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[CDO] react on remote model changes [message #930417]

Tue, 02 October 2012 09:47

Christian Stellwag

Messages: 48
Registered: July 2009
Location: Munich

Member

Hello Forum Readers,

I need some clarification on this topic.
Using CDO version 4.0.99 in a client/server application (RCP) we need mechanism to update clients when underlying data was changed (usually by different user).

Our current implementation registers as IListener on the CDOView and receives
notifyEvent(IEvent) change notifications.

As I understood from reading forum entries and docu this is one out of 3 possibilities to get informed (CDOSession.addListener and object.eAdapter().add(yourAdapter) being the other 2).

From Debugging the application I learned that notifyEvent is called twice,
first time with IEvent being CDOViewInvalidationEvent carrying information about what has changed (getDirtyObjects() and getDetachedObjects()).
Second time with CDOViewAdaptersNotifiedEvent.

Since I somehow rely on both events in this sequence my questions are:
- Is there a guarantee that both event notifications are submitted?
- in exactly this order?

I didn't find any exact documentation about this. Does it exist? Where?

Would you rather recommend to only consume CDOViewInvalidationEvent and ignore CDOViewAdaptersNotifiedEvent?

Thanx in advance,
Chris

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Re: [CDO] react on remote model changes [message #930439 is a reply to message #930417]

Tue, 02 October 2012 10:07

Eike Stepper

Messages: 6682
Registered: July 2009

Senior Member

Am 02.10.2012 11:47, schrieb Christian Stellwag:
> Hello Forum Readers,
>
> I need some clarification on this topic.
> Using CDO version 4.0.99 in a client/server application (RCP) we need mechanism to update clients when underlying data
> was changed (usually by different user).
What does 4.0.99 mean?

> Our current implementation registers as IListener on the CDOView and receives
> notifyEvent(IEvent) change notifications.
>
> As I understood from reading forum entries and docu this is one out of 3 possibilities to get informed
> (CDOSession.addListener and object.eAdapter().add(yourAdapter) being the other 2).
Yes, actually there's an old fourth way: CDOInvalidationNotification from pre-CDODeltaNotification times.

> From Debugging the application I learned that notifyEvent is called twice,
> first time with IEvent being CDOViewInvalidationEvent carrying information about what has changed (getDirtyObjects()
> and getDetachedObjects()).
> Second time with CDOViewAdaptersNotifiedEvent.
>
> Since I somehow rely on both events in this sequence my questions are:
> - Is there a guarantee that both event notifications are submitted?
> - in exactly this order?
Yes and yes. Have a look at CDOViewImpl.doInvalidate() where the events/notifications are emitted in the following order:

sendInvalidationNotifications();
fireInvalidationEvent();

if (!deltas.isEmpty() || !detachedObjects.isEmpty())
{
sendDeltaNotifications(deltas, detachedObjects, oldRevisions);
}

fireAdaptersNotifiedEvent(lastUpdateTime);

> I didn't find any exact documentation about this. Does it exist? Where?
The docs are incomplete? You're kidding! :P

> Would you rather recommend to only consume CDOViewInvalidationEvent and ignore CDOViewAdaptersNotifiedEvent?
No. It all depends on what you want to achieve.

Cheers
/Eike

----
http://www.esc-net.de
http://thegordian.blogspot.com
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Cheers
/Eike

----
http://www.esc-net.de
http://thegordian.blogspot.com
http://twitter.com/eikestepper

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