First of all, this post includes multiple questions that I have in my mind but I hope all are related to each other.
I can send notification messages using Notifications composer in the Firebase console and also send text messages using key/value pairs in Custom data. As far as I understand, it is named as "notification messages" unless key/value pairs are included (so this is data messages I guess).
My question is that I don't know how to deliver images with these key/value pairs and want to be sure the way I should go on searching for. Also I need to this working for all cases whether the app is in foreground or background. Do I need to use methods like HTTP Post/Request, Volley, Picasso? Can I use Firebase Storage as an image source to implement these methods?
I watched so many videos and read documents along with basic ones like About FCM messages and tried to understand them but confused a lot.
I think I found some useful links and topics like Firebase Expandable Notification Show image when app is in background and Android Tutorials : Firebase Push Notification Tutorial but these are only valid for push notification tab as far as I understand. Or should I use this? --> Firebase Cloud Messaging HTTP protocol
Also, what is the point of using fcm cloud messaging system if Maximum payload for both message types is 4KB
? Do we have to use external sources for the exceeding case?
I'm inexperienced on this field and also in Stack Overflow but trying to learn so forgive me if I made a conceptual mistake or broke the rules of "Asking Questions" on this platform.