How can I get the originator’s device id from a received message?

If you need this information, you have to include it into your own messages. You can get the unique device id of your Blaubot or BlaubotKingdom instance like this:

// For Blaubot
Blaubot blaubot = // ...
String id = blaubot.getOwnDevice().getUniqueDeviceId();

// For BlaubotKingdom
BlaubotKingdom kingdom = // ...
String id = kingdom.getOwnDevice().getUniqueDeviceId();

How can I publish messages to a subscribed channel without receiving my own message?

For each publish() signature vailable from IBlaubotChannel there is an equivalent which allows you to set a flag excludeSender.

// will not be received by the publishing (this) device
myChannel.publish("Exclude me!".getBytes(), true);

Can I use Bluetooth to discover nearby devices and WiFi to create a network?

Yes, just use a Bluetooth-Beacon implementation and the EthernetAdapter. For Android, use BlaubotBluetoothBeacon from the blaubot-android package.

int acceptorPort = 17171;
IBlaubotDevice ownDevice = new BlaubotDevice();
BlaubotUUIDSet uuidSet = new BlaubotUUIDSet(YOUR_APP_UUID);
InetAddress ownInetAddr = BlaubotFactory.getLocalIpAddress();

// create Blaubot instance
IBlaubotAdapter adapter = new BlaubotEthernetAdapter(ownDevice, uuidSet, acceptorPort, ownInetAddr);
IBlaubotBeacon beacon = new BlaubotBluetoothBeacon();
Blaubot blaubot = BlaubotFactory.createBlaubot(YOUR_APP_UUID, ownDevice, adapter, beacon);

// fire it up

Can I connect from Windows/Linux/MacOS to Android using Bluetooth?

Yes, use the BlaubotBluetoothAdapter from the blaubot-android package for Android and the BlaubotJsr82BluetoothAdapter from the blaubot-jsr82 package for Windows/Linux/MacOS. Note that you have to add bluecove (and on Linux additionally bluecove-gpl) to your dependencies to get it running on Windows/Linux/MacOS. BlueCove hasn’t released an official version since 2009 and you will have difficulties using the older releases on 64-bit systems. Use one of the newer BlueCove snapshot realeases instead.

I published a message to a channel before the onConnected() or after the onDisconnected() event. How do I prevent them from being sent on connection?

You can clear the message queue of the channel:


How can I send a File?

Here is an example using Bluetooth on Android. First we create a Blaubot instance using Bluetooth and NFC for discovery (Beacons) and Bluetooth for the main network communication (Adapter).

UUD MY_UUID = UUID.fromString("33bb1246-1472-11e5-b60b-1697f925ec7b");

// onCreate() or in a service, we create a blaubot instance
// using Bluetooth to form a network and Bluetooth + NFC to find devices
IBlaubotDevice ownDevice = new BlaubotDevice();
BlaubotUUIDSet uuidSet = new BlaubotUUIDSet(MY_UUID);

BlaubotBluetoothAdapter bluetoothAdapter = new BlaubotBluetoothAdapter(uuidSet, ownDevice);
BlaubotNFCBeacon nfcBeacon = new BlaubotNFCBeacon();
BlaubotBluetoothBeacon bluetoothBeacon = new BlaubotBluetoothBeacon();
this.mBlaubot = BlaubotAndroidFactory.createBlaubot(MY_UUID, ownDevice, adapter, nfcBeacon, bluetoothBeacon);

// start to connect

// create a channel to which we will send the file
IBlaubotChannel fileChannel = this.mBlaubot.createChannel(1);

We can now publish messages to the channel. They will be send after we got an onConnected() event.

// convert your file to its bytes
File yourFile = // ... however you get it
// see
byte[] fileBytes = //...

// send it to all connected devices, except the sending device
fileChannel.publish(fileBytes, true);

To receive the file, you have to subscribe and attach a IBlaubotMessageListener to the channel.

// to receive it on the other device, do this:
// subscribe to the channel
fileChannel.subscribe(new IBlaubotMessageListener() {
    public void onMessage(BlaubotMessage message) {
        // extract your bytes from the message
        byte[] fileBytes = message.getPayload();
        // .. do something useful or write it to a file again
        // to write it to a file
        File file = new File(yourFilePath);
        BufferedOutputStream bos = new BufferedOutputStream(new FileOutputStream(file));

I never get onConnected()-Events when I register my LifecycleListener in onKingomConnected(BlaubotKingdom) to the BlaubotKingdom.

And you never will. The onKingdomConnected event happens after onConnected(). You may also have missed some onDeviceConnected() events at this point. But you can poll the connected devices from the KingdomCensusLifecycleListener retrievable from the BlaubotKingdom:

blaubotServer.addServerLifeCycleListener(new IBlaubotServerLifeCycleListener() {
    public void onKingdomConnected(final BlaubotKingdom kingdom) {
        // contains all currently connected devices
        Set<IBlaubotDevice> devices = kingdom.getKingdomCensusLifecycleListener().getDevices();
    public void onKingdomDisconnected(BlaubotKingdom kingdom) {
       // ...

I want to know which devices are currently connected.

You can implement an ILifecycleListener and attach it (pre-start) to your Blaubot or BlaubotKingdom instance to keep track of that via the onDeviceJoined(IBlaubotDevice) and onDeviceLeft(IBlaubotDevice) methods or just use the built-in KingdomCensusLifecycleListener:

IBlaubotDevice ownDevice = blaubot.getOwnDevice();
KingdomCensusLifecycleListener censusListener = new KingdomCensusLifecycleListener(ownDevice);
// contains all currently connected devices
Set<IBlaubotDevice> devices = censusListener.getDevices();

How do I know if the BlaubotServer is reachable?

When any of the network’s devices could establish a connection to your configured BlaubotServer, you will get an onDeviceJoined-Event on all Devices in the network. Since you know your server’s UniqueDeviceId (you configured it with the ServerConnector and on creation of the BlaubotServer), you can just compare the UniqueDeviceIds to tell if a newly joined device is the server or not.

Blaubot blaubot = /* ... creation and configuration of Blaubot ... */;
/* ... create and add your ServerConnector here ... */
final String serverUniqueDeviceId = blaubot.getServerConnector().getServerUniqueDeviceId();

blaubot.addLifecycleListener(new LifecycleListenerAdapter {
    public void onDeviceJoined(IBlaubotDevice device) {
    	if(device.getUniqueDeviceId().equals(serverUniqueDeviceId)) {
	    System.out.println("server is now part of the network");

    public void onDeviceLeft(IBlaubotDevice device) {
        if(device.getUniqueDeviceId().equals(serverUniqueDeviceId)) {
	    System.out.println("server is not part of the network anymore");