Develop Reference

FCM TOPIC Creation in APP Server

Recently I migrated from GCM to FCM for sending the notification via my app, i want to know whether can able to subscribe the members in particular topic from my app server. If possible, then how will find out if a particular member token valid or expired.
Because in my database, i have near to 22L people GCM Registration TOKEN id, so that i will create one topic and subscribe those members via my app server.
Any ideas to resolve this kind of issues.

You can subscribe multiple tokens to Topic via your App Server using the Instance ID API, specifically, using batchAdd. It can also identify if the Registration Token that you were subscribing is invalid by returning a NOT_FOUND error. From the docs:
Manage relationship maps for multiple app instances
Using the Instance ID service's batch methods, you can perform batch management of app instances. For example, you can perform bulk addition or removal of app instances to an FCM or GCM topic. To manage app instances, call the Instance ID service at this endpoint, providing the app instance tokens in the JSON body:
https://iid.googleapis.com/iid/v1:batchAdd
https://iid.googleapis.com/iid/v1:batchRemove
Parameters
Authorization: key=YOUR_API_KEY. Set this parameter in the header.
to : The topic name.
registration_tokens : The array of IID tokens for the app instances you want to add or remove.
Results
On success the call returns HTTP status 200. Empty results indicate successful subscription for the token. For failed subscriptions, the result contains one of these error codes:
NOT_FOUND — The registration token has been deleted or the app has been uninstalled.
INVALID_ARGUMENT — The registration token provided is not valid for the Sender ID.
INTERNAL — The backend server failed for unknown reasons. Retry the request.
TOO_MANY_TOPICS — Excessive number of topics per app instance.
Example POST request
https://iid.googleapis.com/iid/v1:batchAdd
Content-Type:application/json
Authorization:key=API_KEY
{
"to": "/topics/movies",
"registration_tokens": ["nKctODamlM4:CKrh_PC8kIb7O...", "1uoasi24:9jsjwuw...", "798aywu:cba420..."],
}
Example result
HTTP 200 OK
{
"results":[
{},
{"error":"NOT_FOUND"},
{},
]
}

Firebase Notifications - Invalid reg token, please check token format in Android

If I send push message by selecting a package from Firebase console, the push goes to all devices, but during sending to individual device, it displays the error:
Invalid reg token,please check token format
Error Snapshot:

UserID in console is not the registration token for Firebase messaging. By Firebase docs:
on initial startup of your app, the FCM SDK generates a registration token for the client app instance. If you want to target single devices or create device groups, you'll need to access this token by extending FirebaseInstanceIdService.
My last registration token looks like
cpeBAc1NkUE:APA91bEpAKHQTdgkWVdDzDZG8BPon0APaIhbbuSejDpZF-FO1gD2saDV7_EQDo2WEz0H6e5U-uf0i-v4b25NXgGzV2oUrNuboM5675WY7VCP3JcBl8BCNY7eV0VFGHT9oRox0EEoo_ch

In the other answer, you mentioned in the comments that you're Registration Token is:
cbuJIjkg9zQ%3AAPA91bHavuWCuRuWIBrDOoHUK-RsjU1yewigurrYzHe0cP‌​iTQINykKjrLf8E0qEwJj‌​3XmJ1IoTmn0r2EoLR_mA‌​HGOjlA61CnQ8aSn2WxWK‌​KByOwbsnqoVeaeWQIeGU‌​_yh4wnZ67soLtI
I noticed the % (percentage character) included in it, which isn't a usual character included in registration tokens. Figured that it was possible that this was encoded somehow. When decoded, this is the value:
cbuJIjkg9zQ:APA91bHavuWCuRuWIBrDOoHUK-RsjU1yewigurrYzHe0cP‌​iTQINykKjrLf8E0qEwJj‌​3XmJ1IoTmn0r2EoLR_mA‌​HGOjlA61CnQ8aSn2WxWK‌​KByOwbsnqoVeaeWQIeGU‌​_yh4wnZ67soLtI
Notice that the %3A was turned into : (colon). This is one of the usual characters. So I would suggest that you try the value above.
And as a reminder, the InvalidRegistration error (emphasis mine):
Check the format of the registration token you pass to the server. Make sure it matches the registration token the client app receives from registering with Firebase Notifications. Do not truncate or add additional characters.
Don't even encode it. Use it as is. Also, do note that the Registration Token should be kept secret.

Firebase Cloud Messaging - How to validate Tokens?

I am using Firebase Cloud Messaging (FCM) and as per the abreviated code below everytime a new Token is generated on the Customer Device... I send this new TOKEN to my SERVER DB (Cloud) where I save it in order to be able to send future Push Notification from the Server to the Device using the CFM API.
//public class CFMInstanceIDService extends FirebaseInstanceIdService ...
public void onTokenRefresh() {
...
String cfmToken = FirebaseInstanceId.getInstance().getToken();
...
sendRegistrationToServer(customerGuid, cfmToken);
}
By doing this I have on the Server a list of ALL (multiples) Devices where a Customer is logged-in. (Tablet, Phone, iPhone, Android, etc)
Is there any way to verify/validate a Token at any time?
I would like to know/ensure that all the tokens that I have associated to a Customer belong to real Devices. I don't want to send Push Notifications to not-existing Tokens.

Here is an example curl request that shows how to validate a token without actually having to send a message:
curl -H "Content-Type: application/json" -H "Authorization: key=$FCM_API_KEY" https://fcm.googleapis.com/fcm/send -d '{"registration_ids":["$FCMTOKEN"]}'
Example invalid response:
{"multicast_id":7452350602151058088,"success":0,"failure":1,"canonical_ids":0,"results":[{"error":"InvalidRegistration"}]}
Example valid response:
{"multicast_id":9133870199216310277,"success":1,"failure":0,"canonical_ids":0,"results":[{"message_id":"0:1502817580237626%f590ddc2f9fd7ecd"}]}
I got this answer from google's firebase support team.

Actually there is a workaround, you can use dry_run = true
This parameter, when set to true, allows developers to test a request without actually sending a message.
firebase docs
if user unsubscribe, you have a response with NotRegistered but real sending won't be performed

You can validate the FCM token by calling the
(GET) https://iid.googleapis.com/iid/info/YOUR_APP_TOKEN_HERE
[Header] => 'Authorization: key=YOUR_KEY'
Simple and easy.
If token is valid then it will return 200 status code with some more details in JSON format or if it's invalid then status code will be 400 with error detail in JSON format.

No such thing exists, the only information you can get from a token is app information and not wether it is valid or not
https://developers.google.com/instance-id/reference/server#get_information_about_app_instances
what you should be doing is watching for the response when you go to send push's out and if keys are not valid anymore the response will tell you what keys should be deleted withNotRegistered
https://firebase.google.com/docs/cloud-messaging/server

There is no way to validate if a token is still valid prior to send the downstream message. What you need to do is to check the response after sending the message and then check if the response contains any error.
For example, if the server returns an 200 + error:NotRegistered http code, it means that an existing registration token may cease to be valid.
In the section "Downstream message error response codes of FGC", you will find documented every possible status response.

InstanceID returns invalid token

I'm using GCM on Android.
I use InstanceID.getInstance(...).getToken(...) to receive a push token, but in some cases (after application updates or re-install) I receive an invalid token.
When the server returns a NotRegistered error, I've connected with a debugger and called InstanceID.getInstance(...).getToken(...). But this token is not valid (I've tried to send push via curl -s "https://android.googleapis.com/gcm/send" ... using this token), I receive NotRegistered error.
Why instanceID could return invalid token?

It shouldn't give invalid token.
Have you applied all procedures?
InstanceIDListenerService: When the token changes via the app
updates, etc.
RegistrationIntentService: When the token changes, you receive it via InstanceIDListenerService and call this intent to get a new
token.

Finally, I found a solution.
I worked with instanceID from two different threads. I called getToken(...) two times simultaneously. If instance doesn't have a cache, it get token from network. I think, it sends two requests in my case and there is no guarantee of it's order. So instanceID cached one token, but google cloud another one.

Getting 401 response from C2DM

I am getting exception from google saying:
java.io.IOException: Received authentication challenge is null
I read that this is reproducing 401 error. So this
Indicates that the ClientLogin AUTH_TOKEN used to validate the sender is invalid.
But i have everything registreted and logined with ClientLogin successfully.
So what wrong could be?
Also do i need to reigstrate my app here ?
Sing up for C2DM
Because i haven't
Thanks

Have u register your app on the given link . Also you should get mail from C2DM on mail id which you have mention in Contact email address.