Application of Java Technology in Industrial Real-time Systems

Abstract Application of Java Technology in Industrial Real-Time SystemsIndustrial automation is currently characterized by a number of trends induced by the currentmarket situation. The main trends are the pursuit of high flexibility, good scalability, highrobustness of automation systems, and the integration of new technologies in all fields and levelsof automation. Of special interest is the integration of technologies into the control area.In this context, object-oriented languages have gained importance. In particular, there is anincreasingly growing interest in Real-Time Java because of its challenges and its potentialimpact on the development of embedded and real-time applications.Java applications are executable on every platform, which can run a Java Virtual machine, JVM.Together with typical concepts of object-orientation, Java opens many possibilities for areusability of the code. Java also provides high stability of applications, which makes it aninteresting programming language for control engineering.Although the creation of a uniform specification for real-time behavior in Java is vitallyimportant right against the background of platform independence, it was not possible to find acommon approach of all parties thereto. Currently, there are suggestions for theenhancement/modification of the standard-Java-specification by two consortia with the goal ofmaking Java applicable to real-time systems.The suggested real-time extensions for the Java language are: Real-Time Specification for Java(RTSJ), developed by the Real-Time for Java Expert Group under the auspices of SunMicrosystems; Real-Time Core Extensions (RTCE), developed by the Real-Time Java WorkingGroup operating within J-Consortium; and finally the Real-Time Data Access (RTDA)specification, developed by the Real-Time Data Access Working Group (RTAWG), andoperating within J-Consortium.These specifications are compared together. It can be stated that all of them follow differentapproaches but also focus on different application areas. The RTSJ and RTCE have the goal toprovide a more general way of enabling Java to become usable in the real-time domain, while theRTDA focuses on the special application field of industrial automation and understands real-timecapabilities only as one of several requirements, which are typical for this area.The use of Java for control programming at the field level shows advantages, especially insystems where Java is also used for non-real-time applications. For implementing such systems,special attention has to be paid to restrictions regarding the mutual interactions of the controlapplication running under real-time conditions and the non-real-time application.If the real-time Java platform provides support in this respect, this can be realized very easily.However, most real-time Java products and specifications do not follow the requirements ofindustrial control applications; hence, special attention that has to be paid to these aspects isdiscussed.This paper is to present a practical teaching module which introduces and exposes Javaprogramming techniques to electronics engineering technology in a junior level-course. It alsoattempts to serve as an innovative way to expose technology students to this difficult topic andgive them the fresh taste of Java programming while having fun learning the IndustrialApplications.