Background

The VCL backend code was significantly reworked in version 2.0 to utilize a "modularized" framework.  This framework allows certain parts of the code to be separated from the core code through the implementation of modules.  For example, VCL interacts with external technologies including:

• provisioning engines
• operating systems
• monitoring utilities

The technology being used may vary based on the VCL deployment, management node, image, computer, and so on.  Modules make configuring VCL to use a certain technology easy, while simplifying the core code.

The advantages of implementing modules are not limited to external technologies.  Modules may be implemented for functions applicable only to VCL, but may vary based on the environment.  For example, research is being conducted to compare different algorithms which are used to select the image that is loaded on a computer after a reservation is complete.  A module is created for each algorithm, and configuring a managment node to use a certain algoritym is as simple as changing one value in the database.

A module is comprised of a Perl module file.