Firebase Cloud Messaging (FCM) for Android and iOS

Gem Version Build Status

The FCM gem lets your ruby backend send notifications to Android and iOS devices via Firebase Cloud Messaging.

Installation

$ gem install fcm

or in your Gemfile just include it:

gem 'fcm'

Requirements

For Android you will need a device running 2.3 (or newer) that also have the Google Play Store app installed, or an emulator running Android 2.3 with Google APIs. iOS devices are also supported.

A version of supported Ruby, currently: ruby >= 2.4

Getting Started

To use this gem, you need to instantiate a client with your firebase credentials:

fcm = FCM.new(
  GOOGLE_APPLICATION_CREDENTIALS_PATH,
  FIREBASE_PROJECT_ID
)

About the GOOGLE_APPLICATION_CREDENTIALS_PATH

The GOOGLE_APPLICATION_CREDENTIALS_PATH is meant to contain your firebase credentials.

The easiest way to provide them is to pass here an absolute path to a file with your credentials:

fcm = FCM.new(
  '/path/to/credentials.json',
  FIREBASE_PROJECT_ID
)

As per their secret nature, you might not want to have them in your repository. In that case, another supported solution is to pass a StringIO that contains your credentials:

fcm = FCM.new(
  StringIO.new(ENV.fetch('FIREBASE_CREDENTIALS')),
  FIREBASE_PROJECT_ID
)

Usage

HTTP v1 API

To migrate to HTTP v1 see: https://firebase.google.com/docs/cloud-messaging/migrate-v1

fcm = FCM.new(
  GOOGLE_APPLICATION_CREDENTIALS_PATH,
  FIREBASE_PROJECT_ID
)
message = {
  'token': "000iddqd", # send to a specific device
  # 'topic': "yourTopic",
  # 'condition': "'TopicA' in topics && ('TopicB' in topics || 'TopicC' in topics)",
  'data': {
    payload: {
      data: {
        id: 1
      }
    }.to_json
  },
  'notification': {
    title: notification.title_th,
    body: notification.body_th,
  },
  'android': {},
  'apns': {
    payload: {
      aps: {
        sound: "default",
        category: "#{Time.zone.now.to_i}"
      }
    }
  },
  'fcm_options': {
    analytics_label: 'Label'
  }
}

fcm.send_v1(message) # or fcm.send_notification_v1(message)

Device Group Messaging

With device group messaging, you can send a single message to multiple instance of an app running on devices belonging to a group. Typically, "group" refers a set of different devices that belong to a single user. However, a group could also represent a set of devices where the app instance functions in a highly correlated manner. To use this feature, you will first need an initialised FCM class.

The maximum number of members allowed for a notification key is 20. https://firebase.google.com/docs/cloud-messaging/android/device-group#managing_device_groups

Generate a Notification Key for device group

Then you will need a notification key which you can create for a particular key_name which needs to be uniquely named per app in case you have multiple apps for the same project_id. This ensures that notifications only go to the intended target app. The create method will do this and return the token notification_key, that represents the device group, in the response:

project_id is the SENDER_ID in your cloud settings. https://firebase.google.com/docs/cloud-messaging/concept-options#senderid

params = { key_name: "appUser-Chris",
                project_id: "my_project_id",
                registration_ids: ["4", "8", "15", "16", "23", "42"] }
response = fcm.create(*params.values)

Send to Notification device group

To send messages to device groups, use the HTTP v1 API, Sending messages to a device group is very similar to sending messages to an individual device, using the same method to authorize send requests. Set the token field to the group notification key

message = {
  'token': "NOTIFICATION_KEY", # send to a device group
  # ...data
}

fcm.send_v1(message)

Add/Remove Registration Tokens

You can also add/remove registration Tokens to/from a particular notification_key of some project_id. For example:

params = { key_name: "appUser-Chris",
                project_id: "my_project_id",
                notification_key:"appUser-Chris-key",
                registration_ids:["7", "3"] }
response = fcm.add(*params.values)

params = { key_name: "appUser-Chris",
                project_id: "my_project_id",
                notification_key:"appUser-Chris-key",
                registration_ids:["8", "15"] }
response = fcm.remove(*params.values)

Send Messages to Topics

FCM topic messaging allows your app server to send a message to multiple devices that have opted in to a particular topic. Based on the publish/subscribe model, one app instance can be subscribed to no more than 2000 topics. Sending to a topic is very similar to sending to an individual device or to a user group, in the sense that you can use the fcm.send_v1 method where the topic matches the regular expression "/topics/[a-zA-Z0-9-_.~%]+":

message = {
  'topic': "yourTopic", # send to a device group
  # ...data
}

fcm.send_v1(message)

Or you can use the fcm.send_to_topic helper:

response = fcm.send_to_topic("yourTopic",
            notification: { body: "This is a FCM Topic Message!"} )

Send Messages to Topics with Conditions

FCM topic condition messaging to send a message to a combination of topics, specify a condition, which is a boolean expression that specifies the target topics.

message = {
  'condition': "'TopicA' in topics && ('TopicB' in topics || 'TopicC' in topics)", # send to topic condition
  # ...data
}

fcm.send_v1(message)

Or you can use the fcm.send_to_topic_condition helper:

response = fcm.send_to_topic_condition(
  "'TopicA' in topics && ('TopicB' in topics || 'TopicC' in topics)",
  notification: {
    body: "This is an FCM Topic Message sent to a condition!"
  }
)

Sending to Multiple Topics

To send to combinations of multiple topics, require that you set a condition key to a boolean condition that specifies the target topics. For example, to send messages to devices that subscribed to TopicA and either TopicB or TopicC:

'TopicA' in topics && ('TopicB' in topics || 'TopicC' in topics)

FCM first evaluates any conditions in parentheses, and then evaluates the expression from left to right. In the above expression, a user subscribed to any single topic does not receive the message. Likewise, a user who does not subscribe to TopicA does not receive the message. These combinations do receive it:

  • TopicA and TopicB
  • TopicA and TopicC

You can include up to five topics in your conditional expression, and parentheses are supported. Supported operators: &&, ||, !. Note the usage for !:

!('TopicA' in topics)

With this expression, any app instances that are not subscribed to TopicA, including app instances that are not subscribed to any topic, receive the message.

The send_to_topic_condition method within this library allows you to specicy a condition of multiple topics to which to send to the data payload.

response = fcm.send_to_topic_condition(
  "'TopicA' in topics && ('TopicB' in topics || 'TopicC' in topics)",
  notification: {
    body: "This is an FCM Topic Message sent to a condition!"
  }
)

Subscribe the client app to a topic

Given a registration token and a topic name, you can add the token to the topic using the Google Instance ID server API.

topic = "YourTopic"
registration_token= "12" # a client registration token
response = fcm.topic_subscription(topic, registration_token)
# or unsubscription
response = fcm.topic_unsubscription(topic, registration_token)

Or you can manage relationship maps for multiple app instances Google Instance ID server API. Manage relationship

topic = "YourTopic"
registration_tokens= ["4", "8", "15", "16", "23", "42"] # an array of one or more client registration tokens
response = fcm.batch_topic_subscription(topic, registration_tokens)
# or unsubscription
response = fcm.batch_topic_unsubscription(topic, registration_tokens)

Get Information about the Instance ID

Given a registration token, you can retrieve information about the token using the Google Instance ID server API.

registration_token= "12" # a client registration token
response = fcm.get_instance_id_info(registration_token)

To get detailed information about the instance ID, you can pass an optional options hash to the get_instance_id_info method:

registration_token= "12" # a client registration token
options = { "details" => true }
response = fcm.get_instance_id_info(registration_token, options)

Mobile Clients

You can find a guide to implement an Android Client app to receive notifications here: Set up a FCM Client App on Android.

The guide to set up an iOS app to get notifications is here: Setting up a FCM Client App on iOS.

ChangeLog

2.0.0

Breaking Changes

  • Remove deprecated API_KEY
  • Remove deprecated send method
  • Remove deprecated send_with_notification_key method
  • Remove subscribe_instance_id_to_topic method
  • Remove unsubscribe_instance_id_from_topic method
  • Remove batch_subscribe_instance_ids_to_topic method
  • Remove batch_unsubscribe_instance_ids_from_topic method

Supported Features

  • Add HTTP v1 API support for send_to_topic_condition method
  • Add HTTP v1 API support for send_to_topic method

1.0.8

  • caches calls to Google::Auth::ServiceAccountCredentials #103
  • Allow faraday versions from 1 up to 2 #101

1.0.7

  • Fix passing DEFAULT_TIMEOUT to faraday #96
  • Fix issue with get_instance_id_info option params #98
  • Accept any IO object for credentials #95

Huge thanks to @excid3 @jsparling @jensljungblad

1.0.3

  • Fix overly strict faraday dependency

1.0.2

1.0.0

  • Bumped supported ruby to >= 2.4
  • Fix deprecation warnings from faraday by changing dependency version to faraday 1.0.0

0.0.7

  • replace httparty with faraday

0.0.2

  • Fixed group messaging url.
  • Added API to recover_notification_key.

0.0.1

  • Initial version.

MIT License

  • Copyright (c) 2016 Kashif Rasul and Shoaib Burq. See LICENSE.txt for details.

Many thanks to all the contributors

Cutting a release

Update version in fcm.gemspec with VERSION and update README.md ## ChangeLog section.

# set the version
# VERSION="1.0.7"
gem build fcm.gemspec
git tag -a v${VERSION} -m "Releasing version v${VERSION}"
git push origin --tags
gem push fcm-${VERSION}.gem