Abstract: A virtual machine with mechanisms for class loading and class structure management in a device having limited file system and/or memory resources. The virtual machine includes a class loader that obtains one or more of a set of predefined classes from a network server, thereby reducing or eliminating the need for a local file system in the device. The class loader stores the predefined classes into a class structure in memory in the device. The virtual machine further includes a memory manager that purges selected ones of the predefined classes from the class structure so as to optimize the use of the memory consumed by the predefined classes in the class structure.

Abstract: A software system with a two tier arrangement for threads support that enhances the adaptability of a virtual machine to differing platforms. The software system includes a virtual machine with a threads interface layer having a set of methods that provide thread support in the virtual machine according to a standard threads interface associated with the virtual machine. The software system includes a native threads interface layer that provides a set of methods that adapt the methods of the threads interface layer to a platform which underlies the software system. The native threads interface layer shields the virtual machine from the particulars of the underlying operating system while the threads interface layer provides a stable interface for application programs and other tasks that benefit from thread support in the virtual machine.

Abstract: A system for creating a custom environment for executing application programs in a target device. The system broadens the applicability of software environments like Java by providing custom pre-loaded classes for application programs and by customizing the procedures for class loading to the available resources in the target device. The system includes tools for generating a pre-load class list that specifies a set of classes needed to support the application program. The tools build the custom environment including a set of code for a virtual machine and a set of code for each of a set of pre-loaded classes specified in the pre-load class list. The virtual machine loads classes from the pre-loaded classes, a file system class library, and/or a networked class library using widely available network protocols.