Real-time tasks are generally classified as – Hard and Soft but on a wide range, Real-time tasks are classified as:
- Hard Real-time Tasks
- Firm Real-time Tasks
- Soft Real-time Tasks
1. Firm Real-time Tasks :
Firm real-time tasks are such type of real-time tasks which are associated with time bound and the task need to produce the result within the deadline. Although firm real-time task is different from hard real-time task as in hard real-time once deadline is crossed and task is not completed, system fails but in case of firm real-time task even after the passing of deadline, system does not fail.
1. Video conferencing 2. Satellite based tracking
2. Soft Real-time Tasks :
Soft real-time tasks are such type of real-time tasks which are also associated with time bound but here timing constraints are not expressed as absolute values. In soft real-time tasks, even after the deadline result is not considered incorrect and system failure does not occur.
1. Web browsing 2. Railway Ticket Reservation
Difference between Firm and Soft Real-time Tasks :
|FIRM REAL-TIME TASKS||SOFT REAL-TIME TASKS|
|It needs to be completed within the deadline.||It also needs to be completed within deadline but not strictly.|
|The value of associated timing constraint is taken as absolute.||The value of associated timing constraint is taken as average value.|
|The utility of result becomes zero after the deadline.||The utility of result decreases after the deadline but it gradually becomes zero.|
|Result obtained after deadline is considered incorrect.||Result obtained after deadline is not incorrect.|
|It is widely used in multimedia applications.||It is less used in such applications.|
|It is less used in practical applications.||It is widely used in practical applications.|
|Example: Satellite based tracking.||Example: Railway ticket reservation.|
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