Real-Time Computing (RTC) System
A Real-Time Computing (RTC) System is a computing system that is a real-time system (which can solve a real-time task within a specified deadline).
- AKA: Reactive Computer System.
- Context:
- It can range from being a Soft Real-Time Computing System, to being a Hard Real-Time Computing System, to being a Firm Real-Time Computing System.
- It can be based on a Real-Time Computing Framework.
- It can range from being a Java-based Real-Time System, Scala-based Real-Time System, ...
- …
- Example(s):
- Counter-Example(s):
- See: Real-Time Simulation, Real-Time Computer Graphics, Time-Utility Function, Event (Synchronization Primitive), Industrial Control System, Synchronous Programming Language.
References
2020
- (Wikipedia, 2020) ⇒ https://en.wikipedia.org/wiki/real-time_computing Retrieved:2020-10-28.
- Real-time computing (RTC), or reactive computing is the computer science term for hardware and software systems subject to a "real-time constraint", for example from event to system response. Real-time programs must guarantee response within specified time constraints, often referred to as "deadlines".[1]
Real-time responses are often understood to be in the order of milliseconds, and sometimes microseconds. A system not specified as operating in real time cannot usually guarantee a response within any timeframe, although typical or expected response times may be given. Real-time processing fails if not completed within a specified deadline relative to an event; deadlines must always be met, regardless of system load.
A real-time system has been described as one which "controls an environment by receiving data, processing them, and returning the results sufficiently quickly to affect the environment at that time". The term "real-time" is also used in simulation to mean that the simulation's clock runs at the same speed as a real clock, and in process control and enterprise systems to mean "without significant delay". Real-time software may use one or more of the following: synchronous programming languages, real-time operating systems, and real-time networks, each of which provide essential frameworks on which to build a real-time software application. Systems used for many mission critical applications must be real-time, such as for control of fly-by-wire aircraft, or anti-lock brakes, both of which demand immediate and accurate mechanical response.
- Real-time computing (RTC), or reactive computing is the computer science term for hardware and software systems subject to a "real-time constraint", for example from event to system response. Real-time programs must guarantee response within specified time constraints, often referred to as "deadlines".[1]
- ↑ Ben-Ari, Mordechai; "Principles of Concurrent and Distributed Programming", ch. 16, Prentice Hall, 1990, , page 164
2011
- (Buttazzo, 2011) ⇒ Giorgio C. Buttazzo. (2011). “Hard Real-Time Computing Systems: Predictable Scheduling Algorithms and Applications.” Springer Publishing Company, Incorporated. ISBN:1461406757, 9781461406754.
- QUOTE: Real-time systems are computing systems that must react within precise time constraints to events in the environment. As a consequence, the correct behavior of these systems depends not only on the value of the computation but also on the time at which the results are produced SR88. A reaction that occurs too late could be useless or even dangerous. Today, real-time computing plays a crucial role in our society, since an increasing number of complex systems rely, in part or completely, on computer control (...)
Depending on the consequences that may occur because of a missed deadline, a realtime task can be distinguished in three categories:
- Hard: A real-time task is said to be hard if producing the results after its deadline may cause catastrophic consequences on the system under control.
- Firm: A real-time task is said to be firm if producing the results after its deadline is useless for the system, but does not cause any damage.
- Soft: A real-time task is said to be soft if producing the results after its deadline has still some utility for the system, although causing a performance degradation.
- QUOTE: Real-time systems are computing systems that must react within precise time constraints to events in the environment. As a consequence, the correct behavior of these systems depends not only on the value of the computation but also on the time at which the results are produced SR88. A reaction that occurs too late could be useless or even dangerous. Today, real-time computing plays a crucial role in our society, since an increasing number of complex systems rely, in part or completely, on computer control (...)
- A real-time operating system that is able to handle hard real-time tasks is called a hard real-time system. Typically, real-world applications include hard, firm, and soft activities; therefore a hard real-time system should be designed to handle all such task categories using different strategies. In general, when an application consists of a hybrid task set, all hard tasks should be guaranteed off line, firm tasks should be guaranteed on line, aborting them if their deadline cannot be met, and soft tasks should be handled to minimize their average response time.
2009a
- (Wiktionary, 2009a) ⇒ http://en.wiktionary.org/wiki/realtime
- 1. (computing) of a system that responds to events or signals within a predictable time after their occurrence; specifically the response time must be within the maximum allowed.
1998
- (Juva, 1998) ⇒ Kanaka Juva (1998). "Real-Time Systems". Carnegie Mellon University. 18-849b Dependable Embedded Systems. Spring 1998
- QUOTE: Real-Time systems span several domains of computer science. They are defense and space systems, networked multimedia systems, embedded automative electronics etc. In a real-time system the correctness of the system behavior depends not only the logical results of the computations, but also on the physical instant at which these results are produced. A real-time system changes its state as a function of physical time, e.g., a chemical reaction continues to change its state even after its controlling computer system has stopped. Based on this a real-time system can be decomposed into a set of subsystems i.e., the controlled object, the real-time computer system and the human operator. A real-time computer system must react to stimuli from the controlled object (or the operator) within time intervals dictated by its environment. The instant at which a result is produced is called a deadline. If the result has utility even after the deadline has passed, the deadline is classified as soft, otherwise it is firm. If a catastrophe could result if a firm deadline is missed, the deadline is hard. Commands and Control systems, Air traffic control systems are examples for hard real-time systems. On-line transaction systems, airline reservation systems are soft real-time systems.
- QUOTE: Real-Time systems span several domains of computer science. They are defense and space systems, networked multimedia systems, embedded automative electronics etc. In a real-time system the correctness of the system behavior depends not only the logical results of the computations, but also on the physical instant at which these results are produced. A real-time system changes its state as a function of physical time, e.g., a chemical reaction continues to change its state even after its controlling computer system has stopped. Based on this a real-time system can be decomposed into a set of subsystems i.e., the controlled object, the real-time computer system and the human operator. A real-time computer system must react to stimuli from the controlled object (or the operator) within time intervals dictated by its environment. The instant at which a result is produced is called a deadline. If the result has utility even after the deadline has passed, the deadline is classified as soft, otherwise it is firm. If a catastrophe could result if a firm deadline is missed, the deadline is hard. Commands and Control systems, Air traffic control systems are examples for hard real-time systems. On-line transaction systems, airline reservation systems are soft real-time systems.