Techniques for implementing pluggable virtual machines

A computer program product for implementing virtual machines suitable for use in a runtime environment suitable for executing selected code, the computer program product being embodied in a computer readable media and comprising:

• computer code that perform library functions suitable for use within the runtime environment, wherein at least some of the library functions are arranged to call functions that perform operations required by a virtual machine;
• and
• a first virtual machine implementation that performs a set of functions for executing substantially all of the virtual machine operations required to provide the virtual machine, wherein the virtual machine operations include substantially all of the operations required by the library functions that are dependent on the implementation of the first virtual machine.

In a runtime environment comprising library functions that call functions declared in virtual machine implementations to execute operations required of the virtual machine and wherein virtual machine operations which are dependent on how the virtual machine is implemented are specified, a method for developing implementations of a virtual machine, comprising:

• declaring in a first virtual machine implementation a set of functions for executing substantially all virtual machine operations required by the library functions that are dependent on the first virtual machine implementation.

A virtual machine implementation suitable for use in a runtime environment, the runtime environment having support libraries that include library functions, and a defined virtual machine interface between the support libraries and the virtual machine, the virtual machine interface defining a number of operations that must be performed by the virtual machine implementation, and wherein at least some of the library functions call virtual machine implementation dependent functions that perform operations that are dependent on the particular virtual machine used to perform the operation, and the virtual machine interface being arranged to define substantially all operations that are virtual machine implementation dependant, the virtual machine implementation comprising a set of implementation functions for executing substantially all of the operations defined by the virtual machine interface.