4 Requirements to an implementation

The range of application for real-time Java is quite huge. It can be used in small micro controller systems as well as in large systems having the power of current personal computers and workstations. The most important requirements to a real-time Java implementation in this context are portability and scalability:

• Portability: The real-time Java implementation should be available for many hardware platforms and the porting effort has to be minimal.
• Scalability: The runtime environment should be used for small resource limited systems up to large systems with graphical user interfaces.

Portability of the Java applications is not explicitly required. It is a Java intrinsic feature that programs are easy to port to different systems. But for the mentioned systems it is necessary to access the hardware directly (access hardware registers, install interrupt handlers, ...). There are frameworks like the Real-Time Data access [5] targeting this issue.