This paper addresses an agent-based negotiation protocol that enables to make flexible trading on resource dealing among distributed organizations. When distributed organizations, categorized into either supply or demand sites, form a temporary negotiation group on the network, negotiation-based commitment is necessary to reach mutual agreement. However, the negotiation process usually involves complicated procedures such as proposal, selection, reply, and cancellation. Furthermore, in asynchronous negotiation, it is quite difficult when to finalize the negotiation procedure under self-interested environment. Also in some situations, self-interested agents may collaborate to increase their profit, that is, coalition structure emerges. We investigate such a negotiation process and design a negotiation protocol.