Monitoring dropped events
When a model receives an event, it may be dropped if the correlator delivers or processes it too late. See
Input blocks and event timing.
The total number of dropped events across all models is periodically published as part of the status operation. The count of the number of dropped events is available as a user-defined status value with the name
user-analytics-oldEventsDropped in the
apama_status parameter of the status operation. See also
Monitoring periodic status for details about the operation.
All dropped input events are also sent to channel AnalyticsDroppedEvents, allowing you to implement your own monitoring of the dropped events. A dropped input event sent to the channel AnalyticsDroppedEvents is packaged inside an event of type apama.analyticskit.DroppedEvent. This allows you to extract the original dropped event and perform any analysis on it, for example, categorizing number of dropped events per device. Examples of some of the mechanisms you can employ include:
Use the
engine_receive tool to display the dropped events.
See Deploying and Managing Apama Applications in the Apama documentation for information on how to use this tool to receive events from a correlator. Write EPL to receive dropped events by subscribing to the dropped event channel and performing analysis on it to find out from which devices events are most likely to be dropped.
Write EPL to publish statistics about dropped events to a dashboard for visual monitoring.
Write custom CEP rules and upload them to
Cumulocity IoT to publish statistics about dropped events as measurements or operations.
See the User guide at http://cumulocity.com/guides/ for information on how to use the Administration application to manage applications.