为什么选择Firebase Cloud Messaging而不是Intent Service？

I am creating an android app which has a chat feature. I would like to create a notification if a new message arrives when the chat is not open. My messages are stored in a firebase database. I see two options for creating these notifications. One is to use the firebase function to trigger a firebase cloud message. The other is to use an Intent Service which runs an onChildAdded Event handler. The Intent Service seems much easier to me. Am I missing something? What would be a good reason to use Cloud Messaging over an Intent Service with the event handler running?I am creating an android app which has a chat f