PLEXIL

Overview

Nodes

• List nodes: List nodes are the internal nodes in a plan. These nodes have child nodes that can be of any type.
• Command nodes: These nodes issue commands that drive the system.
• Assignment nodes: Performs a local operation and assigns a value to a variable.
• Function call nodes:accesses external functions that perform computations, but do not alter the stateof the system.
• Update nodes: Provides information to the planning and decision support interface.
• Library call nodes: This nodes invoke nodes in an external library.
• Empty nodes: Nodes that contain attributes and do not perform any actions.

• Inactive
• Waiting
• Executing
• Finishing
• Iteration_Ended
• Failing
• Finished

• SkipCondition T : The skip condition changes from unknown or false to true.
• StartCondition T : The start condition changes from unknown or false to true.
• InvariantCondition F/U : Invariant condition changes from true to false or unknown.
• EndCondition T : End condition changes to true
• Ancestor_inv_condition F/U : The invariant condition of any ancestor changes to false or unknown.
• Ancestor_end_condition T : The end condition of any ancestor changes to true
• All_children_waiting_or_finished T : This is true when all child nodes are in either in node state waiting or finished and no other states.
• Command_abort_complete T : When the abort for a command action is completed.
• Function_abort_complete T : The abort of a function call is completed.
• Parent_waiting T : The parent of the node transitions to node state waiting.
• Parent_executing T : The parent of the node transitions to node state executing.
• RepeatCondition T/F : the repeat condition changes from unknown to either true or false.