Cron Trigger

Triggers allow events to be periodically generated. Trigger definition can be used to define a trigger. A trigger also works like a stream with a predefined schema.

Features

For some use cases the system should be able to periodically generate events based on a specified time interval to perform some periodic executions.

A trigger can be performed for a 'start' operation, for a given 'time interval', or for a given 'cron expression'.

The following types of triggers are currently supported:

Trigger type	Description
every time_interval	An event is triggered periodically at the given time interval (Minimum supported time interval is millisec)
cron expression	An event is triggered periodically based on the given cron expression
start	An event is triggered when Siddhi is started

Syntax

Trigger uses the following syntax:

    CREATE TRIGGER <trigger name> WITH ( interval = 'time interval' );
    CREATE TRIGGER <trigger name> WITH ( expression = 'start' or 'cron expression' ); 

Example

-- A trigger to generate events every 5 seconds.
1. CREATE TRIGGER FiveSecTrigger WITH ( interval = 5 sec );

-- A trigger to generate events every 100 millisec.
2. CREATE TRIGGER FiveSecTrigger WITH ( interval = 100 millisec );

-- A trigger to generate events at 10.15 AM on every weekdays.
3. CREATE TRIGGER WorkStartTrigger WITH ( expression = '0 15 10 ? * MON-FRI' );

-- A trigger to generate an event at App startup.
4. CREATE TRIGGER InitTrigger WITH ( expression = 'start' );