Server Event & REST Calls

Hi Mates,

In our K2 4.7 workflow we are make use of server event to halt the activity using below code.

K2.Synchronous = false;

Once the backed process has been done we call REST service from our internal tool and make activity complete by using below code in REST service.

ServerItem svrItem = K2Conn.OpenServerItem("[serialNo]");
svrItem.Finish();

Since server event is not supported by K2 FIVE, how we can we achieve this? This should be done in real time when our internal activity done by our other system.

Thanks in Advance