Abstract
With the proliferation of EC, many customers have been participating into online auction or group-buying market over searching internet shopping-malls to purchase goods. To support the customer's convenient transaction, lots of agent systems are developed to facilitate the customer's product brokering, merchant brokering, and negotiation of transaction. However, many of these systems have focused upon supporting transaction at only one type of marketplace. Since these marketplaces have different transaction settlement mechanism, it is necessary to develop the system that utilizes the customer's transaction including the selection of the type of marketplace to buy. Then we classify the kinds of B2C electronic marketplace according to the protocol by which the market operated. The structure of negotiation message is developed using XML schema and RDFS under the characteristics and message example of each marketplace in this research.