Research And Applications Of Database Synchronization Under Networks GAP Condition

With the rapid development and application of the network, network security has become increasingly prominent. More and more government, finance, military, companies have internal network and external networks isolated for security. Internal and external networks still need to exchange data, therefore it has high theoretical and practical value to research the database synchronization technology under networks gap condition.This dissertation deeply studied network isolation and database synchronization technology, then researched database synchronous strategy under networks gap condition and proposed the "Equivalent SQL-statement" database synchronization scheme and gave its realization.The core idea of "Equivalent SQL Statements" database synchronization is: Firstly create tracking changes table (TCT) for the source table in the source database. Secondly, obtaining the changes of source table and operation types into TCT in use of trigger and store procedure. At last, the Synchronization System read the changes and combined SQL statement mode of the target table to constructe the equivalent SQL statement which is equivalent to the SQL statement operating on the source table and can be directly executed in the target database. In this way, synchronous update of target table is achieved.This dissertation used Socket Programming, TCP protocol supported Secure GAP device, had also studied the application layer transceiver protocol and the application layer data packet format to provide efficient, reliable data transfer for the database synchronization under network isolation condition."Equivalent SQL-statement" database synchronization scheme has versatility, reliability, DBMS independence, heterogeneous, accessibility and other technical characteristics which enabled it adapt to the major database synchronization of inner-outer networks under network isolation condition.Finally, the database synchronization systems have been carried out in Hefei Power Plant secondary security system protection projects, and this dissertation introduces its implementation, analyses its performance.