Hi,
onUpdatePeersReceived returns the message in binary format. The message is the same that you have sent by using sendUpdatePeers from client app or using sendUpdatePeersNotification on server side.
So it depends on you how and what are you sending as messages.
The same goes for our QuizUp sample. You need to check out the source code of server application to understand how data is sent. Then you will able to decode the binary message.
The samples that we make are meant to show how to use certain APIs. They are not meant to be used directly in your app. You should use them to understand our product and implement APIs the way they suit you better. For example the quizup sample is using updatepeers, but you can simply use chat messages instead of binary message.
Thanks