The initiate attribute can be

yes

,

no

, or

join

.

A

yes

means that the execution of the activity initializes the correlation set property alias with a value from the message being sent or received. WS-BPEL requires the activity to fault with the standard

bpel:correlationViolation

fault if the correlation set is already initiated.

If there are multiple activities enabled concurrently, and any of them could initiate the correlation set, you should use the

join

attribute.

A

join

means an activity must attempt to initiate the correlation set.

Join

is useful for multi-start activities or any scenario where more than one activity can initiate the correlation set.

The following sections describe different activity types.