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IEventBroker without data [message #822222]

Fri, 16 March 2012 10:16

Beat Schaller

Messages: 42
Registered: July 2009

Member

Hi

I am working heavily with IEventBroker and have some difficulties with it.

If I send, the structure is always:
eventBroker.post(Events.PRODUCER_INITIALIZED, new Oject());
Why do I have to post always an object, if I just want to notify? Sad

On the other hand to receive:
@Inject
void eventReceived(@Optional @UIEventTopic(Events.PRODUCER_INITIALIZED) final Object object) {
if (object!= null) {
...
}
}
If I have this method in a part, I always habe to check if the object is not null, because it always is injected when the part isr created. Even if no Event ist posted!!

Wouldn't it be nice to send Events without arguments? like:
eventBroker.post(Events.PRODUCER_INITIALIZED);

and to get this messages like:
@Inject
void eventReceived(@Optional @UIEventTopic(Events.PRODUCER_INITIALIZED)) {
// i am in this method only if I get an event!
}

regards
Beat

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Re: IEventBroker without data [message #822324 is a reply to message #822222]

Fri, 16 March 2012 13:22

Christoph Keimel

Messages: 482
Registered: December 2010
Location: Germany

Senior Member

Hi Beat

I use the service like this. Note that I use "@Optional" on the function and not on the parameter. This will only be called if a new event is created.

@Inject @Optional
private void openNewSchreibauftrag(@UIEventTopic(SaConstants.TOPIC_INPUT) ISchreibauftrag data) {
	logger.trace("openNewSchreibauftrag called with Event: {}", data);
	...
}

To send an event:

eventBroker.send(SaConstants.TOPIC_INPUT, sa);

Where sa is an instance of ISchreibauftrag

Greetings
Christoph

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Re: IEventBroker without data [message #822344 is a reply to message #822324]

Fri, 16 March 2012 13:51

Beat Schaller

Messages: 42
Registered: July 2009

Member

Thx, yes indeed. Works better in the case of the creation of a part. Only when a message is posted I receive one.

There is still left the "not so beautiful" definition of the interface with an object.
So if I want to send just a notification I have to define:

    eventBroker.post(Events.SAMPLE_EVENT, null);
    // have to send a null-Object

and receiving

    @Inject
    @Optional
    void eventReceived(@UIEventTopic(Events.SAMPLE_EVENT) final Object data) {
        // have to define Object, but can ignore it
    }

Greetings
Beat

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Re: IEventBroker without data [message #822825 is a reply to message #822222]

Sat, 17 March 2012 10:18

Eclipse User

Beat Schaller wrote on Fri, 16 March 2012 12:16

Hi

and to get this messages like:
@Inject
void eventReceived(@Optional @UIEventTopic(Events.PRODUCER_INITIALIZED)) {
// i am in this method only if I get an event!
}

You HAVE to have a parameter because that parameter is actually being annotated. In the snippet above the annotations do not annotate anything. One way would be to move those annotations to the method itself and to overload the post and send methods of the event broker to support just one argument. Also if I remember correctly the annotation itself (uieventtopic) doesn't support method annotation.

If I got you correctly than I believe it is too much of a change just avoid a null check, however tedious it might be.

Sopot

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Re: IEventBroker without data [message #824225 is a reply to message #822825]

Mon, 19 March 2012 12:10

Brian de Alwis

Messages: 242
Registered: July 2009

Senior Member

Rather than pass null or a dummy object when sending/posting your event, why don't you pass your actual consumer instance? It could be helpful for debugging later. And ignore it otherwise. Remember that the IEventBroker/EventAdmin is global across your OSGi framework instance. This could be important if you have multiple producers.

Oh and if the arg type is org.osgi.services.event.Event (from memory), the UIEventTopic/EventTopic injected value will be the actual Event object too, which might be useful.

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