Two report server modes are available, batch mode and service mode:

In scheduled batch mode, report server processes are typically set up to be launched as Windows Tasks (using the Windows Task Scheduler); this type of process runs reports in the specified batch until they have all been run, at which point the process terminates. These are typically set up for periodic runs such as nightly or monthly batches.

In service mode, report server processes are typically run as Windows Services (administered using the Windows Service Manager); this type of process runs reports in the special QADSVC batch and continuously keeps checking for more reports to run even after the batch has been fully processed. This is a long-running process that is intended to run scheduled reports immediately.