According to the Requirements Document for the Student Registration System, one session can include a number of use cases. Later, during the design, we will decompose each use case into one or more transactions. The ACID properties apply to all transactions, but a session that involves more than one transaction might not be isolated or atomic. For example, the transactions of several sessions might be interleaved. Explain why the decision was made not to require sessions to be isolated and atomic. Why is a session not one long transaction?

Question

What will be an ideal response?

Answer 1

Locks would be held too long, delaying other people. Thus the interaction with the user is not part of the transaction. After the user inputs the information required to perform one activity (for example, register for a course), a transaction is executed to perform that activity. If the user then inputs additional information to perform
another activity, another transaction is executed to perform that activity. Thus the two activities are not executed as one atomic unit, but this would be perfectly acceptable for this application.