Both active replication and passive replication in group communication system are limited to implementing the false-tolerance distributed system. In this paper, we have presented a duplicate technique called Semi-Activere plication SAR, which takes in the advantage of two former techniques. As taking events log as synchronous object,employing reliable multicast as synchronous way between copies, and using the substitution method in passivereplication, this new method implements the fault control to the processors in group communication system on thepremise of assuring the consistence between duplicates and deceasing overhead of the system. It is best answer for large distributed system. Finally we apply the method in the distributed applications based on EJB specifications. It is shown that SAG provides a good solution for the false-tolerance distributed system where the communication model between clients and servers is noint-to-ooint.
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