Quick questions on Transaction processing systems characteristics in HSC Information Processes and Technology

In batch processing, transactions are collected over a period and stored, then processed together as a group at a scheduled time. A payroll run that processes every employee's pay at the end of a fortnight is batch processing. Its strengths are efficiency (the system can run the heavy job overnight when demand is low) and simplicity. Its weakness is that the stored data is not current between runs: until the batch is processed, the master file does not reflect the latest transactions.

In real time (or online transaction) processing, each transaction is processed immediately as it occurs, updating the master data at once. An airline reservation system must process a booking instantly so the same seat is not sold twice, and an ATM must update a balance the moment cash is withdrawn. Real time processing keeps data always current, which is essential where decisions depend on up-to-the-second information, but it demands more processing power and a continuously available system.

Data integrity means the data is accurate, consistent and complete. A TPS protects it with validation (range, type and check digit tests on input), concurrency control (locking a record while one user updates it so two updates do not clash), and verification at the source. Because many users hit shared data at once, concurrency control is especially important: without it, two simultaneous withdrawals could both read the same balance and overdraw an account.