How can I get current time stamp and it's operations in WSO2 BPS Server 3.1.0

Question

I am working on the WSO2 BPS Server 3.1.0, How can I get the current timestamp and

How can I perform the subtract operations on these Time Stamp.

I Tried like this:-

get-property('SYSTEM_TIME')

It's not working.

Answer 1

What about current-dateTime() with XPath 2.0?