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

[Tuser]

In the COS notification service the IDLs are given. They are part of the
specification. You therefore do not define any IDL, except the layout of
your events.

If I remember correctly, the Notification service works with a structured
event (Value type), and you can therefore specialize the event. You must
also specify which parts of the event that subscribers can filter on. A
subscriber will receive an event, and thereafter have to down cast it to the
correct event type.

Hope this helps.




Tom O'Reilly wrote:
> 
> 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
> 7700 Sandholdt Road
> Moss Landing, California 95039-9644
> 831-775-1766 (voice)
> 831-775-1620 (FAX)
> oreilly at mbari.org (email)
> http://www.mbari.org (World-wide Web)
> 
> "The machine does not isolate man from the great mysteries
>  of nature, but plunges him more deeply into them."
> 
>    - ANTOINE DE SAINT-EXUPERY
>      "Wind, Sand, and Stars" (1939)
> 
> 
> _______________________________________________
> omniORB-list mailing list
> omniORB-list at omniorb-support.com
> http://www.omniorb-support.com/mailman/listinfo/omniorb-list
> 
> 

-- 
View this message in context: http://www.nabble.com/IDL-semantics-of-event-publication-%28including-event-payload%29-tf4477937.html#a12772728
Sent from the OmniORB - User mailing list archive at Nabble.com.