Stay organized with collections
Save and categorize content based on your preferences.
FCM relies on the following set of components that build, transport, and receive
messages:
Tooling to compose or build message requests. The Notifications composer
provides a GUI-based option for creating notification requests.
For full automation and support for all
message types,
you must build message requests in a trusted
server environment
that supports the Firebase Admin SDK or the FCM server protocol.
This environment could be Cloud Functions for Firebase, App Engine,
or your own app server.
The FCM backend, which (among other functions) accepts message requests,
performs fanout of messages via topics, and generates message metadata such
as the message ID.
A platform-level transport layer, which routes the message to the targeted
device, handles message delivery, and applies platform-specific
configuration where appropriate. This transport layer includes:
Android transport layer (ATL) for Android devices with Google Play services
Apple Push Notification service (APNs) for Apple devices
Web push protocol for web apps
The FCM SDK on the user’s device, where the notification is displayed or
the message is handled according to the app’s foreground/background state
and any relevant application logic.
Lifecycle flow
Register devices to receive messages from FCM. An instance of a client app registers to receive messages, obtaining a registration token that uniquely identifies the app instance.
Send and receive downstream messages.
Send a message. The app server sends messages to the client app:
The message is composed, either in the Notifications composer or a trusted environment, and a message request is sent to the FCM backend.
The FCM backend receives the message request, generates a message ID and other metadata, and sends it to the platform specific transport layer.
When the device is online, the message is sent via the platform-specific transport layer to the device.
On the device, the client app receives the message or notification.
[[["Easy to understand","easyToUnderstand","thumb-up"],["Solved my problem","solvedMyProblem","thumb-up"],["Other","otherUp","thumb-up"]],[["Missing the information I need","missingTheInformationINeed","thumb-down"],["Too complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-28 UTC."],[],[],null,["\u003cbr /\u003e\n\nFCM relies on the following set of components that build, transport, and receive\nmessages:\n\n1. Tooling to compose or build message requests. The Notifications composer\n provides a GUI-based option for creating notification requests.\n For full automation and support for all\n [message types](https://firebase.google.com/docs/cloud-messaging/concept-options#notifications_and_data_messages),\n you must build message requests in a trusted\n [server environment](https://firebase.google.com/docs/cloud-messaging/server)\n that supports the Firebase Admin SDK or the FCM server protocol.\n This environment could be Cloud Functions for Firebase, App Engine,\n or your own app server.\n\n2. The FCM backend, which (among other functions) accepts message requests,\n performs fanout of messages via topics, and generates message metadata such\n as the message ID.\n\n3. A platform-level transport layer, which routes the message to the targeted\n device, handles message delivery, and applies platform-specific\n configuration where appropriate. This transport layer includes:\n\n - Android transport layer (ATL) for Android devices with Google Play services\n - Apple Push Notification service (APNs) for Apple devices\n - Web push protocol for web apps\n\n | **Note:** Platform-level transport layers are outside the core FCM product. FCM messages routed to a platform-level transport layer may be subject to terms specific to that platform rather than FCM's terms of service. Android message routing via ATL falls under the [Google APIs terms of service](https://www.google.com/url?q=https://developers.google.com/terms/&sa=D&ust=1558536676246000&usg=AFQjCNFrlRMLv51d1S9NkWxD0IoYSqJ2Ng).\n4. The FCM SDK on the user's device, where the notification is displayed or\n the message is handled according to the app's foreground/background state\n and any relevant application logic.\n\nLifecycle flow\n\n- **Register devices to receive messages from FCM**. An instance of a client app registers to receive messages, obtaining a registration token that uniquely identifies the app instance.\n- **Send and receive downstream messages** .\n - Send a message. The app server sends messages to the client app:\n 1. The message is composed, either in the Notifications composer or a trusted environment, and a message request is sent to the FCM backend.\n 2. The FCM backend receives the message request, generates a message ID and other metadata, and sends it to the platform specific transport layer.\n 3. When the device is online, the message is sent via the platform-specific transport layer to the device.\n 4. On the device, the client app receives the message or notification."]]
