Windows (Phone) 8 NFC App Scenarios

Windows (Phone) 8
NFC App Scenarios
Andreas Jakl, Mopius

Windows (Phone) 8 NFC App Scenarios v3.0.0 © 2014 Andreas Jakl
NFC Forum and the NFC Forum logo are trademarks of the Near Field Communication Forum.

1

Andreas Jakl
Twitter: @mopius
Email: andreas.jakl@mopius.com
Trainer & app developer
– mopius.com
– nfcinteractor.com

Nokia: Technology Wizard
FH Hagenberg, Mobile Computing: Assistant Professor
Siemens / BenQ Mobile: Augmented Reality-Apps

2

Near Field
Communication

Discover Your App

NDEF Library

Nfc Interactor

Share to Others

Seamless MultiUser Games &
Collaboration


3

PROXIMITY & TAPPING

4

NFC Scenarios

Connect Devices

Exchange Digital Objects

Acquire Content


5

Tap and Do
A gesture that is a natural interaction between people in close proximity used
to trigger doing something together between the devices they are holding.

System: Near Field Proximity
(e.g., NFC)

Documentation: bit.ly/ProximitySpec

6

Proximity APIs
Windows Phone 8 +
Windows 8
Documentation
Win8: bit.ly/ProximityAPI
WP8: bit.ly/ProximityAPIwp8


7

APP SCENARIOS

8

Discover Your App

Share to Others

Seamless Multi-User
Games &
Collaboration


9

General Project Setup
1 Add Proximity Capability
2 Initialize ProximityDevice
_device = ProximityDevice.GetDefault();

Connect to HW
Detect devices in range
Publish & subscribe to messages


10

How to Launch Apps

either or

Win8 + WP8

Tag directly contains
app name and
custom data.
No registration necessary.

Custom URI scheme
launches app.
App needs to register.


11

parameters

platform 1

app name 1

platform 2

app name 2

…

Encoded into NDEF message*

Directly launch App
* For your low-level interest: type: Absolute URI, type name format: windows.com/LaunchApp. Contents re-formatted, e.g., with string lengths before each value

12

Write LaunchApp Tags
1 Launch parameters, platforms + app IDs
// Arguments to pass to app, valid for all platforms
var launchArgs = "user=default";
// WP8: app's product id from the app manifest, wrapped in {}
var wp8App = "{5e506af4‐4586‐4c90‐bc5f‐428b12cf48bc}";
// Win8: app ID: Package.appxmanifest ‐> source ‐> <Application Id="...">
var win8AppId = "Proximity.App";
var win8App = Windows.ApplicationModel.Package.Current.Id.FamilyName +
"!" + win8AppId;
// Combine to LaunchApp Message
var launchAppMessage = launchArgs +
"tWindowsPhonet" + wp8App + "tWindowst" + win8App;

13

Write LaunchApp Tags
2 Convert to byte array
var dataWriter = new Windows.Storage.Streams.DataWriter
{UnicodeEncoding = Windows.Storage.Streams.UnicodeEncoding.Utf16LE};
dataWriter.WriteString(launchAppMessage);

3 Write to tags
_device.PublishBinaryMessage("LaunchApp:WriteTag",
dataWriter.DetachBuffer());


14

nearspeak: Good+morning.
Protocol
name

Custom data
Encoded Launch URI

Examples*
skype:mopius?call
spotify:search:17th%20boulevard

* Definition & examples: http://en.wikipedia.org/wiki/URI_scheme

15

User Experience

No app installed

1 app installed

2+ apps installed


16

WP Protocol Association

Note: different
in Win8 / WP8

1 Specify protocol name in WMAppManifest.xml
...</Tokens>
Protocol
<Extensions>
name
<Protocol Name="nearspeak"
NavUriFragment="encodedLaunchUri=%s"
TaskID="_default" />
Fixed
</Extensions>


17


Note: different
in Win8 / WP8

2 Create UriMapper class to parse parameters
class NearSpeakUriMapper : UriMapperBase
{
public override Uri MapUri(Uri uri)
{
// Example: "Protocol?encodedLaunchUri=nearspeak:Good+morning."
var tempUri = HttpUtility.UrlDecode(uri.ToString());
var launchContents = Regex.Match(tempUri, @"nearspeak:(.*)$").Groups[1].Value;
if (!String.IsNullOrEmpty(launchContents))
{
// Launched from associated "nearspeak:" protocol
// Call MainPage.xaml with parameters
return new Uri("/MainPage.xaml?ms_nfp_launchargs=" + launchContents, UriKind.Relative);
}
// Include the original URI with the mapping to the main page
return uri;
}}

Argument already handled in step 9 of LaunchApp
tags (MainPage.OnNavigatedTo)


18

3 Use UriMapper in App.xaml.cs
(region:

)

private void InitializePhoneApplication() {
RootFrame = new PhoneApplicationFrame();
RootFrame.UriMapper = new NearSpeakUriMapper();
}

– If needed: launch protocol from app (for app2app comm)
await Windows.System.Launcher.LaunchUriAsync(
new Uri("nearspeak:Good+morning."));


19

Register for URI Schemes
Win 8

Specify URI scheme, display name + optional im


20

Tag Data After Launch
Win 8

Activtion arguments in App.xaml.cs
protected override async void OnActivated(IActivatedEventArgs args)
{
if (args.Kind == ActivationKind.Protocol)
{
ProtocolActivatedEventArgs protocolArgs = args as
ProtocolActivatedEventArgs;
}
}


21

User Experience
Win 8


22

Discover Your App

Share to Others

Seamless Multi-User
Games &
Collaboration


23

Publish Messages
1 Start publishing
_publishingMessageId = _device.PublishUriMessage(
new Uri("nfcinteractor:compose"));

Proximity devices only
– (doesn’t write tags)

Contains
scheme,
platform &
App ID

Windows Protocol + URI record
– Encapsulated in NDEF


24

Write Tags
1 Prepare & convert data
var dataWriter =
new Windows.Storage.Streams.DataWriter {
UnicodeEncoding = Windows.Storage.Streams.
UnicodeEncoding.Utf16LE};
dataWriter.WriteString("nfcinteractor:compose");
var dataBuffer = dataWriter.DetachBuffer();

Mandatory
encoding

2 Write tag (no device publication)
_device.PublishBinaryMessage("WindowsUri:WriteTag", dataBuffer);

bit.ly/PublishTypes

25

Discover Your App

Share to Others

Seamless Multi-User
Games &
Collaboration


26

Collaboration

Tap for

Quick Data
Exchange

Long Term
Connection

ProximityDevice

PeerFinder

Exchange Windows /
NDEF messages,
SNEP protocol

Automatically builds
Bt / WiFi Direct
socket connection


27

Establishing

Trigger

Long Term
Connection
Browse

Interact with Tap

Start Search

NFC

Bt, WiFi, etc.


28

Tap to Trigger

App not installed

App installed

29

Connection State
Proximity gesture complete
Devices can be pulled away

Which device initiated tap gesture?
→ Connecting, other device Listening

1
PeerFound

2
Connecting /
Listening

Access socket of persistent transport
(e.g., TCP/IP, Bt)

3
Completed


30

Find Peers
1 Start waiting for triggered connections
PeerFinder.TriggeredConnectionStateChanged +=
TriggeredConnectionStateChanged;
PeerFinder.Start();

2 Peer found & connection established? Send message over socket
private async void TriggeredConnectionStateChanged(object sender,
TriggeredConnectionStateChangedEventArgs eventArgs) {
if (eventArgs.State == TriggeredConnectState.Completed) {
// Socket connection established!
var dataWriter = new DataWriter(eventArgs.Socket.OutputStream);
dataWriter.WriteString("Hello Peer!");
var numBytesWritten = await dataWriter.StoreAsync();
3
}}
* For URI records + simple Smart Poster (w/o title), use the WindowsUri type.

31
Completed

TOOLS & RESOURCES

32

UX Recommendations*
User initiated peer
search only

Ask for consent

Show connection
state

Failed
connection?
Inform & revert to
single-user mode

Let user get out of
proximity
experience

Proximity: only if
connection details
not relevant

* bit.ly/ProximityUX

33

NFC Tools
Proximity Tapper for WP emulator
– http://proximitytapper.codeplex.com/

Open NFC Simulator
– http://open-nfc.org/wp/editions/android/

NFC plugin for Eclipse: NDEF Editor
– https://code.google.com/p/nfc-eclipse-plugin/

34

nfcinteractor.com


35

NFC Resources
 NFC News: nfcworld.com
 NFC developer comparison
(WP, Android, BlackBerry):
bit.ly/NfcDevCompare
 Specifications: nfc-forum.org

36

Standardized NFC Tag Contents

NDEF HANDLING

37

NFC Data
NDEF Record
(e.g., URL)

…

NDEF Message
NDEF = NFC Data Exchange Format


38

SNEP = Simple NDEF Exchange Protocol
NDEF Record
(e.g., URL)

…

NDEF Message


39

Reading NDEF
1 Subscribe to all NDEF messages
_subscribedMessageId = _device.SubscribeForMessage(
"NDEF", MessageReceivedHandler);

2 Parse raw byte array in handler 

http://www.nfc-forum.org/specs/


40

Reading NDEF
// Convert the language code to a byte array

Simple example:
assembling payload of Text record

1 Subscribe to all NDEF messages= Encoding.UTF8;
var languageEncoding

var encodedLanguage = languageEncoding.GetBytes(languageCode);
// Encode and convert the text to a byte array
var encoding = (textEncoding == TextEncodingType.Utf8) ? Encoding.UTF8 : Encoding.BigEndianUnicode;
var encodedText = encoding.GetBytes(text);
// Calculate the length of the payload & create the array
var payloadLength = 1 + encodedLanguage.Length + encodedText.Length;
Payload = new byte[payloadLength];

_subscribedMessageId = _device.SubscribeForMessage(
"NDEF", MessageReceivedHandler);

2 Parse raw byte array in handler 

// Assemble the status byte
Payload[0] = 0; // Make sure also the RFU bit is set to 0
// Text encoding
if (textEncoding == TextEncodingType.Utf8)
Payload[0] &= 0x7F; // ~0x80
else
Payload[0] |= 0x80;

http://www.nfc-forum.org/specs/

// Language code length
Payload[0] |= (byte)(0x3f & (byte)encodedLanguage.Length);
// Language code
Array.Copy(encodedLanguage, 0, Payload, 1, encodedLanguage.Length);
// Text
Array.Copy(encodedText, 0, Payload, 1 + encodedLanguage.Length, encodedText.Length);


41

NDEF.codeplex.com
Create NDEF
messages & records
(standard compliant)

Reusable
NDEF classes

Parse information
from raw byte arrays

Fully documented
Open Source LGPL license
(based on Qt Mobility)


42

NDEF Subscriptions
1 Subscribe to all NDEF formatted tags
_subscribedMessageId = _device.SubscribeForMessage("NDEF",
MessageReceivedHandler);

2 Parse NDEF message
private void MessageReceivedHandler(ProximityDevice sender,
ProximityMessage message)
{
var msgArray = message.Data.ToArray();
NdefMessage ndefMessage = NdefMessage.FromByteArray(msgArray);
[...]
}

43

NDEF Subscriptions
3 Analyze all contained NDEF records with specialized classes
foreach (NdefRecord record in ndefMessage)
{
Debug.WriteLine("Record type: " +
Encoding.UTF8.GetString(record.Type, 0, record.Type.Length));
// Check the type of each record ‐ handling a Smart Poster in this example
if (record.CheckSpecializedType(false) == typeof(NdefSpRecord))
{
// Convert and extract Smart Poster info
var spRecord = new NdefSpRecord(record);
Debug.WriteLine("URI: " + spRecord.Uri);
Debug.WriteLine("Titles: " + spRecord.TitleCount());
Debug.WriteLine("1. Title: " + spRecord.Titles[0].Text);
Debug.WriteLine("Action set: " + spRecord.ActionInUse());
}
}

44

Write NDEF
1 Prepare & convert data
// Initialize Smart Poster record with URI, Action + 1 Title
var spRecord = new NdefSpRecord
{ Uri = "http://www.nfcinteractor.com" };
spRecord.AddTitle(new NdefTextRecord
{ Text = "Nfc Interactor", LanguageCode = "en" });
// Add record to NDEF message
var msg = new NdefMessage { spRecord };

2a Write tag
// Publish NDEF message to a tag
_device.PublishBinaryMessage("NDEF:WriteTag", msg.ToByteArray().AsBuffer());

2b Publish to devices
// Alternative: send NDEF message to another NFC device
_device.PublishBinaryMessage("NDEF", msg.ToByteArray().AsBuffer());

45

Supported Record Types
Smart Poster
URI
Text
LaunchApp
Android Application Record (AAR)
Windows Phone Settings
Nokia Accessories Record
NearSpeak Voice Messages

Geo tags
Social tags
SMS tags
Telephone call
Mailto tags

ndef.mopius.com


46

Near Field
Communication

Discover Your App

NDEF Library

Nfc Interactor

Share to Others

Collaboration


47

Thank You.
Andreas Jakl
@mopius
mopius.com
nfcinteractor.com


48

Windows (Phone) 8 NFC App Scenarios

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