activiti learning summary 1

Process Definition (ProcessDefinition):
  defines what links in the process and how to execute the XML file
  process definition that needs to be persisted to the data air
  . The process definition links are divided into two categories 
      : 1: waiting node (when the process executes to the waiting node, the process stops,
        know Process API to let the process continue to execute), such as userTask
     2: do not wait for nodes,
        such as startEvent, endEvent, serviceTask
     <process id="leave" name="leave application">
     </process>

ProcessInstance (ProcessInstance)
  1 process definition can Generate multiple process instances,
  process definitions and process instances have a one-to-many relationship, similar to the relationship between classes and objects. When a

task
   process instance is executed, it is generally the userTask that generates the process task. The

process execution object (Execution)
  represents the execution process