Hi , I am using Activiti engine source code, I cannot understand the relation between the main component( Process , Process instance , Activity , Task , case ,variable , user, group , role) of the process engine API .Is there any meta model (UML diagram or other ) that helps me to understand how does it work .Acutely I used a reengineering tool to transform the code source to a UML diagram but the result was catastrophic.
