Abstract: With the Internet being the main runtime environment, the computer model is increasingly under the more open, dynamic and variable environment. So the software must dynastically adjust the organization or behavior to satisfy the changing requirement. Based on the command pattern, utilizing the isolation of method invocation and method execution and using centralized schedule, we designed a flexible online evolution mechanism. Finally the mechanism was testified to be convenient for changing system function and logic flow.

Key words: Self-adaptive software, Design pattern, Command pattern, Centralized schedule