Time lag is one characteristic used to distinguish between batch and real-time systems. Explain. Give an example of when each is a realistic choice

Answer 1

Batch processing collects similar transactions into groups (batches) and processes them all at once. Hence, affected files are up to date immediately after the update, but can be expected to be out of date until the next run. Hence, there is a time lag between the event and its recording in the system. A payroll system is often handled with batch processing since it must be up to date at fixed time periods and need not be modified between pay dates.

Real-time systems process each transaction as it occurs and files are always up to date–there is no time lag. This is preferred when there may be a need to query the system for the status of transactions. A sales order processing system would benefit from real-time processing. Hence, customer questions could be answered easily, without waiting for the next update (as would be required if the system was batch).