OSB - How to change the logging level

Problem:
I created a proxy service and added a Log action to log out the message body, but I didn't see the log on WebLogic console.

Solution:
The problem is related with log level as the default level is higher than info level. Change the log level will solve  it.

1. Enter the WSL admin console
2. Click on Environment->Servers
3. Click on Admin Server (or the appropriate server name of yours)
4. Select Logging tab
5. Click Advanced
6. Set Severity Level of Standard Out to Debug.
7. Click Save

After that, maybe a restart is needed.

OSB - XQuery expression validation failed.

Problem:
OSB fault cannot be used directly in exception hanlder and got an error message as "Xquery expression validation failed: The variable "fault" cannot be used here. "

Solution:
In the exception handler, first use "Assign" to assign the $fault to a variable, e.g. $myFault, then you can use the variable as what you need.