Real-time Java Applications

The Java is an Object-Oriented Programming language. It is a kind of language that is suitable for distributed computing . Since Java was introduced by Sun Company in May. 1995, in several years, the Java has become the most popular program language. The Real-Time Java technique is a new technique.Basing on Java , it will be suitable for real-time application development. Real-Time Java( Real- Time Java, RTJava) can handle some real-time systems. It is very suitable for the real-time application environment in which their request is not too rigor. The Real-Time Java may be the most useful to develop the real-time interactive application .The purpose of extending Real-Time Java is on keeping the compatibility of the present Java' s mode, properly extending the platform towards the real-time.This extending is not to make the Java run quicker.But quicker hardware and improved algorithm make up for the fixed extra expense.This is the choice that the standard Java made when it is extended to the real-time field:that is using the extra expense of the processor to exchange the robust software and quicker speed of development.First this article introducs Java' s characteristics and real-time Java platforms and detailedly analyze the Java' s disadvantageous factor applying in real-time environment and which aspects need to be improved if real-time Java wants to be realized.The aspects demanded extension involve virtual machine, byte code analyzer, byte code interpreter ,the real-time run and the contents of the real-time task etc.Through the research of the RTSJ (Real-Time Java Specification ) and its APIs, the article discusses each aspect which bases on thetraditional Java . We know, the Real-Time Java Specification is an extension of the standard Java, enhance the contents which can increase the real-time performance.Basing on RTSJ , the article give a multithread extension mode. It discussed the syntax of the constructors of the RealTimethread and the NoHeapRealTimethread and discussed each parameter' s meaning of the constructor and gave some methods of the RealTimethread. And it discussd the advantage and disadvantage of the fixed priority scheduler,and put forward the timeslice dynamic priority scheduler, divided the Java' s run time into timeslice,satisfied the time limit of the beginning of the real-time task to the best(the responser time namely). This is the scheduling policy that is suitable for developing the real-time interactive application . The article gives the syntax of the constructors of the scheduler. For the priority inversion happen when high priority thread share with low priority thread a certain resource^ e. The article puts forward three priority inversion avoidance, priority in_ heritance protocol .priority ceiling emulation protocol, and thread copy protocol. Finally, the article gives an example of chess, and gives some design about the scheduler.