Oracle DB could notify client, when table data changes. Data could be changed by third party process or by different client session. Notification implementation is important, when we want to inform client about changes in the data, without manual re-query. I had a post about ADS (Active Data Service), where notifications were received from DB through change notification listener – Practical Example for ADF Active Data Service. Now I would like to focus on change notification listener, because it can be used in ADF not only with ADS, but also with WebSockets. ADF BC is using change notification to reload VO, when configured for auto refresh – Auto Refresh for ADF BC Cached LOV.
Change notification is iniatilized by DB and handled by JDBC listener. There are two important steps for such listener – start and stop. Sample application – WebSocketReusableApp.zip, implements servlet DBNotificationManagerImpl. I’m starting and stopping DB change listener in servlet init and destroy methods: Read the complete article here.
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