Looping (Oracle Workflow API Reference)

Oracle Workflow API Reference
Release 2.6.3
Part Number B10286-02


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Looping

Looping occurs when the completion of an activity causes a transition to another activity that has already been completed. The first activity that gets detected as a revisited activity is also called a loop point or pivot activity. The Workflow Engine can handle a revisited activity in one of three ways:

Ignore the activity, and stop further processing of the thread, so in effect, the activity can only run once.

Reset the loop to the loop point before reexecuting by first running logic to undo the activities within the loop.

Reexecute the loop point and all activities within the loop without running any logic.

Every activity has an On Revisit poplist field in its Oracle Workflow Builder Details property page. The On Revisit poplist lets you specify the behavior of the Workflow Engine when it revisits the activity in a workflow process. You can set the field to Ignore, Reset, or Loop.

Setting On Revisit to Ignore is useful for implementing activities that should only run once, even though they can be transitioned to from multiple sources. For example, this mode allows you to implement a "logical OR"-type of activity which is transitioned to multiple times, but completes after the first transition only.

Setting On Revisit to Reset for an activity is useful when you want to reexecute activities in a loop, but you want to first reset the status of the activities in the loop. Reset causes the Workflow Engine to do the following:

Build a list of all activities visited following the pivot activity.

Traverse the list of activities, cancelling each activity and resetting its status.

Cancelling an activity is similar to executing the activity, except that the activity is executed in "CANCEL" mode rather than "RUN" mode. You can include compensatory logic in "CANCEL" mode that reverses any operation performed earlier in "RUN" mode.

If you set On Revisit to Reset for the pivot activity of a loop that includes an FYI notification activity, the Workflow Engine cancels the previous notification before reexecuting the loop and sending a new notification to the current performer of the notification activity.

Setting On Revisit to Loop for an activity is useful when you want to simply reexecute activities in a loop without resetting the status of the activities in the loop. Loop causes the Workflow Engine to reexecute the activity in "RUN" mode without executing any "CANCEL" mode logic for the activity.

If you set On Revisit to Loop for the pivot activity of a loop that includes an FYI notification activity, previous notifications remain open when the Workflow Engine reexecutes the loop and sends a new notification to the current performer of the notification activity.


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