Application developers can use APIs, SDKs, and IDEs to write and debug applications that run in virtual machines.

VIX API
You can use the VIX API to write programs that automate virtual machine operations. The API is easy to use and useful for both script writers and application programmers. Functions enable you to power virtual machines on and off, register them, and run programs to manipulate files in the guest operating systems. Additional language bindings are available for Perl, COM, and shell scripts (for example, vmrun).
VMCI Sockets Interface
VMCI Sockets is a network sockets API for the Virtual Machine Communication Interface. It provides a fast means of communication between a host and its guest virtual machines. This API is well-suited for client-server applications. See the VMCI Sockets Programming Guide.
Integrated Virtual Debuggers for Eclipse
The integrated development environment (IDE) plug-ins provide a configurable interface between virtual machines and Eclipse. They let you test, run, and debug programs in virtual machines. See the Integrated Virtual Debugger for Eclipse Developer’s Guide.