Events & Transaction Callbacks

@TransactionalEventListener ties an event handler to the transaction outcome so side effects like SMS or email fire only when the transaction truly commits, preventing false confirmations.

readOnly=true skips Hibernate dirty-checking and hints replica routing for read-heavy queries, while @TransactionalEventListener phases let you fire side effects at the right moment in the transaction lifecycle.

TransactionSynchronization is a Spring callback interface that lets you hook custom logic into the lifecycle of the current transaction, running the right side effect at the right moment: notify only after commit, clean up always after completion.