(a) Transaction Processing Systems
(b) Management Information Systems
(c) Decision Support Systems
(d) Expert System (20 Marks)
(a) Transaction Processing Systems
A Transaction Processing System is a set of information which process the data transaction in database system that monitors transaction programs. The essence of a transaction program is that it manages data that must be left in a consistent state. E.g. if an electronic payment is made, the amount must be either both withdrawn from one account and added to the other, or none at all.
In case of a failure preventing transaction completion, the partially executed transaction must be 'rolled back' by the TPS. While this type of integrity must be provided also for batch transaction processing, it is particularly important for online processing: if e.g. an airline seat reservation system is accessed by multiple operators, after an empty seat inquiry, the seat reservation data must be locked until the reservation is made, otherwise another user may get the impression a seat is still free while it is actually being booked at the time. Without proper transaction monitoring, double bookings may occur. Other transaction monitor functions include deadlock detection and resolution (deadlocks may be inevitable in certain cases of cross-dependence on data), and transaction logging (in 'journals') for 'forward recovery' in case of massive failures.
Transaction Processing is not limited to application programs. The 'journaled file system' provided with IBMs AIX Unix operating system employs similar techniques to maintain file system integrity, including a journal.
But all of this is about to change drastically, and it's all because of the Internet. Today, many small companies, non-commercial organizations, and even private individuals are discovering applications that can benefit from a Transaction Processing System.
The main problems addressed by Transaction Processing Systems are:
- the need to handle hundreds, even thousands of simultaneous Users
- the need to allow many Users to work on the same set of data, with immediate updating
- the need to handle errors in a safe and consistent manner
In businesses and other organizations, internal reporting was made manually and only periodically, as a by-product of the accounting system and with some additional statistic(s), and gave limited and delayed information on management performance.
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