The status of execution of jobs (used to characterize cells) is notified
asynchronously. As a result, the processing and network resources may be
optimally used. In an embodiment, a flow controller divides an entire
characterization task into multiple jobs, and schedules each job for
execution on one of several client machines. The client machine sends a
notification asynchronously after completion of execution of the job. In
an embodiment, the asynchronous communication is implemented using socket
interface on top of TCP/IP protocol.