Alerts define metrics for watching database data and if any metric exceeds its limit then alert is activated and further operation can be executed.
Metrics are configured - the SQL query for getting count of items and limit for checking.
Examples of alerts (also with follow-up operations):
- when count of failed messages for last 10 minutes exceeds 5 then sends email to administrators
- when count of messages which wait for response from external system for more then 5 minutes exceeds 10 then sends email to administrators
Alerts checking is scheduled operation that is determined by ohf.alerts.repeatTime configuration parameter - checking is executed every 5 minutes by default.
There are the following configuration possibilites:
- property files (default option)
Properties alerts configuration
Alerts configuration uses the same model as rest of OpenHub framework, see External configuration model
Property file configuration format and example (from application.properties):
JMX alerts configuration
JMX configuration allows change alert limits and enable/disable selected alerts.
Reaction to alert activation
There are listeners org.openhubframework.openhub.spi.alerts.AlertListener which are called when specified alert is activated.
There is default org.openhubframework.openhub.core.alerts.EmailAlertListenerSupport implementation that sends email notifications to admin emails.
If you want to implement more actions and you can implement AlertListener or extends default implementation EmailAlertListenerSupport.