How to Build an NFC-enabled App


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This presentation gives developers a look into how to build NFC-enabled applications. Included is a brief introduction to NFC architecture, NDEF Tags, developing tag readers, using WebWorks to read tags, and how to write a peer-to-peer app.

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How to Build an NFC-enabled App

  1. 1. How to Build an NFC-enabled AppJohn Murray and Martin WoolleyDEV 311February 7-8, 2012
  2. 2. Session Overview Introductions Brief introduction to NFC How to read NDEF Tags How to write a Peer-to-Peer App Close @BlackBerryDev – 2
  3. 3. NFC Forum Architecture  We will look at examples of:  Reading NDEF Tags NDEF Tags  Peer to Peer using SNEP SNEP 3
  4. 4. Reading NDEF tagsMartin Woolley
  5. 5. NFC Forum Architecture  We will look at examples of:  Reading NDEF Tags NDEF Tags  Peer to Peer using SNEP 5
  6. 6. About NFC Tags An NFC tag is typically a passive device (for example, integrated in a smart poster) that stores data that can be read by an NFC-enabled device. 4 types are defined by the NFC Forum. A card and a tag are technically the same. Think of a tag as being a card with a predefined, relatively simple and standardised application. Data is stored in the NDEF format It’s the standardisation that makes tags so useful! 6
  7. 7. The Smart Tags AppYour BlackBerry had a standard tagreader/write app already…..
  8. 8. About NFC Tags The standard BlackBerry® application “Smart Tags” was able to read the NFC smart poster at this bus stop in France  The browser opened at the transport company’s web site and the next bus time was displayed  Think about this! No special software from the bus company and extra infrastructure was required at the bus stop. 8
  9. 9. A simple NDEF tag readerLet’s take a look at a simple NDEF tag readerin action. We’ll then examine the coderequired to build this kind of application.
  10. 10. Developing your own tag readerThree simple steps:1. Implement the NDEFMessageListener interface2. Register your listener with the system, indicating the NDEF record type you are interested in3. Parse and act upon NDEF messages received by your NDEFMessageListener 10
  11. 11. NDEFMessageListenerpublic class NfcReadNdefSmartTagListener implements NDEFMessageListener { public void onNDEFMessageDetected(NDEFMessage message) { // do something with the NDEF message }} 11
  12. 12. Registering the listener ReaderWriterManager rwManager = ReaderWriterManager.getInstance(); rwManager.addNDEFMessageListener ( listener, // the NDEFMessageListener NDEFRecord.TNF_WELL_KNOWN, // a Type Name Format value "Sp” // “Sp” means smart poster );// 7.1 - our app will auto start if it is not already running// 7.0 - must request this behaviour in alternate method signature 12
  13. 13. Parsing the NDEF messagepublic void onNDEFMessageDetected(NDEFMessage message) { NDEFRecord[] records = message.getRecords(); SmartPosterRecord sp = new SmartPosterRecord(records[0]); String uri = sp.getUri(); // do something with the data} 13
  14. 14. Parsing the NDEF messageHelper classes exist for Smart Poster, Text and URI recordsFor other record types, implement your own parserpublic void onNDEFMessageDetected(NDEFMessage message) { NDEFRecord[] records = message.getRecords(); for(int j = records.length - 1; j >= 0; j--) { byte[] payloadBytes = records[j].getPayload(); // process the byte arrays manually and extract what // you are interested in }} 14
  15. 15. Using WebWorks to readNFC smart postersYou can read smart poster NDEF tags fromyour BlackBerry WebWorks application too
  16. 16. WebWorks and NFC tags Later last year, we developed a BlackBerry® WebWorks™ extension which allows you to incorporate NFC smart posters in your WebWorks applications This was described in one of our NFC articles in the developer resource centre:  Development/NFC-NDEF-Tag-Reading-from-WebWorks- Applications/ta-p/1430431  The code is in our GitHub WebWorks Community APIs repo. 16
  17. 17. Register your listenerfunction registerListener(record_type) { var ok = blackberry.nfc.ndef.register_ndef( ndefMessageReceived, onNdefError, record_type ); if (ok) { // }} 17
  18. 18. Implement callback functionsfunction ndefMessageReceived(ndef_message) { alert("NDEF message:"+ndef_message);}function onNdefError(error_message) { alert("NDEF error:"+error_message);} 18
  19. 19. Message formatMessages are JSON formatted for easy handlingin JavaScript! 19
  20. 20. NFC SNEP Responder ExampleDemonstrate how to write an NFC SNEPNDEF Responder application to serve out acontact in vCard format.John Muray
  21. 21. NFC Forum Peer-to-Peer  We will look at examples of:  Reading NDEF Tags  Peer to Peer using SNEP SNEP 21
  22. 22. NCF Peer-to-Peer (7.1) LLCP (Logical Link Control Protocol)  Establishes a two-way communications channel between two endpoints. Connection Handover  Uses NFC LLCP to exchange sufficient information to allow a Bluetooth® connection to be established and subsequently used. NDEF used as the message format. SNEP (Simple NDEF Exchange Protocol)  SNEP is an application level protocol running over LLCP  It uses NDEF messages as the application level messaging format  A client reads a message as if it were from a tag 22
  23. 23. Simple SNEP vCard Server 23
  24. 24. Simple SNEP vCard Server 24
  25. 25. Developing your own SNEP appThree simple steps:1. Implement the NDEFMessageBuilder interface2. Implement the NDEFPushStatusCallback interface3. Register instances of these with the system via the single instance of the NDEFPushManager 25
  26. 26. Simple SNEP vCard Serverpublic static final String VCARD_MIME_TYPE = "text/x-vCard";public static final String VCARD_DATA = For purpose of this example "BEGIN:VCARDn" + the vCard data will be built "VERSION:3.0n" + into the application statically – "N:Murray;John;;;n" + in a real app this could be "FN:John Murrayn" + dynamic. "ADR;TYPE=WORK:;;200, Bath Road;Slough;Berkshire;SL1 3XE;UKn" +... "URL:http://www.rim.comn" + "X-ORG-URL:http://www.rim.comn" + "END:VCARD";} 26
  27. 27. Simple SNEP vCard Serverpublic final class NfcSnepResponderScreen extends MainScreen {... private NDEFPushManager _ndefPushManager = null;... Retrieves the system instance public NfcSnepResponderScreen() { of NDEFPushManager which... allows access to the NDEF try { Push features of the API. _ndefPushManager = NDEFPushManager.getInstance(); } catch(NFCException e) { ... }...} 27
  28. 28. Simple SNEP vCard Serverprotected void registerForNdefPush() {... _myMsgBuilder = new NfcSnepResponderMsgBuilder(); _myStatusCallBack = new NfcSnepResponderCallBack();... if (_ndefPushManager != null) { _ndefPushId = _ndefPushManager.pushNDEF( _myMsgBuilder, _myStatusCallBack);... Register an instance that will } else { ... } build the correct NDEF} message on demand and one that will be notified of the result. 28
  29. 29. Simple SNEP vCard Serverprotected void unRegisterForNdefPush() {... if (_ndefPushManager != null) { _ndefPushManager.cancelNDEFPush( _ndefPushId );... } else { ... }} Cancel the registration using the identifier that we were presented with on registration. 29
  30. 30. Simple SNEP vCard Serverpublic class NfcSnepResponderMsgBuilder implements NDEFMessageBuilder {... Build the NDEFMessage that public NDEFMessage[] buildNDEFMessages() { will be served out using SNEP NDEFMessage[] listOfNdefMessages = null; when a NDEFMessage myNdefMessage; try { myNdefMessage = NDEFMessageUtils.createMediaTypeNDEFMessage( Constants.VCARD_MIME_TYPE, Constants.VCARD_DATA.getBytes(“US-ASCII”)); listOfNdefMessages = new NDEFMessage[]{myNdefMessage}; } catch(NFCException e) { ... } return listOfNdefMessages; }} 30
  31. 31. Simple SNEP vCard Serverpublic class NfcSnepResponderCallBack implements NDEFPushStatusCallback {... public void onNDEFPushStatusUpdate(NDEFMessage ndefMessage, int stat){... switch (stat) { case NDEFPushStatusCallback.SUCCESS: // do something ... Figure out what happened to break; the request that was served out... to the SNEP client. }} 31
  32. 32. Closing RemarksMartin Woolley
  33. 33. For More Information… Articles we’ve written:  Primer-for-Developers/ta-p/1334857  Development/Reading-and-Writing-NFC-Smart-Tags/ta-p/1379453  Development/NFC-NDEF-Tag-Reading-from-WebWorks- Applications/ta-p/1430431  Virtual-Target-Emulation/ta-p/1509687 33
  34. 34. For More Information… Our Sample Code on GitHub   Documentation  Javadoc™  Network and Communications Developer Guide 34
  35. 35. THANK YOUJohn Murray and Martin WoolleyDEV311February 7-8, 2012