An additional process, called the DPL server runs on each workstation. This buffers messages between the client and its workers. A VM is just a particular configuration of workers spread over a specified group of machines. Configurations are store in a plain text file. The client creates a server process on each workstation which in turn creates the worker processes.
Job queues can be of two kinds, symmetric or sequential.
In symmetric queues each job submitted is executed on every worker in the virtual machine. Such queues are useful for performing data loading or resetting operations. Sequential queues are the means by which useful parallel computation is performed. Each job submitted to such a queue executes on the next available worker. Data is returned to the client by specifying an optional callback routine when the job is submitted.