Bi-directional communication with TCP Server is achieved in Module for ISO_8583 by configuring the Request Response Listener. The messages are sent and received using Request Response Listener. The Request Response Listener invokes the configured Response Handler service, on receiving an inbound message. The SendAsync service is used to send the messages through Request Response Listener. For more information on SendAsync service, refer wm.estd.iso8583.service:sendAsync.