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I have a question here about getting an Invalid Registration FCM error. I want to send notification to specific device through Backend .Net (EF)
First of all I saved the deviceToken to the server (Xamarin iOS).
I read the error from https://firebase.google.com/docs/cloud-messaging/http-server-ref
200 + error:InvalidRegistration 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.
public override void RegisteredForRemoteNotifications(UIApplication application, NSData deviceToken)
{
//FirebasePushNotificationManager.DidRegisterRemoteNotifications(deviceToken);
//byte[] bytes = deviceToken.ToArray<byte>();
//string[] hexArray = bytes.Select(b => b.ToString("x2")).ToArray();
//DeviceToken = string.Join(string.Empty, hexArray);
string deviceTokenString;
if (UIDevice.CurrentDevice.CheckSystemVersion(13, 0))
{
deviceTokenString = BitConverter.ToString(deviceToken.ToArray());
}
else
{
deviceTokenString = deviceToken.ToString();
}
Preferences.Set("TokenDevice", deviceTokenString);
}
I saved the deviceToken to Preferences and also saved it to the server. My deviceToken code on Xamarin iOS:
1A-F5-BE-DC-E4-22-07-46-AA-C4-87-CC-08-F5-D7-09-D4-AB-43-18-26-E0-65-3B-39-4E-6F-5E-02-35-9E-3A
I don't know if this method of getting the deviceToken on Xamarin iOS is really correct at this time?
Backend I write API to send:
private static Uri FireBasePushNotificationsURL = new Uri("https://fcm.googleapis.com/fcm/send");
private static string ServerKey = "key=AAAAqOId6Is:APxxxxxxxxxxxxxxxxxxxx....";
[HttpPost]
public async void PushNotificationToFCM(string deviceTokens, string title, string body, object data, string linkdirection)
{
using (var client = new HttpClient())
{
var messageInformation = new Message()
{
notification = new NotificationFirebases()
{
title = title,
text = body
},
data = new Dictionary<string, string>()
{
{ "link", linkdirection },
},
to = deviceTokens
};
//Object to JSON STRUCTURE => using Newtonsoft.Json;
string jsonMessage = JsonConvert.SerializeObject(messageInformation);
string postBody = JsonConvert.SerializeObject(messageInformation).ToString();
client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
client.DefaultRequestHeaders.TryAddWithoutValidation("Authorization", ServerKey);
var response = client.PostAsync(FireBasePushNotificationsURL, new StringContent(postBody, Encoding.UTF8, "application/json"));
var responseString = response.Result.Content.ReadAsStringAsync().Result;
}
}
public class Message
{
public string to { get; set; }
public NotificationFirebases notification { get; set; }
public object data { get; set; }
}
public class NotificationFirebases
{
public string title { get; set; }
public string text { get; set; }
}
When I test I get the error:
{\"multicast_id\":7343900550378569449,\"success\":0,\"failure\":1,\"canonical_ids\":0, \" results\":[{\"error\":\"InvalidRegistration\"}]}. I have tried with deviceToken on Android and it succeeds. Appears only with deviceToken on Xamarin iOS
Please note that I tried sending a notification in Firebase Cloud Messaging: https://console.firebase.google.com/u/0/project/.... then I got a notification, so you can see that my APNS configuration is not wrong.
Looking forward to everyone's help. I also spent more than 2 weeks searching and trying to no avail. Thank you very much.
Update Backend I write API to send:
public void PushNotificationToFCM(string deviceTokens, string title, string body, object data, string linkdirection)
{
FirebaseApp.Create(new AppOptions() {
Credential= GoogleCredential.FromFile("private_key.json")
});
// This registration token comes from the client FCM SDKs.
var registrationToken = deviceTokens;
// See documentation on defining a message payload.
var message = new Message()
{
Apns = new ApnsConfig { Aps = new Aps { ContentAvailable = true, Sound = "default" } },
Data = new Dictionary<string, string>()
{
{ "link", linkdirection },
},
Token = registrationToken,
Notification= new FirebaseAdmin.Messaging.Notification()
{
Title = title,
Body = body,
}
};
// Send a message to the device corresponding to the provided
// registration token.
string response = FirebaseMessaging.DefaultInstance.SendAsync(message).Result;
// Response is a message ID string.
Debug.WriteLine("Successfully sent message: " + response);
}
I don't know if such iOS device's TokenDevice code is correct? I tried to submit it, however getting the error: System.AggregateException: 'One or more errors occurred. (The registration token is not a valid FCM registration token)'
I uninstalled and reinstalled the app, I got a new tokenDevice. However when I send the notification I still get the same error
As an alternative workaround, you can use this NuGet package Plugin.FirebasePushNotification.
1. After Creating the iOS Project, add "GoogleService-Info.plist" file to your iOS Project and update the property to BundleResource.
2. In Info.plist and FinishedLaunching method, add following line:
<key>FirebaseAppDelegateProxyEnabled</key>
<false/>
public override bool FinishedLaunching(UIApplication app, NSDictionary options)
{
global::Xamarin.Forms.Forms.Init();
LoadApplication(new App());
FirebasePushNotificationManager.Initialize(options, true);
return base.FinishedLaunching(app, options);
}
3. Then add the below in App Construct.
CrossFirebasePushNotification.Current.OnTokenRefresh += (s, p) =>
{
System.Diagnostics.Debug.WriteLine($"TOKEN : {p.Token}");
};
CrossFirebasePushNotification.Current.OnNotificationReceived += (s, p) =>
{
System.Diagnostics.Debug.WriteLine("Received");
foreach (var data in p.Data)
{
System.Diagnostics.Debug.WriteLine($"{data.Key} : {data.Value}");
}
};
CrossFirebasePushNotification.Current.OnNotificationOpened += (s, p) =>
{
System.Diagnostics.Debug.WriteLine("Opened");
foreach (var data in p.Data)
{
System.Diagnostics.Debug.WriteLine($"{data.Key} : {data.Value}");
}
};
4. After getting the FCM registration token. then click Test, the targeted client device (with the app in the background) should receive the notification in the system notifications tray.
AFAIK, the Firebase Instance Token will be refreshed under the following 4 conditions:
App deletes Instance ID
App is restored on a new device
User uninstalls/reinstall the app
User clears app data
Suppose a user is using Token A as his 'FCM address'. Every time when he logs in the app, he will register the Token A to the Firestore along with this user's UUID so user-specific cloud message can be sent to him. When he logs out, the system will fire a request to firestore for removing the token A record.
Now, when the user reinstalls the app, the instance id is refreshed and a new Token B is generated. The Token A becomes useless. Unfortunately, if the user does not log out before the uninstallation, token A will stay in the firestore forever.
Any workaround or wiser way to handle this case?
Keeping your token registry up to date requires two steps:
Remove outdated tokens from your application code.
Check for outdated tokens and remove them when you send messages.
Your approach of removing a token that is no longer used, is #1.
The second step though is to remove tokens from your registry/database when you get a messaging/invalid-registration-token or messaging/registration-token-not-registered response when trying to send a message to it. The functions-samples repo contains a great example of this:
admin.messaging().sendToDevice(tokens, payload).then((response) => {
// For each message check if there was an error.
const tokensToRemove = [];
response.results.forEach((result, index) => {
const error = result.error;
if (error) {
console.error('Failure sending notification to', tokens[index], error);
// Cleanup the tokens who are not registered anymore.
if (error.code === 'messaging/invalid-registration-token' ||
error.code === 'messaging/registration-token-not-registered') {
// TODO: remove the token from your registry/database
}
}
});
});
The above code uses the Firebase Admin SDK for Node.js, but the same logic could also be applied to other platforms or when sending messages through the HTTPS endpoints.
As Frank mentioned in his answer you can remove them when sending messages and getting not registered error.
Here how I delete outdated registration tokens when registering a new one using C#.
First of all using Instance ID API I get token info as following:
public async Task<FCMTokenInfo> GetTokenInfoAsync(string token)
{
try
{
HttpClient client = new HttpClient();
client.BaseAddress = new Uri("https://iid.googleapis.com");
client.DefaultRequestHeaders.TryAddWithoutValidation("Authorization", String.Format("key={0}", "your-authorization-key"));
var uri = $"/iid/info/{token}";
var httpResponse = await client.GetAsync(uri);
var responseStr = await httpResponse.Content.ReadAsStringAsync();
if (httpResponse.StatusCode != HttpStatusCode.OK)
{
//log 400 bad request and do whatever you want
}
var result = JsonConvert.DeserializeObject<FCMTokenInfo>(responseStr);
return result;
}
catch (Exception ex)
{
//log the exception
throw;
}
}
FCMTokenInfo.cs
public class FCMTokenInfo
{
public string Application { get; set; }
public string Subtype { get; set; }
public string Scope { get; set; }
public string AuthorizedEntity { get; set; }
public string Platform { get; set; }
}
And then inside the service that saves registration tokens inside the database:
//this method gets called when a new token is sent by the javascript web app
public async Task AddTokenAsync(Guid accountId, string token)
{
try
{
//getting TokenInfo of the current token(or refreshed one for that app)
var fcmTokenInfo = await firebaseServices.GetTokenInfoAsync(token);
//adding the current token
dbContext.FcmRegisterationTokens.Add(new FcmRegisterationToken
{
Token = token,
AccountId = accountId,
AddingDate = DateTimeOffset.UtcNow,
Application = fcmTokenInfo.Application,
Subtype = fcmTokenInfo.Subtype,
AuthorizedEntity = fcmTokenInfo.AuthorizedEntity,
Scope = fcmTokenInfo.Scope,
Platform = fcmTokenInfo.Platform
});
var outdatedTokens = await dbContext.FcmRegisterationTokens
.Where(x => x.AccountId == accountId
&& x.Application == fcmTokenInfo.Application
&& x.Platform == fcmTokenInfo.Platform
).ToListAsync();
//remove them
dbContext.FcmRegisterationTokens.RemoveRange(outdatedTokens);
dbContext.SaveChanges();
}
catch (Exception)
{
throw;
}
}
After searching the docs I could not find any info on how to send device to device messages using FCM without the use of an external server.
For example, if I was creating a chat application I would need to send push notifications to users about unread messages since they won't be online all the time and I can't have a persistent service in the background that would always be connected to the real time database because that would be too resource heavy.
So how would I send a push notification to a user "A" when a certain user "B" sends him/her a chat message? Do I need an external server for this or can it be done with just Firebase servers?
UPDATE: It is now possible to use firebase cloud functions as the server for handling push notifications. Check out their documentation here
============
According to the docs you must implement a server for handling push notifications in device to device communication.
Before you can write client apps that use Firebase Cloud Messaging, you must have an app server that meets the following criteria:
...
You'll need to decide which FCM connection server protocol(s) you want to use to enable your app server to interact with FCM connection servers. Note that if you want to use upstream messaging from your client applications, you must use XMPP. For a more detailed discussion of this, see Choosing an FCM Connection Server Protocol.
If you only need to send basic notifications to your users from the server. You can use their serverless solution, Firebase Notifications.
See a comparison here between FCM and Firebase Notifications:
https://firebase.google.com/support/faq/#messaging-difference
Making a HTTP POST request with the link https://fcm.googleapis.com/fcm/send with required header and data helped me. In the below code snippet
Constants.LEGACY_SERVER_KEY is a local class variable, you can find this at your Firebase Project Settings->Cloud Messaging->Legacy Server key. You need to pass device registration token i.e. regToken in below code snippet referenced HERE.
At last you need okhttp library dependency in order to get this snippet work.
public static final MediaType JSON
= MediaType.parse("application/json; charset=utf-8");
private void sendNotification(final String regToken) {
new AsyncTask<Void,Void,Void>(){
#Override
protected Void doInBackground(Void... params) {
try {
OkHttpClient client = new OkHttpClient();
JSONObject json=new JSONObject();
JSONObject dataJson=new JSONObject();
dataJson.put("body","Hi this is sent from device to device");
dataJson.put("title","dummy title");
json.put("notification",dataJson);
json.put("to",regToken);
RequestBody body = RequestBody.create(JSON, json.toString());
Request request = new Request.Builder()
.header("Authorization","key="+Constants.LEGACY_SERVER_KEY)
.url("https://fcm.googleapis.com/fcm/send")
.post(body)
.build();
Response response = client.newCall(request).execute();
String finalResponse = response.body().string();
}catch (Exception e){
//Log.d(TAG,e+"");
}
return null;
}
}.execute();
}
further if you want to send message to a particular topic, replace regToken in json like this
json.put("to","/topics/foo-bar")
and don't forget to add INTERNET permission in your AndroidManifest.xml.
IMPORTANT : - Using above code means your server key resides in the client application. That is dangerous as someone can dig into your application and get the server key to send malicious notifications to your users.
You can do it using Volly Jsonobject request....
follow this Steps first:
1 copy legacy server key and store it as Legacy_SERVER_KEY
Legacy Server key
you can see in picture how to get
2 You need Volley dependency
compile 'com.mcxiaoke.volley:library:1.0.19'
Code for send Push:-
private void sendFCMPush() {
String Legacy_SERVER_KEY = YOUR_Legacy_SERVER_KEY;
String msg = "this is test message,.,,.,.";
String title = "my title";
String token = FCM_RECEIVER_TOKEN;
JSONObject obj = null;
JSONObject objData = null;
JSONObject dataobjData = null;
try {
obj = new JSONObject();
objData = new JSONObject();
objData.put("body", msg);
objData.put("title", title);
objData.put("sound", "default");
objData.put("icon", "icon_name"); // icon_name image must be there in drawable
objData.put("tag", token);
objData.put("priority", "high");
dataobjData = new JSONObject();
dataobjData.put("text", msg);
dataobjData.put("title", title);
obj.put("to", token);
//obj.put("priority", "high");
obj.put("notification", objData);
obj.put("data", dataobjData);
Log.e("!_#rj#_##_PASS:>", obj.toString());
} catch (JSONException e) {
e.printStackTrace();
}
JsonObjectRequest jsObjRequest = new JsonObjectRequest(Request.Method.POST, Constants.FCM_PUSH_URL, obj,
new Response.Listener<JSONObject>() {
#Override
public void onResponse(JSONObject response) {
Log.e("!_##_SUCESS", response + "");
}
},
new Response.ErrorListener() {
#Override
public void onErrorResponse(VolleyError error) {
Log.e("!_##_Errors--", error + "");
}
}) {
#Override
public Map<String, String> getHeaders() throws AuthFailureError {
Map<String, String> params = new HashMap<String, String>();
params.put("Authorization", "key=" + Legacy_SERVER_KEY);
params.put("Content-Type", "application/json");
return params;
}
};
RequestQueue requestQueue = Volley.newRequestQueue(this);
int socketTimeout = 1000 * 60;// 60 seconds
RetryPolicy policy = new DefaultRetryPolicy(socketTimeout, DefaultRetryPolicy.DEFAULT_MAX_RETRIES, DefaultRetryPolicy.DEFAULT_BACKOFF_MULT);
jsObjRequest.setRetryPolicy(policy);
requestQueue.add(jsObjRequest);
}
Just Call sendFCMPush();
1) subscribe an identical topic name, for example:
ClientA.subcribe("to/topic_users_channel")
ClientB.subcribe("to/topic_users_channel")
2) send messages inside the application
GoogleFirebase : How-to send topic messages
Yes, it's possible to do it without any server. You can create a device group client side and then you exchange messages in the group. However there are limitations:
You have to use the same Google account on the devices
You can't send high priority messages
Reference: Firebase doc See the section "Managing device groups on Android client apps"
Google Cloud Functions make it now possible send push notifications from device-to-device without an app server.
I have made cloud function which is trigger when new message is added in database
It is node.js code
'use strict';
const functions = require('firebase-functions');
const admin = require('firebase-admin'); admin.initializeApp();
exports.sendNotification = functions.database.ref('/conversations/{chatLocation}/{messageLocation}')
.onCreate((snapshot, context) => {
// Grab the current value of what was written to the Realtime Database.
const original = snapshot.val();
const toIDUser = original.toID;
const isGroupChat = original.isGroupChat;
if (isGroupChat) {
const tokenss = admin.database().ref(`/users/${toIDUser}/tokens`).once('value').then(function(snapshot) {
// Handle Promise
const tokenOfGroup = snapshot.val()
// get tokens from the database at particular location get values
const valuess = Object.keys(tokenOfGroup).map(k => tokenOfGroup[k]);
//console.log(' ____________ddd((999999ddd_________________ ' + valuess );
const payload = {
notification: {
title: original.senderName + " :- ",
body: original.content
}
};
return admin.messaging().sendToDevice(valuess, payload);
}, function(error) {
console.error(error);
});
return ;
} else {
// get token from the database at particular location
const tokenss = admin.database().ref(`/users/${toIDUser}/credentials`).once('value').then(function(snapshot) {
// Handle Promise
// The Promise was "fulfilled" (it succeeded).
const credentials = snapshot.val()
// console.log('snapshot ......snapshot.val().name****^^^^^^^^^^^^kensPromise****** :- ', credentials.name);
//console.log('snapshot.....****snapshot.val().token****^^^^^^^^^^^^kensPromise****** :- ', credentials.token);
const deviceToken = credentials.token;
const payload = {
notification: {
title: original.senderName + " :- ",
body: original.content
}
};
return admin.messaging().sendToDevice(deviceToken, payload);
}, function(error) {
console.error(error);
});
}
return ;
});
Google Cloud Functions make it now possible send push notifications from device-to-device without an app server.
From the relevant page on Google Cloud Functions:
Developers can use Cloud Functions to keep users engaged and up to
date with relevant information about an app. Consider, for example, an
app that allows users to follow one another's activities in the app.
In such an app, a function triggered by Realtime Database writes to
store new followers could create Firebase Cloud Messaging (FCM)
notifications to let the appropriate users know that they have gained
new followers.
Example:
The function triggers on writes to the Realtime Database path where followers are stored.
The function composes a message to send via FCM.
FCM sends the notification message to the user's device.
Here is a demo project for sending device-to-device push notifications with Firebase and Google Cloud Functions.
You can use firebase realtime database to do so. You can create data structure for storing chats and add observers for the conversation threads for both users. It still does device - server - device architecture, but in this case there is no additional server on the developers' part. This uses the firebase servers. You can check out a tutorial here (ignore the UI part, although, that is also a good starting point for chat UI frameworks).
Firebase Realtime Chat
If you have fcm(gcm) token of the device to whom you want to send notification. It's just a post request to send the notification.
https://github.com/prashanthd/google-services/blob/master/android/gcm/gcmsender/src/main/java/gcm/play/android/samples/com/gcmsender/GcmSender.java
In my case I use retrofit with this class Message:
public class Message {
private String to;
private String collapseKey;
private Notification notification;
private Data data;
public Message(String to, String collapseKey, Notification notification, Data data) {
this.to = to;
this.collapseKey = collapseKey;
this.notification = notification;
this.data = data;
}
}
Data
public class Data {
private String body;
private String title;
private String key1;
private String key2;
public Data(String body, String title, String key1, String key2) {
this.body = body;
this.title = title;
this.key1 = key1;
this.key2 = key2;
}
}
Notification
public class Notification {
private String body;
private String title;
public Notification(String body, String title) {
this.body = body;
this.title = title;
}
}
this the call
private void sentToNotification() {
String to = "YOUR_TOKEN";
String collapseKey = "";
Notification notification = new Notification("Hello bro", "title23");
Data data = new Data("Hello2", "title2", "key1", "key2");
Message notificationTask = new Message(to, collapseKey, notification, data);
Retrofit retrofit = new Retrofit.Builder()
.baseUrl("https://fcm.googleapis.com/")//url of FCM message server
.addConverterFactory(GsonConverterFactory.create())//use for convert JSON file into object
.build();
ServiceAPI api = new retrofit.create(ServiceAPI.class);
Call<Message> call = api .sendMessage("key=YOUR_KEY", notificationTask);
call.enqueue(new Callback<Message>() {
#Override
public void onResponse(Call<Message> call, retrofit2.Response<Message> response) {
Log.d("TAG", response.body().toString());
}
#Override
public void onFailure(Call<Message> call, Throwable t) {
Log.e("TAG", t.getMessage());
}
});
}
our ServiceAPi
public interface ServiceAPI {
#POST("/fcm/send")
Call<Message> sendMessage(#Header("Authorization") String token, #Body Message message);
}
You can use Retrofit. Subscribe devices to topic news. Send notification from one device to other.
public void onClick(View view) {
HttpLoggingInterceptor logging = new HttpLoggingInterceptor();
logging.setLevel(HttpLoggingInterceptor.Level.BODY);
OkHttpClient.Builder httpClient = new OkHttpClient.Builder();
httpClient.addInterceptor(new Interceptor() {
#Override
public okhttp3.Response intercept(Chain chain) throws IOException {
Request original = chain.request();
// Request customization: add request headers
Request.Builder requestBuilder = original.newBuilder()
.header("Authorization", "key=legacy server key from FB console"); // <-- this is the important line
Request request = requestBuilder.build();
return chain.proceed(request);
}
});
httpClient.addInterceptor(logging);
OkHttpClient client = httpClient.build();
Retrofit retrofit = new Retrofit.Builder()
.baseUrl("https://fcm.googleapis.com")//url of FCM message server
.client(client)
.addConverterFactory(GsonConverterFactory.create())//use for convert JSON file into object
.build();
// prepare call in Retrofit 2.0
FirebaseAPI firebaseAPI = retrofit.create(FirebaseAPI.class);
//for messaging server
NotifyData notifydata = new NotifyData("Notification title","Notification body");
Call<Message> call2 = firebaseAPI.sendMessage(new Message("topic or deviceID", notifydata));
call2.enqueue(new Callback<Message>() {
#Override
public void onResponse(Call<Message> call, Response<Message> response) {
Log.d("Response ", "onResponse");
t1.setText("Notification sent");
}
#Override
public void onFailure(Call<Message> call, Throwable t) {
Log.d("Response ", "onFailure");
t1.setText("Notification failure");
}
});
}
POJOs
public class Message {
String to;
NotifyData notification;
public Message(String to, NotifyData notification) {
this.to = to;
this.notification = notification;
}
}
and
public class NotifyData {
String title;
String body;
public NotifyData(String title, String body ) {
this.title = title;
this.body = body;
}
}
and FirebaseAPI
public interface FirebaseAPI {
#POST("/fcm/send")
Call<Message> sendMessage(#Body Message message);
}
Here is walk around how to get notifications without second server apart from the Firebase one. So we use Firebase only, without additional server.
At the mobile app code, we create its own notifications function by Android libraries like here, not using Firebase libraries like here, without Firebase Cloud messaging.
Here is an example with Kotlin:
private fun notification() {
createNotificationChannel()
val intent = Intent(this, LoginActivity::class.java).apply {
flags = Intent.FLAG_ACTIVITY_NEW_TASK or Intent.FLAG_ACTIVITY_CLEAR_TASK
}
val pendingIntent: PendingIntent = PendingIntent.getActivity(this, 0, intent, 0)
val notificationBuilder = NotificationCompat.Builder(this, "yuh_channel_id")
.setSmallIcon(R.drawable.ic_send)
.setContentText("yuh")
.setContentText("yuh")
.setAutoCancel(true)
.setPriority(NotificationCompat.PRIORITY_DEFAULT)
.setContentIntent(pendingIntent)
val notificationManager =
getSystemService(Context.NOTIFICATION_SERVICE) as NotificationManager
notificationManager.notify(0, notificationBuilder.build())
with(NotificationManagerCompat.from(this)) {
// notificationId is a unique int for each notification that you must define
notify(0, notificationBuilder.build())
}
}
private fun createNotificationChannel() {
// Create the NotificationChannel, but only on API 26+ because
// the NotificationChannel class is new and not in the support library
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
val name = "yuh_channel"
val descriptionText = "yuh_description"
val importance = NotificationManager.IMPORTANCE_DEFAULT
val CHANNEL_ID = "yuh_channel_id"
val channel = NotificationChannel(CHANNEL_ID, name, importance).apply {
description = descriptionText
}
// Register the channel with the system
val notificationManager: NotificationManager =
getSystemService(Context.NOTIFICATION_SERVICE) as NotificationManager
notificationManager.createNotificationChannel(channel)
}
In the Firebase database, create collection "pending notifications". Documents should contain user name (to send notification to) and source name (where should user go upon tapping the notification).
In the app code, implement option for adding new records to the Pending Notifications collection. E. g. if user A sends message to user B, then the document with the id of user B (who will be notified) is created in the collection.
In the app code, set up background (when the app is not visible to the user) service. Like here. In the background service, set up a listener for changes in the "Notifications Pending" collection. When the new record with the user id comes to the collection, call the notification function created in the paragrath 1 supra and delete the consequent record from the collection.
So I had an idea here. See: If the FCM, as well as the GCM, has a endpoit to http request where we can send a post json with our message data, including the token (s) of devices that we want this message to be delivered.
So why not send a post to Firebase server with this notification to be delivered to user B? you understand ?
So, you send the message and chat with a call post to ensure delivery of the notification if the user is with your app in the background. I am also in need of it soon, I will test later. What do you say about?
Simplest way :
void sendFCMPush(String msg,String token) {
HttpLoggingInterceptor logging = new HttpLoggingInterceptor();
logging.setLevel(HttpLoggingInterceptor.Level.BODY);
OkHttpClient.Builder httpClient = new OkHttpClient.Builder();
httpClient.addInterceptor(new Interceptor() {
#Override
public okhttp3.Response intercept(Chain chain) throws IOException {
Request original = chain.request();
// Request customization: add request headers
Request.Builder requestBuilder = original.newBuilder()
.header("Authorization", "key="+Const.FIREBASE_LEGACY_SERVER_KEY); // <-- this is the important line
Request request = requestBuilder.build();
return chain.proceed(request);
}
});
httpClient.addInterceptor(logging);
OkHttpClient client = httpClient.build();
Retrofit retrofit = new Retrofit.Builder()
.baseUrl("https://fcm.googleapis.com/")//url of FCM message server
.client(client)
.addConverterFactory(GsonConverterFactory.create())//use for convert JSON file into object
.build();
// prepare call in Retrofit 2.0
FirebaseAPI firebaseAPI = retrofit.create(FirebaseAPI.class);
//for messaging server
NotifyData notifydata = new NotifyData("Chatting", msg);
Call<Message> call2 = firebaseAPI.sendMessage(new Message(token, notifydata));
call2.enqueue(new Callback<Message>() {
#Override
public void onResponse(Call<Message> call, retrofit2.Response<Message> response) {
Log.e("## SUCCES #E$#", response.body().toString());
}
#Override
public void onFailure(Call<Message> call, Throwable t) {
Log.e("E$ FAILURE E$#", t.getMessage());
}
});
}
Create Class to make Object:
public class Message {
String to;
NotifyData data;
public Message(String to, NotifyData data) {
this.to = to;
this.data = data;
}
}
Create Class to make Object:
public class Notification {
String title;
String message;
enter code here`enter code here`
public Notification(String title, String message) {
this.title = title;
this.message = message;
}
}
After searching the docs I could not find any info on how to send device to device messages using FCM without the use of an external server.
For example, if I was creating a chat application I would need to send push notifications to users about unread messages since they won't be online all the time and I can't have a persistent service in the background that would always be connected to the real time database because that would be too resource heavy.
So how would I send a push notification to a user "A" when a certain user "B" sends him/her a chat message? Do I need an external server for this or can it be done with just Firebase servers?
UPDATE: It is now possible to use firebase cloud functions as the server for handling push notifications. Check out their documentation here
============
According to the docs you must implement a server for handling push notifications in device to device communication.
Before you can write client apps that use Firebase Cloud Messaging, you must have an app server that meets the following criteria:
...
You'll need to decide which FCM connection server protocol(s) you want to use to enable your app server to interact with FCM connection servers. Note that if you want to use upstream messaging from your client applications, you must use XMPP. For a more detailed discussion of this, see Choosing an FCM Connection Server Protocol.
If you only need to send basic notifications to your users from the server. You can use their serverless solution, Firebase Notifications.
See a comparison here between FCM and Firebase Notifications:
https://firebase.google.com/support/faq/#messaging-difference
Making a HTTP POST request with the link https://fcm.googleapis.com/fcm/send with required header and data helped me. In the below code snippet
Constants.LEGACY_SERVER_KEY is a local class variable, you can find this at your Firebase Project Settings->Cloud Messaging->Legacy Server key. You need to pass device registration token i.e. regToken in below code snippet referenced HERE.
At last you need okhttp library dependency in order to get this snippet work.
public static final MediaType JSON
= MediaType.parse("application/json; charset=utf-8");
private void sendNotification(final String regToken) {
new AsyncTask<Void,Void,Void>(){
#Override
protected Void doInBackground(Void... params) {
try {
OkHttpClient client = new OkHttpClient();
JSONObject json=new JSONObject();
JSONObject dataJson=new JSONObject();
dataJson.put("body","Hi this is sent from device to device");
dataJson.put("title","dummy title");
json.put("notification",dataJson);
json.put("to",regToken);
RequestBody body = RequestBody.create(JSON, json.toString());
Request request = new Request.Builder()
.header("Authorization","key="+Constants.LEGACY_SERVER_KEY)
.url("https://fcm.googleapis.com/fcm/send")
.post(body)
.build();
Response response = client.newCall(request).execute();
String finalResponse = response.body().string();
}catch (Exception e){
//Log.d(TAG,e+"");
}
return null;
}
}.execute();
}
further if you want to send message to a particular topic, replace regToken in json like this
json.put("to","/topics/foo-bar")
and don't forget to add INTERNET permission in your AndroidManifest.xml.
IMPORTANT : - Using above code means your server key resides in the client application. That is dangerous as someone can dig into your application and get the server key to send malicious notifications to your users.
You can do it using Volly Jsonobject request....
follow this Steps first:
1 copy legacy server key and store it as Legacy_SERVER_KEY
Legacy Server key
you can see in picture how to get
2 You need Volley dependency
compile 'com.mcxiaoke.volley:library:1.0.19'
Code for send Push:-
private void sendFCMPush() {
String Legacy_SERVER_KEY = YOUR_Legacy_SERVER_KEY;
String msg = "this is test message,.,,.,.";
String title = "my title";
String token = FCM_RECEIVER_TOKEN;
JSONObject obj = null;
JSONObject objData = null;
JSONObject dataobjData = null;
try {
obj = new JSONObject();
objData = new JSONObject();
objData.put("body", msg);
objData.put("title", title);
objData.put("sound", "default");
objData.put("icon", "icon_name"); // icon_name image must be there in drawable
objData.put("tag", token);
objData.put("priority", "high");
dataobjData = new JSONObject();
dataobjData.put("text", msg);
dataobjData.put("title", title);
obj.put("to", token);
//obj.put("priority", "high");
obj.put("notification", objData);
obj.put("data", dataobjData);
Log.e("!_#rj#_##_PASS:>", obj.toString());
} catch (JSONException e) {
e.printStackTrace();
}
JsonObjectRequest jsObjRequest = new JsonObjectRequest(Request.Method.POST, Constants.FCM_PUSH_URL, obj,
new Response.Listener<JSONObject>() {
#Override
public void onResponse(JSONObject response) {
Log.e("!_##_SUCESS", response + "");
}
},
new Response.ErrorListener() {
#Override
public void onErrorResponse(VolleyError error) {
Log.e("!_##_Errors--", error + "");
}
}) {
#Override
public Map<String, String> getHeaders() throws AuthFailureError {
Map<String, String> params = new HashMap<String, String>();
params.put("Authorization", "key=" + Legacy_SERVER_KEY);
params.put("Content-Type", "application/json");
return params;
}
};
RequestQueue requestQueue = Volley.newRequestQueue(this);
int socketTimeout = 1000 * 60;// 60 seconds
RetryPolicy policy = new DefaultRetryPolicy(socketTimeout, DefaultRetryPolicy.DEFAULT_MAX_RETRIES, DefaultRetryPolicy.DEFAULT_BACKOFF_MULT);
jsObjRequest.setRetryPolicy(policy);
requestQueue.add(jsObjRequest);
}
Just Call sendFCMPush();
1) subscribe an identical topic name, for example:
ClientA.subcribe("to/topic_users_channel")
ClientB.subcribe("to/topic_users_channel")
2) send messages inside the application
GoogleFirebase : How-to send topic messages
Yes, it's possible to do it without any server. You can create a device group client side and then you exchange messages in the group. However there are limitations:
You have to use the same Google account on the devices
You can't send high priority messages
Reference: Firebase doc See the section "Managing device groups on Android client apps"
Google Cloud Functions make it now possible send push notifications from device-to-device without an app server.
I have made cloud function which is trigger when new message is added in database
It is node.js code
'use strict';
const functions = require('firebase-functions');
const admin = require('firebase-admin'); admin.initializeApp();
exports.sendNotification = functions.database.ref('/conversations/{chatLocation}/{messageLocation}')
.onCreate((snapshot, context) => {
// Grab the current value of what was written to the Realtime Database.
const original = snapshot.val();
const toIDUser = original.toID;
const isGroupChat = original.isGroupChat;
if (isGroupChat) {
const tokenss = admin.database().ref(`/users/${toIDUser}/tokens`).once('value').then(function(snapshot) {
// Handle Promise
const tokenOfGroup = snapshot.val()
// get tokens from the database at particular location get values
const valuess = Object.keys(tokenOfGroup).map(k => tokenOfGroup[k]);
//console.log(' ____________ddd((999999ddd_________________ ' + valuess );
const payload = {
notification: {
title: original.senderName + " :- ",
body: original.content
}
};
return admin.messaging().sendToDevice(valuess, payload);
}, function(error) {
console.error(error);
});
return ;
} else {
// get token from the database at particular location
const tokenss = admin.database().ref(`/users/${toIDUser}/credentials`).once('value').then(function(snapshot) {
// Handle Promise
// The Promise was "fulfilled" (it succeeded).
const credentials = snapshot.val()
// console.log('snapshot ......snapshot.val().name****^^^^^^^^^^^^kensPromise****** :- ', credentials.name);
//console.log('snapshot.....****snapshot.val().token****^^^^^^^^^^^^kensPromise****** :- ', credentials.token);
const deviceToken = credentials.token;
const payload = {
notification: {
title: original.senderName + " :- ",
body: original.content
}
};
return admin.messaging().sendToDevice(deviceToken, payload);
}, function(error) {
console.error(error);
});
}
return ;
});
Google Cloud Functions make it now possible send push notifications from device-to-device without an app server.
From the relevant page on Google Cloud Functions:
Developers can use Cloud Functions to keep users engaged and up to
date with relevant information about an app. Consider, for example, an
app that allows users to follow one another's activities in the app.
In such an app, a function triggered by Realtime Database writes to
store new followers could create Firebase Cloud Messaging (FCM)
notifications to let the appropriate users know that they have gained
new followers.
Example:
The function triggers on writes to the Realtime Database path where followers are stored.
The function composes a message to send via FCM.
FCM sends the notification message to the user's device.
Here is a demo project for sending device-to-device push notifications with Firebase and Google Cloud Functions.
You can use firebase realtime database to do so. You can create data structure for storing chats and add observers for the conversation threads for both users. It still does device - server - device architecture, but in this case there is no additional server on the developers' part. This uses the firebase servers. You can check out a tutorial here (ignore the UI part, although, that is also a good starting point for chat UI frameworks).
Firebase Realtime Chat
If you have fcm(gcm) token of the device to whom you want to send notification. It's just a post request to send the notification.
https://github.com/prashanthd/google-services/blob/master/android/gcm/gcmsender/src/main/java/gcm/play/android/samples/com/gcmsender/GcmSender.java
In my case I use retrofit with this class Message:
public class Message {
private String to;
private String collapseKey;
private Notification notification;
private Data data;
public Message(String to, String collapseKey, Notification notification, Data data) {
this.to = to;
this.collapseKey = collapseKey;
this.notification = notification;
this.data = data;
}
}
Data
public class Data {
private String body;
private String title;
private String key1;
private String key2;
public Data(String body, String title, String key1, String key2) {
this.body = body;
this.title = title;
this.key1 = key1;
this.key2 = key2;
}
}
Notification
public class Notification {
private String body;
private String title;
public Notification(String body, String title) {
this.body = body;
this.title = title;
}
}
this the call
private void sentToNotification() {
String to = "YOUR_TOKEN";
String collapseKey = "";
Notification notification = new Notification("Hello bro", "title23");
Data data = new Data("Hello2", "title2", "key1", "key2");
Message notificationTask = new Message(to, collapseKey, notification, data);
Retrofit retrofit = new Retrofit.Builder()
.baseUrl("https://fcm.googleapis.com/")//url of FCM message server
.addConverterFactory(GsonConverterFactory.create())//use for convert JSON file into object
.build();
ServiceAPI api = new retrofit.create(ServiceAPI.class);
Call<Message> call = api .sendMessage("key=YOUR_KEY", notificationTask);
call.enqueue(new Callback<Message>() {
#Override
public void onResponse(Call<Message> call, retrofit2.Response<Message> response) {
Log.d("TAG", response.body().toString());
}
#Override
public void onFailure(Call<Message> call, Throwable t) {
Log.e("TAG", t.getMessage());
}
});
}
our ServiceAPi
public interface ServiceAPI {
#POST("/fcm/send")
Call<Message> sendMessage(#Header("Authorization") String token, #Body Message message);
}
You can use Retrofit. Subscribe devices to topic news. Send notification from one device to other.
public void onClick(View view) {
HttpLoggingInterceptor logging = new HttpLoggingInterceptor();
logging.setLevel(HttpLoggingInterceptor.Level.BODY);
OkHttpClient.Builder httpClient = new OkHttpClient.Builder();
httpClient.addInterceptor(new Interceptor() {
#Override
public okhttp3.Response intercept(Chain chain) throws IOException {
Request original = chain.request();
// Request customization: add request headers
Request.Builder requestBuilder = original.newBuilder()
.header("Authorization", "key=legacy server key from FB console"); // <-- this is the important line
Request request = requestBuilder.build();
return chain.proceed(request);
}
});
httpClient.addInterceptor(logging);
OkHttpClient client = httpClient.build();
Retrofit retrofit = new Retrofit.Builder()
.baseUrl("https://fcm.googleapis.com")//url of FCM message server
.client(client)
.addConverterFactory(GsonConverterFactory.create())//use for convert JSON file into object
.build();
// prepare call in Retrofit 2.0
FirebaseAPI firebaseAPI = retrofit.create(FirebaseAPI.class);
//for messaging server
NotifyData notifydata = new NotifyData("Notification title","Notification body");
Call<Message> call2 = firebaseAPI.sendMessage(new Message("topic or deviceID", notifydata));
call2.enqueue(new Callback<Message>() {
#Override
public void onResponse(Call<Message> call, Response<Message> response) {
Log.d("Response ", "onResponse");
t1.setText("Notification sent");
}
#Override
public void onFailure(Call<Message> call, Throwable t) {
Log.d("Response ", "onFailure");
t1.setText("Notification failure");
}
});
}
POJOs
public class Message {
String to;
NotifyData notification;
public Message(String to, NotifyData notification) {
this.to = to;
this.notification = notification;
}
}
and
public class NotifyData {
String title;
String body;
public NotifyData(String title, String body ) {
this.title = title;
this.body = body;
}
}
and FirebaseAPI
public interface FirebaseAPI {
#POST("/fcm/send")
Call<Message> sendMessage(#Body Message message);
}
Here is walk around how to get notifications without second server apart from the Firebase one. So we use Firebase only, without additional server.
At the mobile app code, we create its own notifications function by Android libraries like here, not using Firebase libraries like here, without Firebase Cloud messaging.
Here is an example with Kotlin:
private fun notification() {
createNotificationChannel()
val intent = Intent(this, LoginActivity::class.java).apply {
flags = Intent.FLAG_ACTIVITY_NEW_TASK or Intent.FLAG_ACTIVITY_CLEAR_TASK
}
val pendingIntent: PendingIntent = PendingIntent.getActivity(this, 0, intent, 0)
val notificationBuilder = NotificationCompat.Builder(this, "yuh_channel_id")
.setSmallIcon(R.drawable.ic_send)
.setContentText("yuh")
.setContentText("yuh")
.setAutoCancel(true)
.setPriority(NotificationCompat.PRIORITY_DEFAULT)
.setContentIntent(pendingIntent)
val notificationManager =
getSystemService(Context.NOTIFICATION_SERVICE) as NotificationManager
notificationManager.notify(0, notificationBuilder.build())
with(NotificationManagerCompat.from(this)) {
// notificationId is a unique int for each notification that you must define
notify(0, notificationBuilder.build())
}
}
private fun createNotificationChannel() {
// Create the NotificationChannel, but only on API 26+ because
// the NotificationChannel class is new and not in the support library
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
val name = "yuh_channel"
val descriptionText = "yuh_description"
val importance = NotificationManager.IMPORTANCE_DEFAULT
val CHANNEL_ID = "yuh_channel_id"
val channel = NotificationChannel(CHANNEL_ID, name, importance).apply {
description = descriptionText
}
// Register the channel with the system
val notificationManager: NotificationManager =
getSystemService(Context.NOTIFICATION_SERVICE) as NotificationManager
notificationManager.createNotificationChannel(channel)
}
In the Firebase database, create collection "pending notifications". Documents should contain user name (to send notification to) and source name (where should user go upon tapping the notification).
In the app code, implement option for adding new records to the Pending Notifications collection. E. g. if user A sends message to user B, then the document with the id of user B (who will be notified) is created in the collection.
In the app code, set up background (when the app is not visible to the user) service. Like here. In the background service, set up a listener for changes in the "Notifications Pending" collection. When the new record with the user id comes to the collection, call the notification function created in the paragrath 1 supra and delete the consequent record from the collection.
So I had an idea here. See: If the FCM, as well as the GCM, has a endpoit to http request where we can send a post json with our message data, including the token (s) of devices that we want this message to be delivered.
So why not send a post to Firebase server with this notification to be delivered to user B? you understand ?
So, you send the message and chat with a call post to ensure delivery of the notification if the user is with your app in the background. I am also in need of it soon, I will test later. What do you say about?
Simplest way :
void sendFCMPush(String msg,String token) {
HttpLoggingInterceptor logging = new HttpLoggingInterceptor();
logging.setLevel(HttpLoggingInterceptor.Level.BODY);
OkHttpClient.Builder httpClient = new OkHttpClient.Builder();
httpClient.addInterceptor(new Interceptor() {
#Override
public okhttp3.Response intercept(Chain chain) throws IOException {
Request original = chain.request();
// Request customization: add request headers
Request.Builder requestBuilder = original.newBuilder()
.header("Authorization", "key="+Const.FIREBASE_LEGACY_SERVER_KEY); // <-- this is the important line
Request request = requestBuilder.build();
return chain.proceed(request);
}
});
httpClient.addInterceptor(logging);
OkHttpClient client = httpClient.build();
Retrofit retrofit = new Retrofit.Builder()
.baseUrl("https://fcm.googleapis.com/")//url of FCM message server
.client(client)
.addConverterFactory(GsonConverterFactory.create())//use for convert JSON file into object
.build();
// prepare call in Retrofit 2.0
FirebaseAPI firebaseAPI = retrofit.create(FirebaseAPI.class);
//for messaging server
NotifyData notifydata = new NotifyData("Chatting", msg);
Call<Message> call2 = firebaseAPI.sendMessage(new Message(token, notifydata));
call2.enqueue(new Callback<Message>() {
#Override
public void onResponse(Call<Message> call, retrofit2.Response<Message> response) {
Log.e("## SUCCES #E$#", response.body().toString());
}
#Override
public void onFailure(Call<Message> call, Throwable t) {
Log.e("E$ FAILURE E$#", t.getMessage());
}
});
}
Create Class to make Object:
public class Message {
String to;
NotifyData data;
public Message(String to, NotifyData data) {
this.to = to;
this.data = data;
}
}
Create Class to make Object:
public class Notification {
String title;
String message;
enter code here`enter code here`
public Notification(String title, String message) {
this.title = title;
this.message = message;
}
}
In the latest version of Asp.Net SignalR, was added a new way of sending a message to a specific user, using the interface "IUserIdProvider".
public interface IUserIdProvider
{
string GetUserId(IRequest request);
}
public class MyHub : Hub
{
public void Send(string userId, string message)
{
Clients.User(userId).send(message);
}
}
My question is: How do I know to whom I am sending my message? The explanation of this new method is very superficial. And the draft Statement of SignalR 2.0.0 with this bug and does not compile. Has anyone implemented this feature?
More Info : http://www.asp.net/signalr/overview/signalr-20/hubs-api/mapping-users-to-connections#IUserIdProvider
Hugs.
SignalR provides ConnectionId for each connection. To find which connection belongs to whom (the user), we need to create a mapping between the connection and the user. This depends on how you identify a user in your application.
In SignalR 2.0, this is done by using the inbuilt IPrincipal.Identity.Name, which is the logged in user identifier as set during the ASP.NET authentication.
However, you may need to map the connection with the user using a different identifier instead of using the Identity.Name. For this purpose this new provider can be used with your custom implementation for mapping user with the connection.
Example of Mapping SignalR Users to Connections using IUserIdProvider
Lets assume our application uses a userId to identify each user. Now, we need to send message to a specific user. We have userId and message, but SignalR must also know the mapping between our userId and the connection.
To achieve this, first we need to create a new class which implements IUserIdProvider:
public class CustomUserIdProvider : IUserIdProvider
{
public string GetUserId(IRequest request)
{
// your logic to fetch a user identifier goes here.
// for example:
var userId = MyCustomUserClass.FindUserId(request.User.Identity.Name);
return userId.ToString();
}
}
The second step is to tell SignalR to use our CustomUserIdProvider instead of the default implementation. This can be done in the Startup.cs while initializing the hub configuration:
public class Startup
{
public void Configuration(IAppBuilder app)
{
var idProvider = new CustomUserIdProvider();
GlobalHost.DependencyResolver.Register(typeof(IUserIdProvider), () => idProvider);
// Any connection or hub wire up and configuration should go here
app.MapSignalR();
}
}
Now, you can send message to a specific user using his userId as mentioned in the documentation, like:
public class MyHub : Hub
{
public void Send(string userId, string message)
{
Clients.User(userId).send(message);
}
}
Here's a start.. Open to suggestions/improvements.
Server
public class ChatHub : Hub
{
public void SendChatMessage(string who, string message)
{
string name = Context.User.Identity.Name;
Clients.Group(name).addChatMessage(name, message);
Clients.Group("2#2.com").addChatMessage(name, message);
}
public override Task OnConnected()
{
string name = Context.User.Identity.Name;
Groups.Add(Context.ConnectionId, name);
return base.OnConnected();
}
}
JavaScript
(Notice how addChatMessage and sendChatMessage are also methods in the server code above)
$(function () {
// Declare a proxy to reference the hub.
var chat = $.connection.chatHub;
// Create a function that the hub can call to broadcast messages.
chat.client.addChatMessage = function (who, message) {
// Html encode display name and message.
var encodedName = $('<div />').text(who).html();
var encodedMsg = $('<div />').text(message).html();
// Add the message to the page.
$('#chat').append('<li><strong>' + encodedName
+ '</strong>: ' + encodedMsg + '</li>');
};
// Start the connection.
$.connection.hub.start().done(function () {
$('#sendmessage').click(function () {
// Call the Send method on the hub.
chat.server.sendChatMessage($('#displayname').val(), $('#message').val());
// Clear text box and reset focus for next comment.
$('#message').val('').focus();
});
});
});
Testing
This is how use SignarR in order to target a specific user (without using any provider):
private static ConcurrentDictionary<string, string> clients = new ConcurrentDictionary<string, string>();
public string Login(string username)
{
clients.TryAdd(Context.ConnectionId, username);
return username;
}
// The variable 'contextIdClient' is equal to Context.ConnectionId of the user,
// once logged in. You have to store that 'id' inside a dictionaty for example.
Clients.Client(contextIdClient).send("Hello!");
Look at SignalR Tests for the feature.
Test "SendToUser" takes automatically the user identity passed by using a regular owin authentication library.
The scenario is you have a user who has connected from multiple devices/browsers and you want to push a message to all his active connections.
Old thread, but just came across this in a sample:
services.AddSignalR()
.AddAzureSignalR(options =>
{
options.ClaimsProvider = context => new[]
{
new Claim(ClaimTypes.NameIdentifier, context.Request.Query["username"])
};
});
For anyone trying to do this in asp.net core. You can use claims.
public class CustomEmailProvider : IUserIdProvider
{
public virtual string GetUserId(HubConnectionContext connection)
{
return connection.User?.FindFirst(ClaimTypes.Email)?.Value;
}
}
Any identifier can be used, but it must be unique. If you use a name identifier for example, it means if there are multiple users with the same name as the recipient, the message would be delivered to them as well. I have chosen email because it is unique to every user.
Then register the service in the startup class.
services.AddSingleton<IUserIdProvider, CustomEmailProvider>();
Next. Add the claims during user registration.
var result = await _userManager.CreateAsync(user, Model.Password);
if (result.Succeeded)
{
await _userManager.AddClaimAsync(user, new Claim(ClaimTypes.Email, Model.Email));
}
To send message to the specific user.
public class ChatHub : Hub
{
public async Task SendMessage(string receiver, string message)
{
await Clients.User(receiver).SendAsync("ReceiveMessage", message);
}
}
Note: The message sender won't be notified the message is sent. If you want a notification on the sender's end. Change the SendMessage method to this.
public async Task SendMessage(string sender, string receiver, string message)
{
await Clients.Users(sender, receiver).SendAsync("ReceiveMessage", message);
}
These steps are only necessary if you need to change the default identifier. Otherwise, skip to the last step where you can simply send messages by passing userIds or connectionIds to SendMessage. For more