[omniORB] IDL semantics of event publication (including event payload)

[Tom O'Reilly]

My question is not omniORB-specific; my apologies if this is not the appropriate forum..
I'm implementing a "vehicle navigation service" that can supply information to clients in two ways:

1. "Synchronous": client obtains navigation service proxy through Naming service, then invokes IDL-defined operation to get position

2. Subscribe-publish: Client subscribes to "new position" events from the navigation service through CosNotification;  the navigation service will then supply events - including vehicle coordinates as event "payload" - to CosNotification service, which will distribute to subscribers. 


How to best express these two capabilities in IDL?  The synchronous operation is obviously straightforward. But how do developer's (client and server programmers) know from the IDL that the service can publish "new position" events as well, and that the event "payload" includes the new position coordinates?

Here is an example of the IDL I am starting with;

module auv {

  interface Navigation {

    struct Position {
      float latitude;
      float longitutde;
      float altitude;
    };

    // Synchronous operation to get vehicle position
    void getPosition(out Position p);

    // Define event name that client can subscribe to
    const string NewPositionEvent = "NewPosition";

    // How to express the event payload contents here, such that compiler enforces it???

  };
};


Thanks,
Tom


--------------------------------------------------
Thomas C. O'Reilly
Monterey Bay Aquarium Research Institute
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     "Wind, Sand, and Stars" (1939)

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