Timers

    <bpmn:intermediateCatchEvent id="Event_timer">
      <bpmn:incoming>Flow_1sg7v2d</bpmn:incoming>
      <bpmn:outgoing>Flow_1nku8og</bpmn:outgoing>
      <bpmn:timerEventDefinition id="TimerEventDefinition_07xu06a">
        <bpmn:timeDuration xsi:type="bpmn:tExpression">PT2S</bpmn:timeDuration>
      </bpmn:timerEventDefinition>
    </bpmn:intermediateCatchEvent>

All Timers are persisted, therefore, if the Node.js session is restared timers will pickup where they left

Timer Types

DateTime (not supported)

  <timerEventDefinition>
        <timeDate>2011-03-11T12:13:14Z</timeDate>
    </timerEventDefinition>

Duration

Example (interval lasting 10 days):

    <timerEventDefinition>
        <timeDuration>P10D</timeDuration>
    </timerEventDefinition>

Time Cycle

Example (3 repeating intervals, each lasting 10 hours):

    <timerEventDefinition>
        <timeCycle>R3/PT10H</timeCycle>
    </timerEventDefinition>

Time Cycle accepts both ISO 8601 format and Cron format

Example for cron format:

    <timerEventDefinition>
        <bpmn:timeCycle xsi:type="bpmn:tFormalExpression">5 * * * *</bpmn:timeCycle>
    </timerEventDefinition>

ISO 8601 format:

This format displays a duration in the following format: PnYnMnDTnHnMnS where n is the number for the corresponding interval:

Y = years

M = months

W = weeks

D = days

T = delineator between dates and times, necessary to disambiguate between months and minutes

H = hours

M = minutes

S = seconds

You can leave certain intervals off if they don't apply, but you must include the T before any time intervals (PT). Valid examples include:

P3Y6M4DT12H30M5S (3 years, 6 months, 4 days, 12 hours, 30 minutes, and 5 seconds)

P3DT12H (3 days and 12 hours)

P1M (1 month)

PT1M (1 minute)

PT0S (0)

P0.5Y (1/2 a year)

PT1M3.025S (1 minute and 3025 milliseconds)

Development/Test Environment Timer modification

bpmn-server allow you to modify the timer behaviour during development without changing bpmn definition

By changing the configuration.ts to force timers to specific time

let definitionsPath = __dirname + '/processes/';
var configuration = new Configuration(
    {
        definitionsPath: definitionsPath,
        timers: {
            forceTimersDelay: 1000,
            precision: 3000,
        },

Event Types

Event Type	TimeDate	Duration	TimeCycle	TimeCycle Repeat
Start	NA	NA	Yes	Default
Intermediate	NA	Yes	Yes	NA
Boundary Event	NA	Yes	Yes	Yes

• Start Event support 'Time Cycle' only since duration and timeDate make no sense.

• Intermediate Events are implemented as a normal event, will start the timer at start of the node and once the timer is completed the node will end.

• Start Event Timers will start a new execution, therefore, they are scheduled by a cron job managed by bpmn-server.

Timer Expression

• Timer value can be a text string like PT30S or can be a JavaScript Expression $appServices.getTimerDelay(this)

      <bpmn2:boundaryEvent id="Event_0hx26qc" cancelActivity="false" attachedToRef="Activity_0cijuru">
        <bpmn2:timerEventDefinition id="TimerEventDefinition_0hwwvzf">
          <bpmn2:timeDuration xsi:type="bpmn2:tFormalExpression">$appServices.getTimerDelay(this)</bpmn2:timeDuration>
        </bpmn2:timerEventDefinition>
      </bpmn2:boundaryEvent>
  

  In this case it is calling an appServices.ts method:

      getTimerDelay(item) {
          // item passed is that of the boundary event
          // need to find parent item
          const parentItem = item.token.parentToken.currentItem;
          const priority= parentItem.priority;
          if (priority === 'high') {  
              return 'PT5S'; // 5 Seconds ISO 8601 duration format
          } else if (priority === 'medium') {
              return 'PT10S'; // 10 Seconds ISO 8601 duration format
          } else if (priority === 'low') {
              return 'PT15S'; // 15 Seconds ISO 8601 duration format
          }
      }
  

Implementation:

On Server start:

1. All start event are re-evaluated and reschedules
2. other events that are in wait state are re-evaluated and reschedules