B4A Library FirebaseNotifications - Push messages / Firebase Cloud Messaging (FCM)

This library requires B4A v6+.

Firebase Cloud Messaging service is a layer above Google Cloud Messaging service.
It makes it simple to add support for push messages. Although it is not clear in their documentation you don't need any additional server.

Sending messages is done with a simple HTTP request. It is also possible to send message from the Firebase console, though it is not very useful and is actually more complicated than using the REST api.

1. The first step is to follow the Firebase integration tutorial:
https://www.b4x.com/android/forum/threads/integrating-firebase-services.67692/

Make sure to add the Notifications snippet.

2. Add a Service named FirebaseMessaging to your app (must be this name):

Code:

Sub Process_Globals
   Private fm As FirebaseMessaging
End Sub

Sub Service_Create
   fm.Initialize("fm")
End Sub

Public Sub SubscribeToTopics
   fm.SubscribeToTopic("general") 'you can subscribe to more topics
End Sub

Sub Service_Start (StartingIntent As Intent)
   If StartingIntent.IsInitialized AND fm.HandleIntent(StartingIntent) Then Return
End Sub

Sub fm_MessageArrived (Message As RemoteMessage)
   Log("Message arrived")
   Log($"Message data: ${Message.GetData}"$)
   Dim n As Notification
   n.Initialize
   n.Icon = "icon"
   n.SetInfo(Message.GetData.Get("title"), Message.GetData.Get("body"), Main)
   n.Notify(1)
End Sub

Sub Service_Destroy

End Sub

fm_MessageArrived will be raised whenever a message is received. In this case we show a notification. You can do whatever you need.

We call SubscribeToTopics from the starter service to make sure that the app will be subscribed when it starts:

Code:

'Starter service
Sub Process_Globals

End Sub

Sub Service_Create
   CallSubDelayed(FirebaseMessaging, "SubscribeToTopics")
End Sub

Now we can send messages to a "topic" and all the subscribed devices will receive it.

This is done with this request:

Code:

Private Sub SendMessage(Topic As String, Title As String, Body As String)
   Dim Job As HttpJob
   Job.Initialize("fcm", Me)
   Dim m As Map = CreateMap("to": $"/topics/${Topic}"$)
   Dim data As Map = CreateMap("title": Title, "body": Body)
   m.Put("data", data)
   Dim jg As JSONGenerator
   jg.Initialize(m)
   Job.PostString("https://fcm.googleapis.com/fcm/send", jg.ToString)
   Job.GetRequest.SetContentType("application/json;charset=UTF-8")
   Job.GetRequest.SetHeader("Authorization", "key=" & API_KEY)
End Sub


Sub JobDone(job As HttpJob)
   Log(job)
   If job.Success Then
     Log(job.GetString)
   End If
   job.Release
End Sub

API_KEY is the server key from:



A simple non-ui B4J program is attached.

Note that messages sent from Firebase Console will not arrive in some cases. Use the B4J code to test it.

 

Probably yes. However it will take some time.

 

Try to set the content type in the sender code to:
"application/json;charset=UTF-8"

If it will not work then you can always get the string bytes, encode them as base64 string with StringUtils and send the encoded string.