This article is just a note. It is the original copy of my reply in the forum, so it is of little value. If you have nothing to do, you can check it out.
The arrow line connecting two activities in a shark is called transition. It has several key attributes.
Fromactivitydefinition (Source Activity definition) and toactivitydefinition (target activity definition)
Expression)
Assume that an activity is defined as "Application for leave ". When the engine completes an activity of "Application for leave", for example, "Application for leave _ instance _ 1", the engine searches for transition where fromactivitydefinition is "Application for leave" in the process definition, then, the expression is used to determine whether the conditions are successful. If the result is true, the toactivitydefinition instance of the transition is created.