3. An Over view at Systems that are Real-time, Distributed, and
Embedded
Before discussing the detailed problems involved in designing our elevator system with UML, the
definitions of real time system, distributed system, and embedded system are necessary to be
presented here, the difference between real-time distributed systems and software systems in the
common sense that most object-oriented design and analysis pays effort on by UML are briefly
stated. In the rest parts of this paper, the pros and cons of UML used in designing distributed
embedded systems are largely discussed.
According to Kopetz, a real time computer system is a computer system in which the correctness
of the system behavior depends not only on the logical results of the computations, but also on the
physical instant at which these results are produced[1]. As the saying goes: “The right answer late
is wrong”, in real time systems, performance requirements are as important as functional
requirements, so not only do we have to perform the correct functions, but there are clear bounds
within which these must be completed. An embedded computer system is a system that uses a
computer as a component, but whose prime function is not that of a computer.
As one of the object-oriented techniques, UML is basically suitable for real time system
development. There are techniques within UML definition that are a natural fit for specifying and
designing real-time systems. Use cases allow the designers to describe the way in which humans
and external devices, interact with the system. Object sequence diagrams, describe for a given use
case, the events which cause the interaction and the detailed system response, including timing.
3. An Over view at Systems that are Real-time, Distributed, and
Embedded
Before discussing the detailed problems involved in designing our elevator system with UML, the
definitions of real time system, distributed system, and embedded system are necessary to be
presented here, the difference between real-time distributed systems and software systems in the
common sense that most object-oriented design and analysis pays effort on by UML are briefly
stated. In the rest parts of this paper, the pros and cons of UML used in designing distributed
embedded systems are largely discussed.
According to Kopetz, a real time computer system is a computer system in which the correctness
of the system behavior depends not only on the logical results of the computations, but also on the
physical instant at which these results are produced[1]. As the saying goes: “The right answer late
is wrong”, in real time systems, performance requirements are as important as functional
requirements, so not only do we have to perform the correct functions, but there are clear bounds
within which these must be completed. An embedded computer system is a system that uses a
computer as a component, but whose prime function is not that of a computer.
As one of the object-oriented techniques, UML is basically suitable for real time system
development. There are techniques within UML definition that are a natural fit for specifying and
designing real-time systems. Use cases allow the designers to describe the way in which humans
and external devices, interact with the system. Object sequence diagrams, describe for a given use
case, the events which cause the interaction and the detailed system response, including timing.
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