clients can filter messages by message topic or by geometry. In addition to a push mode, the IDS Event Service also offers a pull mode, so that clients can retrieve messages even if not being continuously connected to the network.

7.4.2.1 Architecture

The IDS Event Service implements the OASIS WS-Brokered Notification specification. The entities involved are as follows:  Publisher: A Publisher is an entity that produces Notifications AIXM messages in this scenario and sends it to a Broker. A Publisher can specify on what topics it wishes to publish a notification. Copyright © 2011 Open Geospatial Consortium, Inc. All Rights Reserved. 31  Broker: The Broker is the entity in charge of disseminating notifications on behalf of Publishers to Consumers. Its role is routing Notifications created by Publishers to Consumers who own a matching subscription.  Consumer: A Consumer is an endpoint designated to receive Notifications produced by a Publisher, delivered by a Broker as a result of a subscription. A Subscription represents the relationship between a Consumer and the Broker, including any filtering parameters such as Topic and spatial filter expressions. All communication with the IDS Event Service is done via SOAP messages over HTTP. The IDS Event Service architecture is described in Figure 6. Figure 6 – IDS Event Service Architecture In the OWS8 scenario, the IDS Event Service implements a Notification Broker; publishers are AIXM message producers; consumers are the client applications.

7.4.2.2 Services Description

The operations offered by the IDS Event Service are: Notify: This is the basic method to send notifications e.g. digital NOTAMs from a notification producer to the Event Service and from the Event Service to a Notification Consumer e.g. the clients. No response is expected from the Event Service and Notification Consumer upon receipt of this message.