Cosc 5/4730

Bluetooth: Blackberry (JSR 82) And Android

Bluetooth Basics

• First off Bluetooth is NOT – Infrared, which requires line-of-sight– 802.11a/b/g/n . It was designed as a network (LAN)

technology. About 300 feet or 100 meters• Bluetooth is– a cable replacement technology.

• PAN (Personal Area Network) of about 30 feet (10 meters)• Transfer speed about 1 Mbit/sec and burst speed of about 20

Mbit/sec

– Signals are omni-directional and can pass through walls and briefcases.

Bluetooth Network Topology

• Bluetooth-enabled devices are organized in groups called piconets. – A piconet consists of a master and up to seven active slaves. – A master and a single slave use point-to-point communication;

• if there are multiple slaves, point-to-multipoint communication is used.

– A master unit is the device that initiates the communication. – A device in one piconet can communicate to another device in

another piconet, forming a scatternet, as depicted in next slide.

Bluetooth Network Topology

• Notice that a master in one piconet may be a slave in another piconet.

Establishing a Connection• the following procedures are carried out automatically when a application uses a bluetooth connection1. Inquire: In a new environment, the device automatically initiates an inquiry to find an access point. All nearby

access points respond with their addresses, and the device picks one.2. Page: The paging procedure synchronizes the device with the access point.3. Establish a link: The Link Manager Protocol establishes a link with the access point.4. Discover services: The LMP uses the Service Discovery Protocol (SDP) to find out what services are available from

the access point. Here we assume that the email service is available.5. Create an L2CAP Channel: The LMP uses information obtained from the Service Discovery Protocol (SDP) to

create an L2CAP channel to the access point. The application may use this channel directly or use a protocol like RFCOMM (Radio Frequency Communications Protocol) that might be running over L2CAP. RFCOMM emulates a serial line.

6. Create an RFCOMM channel: Depending on the needs of the application, an RFCOMM channel (or another channel) is created over the L2CAP channel. Creating an RFCOMM channel allows an existing application that works with serial ports to work with Bluetooth as well, without any modifications.

7. Authenticate: This is the only step that requires input from the user. If the access point requires authentication, it will send an authentication request, and the user will be prompted to enter a PIN to access the service. For security reasons, the PIN code itself is not sent over the wireless link, but rather a key generated from it.

8. Log in: If the devices use the Point-to-Point Protocol (PPP) over RFCOMM, a serial port is emulated, and user may login to the service, such as email (if that's the application).

9. Send and receive data: The email client and the access point now use standard network protocols like TCP/IP to send and receive data.

Bluetooth Profiles• Note that Bluetooth devices cannot interact unless they conform to a particular profile

– having the bare minimum Bluetooth stack isn't enough.• The Generic Access Profile defines connection procedures, device discovery, and link

management. – It also defines procedures related to use of different security models and common format

requirements for parameters accessible on the user interface level. At a minimum all Bluetooth devices must support this profile.

• The Service Discovery Application and Profile defines the features and procedures for an application in a Bluetooth device to discover services registered in other Bluetooth devices, and retrieves information related to the services.

• The Serial Port Profile defines the requirements for Bluetooth devices that need to set up connections that emulate serial cables and use the RFCOMM protocol.

• The LAN Access Profile defines how Bluetooth devices can access the services of a LAN using PPP, and shows how PPP mechanisms can be used to form a network consisting of Bluetooth devices.

• The Synchronization Profile defines the application requirements for Bluetooth devices that need to synchronize data on two or more devices.

Bluetooth Security

• All Bluetooth-enabled devices must implement the Generic Access Profile, which contains all the Bluetooth protocols and possible devices. This profile defines a security model that includes three security modes: – Mode 1 is an insecure mode of operation. No security procedures

are initiated.– Mode 2 is known as service-level enforced security. When devices

operate in this mode, no security procedures are initiated before the channel is established. This mode enables applications to have different access policies and run them in parallel.

– Mode 3 is known as link-level enforced security. In this mode, security procedures are initiated before link setup is complete.

Standard Bluetooth Applications• File transfer.• Ad-hoc networking

– Communicating devices can spontaneously form a community of networks that persists only as long as it's needed

• Device synchronization – Seamless connectivity among PDAs, computers, and mobile phones allows

applications to update information on multiple devices automatically when data on any one device changes.

• Peripheral connectivity• Car kits

– Hands-free packages enable users to access phones and other devices without taking their hands off the steering wheel

• Mobile payments– Your Bluetooth-enabled phone can communicate with a Bluetooth-enabled

vending machine to buy a can of Diet Pepsi, and put the charge on your phone bill.

BlackberryJSR 82

JSR 82• The API is intended to provide the following capabilities

1. Manage the Local Bluetooth Device settings.2. Discover other bluetooth devices and services in the neighborhood.3. Search for bluetooth devices on the discovered bluetooth devices.4. Connect to any of those bluetooth service and communicate with it.

• Establish RFCOMM, L2CAP, and OBEX connections between devices• Using those connections, send and receive data (voice communication are

likely not supported)

5. Register a bluetooth service on the Local Bluetooth Device, so that other bluetooth devices can connect to it.

6. Manage and control the communication connections.7. Provide the security to all of the above options.

Packages• javax.bluetooth: core Bluetooth

API• javax.obex: APIs for the Object

Exchange (OBEX) protocol– the OBEX APIs are defined

independently of the Bluetooth transport layer and packaged separately.

– Each of the above packages represents a separate optional package, which means that a CLDC implementation can include either package or both.

– MIDP-enabled devices are expected to be the kind of devices to incorporate this specification.

Developing a Bluetooth app• To develop a Bluetooth application in Java using the JSR-82, you need to

have the following1. JSR-82 Compliant Bluetooth Stack.

– You need a JSR-82 Implementation to successfully develop and test a Java Bluetooth application. You either need to have a simulated enviorment like the Sun Java Wireless Toolkit or Java Platform Micro Edition Software Development Kit 3.0, or a real Java Bluetooth Stack like ElectricBlue or Avelink. The simulator allows you to test the Bluetooth application in a simulated environment, with no access to real bluetooth device.

2. Local Bluetooth Device.– If you are using a simulator, this is not needed. But to test your application in real

world over a java bluetooth stack, you need to have a bluetooth enabled system. This can either be a Bluetooth USB Dongle plugged in to your system, or the internal built in bluetooth device. The java application that you writes, runs over this bluetooth device, and this bluetooth device is called as the ‘LocalDevice’ in JSR-82.

Device management

• LocalDevice and RemoteDevice– Provide management capabilities as defined in the

Generic Access Profile• LocalDevice needs javax.bluetooth.DeviceClass to

retrieve the device's type and the kinds of services it offers• The RemoteDevice class represents a remote device (a

device within a range of reach) and provides methods to retrieve information about the device, including its Bluetooth address and name

LocalDevice example

// retrieve the local Bluetooth device objectLocalDevice local = LocalDevice.getLocalDevice();// retrieve the Bluetooth address of the local deviceString address = local.getBluetoothAddress();// retrieve the name of the local Bluetooth deviceString name = local.getFriendlyName();• Another useful methodboolean isPowerOn()

RemoveDevice Example// retrieve the device that is at the other end of the Bluetooth Serial

Port Profile connection, L2CAP connection, or OBEX over RFCOMM connection

RemoteDevice remote = RemoteDevice.getRemoteDevice( javax.microedition.io.Connection c);

// retrieve the Bluetooth address of the remote deviceString remoteAddress = remote.getBluetoothAddress();// retrieve the name of the remote Bluetooth deviceString remoteName = local.getFriendlyName(true);• The RemoteDevice class also provides methods to authenticate,

authorize, or encrypt data transferred between local and remote devices.

Device Discovery

• Because wireless devices are mobile they need a mechanism that allows them to find other devices and gain access to their capabilities.

• The core Bluetooth API's DiscoveryAgent class and DiscoveryListener interface provide the necessary discovery services.

• A Bluetooth device can use a DiscoveryAgent object to obtain a list of accessible devices– There are a couple of ways to do this

Implement the DiscoveryListener

• The DiscoveryAgent.startInquiry method places the device into an inquiry mode.

• To take advantage of this mode, the application must specify an event listener that will respond to inquiry-related events.– DiscoveryListener.deviceDiscovered is called each time an

inquiry finds a device. – When the inquiry is completed or canceled,

DiscoveryListener.inquiryCompleted is invoked. – Two more that needed be implemented,

serviceSearchCompleted and servicesDiscovered

DiscoveryListener example

SampleSPPClient client=new SampleSPPClient();– SampleSPPClient declared on the next slide.

DiscoveryAgent agent = localDevice.getDiscoveryAgent();agent.startInquiry(DiscoveryAgent.GIAC, client);//client is the class that has the listener, use this if

implemented in the same class.//The inquiry access code for General/Unlimited Inquiry

Access Code (GIAC)//to cancel an inquiry agent.cancelInquire(client)

DiscoveryListener example (2) class SampleSPPClient implements DiscoveryListener{ //required methods of DiscoveryListenerpublic void deviceDiscovered(RemoteDevice btDevice, DeviceClass cod) { //Found a Device, btDevice is RemoteDevice needed to talk to the device}

public void servicesDiscovered(int transID, ServiceRecord[] servRecord) { //needed once we have found a device, and want to search for the services that device provides //this is called when services are found and SerivceRecord contains the information.}

//See the Field Summary for DisType and respCode constants.public void serviceSearchCompleted(int transID, int respCode) { //search for services has completed}public void inquiryCompleted(int discType) { //search for devices has completed.}

Other ways

• If the device doesn't wish to wait for devices to be discovered– it can use the DiscoveryAgent.retrieveDevices

method to retrieve an existing list. • Based on the parameter either:

– return either a list of devices that were found in a previous inquiry (cached)

– return a list of pre-known devices that the local device has told the Bluetooth Control Center it will contact often.

– No Listener is needed.

Other ways Example

// retrieve the discovery agent DiscoveryAgent agent = local.getDiscoveryAgent();

// return an array of pre-known devicesRemoteDevice[] devices =

agent.retrieveDevices(DiscoveryAgent.PREKNOWN);OR// return an array of devices found in a previous inquiryRemoteDevice[] devices =

agent.retrieveDevices(DiscoveryAgent.CACHED);

Service Discovery

• Once the local device has discovered at least one remote device, it can begin to search for available services - Bluetooth applications it can use to accomplish useful tasks.

• Because service discovery is much like device discovery, DiscoveryAgent also provides methods to discover services on a Bluetooth server device, and to initiate service-discovery transactions.– As seen in listener example.

• Note that the API provides mechanisms to search for services on remote devices, but not for services on the local device.

ServicesDiscovered//From the implemented Listener classpublic void servicesDiscovered(int transID, ServiceRecord[] servRecord) { if(servRecord!=null && servRecord.length>0){ connectionURL=servRecord[0].getConnectionURL(0,false); }}

//Then in the "main" codeStreamConnection streamConnection=(StreamConnection)Connector.open(connectionURL);//output streanOutputStream outStream=streamConnection.openOutputStream();OutputStreamWriter out= new OutputStreamWriter(outStream);//input streamInputStream inStream=streamConnection.openInputStream();InputStreamReader in =new InputStreamReader(inStream);

Server side Bluetooth

• Before a service can be discovered, it must first be registered - advertised on a Bluetooth server device. The server is responsible for:– Creating a service record that describes the service offered– Adding the service record to the server's Service Discovery

DataBase (SDDB), so it's visible and available to potential clients– Registering the Bluetooth security measures associated with the

service (enforced for connections with clients)– Accepting connections from clients– Updating the service record in the SDDB whenever the service's

attributes change– Removing or disabling the service record in the SDDB when the

service is no longer available

Service Registration1. To create a new service record that represents the service, invoke

Connector.open with a server connection URL argument, and cast the result to a StreamConnectionNotifier that represents the service– StreamConnectionNotifier service = (StreamConnectionNotifier)

Connector.open("someURL");

2. Obtain the service record created by the server device:– ServiceRecord sr = local.getRecord(service);Not necessary if you don't plan to change the ServiceRecord.

3. Indicate that the service is ready to accept a client connection:– StreamConnection connection = service.acceptAndOpen();Note that acceptAndOpen blocks until a client connects.

4. When the server is ready to exit, close the connection and remove the service record:– service.close();

Connector.open("someURL");

• Serial Port Profile – The RFCOMM protocol, which is layered over the L2CAP

protocol, emulates an RS-232 serial connection. The Serial Port Profile (SPP) eases communication between Bluetooth devices by providing a stream-based interface to the RFCOMM protocol. Some capabilities and limitations to note: • Two devices can share only one RFCOMM session at a time.• Up to 60 logical serial connections can be multiplexed over this session.

– implementation may vary and maybe less.

• A single Bluetooth device can have at most 30 active RFCOMM services.– implementation may vary and maybe less.

• A device can support only one client connection to any given service at a time.

SPP URL

• // assuming the service UID has been retrieved

• String serviceURL = "btspp://localhost:" + serviceUID.toString());

• // more explicitly: • String ServiceURL =

"btspp://localhost:10203040607040A1B1C1DE100;name=SPP Server1";

SPP with UUID

• Create a UUID object from the string provided, using the ShortUUID method.

UUID uuid = new UUID("1101", true);• //Create the service urlString connectionString = "btspp://localhost:" +

uuid +";name=Sample SPP Server";

• What is UUID?

What is UUID?• The UUID class defines universally unique identifiers. • These 128-bit unsigned integers are guaranteed to be unique

across all time and space. – Accordingly, an instance of this class is immutable. – The Bluetooth specification provides an algorithm describing how a 16-

bit or 32-bit UUID could be promoted to a 128-bit UUID. – Accordingly, this class provides an interface that assists applications in

creating 16-bit, 32-bit, and 128-bit long UUIDs. – The methods supported by this class allow equality testing of two UUID

objects. • The Bluetooth Assigned Numbers document (

http://www.bluetooth.org/assigned-numbers/sdp.htm) defines a large number of UUIDs for protocols and service classes.

Most common UUIDsName Value Size

Base UUID Value (Used in promoting 16-bit and 32-bit UUIDs to 128-bit UUIDs) 0x0000000000001000800000805F9B34FB 128-bit

SDP 0x0001 16-bit

RFCOMM 0x0003 16-bit

OBEX 0x0008 16-bit

HTTP 0x000C 16-bit

L2CAP 0x0100 16-bit

BNEP 0x000F 16-bit

Serial Port 0x1101 16-bit

ServiceDiscoveryServerServiceClassID 0x1000 16-bit

BrowseGroupDescriptorServiceClassID 0x1001 16-bit

PublicBrowseGroup 0x1002 16-bit

OBEX Object Push Profile 0x1105 16-bit

OBEX File Transfer Profile 0x1106 16-bit

Personal Area Networking User 0x1115 16-bit

Network Access Point 0x1116 16-bit

Group Network 0x1117 16-bit

Pulling it all together• The server registers a service, then blocks while waiting for a

connection (just like network code).• From the server connection:

– StreamConnection connection=streamConnNotifier.acceptAndOpen(); – //input :– InputStream inStream=connection.openInputStream();– InputStreamReader in =new InputStreamReader(inStream);– //output:– OutputStream outStream=connection.openOutputStream();– OutputStreamWriter out= new OutputStreamWriter( outStream);

• We have our standard Streams for both client and server side, so just like network code at this point.

Simulator note

• No Bluetooth in the Blackberry (or android) simulators

BlackBerry specific• Implements the full JSR 82 standard.• Also adds

– net.rim.device.api.bluetooth• Provides serial communication support for Bluetooth connections. • This api needs a signed key.• See the BluetoothDemo in sample code for use. While the Bluetooth code is

much simpler then JSR 82, the example of how to use it, IS NOT!

• This simulator requires a specific bluetooth board connected to the PC, in order for bluetooth to usable in the simulator, otherwise there is NO bluetooth in the simulator.– the Casira tool is this: http://www.btdesigner.com/devcasira.htm

• may cost about $3,000 … • In the JDE, simlulator preferences, select Ports and enter the com port number

the Casira board is using. (ie com1, then enter 1).

Blackberry Phones.

• To get the example code to work• Turn on Bluetooth– App will attempt to turn it on, but sometimes

locks up.• In Bluetooth options– Discovery: YES– It’s a security problem, so if you are using your

own phone, change the setting back to NO once you are done.

JSR 82 References

• Java Docs for JSR 82– http://java.sun.com/javame/reference/apis/jsr082/

• http://developers.sun.com/mobility/midp/articles/bluetooth2/• Wireless Application Programming with J2ME and Bluetooth

– http://developers.sun.com/mobility/midp/articles/bluetooth1/• Part II: The Java APIs for Bluetooth Wireless Technology

– http://developers.sun.com/mobility/midp/articles/bluetooth2/• JSR-82 : Java Bluetooth

– http://www.jsr82.com/jsr-82-basics/• More example code

– http://www.codeguru.com/java/article.php/c13147

AndroidPackage: android.bluetooth

Android

• Does not implement JSR-82 (nor OBEX).– Uses it own functions.– Found in the android.bluetooth package.

android.bluetooth package• BluetoothAdapter

– Represents the local Bluetooth adapter (Bluetooth radio). The BluetoothAdapter is the entry-point for all Bluetooth interaction. Using this, you can discover other Bluetooth devices, query a list of bonded (paired) devices, instantiate a BluetoothDevice using a known MAC address, and create a BluetoothServerSocket to listen for communications from other devices.

• BluetoothDevice– Represents a remote Bluetooth device. Use this to request a connection with a remote device through a

BluetoothSocket or query information about the device such as its name, address, class, and bonding state.• BluetoothSocket

– Represents the interface for a Bluetooth socket (similar to a TCP Socket). This is the connection point that allows an application to exchange data with another Bluetooth device via InputStream and OutputStream.

• BluetoothServerSocket– Represents an open server socket that listens for incoming requests (similar to a TCP ServerSocket). In order

to connect two Android devices, one device must open a server socket with this class. When a remote Bluetooth device makes a connection request to the this device, the BluetoothServerSocket will return a connected BluetoothSocket when the connection is accepted.

• BluetoothClass– Describes the general characteristics and capabilities of a Bluetooth device. This is a read-only set of

properties that define the device's major and minor device classes and its services. However, this does not reliably describe all Bluetooth profiles and services supported by the device, but is useful as a hint to the device type.

Bluetooth Permissions

• Like sms, you need to add a permission line in the androidManifest.xml file

<manifest ... > ... <uses-permission

android:name="android.permission.BLUETOOTH" /><uses-permission

android:name="android.permission.BLUETOOTH_ADMIN" />– Needed if you turn on/off bluetooth or change how the device

functions.

</manifest>

Setting Up Bluetooth

• The BluetoothAdapter is required for any and all Bluetooth activity

BluetoothAdapter mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();if (mBluetoothAdapter == null) { // Device does not support Bluetooth}

• To check and see if Bluetooth is enabled • and enable it private static final int REQUEST_ENABLE_BT = 2…if (!mBluetoothAdapter.isEnabled()) { Intent enableBtIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE); startActivityForResult(enableBtIntent, REQUEST_ENABLE_BT);}

Paired devices

• If the device you need has already been paired, then you can query to find out if it is connected or not.

Set<BluetoothDevice> pairedDevices = mBluetoothAdapter.getBondedDevices();

// If there are paired devicesif (pairedDevices.size() > 0) { // Loop through paired devices for (BluetoothDevice device : pairedDevices) { // Add the name and address to an array adapter to show in a ListView mArrayAdapter.add(device.getName() + "\n" + device.getAddress()); }}

Enabling DiscoverabilityIntent discoverableIntent = new

Intent(BluetoothAdapter.ACTION_REQUEST_DISCOVERABLE);discoverableIntent.putExtra( BluetoothAdapter.EXTRA_DISCOVERABLE_DURA

TION, 300);startActivity(discoverableIntent);

• By default, the device will become discoverable for 120 seconds, but this code changes it to 300 seconds.

• Note the user may get this screen

Discovering Devices

• To find a device, you use startDiscovery(), via a BroadcastReceiver.

// Create a BroadcastReceiver for ACTION_FOUNDprivate final BroadcastReceiver mReceiver = new BroadcastReceiver() { public void onReceive(Context context, Intent intent) { String action = intent.getAction(); // When discovery finds a device if (BluetoothDevice.ACTION_FOUND.equals(action)) { // Get the BluetoothDevice object from the Intent BluetoothDevice device = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE); // Add the name and address to an array adapter to show in a ListView mArrayAdapter.add(device.getName() + "\n" + device.getAddress()); } }};// Register the BroadcastReceiverIntentFilter filter = new IntentFilter(BluetoothDevice.ACTION_FOUND);registerReceiver(mReceiver, filter); // Don't forget to unregister during onDestroy

Managing the devices

• Before you can connection to each, unpaired devices will be paired.

• This is done automatically in the framework, but the user will get a pairing dialog– It will fail if the user says no or the pairing times

out.

• Once the two devices are paired, then a connection can be made.

Server Side bluetooth

• Like networking, you setup a socket (BluetoothServerSocket) and accept a connection.– Use the

listenUsingRfcommWithServiceRecord( String, UUID).

– String is the Name– UUID is similar to UUID before (see the note on

android website)

Server Side bluetooth example // Name for the SDP record when creating server socketprivate static final String NAME = "BluetoothChat";// Unique UUID for this applicationprivate static final UUID MY_UUID = UUID.fromString("fa87c0d0-afac-11de-8a39-0800200c9a66");

BluetoothServerSocket mmServerSocket = null;BluetoothSocket socket = null;try {

// MY_UUID is the app's UUID string, also used by the client codemmServerSocket = mAdapter.listenUsingRfcommWithServiceRecord(NAME, MY_UUID);socket = mmServerSocket.accept();

} catch (IOException e) { }

Client side bluetooth

• To initiate a connection with a remote device, first you discover the BluetoothDevice object that represents the remote device.– Shown in Discovering Devices and in paired devices.

• Using the BluetoothDevice, get a BluetoothSocket by calling createRfcommSocketToServiceRecord(UUID).

• Initiate the connection by calling connect().– Note connect is blocking and should be not called when

in discovery mode.

Client side bluetooth example// Unique UUID for this applicationprivate static final UUID MY_UUID = UUID.fromString("fa87c0d0-afac-11de-8a39-0800200c9a66");

//find remote device... //from discovery example previously.// Get a BluetoothSocket to connect with the given BluetoothDevice;BluetoothDevice device =

intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE); ...BluetoothSocket mmSocket=null;try {

// MY_UUID is the app's UUID string, also used by the server codemmSocket = device.createRfcommSocketToServiceRecord(MY_UUID); mmSocket.connect();

} catch (IOException e) { }

Connected via Android bluetooth

• Once both the client and server are setup with sockets– Now it's just like standard network code.

– PrintWriter out = new PrintWriter( new BufferedWriter( new OutputStreamWriter(socket.getOutputStream())),true);

– BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream()));

– But you will likely need to deal with disconnections, if either of the "phones" is moved out of connection range, then the connection will fail and have to be restarted once they are in range again.

Android References

• http://developer.android.com/intl/zh-CN/guide/topics/wireless/bluetooth.html

• Android BluetoothChat example found in SDK and/or the development website.

QA&