Abstract: A method and system for providing exactly-once semantics for web-based transaction processing in a system that includes a client and a server. The client requests a form from the server. The server in response generates a unique identifier for identifying a particular transaction and provides a form with the unique identifier to the client. A user fills out the form and posts the filled out form to the server. Upon receiving the filled out form, the server generates a status page for informing the user that the transaction is being processed and returns the status page to the client. The status page includes client-side error handling logic. After returning the status page, the server performs transaction processing. In the event of failures, the error handling mechanism provides either exactly-one error handling semantics, which does not require user intervention, or at-most once error handling semantics that involves the user in error recovery.