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Sigma KEE - DesignPatternAttribute
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DesignPatternAttribute
This is a subclass of RealtimeSystemAttribute, which includes Guidance-DesignPattern, Initiation-DesignPattern, and Assessment-DesignPattern.
Relationships      
Parents RealtimeSystemAttribute The class of Attributes which describe instances of the class RealtimeSystem.
Children AssessmentDesignPatternAn instance of the class RealtimeSystem has Initiation-DesignPattern if it consists of sensors connected to a software module that filters data from the sensors and sends the filtered data to another software module that evaluates the filtered data and sends decisions to a subsystem. The design pattern is a data source that produces a data stream for a data handler. The data source is typically a periodically sampled collection of sensors. The data stream's size may vary and is unbounded. Data may be either homogeneous or heterogeneous. The workload per data element for homogeneous data is constant. The workload per data element for heterogeneous data is a function of each element type. There is one deadline for real-time situation assessment systems. It is the upper bound on the time to process all elements in the data stream once.
 GuidanceDesignPatternInstances of RealtimeSystems are described as systems with Guidance-DesignPattern if they consist of sensors connected to a software module that filters data from the sensors and sends the filtered data to a software module that evaluates the filtered data and sends instructions to a software module that commands actuators. The design pattern is an event source that produces events and a data source that produces data, both executing in parallel and handled by a single event-driven periodic data handler. The two separate input streams have fundamentally different characteristics. The event stream is necessarily asychronous, or transient. Once an event is sensed, the handler accepts data from the data stream, which has an invariant cycle time. There are two deadlines for a real-time guidance system. The period deadline is the time to process all elements in the data stream once and generate an actuator command. The action completion deadline is the time to guide the actuator to completion of the action.
 InitiationDesignPatternAn instance of the class RealtimeSystem has Initiation-DesignPattern if it consists of one software module and the actuators it commands. The design pattern is an event source which produces events for an event handler. The event source is typically an evaluate-and-decide software module. The event stream is necessarily asynchronous, or transient. The arrival rate of events may vary and is unbounded. Events may be either homogeneous or heterogeneous. The workload per event for homogeneous events is constant. The workload per event for heterogeneous events is a function of each event type. There is one deadline for real-time action initiation systems. It is the upper bound on the time to generate a command for the actuator.


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