Activiti EnterpriseActiviti Enterprise Documentation Alfresco Modeling Application Processes BPMN elementsTimer events

Timer events

Timer events are used to influence events at specific times, after a set amount of time has passed or at intervals. All timer events use the international standard ISO 8601 for specifying time formats.

Timer events are graphically represented by a clock icon inside different shapes that differentiate between the event types.

The following are timer events:

All timer events require either a timeDate, timeDuration or timeCycle property included within the timerEventDefinition to define the timer trigger behaviour.

timeDate

The timeDate property for timer events defines a specific date and time in ISO 8601 format for when the trigger will be fired and can include a specified time zone.

The following is an example of the timerEventDefinition using a timeDate:

2017-05-17 represents the 17th May 2017 in YYYY-MM-DD format
T12:42:23 represents the time of 12:42:23 in hh:mm:ss format
Z represents that the time format is in UTC (Coordinated Universal Time). The time can also contain UTC offsets such as +01 for an hour ahead of UTC. When an offset is defined the Z is not required, for example: T12:42:23+01

<bpmn2:timerEventDefinition> 
  <bpmn2:timeDate xsi:type="bpmn2:tFormalExpression">2017-05-17T12:42:23Z</bpmn2:timeDate>
</bpmn2:timerEventDefinition>

timeDuration

The timeDuration property for timer events defines how long a timer should wait in ISO 8601 format before the trigger is fired.

The following are the letters used to refer to duration:

Letter	Description	Example
`P`	Designates that the following letters and numbers represent a duration. Must always be present
`Y`	Represents a year and follows the number of years	`P2Y` for 2 years
`M`	Represents a month and follows the number of months when preceded by a `P`	`P3Y4M` for 2 years and 4 months
`W`	Represents a week and follows the number of weeks	`P10W` for 10 weeks
`D`	Represents a day and follows the number of days	`P1Y1M1D` for 1 year, 1 month and 1 day
`T`	Designates that the following letters represent a duration of hours to seconds. Must always be present to refer to hours, minutes and seconds
`H`	Represents an hour and follows the number of hours	`P1DT0.5H` for 1 day and half an hour
`M`	Represents a minute and follows the number of minutes when preceded by a `T`	`PT1M` for 1 minute
`S`	Represents a second and follows the number of seconds	`P2Y3M4DT5H6M7S` for 2 years, 3 months, 4 days, 5 hours, 6 minutes and 7 seconds

The following is an example of the timerEventDefinition using a timeDuration to represent a duration of 5 days:

<bpmn2:timerEventDefinition>
  <bpmn2:timeDuration xsi:type="bpmn2:tFormalExpression">P5D</bpmn2:timeDuration>
</bpmn2:timerEventDefinition>

timeCycle

The timeCycle property for timer events defines intervals for the trigger to fire at. Intervals can be defined using the time intervals that adhere to the ISO 8601 standard or by using cron expressions.

Time intervals

Time intervals use the syntax R/ to set a number of repetitions, for example R5/ would repeat five times.

Following the repetition, a duration can be set for when the repetition occurs, for example R5/PT10H would repeat every 10 hours, five times.

Note The duration uses the same format as for timeDuration.

An optional end date can also be set after the duration and separated by a /.

Note: The end date uses the same format as for timeDate.

The following is an example of the timerEventDefinition using time interval syntax for timeCycle to represent three repetitions every 30 minutes:

<bpmn2:timerEventDefinition>
  <bpmn2:timeCycle xsi:type="bpmn2:tFormalExpression">R3/PT30M</bpmn2:timeCycle>
</bpmn2:timerEventDefinition>

Cron expression intervals

Cron expressions can be used to define repeating triggers for timer events.

The following is an example of the timerEventDefinition using a cron expression for timeCycle to represent a trigger firing every 5 minutes beginning at the top of the hour:

<bpmn2:timerEventDefinition>
  <bpmn2:timeCycle>0 0/5 * * * ?</bpmn2:timeCycle>
</bpmn2:timerEventDefinition>

Timer expressions

All properties within timerEventDefinition can accept process variables as their values as long as they are in ISO 8601 or cron expression format.

The following is an example of the process variable {$duration} being used:

<bpmn2:timerEventDefinition>
    <bpmn2:timeDuration xsi:type="bpmn2:tFormalExpression">${duration}</bpmn2:timeDuration>
</bpmn2:timerEventDefinition>

Timer intermediate catch events

Timer intermediate catching events cause the process flow to wait until a specific time or interval is reached. The time to wait is defined in the timerEventDefinition property.

Timer intermediate catching events are graphically represented by two thin concentric circles with a clock icon inside.

The XML representation of timer intermediate catching events is:

<bpmn2:intermediateCatchEvent id="IntermediateCatchEvent5">
    <bpmn2:incoming>SequenceFlow_3</bpmn2:incoming>
    <bpmn2:outgoing>SequenceFlow_4</bpmn2:outgoing>
    <bpmn2:timerEventDefinition>
        <bpmn2:timeDuration xsi:type="bpmn2:tFormalExpression">P5D</bpmn2:timeDuration>
    </bpmn2:timerEventDefinition>
</bpmn2:intermediateCatchEvent>

Note: This will wait five days before continuing the process.

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