Simple Sequence of Tasks

When you simulate performance of an activity modeled as a simple sequence of tasks, then ending of one simulation task instance leads to the immediate activation of the next simulation task instance (Figure 1).

Figure 1. A diagram with a simple sequence of BPMN tasks

Use a BPMN diagram to model the following situation: you’ve got a sequence of steps on a diagram, but you need to stop for a while before one of the steps. To model this, add an intermediate event shape before the shape of a task you want to pause (see Figure 2, the "Courier is here" event).

Figure 2. Modeling a waiting period before a "Give package to courier" task instance starts. BPMN diagram

Then define rules or occurrence conditions for an intermediate event. In other words, you either design an event instantiation model (see the Modelling Activation of a Process Instance article) or set conditions (see the Setting up Conditions in the Branching Point article).

Note that value of the Random value type property defines the way of calculating the event occurrence moment in case you create an event instantiation model.

Example. How to model a period of waiting for a message from another process instance

Look at Figure 3. Event instantiation model is created for the "Answer from technical support received" event, and Timer is selected as a value of the Random value type property.

Figure 3. Modelling a period of waiting for a message from another process instance on a BPMN diagram

If you run simulation of this process you get the following: occurrence of the "Request sent" event instance pauses performance of the process instance until the "Answer from technical support received" event instance occurs.