“The buffer should be cleared whenever there are messages”, you mean should be cleared after all messages are consumed?
Here is my problem that I have in visualization. I bound screen to the subscription so each time when I switch to another screen
I stop publishing of “non active screen” subscription and start publishing “active screen” subscription. This generally works ok except when
steady state of variables values occur. I am using SubscriptionNotificationListener to receive values.
For example I have on first screen variable which counts from 0 to 255.
I switch to second screen before variable reach 255, for example 185.
Now I am in second screen and wait counter to reach 255.
When I return to first screen the value will be 187 and should be 255.

That is because after firstScreenSubscription.setPublishingEnabled(true) it received messages from notification buffer and because variable is in steady
state no further changes will be received and value will stay 187.

Than I add one poll just before firstScreenSubscription.setPublishingEnabled(true) to pickup real value but I can’t control timing and in log I see
that poll works but after it is overwritten with old messages from notification buffer.

That is why I asked is it possible to clear buffer as it is possible it will resolve my problem, just clear it before poll.

Here is my log:

06.02.2015 15:29:15,241 DEBUG screen activation – !!!!!! ~~~~~~~~ activate()
// start poll
06.02.2015 15:29:15,241 DEBUG pollSubscription – Number of items in subscription: 1
06.02.2015 15:29:15,243 DEBUG notifyChange – Attrib of type class java.lang.Byte has value 255 in state VALID
06.02.2015 15:29:15,244 DEBUG notifyChange – Attrib of type class java.lang.Number has value 255 in state VALID
// end poll, start publishing again
06.02.2015 15:29:15,244 DEBUG notifyChange – Set publishing true
06.02.2015 15:29:15,361 DEBUG SubscriptionNotificationListener.onDataChange – item ns=4;s=AllDataTypesDynamic/ItemByte has changed, new value 210
// value 255 is overwritten with old value 210 from notification buffer

The same result is also when poll is after firstScreenSubscription.setPublishingEnabled(true) as poll is very quick.
Could you please help with some advice related to timing control?

BR,

Goran

Hi Aro,
I am using local UaDemoServer.
Yes, I see, managing of subscription is independent from buffer. I tried also to remove/add new subscription listener from/to subscription and the result is the same. As listener become active it consumes old messages from buffer anyway.
The question is why there is only few messages in the buffer? Obviously setPublishingEnabled(false) influence that in the buffer will be only 1-3 messages
and after stop publishing, buffer will not receive any. Can we say that these changes 1-3 registered after set publishing to false are orphans?
Currently I don’t have idea how to resolve this issue.

Thanks,

Goran

Thanks a lot Aro for this post. I will try with change of monitoring mode for these items but I see potential problem as I have same item in multiple subscriptions.
Related to PublishingInterval, SamplingInterval, QueueSize everything is default:
s.setPublishingInterval(publishInterval); // ~200
s.setLifetimeCount(lifeTimeCount); // ~1000
s.setMaxKeepAliveCount(maxKeepAliveCount); // ~50
s.setMaxNotificationsPerPublish(maxNotificationsPerPublish);// ~1000
s.setNotificationBufferSize(100);
MonitoredItem sampling interval is 500ms, queue size is default 1
BR,
Goran