DefaultExecutor

execute fragments:

• filter the ones that the user wants to keep
• sequence the execution so that only parts in between steps are executed concurrently

execute one Execution

execute one fragment

execute fragments, making sure that:

• "join" points are respected, i.e. when a Fragment is a join we must make sure that all previously executing fragments have finished their execution

• the fragments execute sequentially when args.sequential

• the execution stops if one fragment indicates that the result of the previous executions is not correct