Real time Java
From Seo Wiki - Search Engine Optimization and Programming Languages
Java's sophisticated memory management, native support for threading and concurrency, type safety, and relative simplicity have created a demand for its use in many domains. Unfortunately, several properties prevent it from being directly suitable for use in Real time systems:
- Java does not support a strict priority based threading model. Early suggestions that it would support such a model were abandoned because they could not be implemented without native bindings on the target platforms, which were unavailable on Windows and Solaris.
- Because Java threads do not support priorities, Java locking mechanisms do not support priority inversion avoidance techniques, such as priority inheritance or the priority ceiling protocol.
- More critically, the garbage collection behavior may introduce unbounded delays in computation, immediately destroying any chance of making real-time guarantees for programs written in Java, although modern incremental garbage collectors available in many real-time Java implementations now reduce this level of non-determinism.
To overcome these difficulties, the Java Community introduced a specification for real-time Java, JSR001. As of 2007, a number of implementations of the resulting Real-Time Specification for Java (RTSJ) have emerged, including a reference implementation from Timesys, IBM's WebSphere Real Time, Sun Microsystems's Java SE Real-Time Systems, Aonix PERC or JamaicaVM from aicas.
The RTSJ addresses 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 of memory that are not subject to garbage collection, along with threads that are not preemptable by the garbage collector.
Real-Time Specification for Java
The Real-Time Specification for Java (RTSJ) is a set of interfaces and behavioral specifications that allow for real-time programming in the Java programming language. RTSJ 1.0 was developed as JSR 1 under the Java Community Process, which approved the new standard in November, 2001. As of 2006[update], RTSJ 1.1 is being developed under JSR 282.
- Real-Time Specification for Java (RTSJ)
- IBM WebSphere Real Time a fully conformant RTSJ SE VM
- JamaicaVM an RTSJ SE implementation with deterministic garbage collection
- PERC a real-time VM based on Java Standard Edition rather than RTSJ
- Sun Java SE Real-Time System
- Timesys RTSJ implementation and testing toolkit
- jRate (Java Real-Time Extension) an open-source extension of the GNU GCJ compiler front-end and runtime system which adds support for most of the features required by the RTSJ.
- DDC-I Scorpion Java real-time Java SE, with safety-critical and secure versions.
- International Workshop on Java Technologies for Real-time and Embedded Systems (JTRES 2006) JTRES 2007 JTRES 2008ca:Java de Temps Real