We have used the TOracleEvent component with the DBMS_Alert package in Oracle, and thought we had done something really nice. This is used to send alert messages from triggers or from the application, much like a windows message. E.g. when certain data is updated by a user, it tells all the other users that they need to refresh their data as well.

However some of our customers, namely the larger ones, are experiencing a lot of problems when this feature is enabled. It generates two oracle sessions pr user, which seems to generate too much overhead on the server. Is there a way to use this component without generating two sessions instead of one?

It also fills up the oracle alert log with warnings because alert messages are received by sessions which have lost the connection with the client pc. The OracleEvent component is stopped before the OracleSession is logged off when the application closes. Is there something we are missing? What happens if the user just turns off the pc instead of terminating the application as he should, could that be causing the problem?

We haven't tried the new DOA version yeat, are there any enhancements in this area in that version?

We are kind of stuck now, and we don't really want to turn off all the nice functionality we have developed using the TOracleEvent component, so I Really hope to get some help on this one...

The properties are set as follows:
Synchronized :True
Timeout :0
ObjectType: otAlert
ObjectNames : <a long list, separated with ;>

OnError event is not used.

With regards
Helene

The TOracleEvent requires an extra session because it needs to wait for events (dbms_signal.wait), and a session can only do one thing at a time. So either the session waits for events, or it does something else, but not both. Version 3.4 does not change this.

I am not sure about the alert log warnings. If there are a lot of users and it does indeed happen that people turn of the PC or kill the process of your application, you would expect that the corresponding session eventually times out. This could still lead to errors though.

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Marco Kalter
Allround Automations