How to detect if token is expired or not registred firebase FCM notification on app server?

Question

I am using following code to send the FCM notification from server to device :

    String fcmServerKey = externalConfig.getFcmServerKey();
            CloseableHttpClient httpclient = HttpClients.createDefault();
            HttpPost httpPost = new HttpPost(HTTPS_FCM_GOOGLEAPIS_COM_FCM_SEND);

            httpPost.setEntity(new StringEntity(message, ContentType.create("application/json")));
            httpPost.setHeader("Authorization", "key=" + fcmServerKey);

CloseableHttpResponse closeableHttpResponse= httpclient.execute(httpPost);

In above code when I get the response object closeableHttpResponse, how can I detect wether the fcm token used to send this request is expired or not registered ?

When from firebase application dashboard I try sending the notification to a device using its fcm token and After application is removed from device, I see Failed on firebase dashboard, on hovering cursor on Failed I see Unregistered registration token.

How can I detect above error situation of Unregistered registration token from api response object closeableHttpResponse ?

Answer 1

Use the Server Reference API to get the associated information about the device registration token. If the response is empty, it means that the token is expired or not registered.

Example GET request

https://iid.googleapis.com/iid/info/nKctODamlM4:...clJONHoA?details=true
Authorization:key=AIzaSyZ-1u...0GBYzPu7Udno5aA

Example result

HTTP 200 OK
  {
    "application":"com.iid.example",
    "authorizedEntity":"123456782354",
    "platform":"Android",
    "attestStatus":"ROOTED",
    "appSigner":"1a2bc3d4e5",
    "connectionType":"WIFI",
    "connectDate":"2015-05-12
    "rel":{
        "topics":{
          "topicname1":{"addDate":"2015-07-30"},
          "topicname2":{"addDate":"2015-07-30"},
          "topicname3":{"addDate":"2015-07-30"},
          "topicname4":{"addDate":"2015-07-30"}
                  }
           }   
  }