A large e-commerce system adopts distributed system structure, in order to ensure consistency of master-slave data in the Database, need to design and implement a Database Synchronization Tool (Database Synchronization Tool), through the Tool automatically sends the data of a local Database server to a remote server, in order to guarantee data integrity and consistency, and at the same time reduce the network load, are not allowed to run at the same time in the local server multiple Database Synchronization Tool,

According to the above instructions, choose a suitable design pattern to design the database synchronization tool, give the name and definition of design patterns, and combined with examples drawn solution structure diagram, the class name, method name and attribute name can be defined by oneself,