Java and Real Time Storage Applications

Storage systems have storage devices which run real time embedded software. Most storage devices use C and occasionally C++ to manage and control the storage device. Software for the storage device must meet the time and resource constraints of the storage device. The prevailing wisdom in the embedded world is that objects and in particular Java only work for simple problems and can not handle REAL problems, are too slow and can not handle time critical processing and are too big and can’t fit in memory constrained systems. Even though Java's roots are in the embedded application area, Java is more widely used in the desktop and enterprise environment. Use of Java in embedded real time environments where performance and size constraints rule is much less common. Java vendors offer a dizzying array of options, products and choices for real time storage applications. Four main themes emerge when using Java in a real time storage application; compiling Java, executing Java with a software Java Virtual Machine (JVM), executing Java with a hardware JVM and replacing a real time operating system (RTOS) with a JVM. The desktop and enterprise environment traditionally run Java using a software JVM that has been ported to a particular platform. The JVM runs as a task or process hosted by the platform operating system. With the performance and memory available on most workstations and personal computers, running an application on a software JVM is not an issue. However, many desktop and enterprise applications are not faced with the critical time and space constraints of an embedded application. Because of these constraints, running an embedded application on a software JVM incurs the additional overhead of software running software. Although it might be possible to run some embedded applications on a software JVM because of the tremendous speed of some processors, for most embedded applications, this configuration will not met timing or space constraints. For a real-time storage application, running a JVM in software is typically only used for tasks which are not time critical. Typical tasks include hardware configuration,