Android Data Sync Module

Need to create Data Sync /Transfer Module for an existing android application. Data should be sync or transferred from one android application to another. Without any server infrastructure. Android to android transfer. Two device will be connected across LAN. One Application can act like server and another one as client. The data flow required only one way. Data should be always synch once there is any update. Only specific file need to sync. We should able to define the files need to be sync The Application should also automatic detect the client machine becomes online. We have already developed the application so we need only sync module to added to current application In Your proposal explain the process how you will achieve my requirements. Any proposal without explanation will not be accepted. If you have any doubt please Message me.