Data synchronization is one of the most important methods to conciliate conflicts and maintain the data consistency between mobile clients and servers in mobile database systems. The novel concept of data synchronization object is used in Lite/2, a prototype of the mobile database system, to define a transactional synchronization method and is able to maintain the semantic integrity. Synchronization recovery is an important technique combined with the queue mechanism in Lite/2 to optimize the communication costs.The experimental results show that theLite/2 has good performance in bothsynchronization andcommunication.