Sending URL from Android to Windows Phone via NFC gives Play Store link

Question

I am trying to use NFC to send a URL from an Android app to a WP8 phone.

When beaming to an Android device, the URL is sent correctly. However, when beaming to WP8, IE loads a link to the Play Store instead of the one I want to send (e.g. "http://www.stackoverflow.com").

The Play Store link is: "https://play.google.com/store/apps/details?id=com.example.conductrnfc&feature=beam". Where "com.example.conductrnfc" is the package name in the project.

The code I used to generate the NFC message is given below. Is there something I'm doing wrong here that breaks compatibility with WP8?

NfcAdapter nfc = NfcAdapter.getDefaultAdapter(this);
nfc.setNdefPushMessageCallback(new NfcAdapter.CreateNdefMessageCallback() {
    @Override
    public NdefMessage createNdefMessage(NfcEvent event)
    {
        NdefRecord uriRecord = NdefRecord.createUri(urlString);
        return new NdefMessage(new NdefRecord[] { uriRecord });
    }
}, 
this);

Discount

Are you also attaching an AAR to the message? It wouldn't seem like it, given your code, but that's one thing that I know of that leads apps to the Play Store from an NFC message. – Hagai

I haven't attached an AAR, the URL is the only record in the message. – Discount

can you show the link you send to WP8 and what appears in WP8 exactly? – Uncrowned

@M.C. - The actual code is NdefRecord uriRecord = NdefRecord.createUri(webView.getUrl()); with the webView having been pointed to a website (not the play store) in the activity's onCreate. What WP8 sees is the URL mentioned in the question – Revis

@RobertLevy, so any URL you send to WP8, it sends URL to your app in app store? – Uncrowned

Yes, that's what it looks like... except that this app isn't actually in the store – Revis

Android Beam sending the Play Store URL is the default behavior if the app doesn't itself setup any NDEF message for Beam. Can you confirm that the createNdefMessage callback is actually called (e.g. by adding logging)? – Yseulte

It is called in the debugger when I attempt to send a message. – Discount

Can you try if you get the same result if you use setNdefPushMessage to set a static NDEF message instead of creating one dynamically using the callback? (Note that you must not register a callback with setNdefPushMessageCallback in that case!) – Yseulte

Btw. what Android version are you using? – Yseulte

You did not also register for setBeamPushUris or setBeamPushUrisCallback, right? – Yseulte

@MichaelRoland this is 4.4.2 and OP is not calling those functions. should he? – Revis

another clue: i noticed that it's not just our app that is sending Play Store links... it seems android is doing that by default for all apps except a few are sending over custom things (Chrome has no problem sending over whatever URL it is currently showing). Is the code posted in the question insufficient? – Revis

@MichaelRoland correction: createNdefMessage is called when beaming to Android, but not called when beaming to WP8. What could the reason be? – Discount

further strangeness: setNdefPushMessageCallback works android-to-android but not WP8. If we do setNdefPushMessage, that works for both (but we kinda want to use the callback approach to dynamically generate the URL) – Revis

@RobertLevy No, the setBeamPushUri* functions should not need to be called. – Yseulte

@RobertLevy sending Play Store links: That's what I wrote about Android Beam's default behavior above. – Yseulte

Okay then, that's bringing us closer to identifying the issue. Could you add log messages to the lifecycle methods of the activity (onCreate, onStart, onResume, onPause, onStop, onDestroy) and show us the result for both an android-to-android beam and an android-to-wp8 beam? I would guess that there's a difference... – Yseulte

In addition to the above, in case you use a Nexus device, can you check if you receive any log messages with log tag NfcP2pLinkManager (again for both android-to-android and android-to-wp8)? – Yseulte

Answer 1

Can you try this:

NfcAdapter nfc = NfcAdapter.getDefaultAdapter(this);
nfc.setNdefPushMessageCallback(new NfcAdapter.CreateNdefMessageCallback() {
    @Override
    public NdefMessage createNdefMessage(NfcEvent event)
    {
        byte[] payload = urlString.getBytes();
        NdefRecord uriRecord = new NdefRecord(NdefRecord.TNF_WELL_KNOWN, NdefRecord.RTD_URI, new byte[0], payload); 
        return new NdefMessage(new NdefRecord[] { uriRecord });
    }
}, 
this);

Uncrowned

Be sure to replace NdefRecord.TNF_ABSOLUTE_URI with NdefRecord.TNF_WELL_KNOWN. – Yseulte

@MichaelRoland, exactly! Thank you, I added RTD_URI to second parameter just for TNF_WELL_KNOWN, but I missed it. Good catch! – Uncrowned

Just tried this, unfortunately it seems to still give us the same issue. WP8 opens a link to the Play Store instead of the link in the string. – Discount

Answer 2

Eventhough I still miss some more debugging results from the OP, I thought I'd give it a shot:

As the discussion in the commands revealed that the createNdefMessage callback is not called when interacting with a WP8 phone, it would be interesting why this appens and how to prevent this. Unfortunately I have no details about the actual lifecycle of the activity, so I can only guess what might go wrong.

1. One reason why a registered createNdefMessage callback may not be called is that the activity that registered the callback is no longer in the foreground. So there may be a difference between an Android device and a WP8 device that causes the current activity to be paused.

2. Another reason would be that the WP8 device interupts communication before the Android NFC stack had the time to call the createNdefMessage callback method. However, this should be detectable as the Beam UI would typically disappear before the user is able to click it.

One cause for reason 1 may be that the WP8 device itself sends an NDEF message that causes intent processing on the Android device. If that's the case, a method to overcome this problem may be to register for the foreground dispatch system. This would prevent regular intent processing and would directly send all incoming NDEF messages to the current activity:

@Override
public void onResume() {
    super.onResume();
    NfcAdapter adapter = NfcAdapter.getDefaultAdapter(this);
    PendingIntent pi = PendingIntent.getActivity(this, 0, new Intent(this, getClass()).addFlags(Intent.FLAG_ACTIVITY_SINGLE_TOP), 0);
    adapter.enableForegroundDispatch(this, pi, null, null);
}

@Override
public void onNewIntent(Intent intent) {
    if (intent != null) {
        String action = intent.getAction();
        if (NfcAdapter.ACTION_TAG_DISCOVERED.equals(action) ||
            NfcAdapter.ACTION_NDEF_DISCOVERED.equals(action) ||
            NfcAdapter.ACTION_TECH_DISCOVERED.equals(action)) {
            Log.d("NdefTest", "This problem was actually caused by an incoming NDEF message.");
        }
    }
}

Yseulte

Hey sorry we haven't had a chance to dig in and get other details to really solve this. I appreciate your patience and the back and forth troubleshooting effort though so the bounty is all yours. – Revis

Yup, us too :) Will definitely come back to this when time allows and post results here – Revis