Presentation is loading. Please wait.

Presentation is loading. Please wait.

Bruce Scharlau, University of Aberdeen, 2011 Bluetooth Considerations Mobile Computing Some slides from MobEduNet.

Similar presentations


Presentation on theme: "Bruce Scharlau, University of Aberdeen, 2011 Bluetooth Considerations Mobile Computing Some slides from MobEduNet."— Presentation transcript:

1 Bruce Scharlau, University of Aberdeen, 2011 Bluetooth Considerations Mobile Computing Some slides from MobEduNet

2 Bruce Scharlau, University of Aberdeen, 2011 Electronic devices connect to one another in a variety of ways: –Data cable and a docking cradle connect a personal digital assistant (PDA) or a cellular phone to a computer –Radio waves connect a cordless phone to its base unit –Infrared beam connects a remote control to a television Better solution: Bluetooth

3 Bruce Scharlau, University of Aberdeen, 2011 Bluetooth was supposed to replace cables Originally positioned as a replacement for cable, infrared, and other connection media But it offers a variety of other services, like synchronizing devices Works quietly, unconsciously, and automatically

4 Bruce Scharlau, University of Aberdeen, 2011 Bluetooth is better than Infrared Infrared is reliable and cheep, but it has drawbacks: –Line-of-sight: sender must align with its receiver –One-to-one: a device can't send to multiple receivers at the same time Advantages: –Interference is uncommon –Message delivery is reliable

5 Bruce Scharlau, University of Aberdeen, 2011 Bluetooth has different goals from wifi Both operate in the 2.4 GHz band b is designed to connect large devices with lots of power and speed Bluetooth is designed to connect small devices like PDAs, mobile phones, and peripherals

6 Bruce Scharlau, University of Aberdeen, 2011 Bluetooth differs from wifi b: –Communicate at up to 11 Mbit/sec –Distances up to 100 meters Bluetooth: –1 Mbit/sec –Shorter range: 10 meters –Reduced power requirements

7 Bruce Scharlau, University of Aberdeen, 2011 Bluetooth features Wireless and automatic Bluetooth is inexpensive (< $5 per unit) Handles both data and voice Signals are omni-directional and can pass through walls and briefcases Bluetooth uses frequency hopping

8 Bruce Scharlau, University of Aberdeen, 2011 Can do lots with Bluetooth on a mobile Mobile Another Mobile LaptopHeadset GPS

9 Bluetooth connects to sensors BT enabled sensors can be embedded anywhere for training, monitoring, etc Place sensor in shoes, strap to leg, etc for running Place sensor in car components for monitoring performance Place sensor in health equipment for ease of data transfer Bruce Scharlau, University of Aberdeen, 2011

10 Bluetooth provides apps for cars More than music and hands free driving in cars Use bigger screen of car for more detail to find accommodation, food, etc Continuation of using apps in home for tasks Collect sensor data from car for use in other apps Bruce Scharlau, University of Aberdeen, 2011

11 Bruce Scharlau, University of Aberdeen, 2011 Bluetooth uses one of five profile types GAP = generic access profile, which enables other profiles and defines how to do other services PAN = personal area network, such as headset and phone, or laptop and phone SPP = serial port profile (over RFCOMM), such as printers use SP = synchronisation profile, such as synching contacts from phone to laptop SDAP = service discovery application profile, such as when you look for BT enabled devices (inquiry) and their offered services (discovery)

12 Bruce Scharlau, University of Aberdeen, 2011 Security is provided in three ways: Pseudo-random frequency hopping Authentication Encryption Generic Access Profile defines a security model

13 Bruce Scharlau, University of Aberdeen, 2011 Can also create a scatternet with Bluetooth One master and up to seven slaves = piconet A scatternet can have up to ten piconets

14 Bruce Scharlau, University of Aberdeen, 2011 Bluetooth Protocol Stack Radio layer is the physical wireless connection Baseband layer is responsible for controlling and sending data packets over the radio link Link Manager Protocol (LMP) uses the links set up by the baseband to establish connections and manage piconets Host Controller Interface (HCI) is the dividing line between software and hardware Logical Link Control and Adaptation Protocol (L2CAP) receives application data and adapts it to the Bluetooth format

15 Bruce Scharlau, University of Aberdeen, 2011 The Bluetooth stack reaches down into the internals from your application Youll find API docs under docs/JSR082 in WTK

16 Bruce Scharlau, University of Aberdeen, 2011 The client and server roles are clearly defined with Bluetooth Device must initialised Need to find what is nearby Need to advertise, and then supply

17 Bruce Scharlau, University of Aberdeen, 2011 These are the common parts of Bluetooth enabled MIDlets Your device Other devices

18 Bruce Scharlau, University of Aberdeen, 2011 Dukes Auction and Bluetooth AuctionMIDlet AuctionMIDletServer AuctionMIDletService AuctionFinder Log DiscoveryListener Encapsulates URL Server functionality Display errors AuctionMIDlet.jad Permissions, PushRegistry List details in JAD file Used by all classes

19 Bruce Scharlau, University of Aberdeen, 2011 Set up the Push Registry to enable connections from other devices MIDlet-Version: MIDlet-Vendor: Midlet Suite Vendor MIDlet-Jar-URL: AuctionMidlet.jar MicroEdition-Configuration: CLDC-1.1 MIDlet-Permissions: javax.microedition.io.PushRegistry, javax.microedition.io.Connector.bluetooth.client,javax.microedition.io.Con nector.bluetooth.server MicroEdition-Profile: MIDP-1.0 MIDlet-1: AuctionMIDlet,,com.auction.j2me.AuctionMIDlet MIDlet-Name: AuctionMidlet Midlet Suite MIDlet-Push-1: btspp://localhost:F0E0D0C0B0A ;name=com.auctio n.j2me.AuctionMIDlet, * Same UUID detailed in AuctionMIDletService class UUID = 128 bit hexadecimal as a String

20 Bruce Scharlau, University of Aberdeen, 2011 The push registry needs specific details MIDlet-Push-1: btspp://localhost:F0E0D0C0B0A ;name=com.auction.j2 me.AuctionMIDlet, * MIDlet-Push- :,,

21 Bruce Scharlau, University of Aberdeen, 2011 Set up BT to enable specific types of connections based on Generic connection framework A server RFCOMM URL: btspp://localhost:2D FB47C28D9F10B8E C891363;authenticate=false; encrypt=false;name=MyBtService A client RFCOMM URL: btspp:// AF:1;master=false; encrypt=false;authenticate=false

22 Bruce Scharlau, University of Aberdeen, 2011 Initialise the device first LocalDevice bt = LocalDevice.getLocalDevice(); DiscoveryAgent da = bt.getDiscoveryAgent(); boolean success = da.startInquiry(DiscoveryAgent.GIAC, this); mSearching = true; Make us discoverable, and look for others Code from AuctionFinder

23 Bruce Scharlau, University of Aberdeen, 2011 There are two kinds of discoverable settings that you can use GIAC = indefinately discoverable LIAC = limited (usually a minute) discoverability

24 Bruce Scharlau, University of Aberdeen, 2011 Second, discover and then consume services Look for nearby devices Discover what services they offer

25 Bruce Scharlau, University of Aberdeen, 2011 Add new devices to the Service Discovery Database (SDDB) RemoteDevice rd = servRecord[i].getHostDevice(); String name = rd.getFriendlyName(false); String address = rd.getBluetoothAddress(); String url = servRecord[i].getConnectionURL(ServiceRecord.NOAUTH ENTICATE_NOENCRYPT, false); AuctionMIDletService ams = new AuctionMIDletService(name, address, url); mNewServices.addElement(ams); Code from AuctionFinder

26 Bruce Scharlau, University of Aberdeen, 2011 Check for specific services on the device public void deviceDiscovered(RemoteDevice rd, DeviceClass dc) { try { LocalDevice bt = LocalDevice.getLocalDevice(); DiscoveryAgent da = bt.getDiscoveryAgent(); UUID[] uuidSet = {AuctionMIDletService.AUCTIONMIDLET_UUID}; mPendingServiceSearches++; da.searchServices(null, uuidSet, rd, this); } catch … Code from AuctionFinder

27 Bruce Scharlau, University of Aberdeen, 2011 Consume desired service (send a message) private void runURL(String url) throws IOException { StreamConnection sc = null; DataOutputStream dataOut = null; try { sc = (StreamConnection) Connector.open(url); dataOut = new DataOutputStream(sc.openDataOutputStream()); LocalDevice bt = LocalDevice.getLocalDevice(); String from = bt.getFriendlyName() + ":" + bt.getBluetoothAddress(); dataOut.writeUTF(from); dataOut.writeUTF(mMessageField.getString()); } finally { … // close connections Code from AuctionMIDlet

28 Bruce Scharlau, University of Aberdeen, 2011 Find a device, and send a message Sees B A A B B Sees A Sends message to B Receives message from A

29 Bruce Scharlau, University of Aberdeen, 2011 Receive and show the message public void messageReceived(String from, String message) { int layout = Item.LAYOUT_NEWLINE_AFTER; StringItem si; Form messageForm = new Form("Message"); si = new StringItem("From:", from); si.setLayout(layout); messageForm.append(si); si = new StringItem("Message:", message); si.setLayout(layout); messageForm.append(si); messageForm.addCommand(mBackCommand); messageForm.setCommandListener(this); display.setCurrent(messageForm); } Code from AuctionMIDlet

30 Bruce Scharlau, University of Aberdeen, 2011 Third, server advertises, waits for (and serves) clients, stops service UUID uuid = AuctionMIDletService.AUCTIONMIDLET_UUID; String cs = "btspp://localhost:" + uuid.toString() + ";name=AuctionMidlet"; mNotifier = (StreamConnectionNotifier)Connector.open(cs); while (mTrucking) { // Get the next incoming connection. StreamConnection sc = mNotifier.acceptAndOpen(); DataInputStream dataIn = new DataInputStream( sc.openInputStream()); String from = dataIn.readUTF(); String message = dataIn.readUTF(); mAuctionMIDlet.messageReceived(from, message); dataIn.close(); sc.close(); } catch …. Display the message Code from AuctionMIDletServer

31 Bruce Scharlau, University of Aberdeen, 2011 Bluetooth should be done with separate classes so that you can reuse components in your application If everything is in one class, then you need to make the methods reusable

32 Bluetooth on android focuses on four tasks: 1.Set up Bluetooth with adapter class 2.Find available, or paired devices 3.Connect to specified device 4.Transfer data between the connected devices Bruce Scharlau, University of Aberdeen, 2011

33 Android uses five classes for BT BluetoothAdapter - Represents the local Bluetooth adapter and is the entry-point for all Bluetooth interaction. BluetoothDevice - Represents a remote Bluetooth device. BluetoothSocket - Represents the interface for a Bluetooth socket as a connection point to exchange data with another Bluetooth device via InputStream and OutputStream. BluetoothServerSocket - Represents an open server socket that listens for incoming requests andwill return a connected BluetoothSocket when the connection is accepted. BluetoothClass - Describes the general characteristics and capabilities of a Bluetooth device as a read-only set of properties. Bruce Scharlau, University of Aberdeen, 2011

34 Also set permissions in manifest Need to set BLUETOOTH permission for any BT activity Need to set BLUETOOTH_ADMIN for discovery and manipulate BT settings Need to also set BLUETOOTH when using admin. Bruce Scharlau, University of Aberdeen, 2011

35 See dev guide and example reless/bluetooth.htmlhttp://developer.android.com/guide/topics/wi reless/bluetooth.html has all details and link to chat example Bruce Scharlau, University of Aberdeen, 2011


Download ppt "Bruce Scharlau, University of Aberdeen, 2011 Bluetooth Considerations Mobile Computing Some slides from MobEduNet."

Similar presentations


Ads by Google