Costs and times, resources was better decreased than former times because it had been introduced EDI(Electronic Data Interchange) system. Nevertheless, many problems has been raised as before, that is high costs and data re-using, the rapidly changing environment, etc. To solve these problems, it was attempted to introduce XML technology at traditional EDI System. From this point to view, 1 designed and implemented XML/EDI System based on Internet(Internet Messaging System) in this paper. And I selected some services as basic service among many services which is provided at XML/EDI System, that is message sending and message receiving, message retrieval. Other service of client system was composed of MapIn and MapOut module. MapIn Module is to parse the received XML Message and to store XML Data to RDB system. And MapOut module is to generate XML Message after extracting data from RDB system and to transfer XML Message to recipient. Hereby, XML/EDI System(XEDI System) provide document re-using, the various result(output) generation f3r various requirement and directly interface with DB. Therefore, This System(XEDI System) is more various and more flexible than the existing Messaging System that just provide transfer and retrieval service