i found it myself. try to create a double array for read and write seprately and in main function use the pending loop call back. inside the pending loop call back receive the message using appropriate api.
once the message is received send that message to buffer using write buffer function.
now, the messages are stored in buffer. now in main loop create a logic where you check if there is a message in buffer and if yes send that can message to your desired destiation using appropriate api.
