The progress is tracked from the org.apache.myfaces.trinidad.model.BoundedRangeModel attached to this component through its 'value' attribute. The progressIndicator element goes to an indeterminate mode and shows up as a spinner animation if the 'value' or 'maximum' from the BoundedRangeModel is unknown. When these gets known the component switches to a determinate mode and renders a progress bar indicating percentage of task completion. Once the task is complete, ActionEvent is queued and, the page indicated by outcome of 'action' attribute is navigated to.