Is it possible to broadcast data via bluetooth to one ore more connected devices? I mean that each phone will be master and slave at the same time and each phone will broadcast data that should be received by all other phones. Or is the only possibility to use a "client-server"-like topology; one phone acts as a server and listens to all clients and then sends data from each client to the rest of clients in the network?

Which variant should be more effective? If broadcasting is possible then the same implementation can be used for all devices and if one device will die communication between rest of network can continue. And also will there be enough to send one message per device - not message from each device to server and then back to all devices. Am I right?