| 摘要 |
An event dispatching subsystem pre-processes event messages received by an event driven main system having a context consisting of a defined set of major and minor state variables each having a defined range of values. The event dispatching subsystem defines a set of ports, and bands within each port, where each distinct type of event message that can be received is assigned to a respective one of the ports and bands. The messages in each band are stored in a FIFO queue until the messages in the band are processed. Each band has an assigned priority, which imposes a processing priority order on the messages stored in the various bands, and a band status value. An event dispatcher considers one event message at a time, where the event message to be considered is selected in accordance with the priority values of those bands, if any, having a band status value indicating that processing of events messages stored in the band is enabled. The dispatcher selects a disposition for the selected event based on the event's parameter values and the state variable values for the main system. The event dispatcher executes one of a plurality of predefined disposition action procedures, selected in accordance with the selected event disposition, for disposing of each event message. At least one of the disposition action procedures that can be invoked for event messages received by each port sends event messages to the main system for further processing.
|
