Alerts

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.

Alerts configuration

There are the following configuration possibilites:

• property files (default option)
• JMX

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.