On the wireless sensor node "Preon32" the virtual machine is used as the operating software. This virtual machine makes it possible to run applications written in Java™ on the Preon32 module.
Normally a Java compiler compiles Java sources to Java .class files.
A Java Virtual Machine can then load and use these .class files.
The Virtenio VM cannot load and run .class files directly. The class
files are too large for Virtenio's target systems. The ClassLinker was
developed to overcome this restriction by transforming the .class files
into a file format that the Virtenio VM can process. The resulting files
are suffixed with .vmm which stands for Virtual Machine Module.
The Virtual Machine Modules (.vmm) only contain information that is
essential to the Virtenio VM. Each module consists of the translated
information of several .class files. The .vmm files are very small
compared to the .class files of which the module was originally made of.
The entire transformation process from Java sources files to .vmm files
is illustrated in the figure below.
Classlinker to link Java applications
Preparing applications for the virtual machine
Figure: Transformation of Java source files to .vmm files in preparation for subsequent interpretation by the Virtenio VM