Declare trigger and OnChange in pega

OnChange

Declare OnChange rules to run an activity automatically at activity step boundaries when the value of specified property changes. This capability provides a form of automatic forward chaining.

OnChange activity to be executed automatically by a Declare OnChange rule, such activities must not use any methods that directly change the properties or the database.

Trigger Activity

Trigger activity to be executed automatically by a Declare Trigger rule. Because triggered activities run during database commits, they cannot themselves commit database transactions.