South East Training - Business Process Modelling Toolkit

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Repeating Activities 

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Repeating Activities - Basic Notation

  • Basic notation allows us to model simple repeating activities by using a series of gateways. 
    • In the first example below, the intermediate message event will pass the flow immediately to the following gateway as soon as it receives one nomination. 
    • Without the gateway, the sequence flow would continue to process this single nomination. 
    • In practice, it is likely that we will want to batch-process all nominations received.  To achieve this we add an XOR gateway after the intermediate message event that redirects the flow to an earlier point in the sequence if the condition specified continues to be met.  In this case, flow will only continue along the normal path when 10 nominations have been received or a deadline has been reached.
    • Note, the first gateway is a convenient device to join the sequence flow upstream of the intermediate message event.

Repeating Activities - Advanced Notation

  • BPMN offers a simpler way to represent this same sequence.
    • In the second example below, we have used a 'looping activity', denoted by the circular arrow at the bottom of the box, to indicate that the activity will keep looping until the specified condition is met.  In this case, normal flow will continue only once 10 nominations have been received.
    • The third example shows that we can apply the same notation to a sub-process.  We cannot use it, however, with events.
  • The fourth example represents a different condition.  The three vertical lines at the bottom of the sub-process box indicate that this is a multi-instance activity (or sub-process).  It is similar to a looping activity but there are two distinct differences: 
    • For a looping activity we do not know the number of instances and have to set a condition to terminate the activity.  With a multi-instance activity, we do know the number of instances.
    • For a looping activity, instances are dealt with sequentially.  With a multi-instance activity, instances can be dealt with concurrently.  In the example below, you could have two or more interviews being conducted at the same time.

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