In database applications, application programs are performed on clients and issue requests to object servers. Then, the object servers send responses to the clients. On the other hand, programs named agents move to object servers where the agents manipulate objects in a mobile agent approach. If agents complete manipulating objects in the servers, the agents move to other servers. If an agent conflicts with other agents on an object server, the agents negotiate with each other to resolve the confliction under various constraints among servers like atomicity and consistency.