Q: How do I modify the output level of the log?

A: You can access the http://localhost:8090/iserver/manager/logConfig to configure: 

Close: no information. 
Error: only errors. 
Warning: warning messages. The errors are included. 
Information: the business logic information in the server running process, such as the successful messages of service creation. It also contains errors and warnings. 
Debug: the situation of code execution when the server is running, which also contains information, warnings, and errors. 
All: all messages.