A business transaction is an interaction inthe real world, usually between a n enterprise and a person, where something is exchanged. Business transactions, where dealing is made by first requesting the bids and then making the deal, are common in practice. However, such cooperative bidding-based processes cannot be carried out by traditional transactions. In this paper we present appropriate concepts and methods to execute bidding-based business transactions in a distributed workflow context. The main ingredients of the proposed extended business transaction (EBT) model are persistent buffers and semantic locks.