WebAPI/WebNFC: Difference between revisions

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'''nfc-share''' could be used to send large file (Blob) to another NFC peer.
'''nfc-share''' could be used to send large file (Blob) to another NFC peer.
'''nfc-manager''' is used to control the RF state of NFC hardware.
'''nfc-manager''' is used to control the RF state of NFC hardware.
= NFC example =
== NFC Utility function for parsing / constructing NDEF records==
Gaia Application developers can use a helper library (<$GAIA_HOME>/shared/js/nfc_utils.js> to perform routine tasks such as parse incoming  NDEF records or construct NDEF records.
NfcUtils in {{bug|963556}} will provide some basic constants and utility functions to create and parse NDEF messages that follow NFCForum-TS-NDEF_1.0 specifications.
The helper-utility exposes the following public functions:
- parseNDEF            : Parse a NDEF message
- parseHandoverNDEF    : Parse a NDEF message that represents a handover request
                          or a handover select message
- searchForBluetoothAC : Search for a Bluetooth Alternate Carrier in a
                          handover NDEF message
- parseBluetoothSSP    : Parses a Carrier Data Record that contains a
                          Bluetooth Secure Simple Pairing record
- encodeHandoverRequest: Returns a NDEF message that contains a handover
                          request message
- encodeHandoverSelect:  Returns a NDEF message that contains a handover
                          select message
''Sample example to demonstrate the construction of an url as an NDEF Message:''
  var tnf    = NDEF.TNF_WELL_KNOWN;
  var type    = NDEF.RTD_URI;
  var id      = new Uint8Array();
  // Short Record, 0x3 or "http://"
  var payload = new Uint8Array(NfcUtils.fromUTF8('\u0003mozilla.org'));
  var  urlNDEFMsg = [new MozNDEFRecord(tnf, type, id, payload)];
  // Call writeNdef() API with urlNDEFMsg
== NDEF Connect Example ==
To establish an NFC application session, all NFCTag operations require an initial connect. It also selects the technology to use for subsequent operations until close/disconnect.
  nfctag = window.navigator.mozNfc.getNFCTag(sessionToken);
  var connectreq = nfctag.connect("NDEF");
  connectreq.onsuccess = function() {
    console.log('Connect success!');
  };
  connectreq.onerror = function() {
    console.log('ERROR: Failed to connect.');
  };
== NFC Close Example ==
Applications should close() the tag when done to release resources.
  var closereq = nfctag.close();
  closereq.onsuccess = function() {
    console.log('NFC tag close success!');
  };
  closereq.onerror = function() {
    console.log('ERROR: Failed to close.');
  };
== NDEF Details Example ==
  var detailreq = nfctag.getDetailsNDEF();
  detailreq.onsuccess = function() {
    console.log('Max NDEF Message Length: ' + detailreq.result.maxNdefMsgLen);
  };
  detailreq.onerror = function() {
    console.log('ERROR: Failed to get NDEF details.');
  };
== NDEF Read Example ==
The array of ndef records should be passed along in the web activity already read, but applications can still directly read the tag. The session token arrives from a MozActivity. NdefRecord fields are in Uint8Array format, they must first be unpacked in order to be read by applications.
  var conn = nfctag.connect("NDEF");
  conn.onsuccess = function() {
    var req = nfctag.readNDEF();
    req.onsuccess = function() {
      var records = req.result;
      showRecords(records);
      nfctag.close(); // This is a DOMRequest call, truncated code here.
    };
    req.onerror = function() {
      nfctag.close(); // This is a DOMRequest call, truncated code here.
    };
  };
 
  function showRecords(records) {
    records.forEach(function (record) {
      console.log("Found a " + record.tnf + " record" +
                  " of type " + record.type +
                  " with ID " + record.id +
                  " and payload " + record.payload);
    });
  };
== NDEF Write Tag Example ==
  var tnf    = 1;                                                      // NFC Forum Well Known type
  var type    = new Uint8Array(NfcUtils.fromUTF8("U"));                // URL type
  var id      = new Uint8Array(NfcUtils.fromUTF8(""));                  // id
  var payload = new Uint8Array(NfcUtils.fromUTF8("\u0003mozilla.org")); // URL data, with a short record prefix 0x3 replacing http://
 
  var ndefRecords = [new MozNDEFRecord(tnf, type, id, payload)];
 
  var writereq = nfctag.writeNDEF(ndefRecords);
  writereq.onsuccess = function(e) {
    console.log("Successfully wrote records to tag");
  };
  writereq.onerror = function(e) {
    console.log("Write failed!");
  };
== NDEF P2P Send Example ==
Peer to Peer communications to another NFC enabled device does not need a connect, as it will automatically connect implicitly. It also only supports NDEF, which is a common standard data format across different NFC devices.
  var tnf    = 1;                                                      // NFC Forum Well Known type
  var type    = new Uint8Array(NfcUtils.fromUTF8("U"));                // URL type
  var id      = new Uint8Array(NfcUtils.fromUTF8(""));                  // id
  var payload = new Uint8Array(NfcUtils.fromUTF8("\u0003mozilla.org")); // URL data, with a short record prefix 0x3 replacing http://
 
  var ndefRecords = [new MozNDEFRecord(tnf, type, id, payload)];
  var nfcdom = window.navigator.mozNfc;
  nfcdom.onpeerready = function(event) {
    var nfcPeer = nfcdom.getNFCPeer(event.detail);  // 'event.detail' has sessionToken.
    var req = nfcpeer.sendNDEF(ndefRecords); // push NDEF message to other NFC device.
    req.onsuccess = function(e) {
      console.log("Successfully pushed P2P message");
    };
    req.onerror = function(e) {
      console.log("P2P push failed!");
    };
  };
== NDEF P2P SendFile Example ==
During handover scenarios, in order to send a file
  var nfcdom = window.navigator.mozNfc;
  nfcdom.onpeerready = function(event) {
    var nfcPeer = nfcdom.getNFCPeer(event.detail);
    var blob = ... // construct a 'blob' that is of type 'file'.
    // This 'blob' will be passed onto / handover to Bluetooth interface for the actual file transfer. (Wifi handover is not yet supported)
    var req = nfcPeer.sendFile(blob);
    req.onsuccess = function(e) {
      console.log("Successfully sent file");
    };
    req.onerror = function(e) {
      console.log("Send file failed!");
    };
  };
In order to use this api, applications should have the nfc permission 'nfc-write'
== Handover Support ==
'''Only Bluetooth Handover is supported currently'''
Refer to this bug {{bug|903305}} for 'sendFile' api, and for implementation details, refer {{bug|933093}}.


= Application Dispatch Order =
= Application Dispatch Order =

Revision as of 06:59, 21 January 2015

Introduction

Current Status (As to Firefox OS v2.2)

  • Gecko b2g-nfc meta bug, bug 860906
  • Gecko b2g-secure-element meta bug bug 1044428
  • Gaia meta bug, bug 933640
  • nfcd meta bug, bug 1044425
  • Gonk
    • Use a native daemon nfcd which links to native NFC library. nfcd github
  • Hardware
    • Using Nexus-4/Nexus-5, which uses Broadcom NFC chipset with libnfc-nci library.
    • Flame, NXP chipsets with libnfc-nci library.

Security Review (By Paul Theriault and Stephanie Ouillon)

Contributors

  • Gecko Engineers: Arno Puder, Garner Lee, Siddartha Pothapragada, Yoshi Huang, Dimi Lee
  • Early Contributors: Markus Neubrand, Philipp von Weitershausen

Roadmap

First iteration: NDEF (Firefox OS v1.3)

  • meta bug, bug 959692 - (b2g-NFC-1.3) [meta] FxOS v1.3 NFC feature
  • Technologies:
    • Focus on NDEF standard only for now
    • Others (e.g. proprietary MIFARE) to be investigated later.
  • Capabilities:
    • Read/write NDEF records on tags
    • bug 933136 - [Gecko] NFC onpeerready, onpeerlost callbacks
  • Implementation:
    • See bug 674741
    • NDEF-only API is available on MozNFCTag object.
    • Discovered NDEF tags are automatically parsed and dispatched to content in the "nfc-manager-tech-discovered" system message.
    • navigator.mozNfc only available to a specific privileged content page (cf. WebTelephony, WebSMS).
    • For now, content is expected to do filtering and dispatching to handlers e.g. via WebActivity.
  • Gonk
    • bug 906579 - B2G NFC: NFC Daemon for supporting libnfc-nci
  • Hardware
    • Using Nexus-4, which uses Broadcom NFC chipset with libnfc-nci library.

Second iteration: Handover and other bug fixes (Firefox OS v1.4)

  • meta bug : bug 949293 - (b2g-NFC-1.4) [meta] FxOS v1.4 NFC feature
  • Capabilities:
    • bug 933093 NFC handover.
    • bug 916863 - [NFC] NFC support in emulator
    • NFC Manager API
      • bug 952217 - [B2G][NFC] Have a separate NFC application API and NFC Manager API
      • bug 959437 - Refactor NfcManager APIs and implementation details to support sendFile , notifyUserAcceptedP2P and other privileged Nfc operations

Third iteration: NFC Sharing feature, P2P, emulator support, test cases (Firefox OS v2.0)

  • meta bug : bug 949293 - (b2g-NFC-2.0) [meta] FxOS v2.0 NFC feature
  • NFC emulator: bug 973133
  • More Gaia unit tests for NFC in apps/system/test/unit/

Fourth iteration: HCI transaction event (Firefox OS v2.1)

Fifth iteration: Secure Element (Firefox OS v2.2)

  • bug 1044428 b2g-secure-element
    • bug 879861 - NFC Secure Element Support
    • bug 1042851 - (b2g-nfc-privilege) (meta) [NFC] Make NFC APIs available to privileged webapps

Current API

Check DXR for latest NFC IDL

Usage of APIs

https://developer.mozilla.org/en-US/docs/Web/API/NFC_API

Application Permissions

NFC API has three permissions.

  • nfc, which will be used by privileged applications.
  • nfc-share, which will be used by ceritified(internal) applications.
  • nfc-manager', which will be used by System app.

nfc permission could be used for general tag reading/writing, or sending NDEF to NFC Peer. nfc-share could be used to send large file (Blob) to another NFC peer. nfc-manager is used to control the RF state of NFC hardware.

Application Dispatch Order

Dispatch priority is handled by the NFC Manager. In the numbered list below, a low number indicates higher priority. It generally dispatches according to the NFC technology type, and then the NDEF NDEF.TNF field, and the NDEF Record type field. If an activity is to be launched, it will display a activity list if there is more than one match. 

1) Foreground App, if the callback onforegrounddispatch is set.
2) P2P Handover Types (BT transfers, WiFi direct connection, etc.)
3) All other matches.

In #3, unknown tags are dispatched as a "nfc-tag-discovered" activity.

NFC on B2G emulator

NFC Resources

Reference

Similar APIs

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