dubbo heartbeat

Reference: http://youaremoon.iteye.com/blog/2280069
Heartbeat interval, for a long connection, when the physical layer is disconnected, such as unplugging the network cable, the TCP FIN message cannot be sent in time, and the other party cannot receive the disconnection event. Heartbeat is needed to help check if the connection has been dropped

Question
What problem does the heartbeat mainly solve? How is it solved? Is there any other way to solve it?