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Processing - 5.3.3

Revision Points: (Full course)
Candidates are expected to be able to:
  • define batch processing, real-time processing and on-line processing
  • identify the circumstances when it is necessary to adopt each different method of processing;

Methods of processing:

    • Batch processing - here the computer does not carry out any processing or produce any output until all the inputs have been collected in. This method is suited to situations where it is not critical that the actual processing takes place immediately.
      • Data is processed in batches so batch processing is suited to non-urgent tasks.
      • A batch process can be started automatically or manually and once started, batch processing needs no human intervention.
      • Batch processing can process huge amounts of data and can run overnight or longer if needed.
      • Once set up, batch processing is very cheap to run.
      • Hardware costs are lower because the time taken to process the data is usually not critical so the computer and network speeds are not too important. Failures in hardware would mean the data has to be processed again.
      • Creating and setting up the software can be time-consuming, and therefore expensive, as any programming mistakes will mean the data has to be processed again.
      • Examples of use:
        • An electricity company produces its monthly bills for customers. All the meter reading would be collected in or estimated over the month then the data batch processed and the bills calculated and printed out.
        • A mail order company receives orders by post throughout the week and then all the details are entered into the computer on the Friday and are processed over the weekend ready for delivery the following week.
        • processing survey results that have been collected in over several weeks.
        • processing wages/payrolls monthly, including bank transfers and the printing out of payslips.
        • processing mail merged letters to go out once a month to subscribers.
    • A modern fly-by-wire aircraft cockpitReal-time processing - here the computer responds immediately to incoming data and produces the appropriate output. This form of processing can be expensive as it requires fast computer processors and good network connections. In critical situations such as aircraft multiple hardware backups may be needed, further increasing costs.
      • Examples of use:
        • an automatic pilot system where the inputs from sensors on the plane need to produce immediate outputs to control the aircraft.
        • a computer controlled production line where sensors are constantly giving feedback on the speed and position of components.
    • On-line processing - here the processing takes place as the data is input but the system does not need to be instant, a delay of a few seconds is not critical. Most examples involve updating some form of database and often involve multiple users over some form of LAN or a WAN such as the Internet.  It is more expensive to set up than a batch processing system as the hardware has to cope with peaks of demand and there must be a reliable backup system.
      • Examples of use:
        • an airline ticket booking system used by a travel agent or accessed directly by customers over the Internet. Each booking updates a central database almost immediately to avoid double booking seats.
        • a reservation system for booking theatre tickets.  This could be accessed by booking staff at the theatre or directly by customers over the Internet.

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