I am an absolute beginner to activiti, and on perusing the manual, the following question burst to my mind: Is it possible to deploy any type of process in Activiti or are there fixed process-structures or even a given set of process types with which any newly created process has to be congruent so that the deployment will be successful?
Activiti runs BPMN 2.0 processes. That's a standard, and it defines how your XML must look like. So as long as your process follows the XML standard, it should be executable on the Activiti engine.