IMPLEMENTATION OF FAULT TOLERANT TECHNOLOGY IN LOGISTICS GUARANTEE AIDED DECISION SYSTEM (APPLIED TO DISTRIBUTED MULTI-TIRED SYSTEM)

摘要

Before, we introduce the technology of fault tolerance in distributed multi-tier system, in this paper, we keep on introducing the technology. After one year's hard work, we improve the performance of the system, overcoming the defect of Delphi's components. Now, the system is more secure and stable. We believe that the application server is crucial in distributed system. It is in charge of accepting the request of client, parsing client's command, sending SQL command to database server in order to save and download the data, packing or depacking the data. Once application servers stop work, the whole system breaks down. So we distribute application server to more computers, under controls of Agent, it can allot application server for client dynamically, so the load of application server is balanced. When some application servers fall break down, client can connect with other application server, even though all application servers fall break down, data are saved in the client's hard disk, once an application server is restored, data are written back to the database automatically, which ensure the data isn't lost.