This chapter will describe the different types of ``disruptions'' or disruptive events the reactive planner is capable of handling. By disruption we mean any action performed by the external user that will change the internal state of the system and will, eventually require some reactive or corrective behavior. We assume that all disruptions are introduced through the graphical user interface. For example, to introduce new patients in the system, the user has to load a file with the patient descriptions; these descriptions will be translated into internal objects. The creation of these objects tells the system that some disruption has occurred. In response to the disruption, the patient router will be triggered or executed to schedule the patients. In this sense, all the system behavior can be considered reactive, the generative behavior being only a special case.
The basic reactive mode of operation can be divided into three clearly defined steps:
The problem-solving methods are then selected based on a combination of user preferences and analysis results. These methods, also called knowledge-sources are the ones that will actually change the solution in order to resolve the conflicts.