I’m actually doing some experiment with the French LoraWan network operated by Objenious. To receive the message on your backend application, one of the way is to build a callback function to proceed the data.
Due to LoraWan protocol, you have different type of possible callback like for: joining network, uplink messages and downlink report.
This post gives an exemple on how to implement an uplink message callback handler, with php, for your application backend server.