This project is an online chat server built using spring boot. The RESTful API is used to request a server and we also used Firebase Cloud Messaging (FCM) to notify clients of new changes like "Getting New Message", in this way, by registering each new message on the server by the FCM, a notification is sent to the rest of the clients informs them of the new changes. We used spring data jpa to access the database.
android client project :https://github.com/MarsDown/chat-client-android-restful