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Real-time Java is a catch-all term for a combination of technologies that enables programmers to writeprograms that meet the demands ofreal-timesystems in theJava programming language.
Java's sophisticatedmemory management, native support forthreading and concurrency,type safety, and relative simplicity have created a demand for its use in many domains. Its capabilities have been enhanced to support real-time computational needs:
The initial proposal[1] for an open standard for real-time Java was put forth by Kelvin Nilsen, then serving as a research faculty member at Iowa State University. A follow-on overview paper was published in theCommunications of the ACM.[2] The overwhelmingly positive response to these early proposals resulted in a series of meetings hosted by the National Institute of Standards and Technology in an effort to establish an open standard for real-time Java. NIST was ultimately told that they were not the appropriate body to establish standards related to the Java language, as Java was trademarked, and the technologies were owned by Sun Microsystems. Therefore, NIST ended their efforts with publication of consensus requirements.[3] that could be considered by future standardization efforts to be hosted by Sun Microsystems.
When theJava Community was formed, the very first effort was the specification for real-time Java, JSR001. A number of implementations of the resultingReal-time specification for Java (RTSJ) have emerged, including areference implementation fromTimesys,IBM's WebSphere Real Time,Sun Microsystems's Java SE Real-Time Systems,[4] PTC Perc fromPTC, Inc.,[5] orJamaicaVM from aicas.
The RTSJ addressed the critical issues by mandating a minimum specification for the threading model (and allowing other models to be plugged into the VM) and by providing for areas ofmemory that are not subject to garbage collection, along with threads that are not preemptable by the garbage collector. These areas are instead managed usingregion-based memory management. The latest specification, 2.0, supports direct device access and deterministic garbage collection as well.
TheReal-Time Specification for Java (RTSJ) is a set ofinterfaces and behavioral refinements that enable real-timecomputer programming in theJava programming language. RTSJ 1.0 was developed as JSR 1 under theJava Community Process, which approved the new standard in November, 2001. RTSJ 2.0 is being developed under JSR 282. A draft version is available at a JCP page.[6] More information can be found from Aicas.[7]