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.
Real-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.
Real-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.