Transaction Processing Systems

• Transaction processing systems (TPS’s) are those information systems that work with the transactions of an organisation.

• A transaction is an event that creates or modifies data that is stored in an information system.

• TPS’s differ from other systems in that they directly support businesses.

• The four important characteristics of a TPS are rapid response, reliability, inflexibility and controlled processing.

• Rapid response: Businesses require quick turnaround time.

• Reliability: Organisations rely on their TPS. If it does fail quick and accurate recovery is essential.

• Inflexibility: Transactions require similitude of data. Non-standard operations would lead to errors and a slower response time.

• Controlled processing: The TPS should enforce the organisational operations in the manner that it allocates rights and responsibilities.

• A TPS minimises the organisation’s costs through a reduction of data handling.

• This means that procedures need to be examined and data needs to be normalised.

• There are two types of transaction processing: real-time processing and batch processing.

• Batch processing is where all the transaction data is collected and processed at a specific time.

• Real-time processing is the immediate processing of data.

• It provides instant confirmation of the transaction.

• Two common examples are airline reservation systems and banking.

• The two main concerns with real time processing are concurrency and atomicity.

• Concurrency ensures that two users cannot change the same data at the same time.

• Atomicity ensures that all the steps involved in a transaction are completed successfully as a group.

• That is, if the first step succeeds and then further steps fail the entire transaction is abandoned and the processes are rolled back.

• All real time transactions have an acceptable user response time factored in.

• If the user exceeds this response time then the transaction is also abandoned.

• Real time processing is more expensive than batch processing due to increased hardware and software costs.

• A transaction processing monitor is software that runs in the background that allows transaction processing applications to run efficiently.

• Differences between real-time and batch processing: (p.116)