I use Firebase Cloud Functions in a Flutter app. How does cloud functions behave when a device is offline in these cases? Is there any situation I can't reliably use cloud functions when the device is offline?
Trigger functions (onUpdate(), onDelete() etc)
Function invocations using function name
If an app is offline, there is nothing it can do to trigger any function. Without network connectivity, the app has no ability to invoke a function directly, no make any changes to a cloud-hosted product that would fire a trigger on the backend.
Related
I have a Flutter app integrated with a Firebase Realtime Database.
I want a notification (actually an alarm kind of thing if possible), when an item (lets call it alarm) in the database is set to "true". I always see firebase_messaging plugin for notifications, but I am not sure if I'm supposed to use this plugin despite that my app doesn't have anything to do with messaging.
I am totally new to both Flutter and Firebase, can you tell me how to listen to the database even if the app is not running?
By the way, I am currently building the app for only Android, but I want to build it for IOS too in the future.
Thanks.
You can use/write firebase cloud fucntion. Using firebase cloud function you can watch any document/field and try to write trigger logic like if a field is set to true then this cloud function will throw an notification via firebase messaging.
https://firebase.flutter.dev/docs/functions/overview/
When the user is not actively using the app there is no reliable way to continue to listen to changes in the Firebase Realtime Database. To notify the user of changes to the database in that situation, you'll need to listen for those change on an environment that is always on, and then send a message to the user through Firebase Cloud Messaging.
One environment that is always in is Cloud Functions, which is also part of Firebase, and allows you to run small snippets of JavaScript code on Google's servers in response to things that happen in your Firebase project. The documentation of Cloud Functions for Firebase as example of how to notify the user when something interesting happens in the database:
Developers can use Cloud Functions to keep users engaged and up to date with relevant information about an app. Consider, for example, an app that allows users to follow one another's activities in the app. Each time a user adds themselves as a follower of another user, a write occurs in the Realtime Database. Then this write event could trigger a function to create Firebase Cloud Messaging (FCM) notifications to let the appropriate users know that they have gained new followers.
The function triggers on writes to the Realtime Database path where followers are stored.
The function composes a message to send via FCM.
FCM sends the notification message to the user's device.
To review working code, see Send FCM notifications.
I am new to Firebase and learning it. With Cloud Functions you can create trigger listeners to events that happen in Firestore (firestore events) or Authentication (auth events). Can I create listeners similarly with the Admin SDK of Firestore or Authentication in my own nodejs environment?
No, Cloud Functions triggers only work on the Cloud Functions backend, as they depend heavily on Google Cloud infrastructure to work efficiently. There is no exact equivalent for other environments. You can certainly use the provided nodejs Firestore SDK to set up a document or query listener, just like web and mobile clients, but it won't behave like a Cloud Functions trigger.
I know how to send messages from Firebase cloud messaging portal to an android device. But my server runs on Google Cloud, I do gcloud app deploy from my local machine and the app logic gets deployed on Google Cloud. Now, I want to send notifications, based on the data stored as Entities in GCP Datastore, to an Android App.
Notification messages can be sent from Firestore-Cloud Messaging portal to an Android device, if I could harness this Firestore Cloud Messaging API in my GCP logic, then my problem will be solved.
I'm trying to look for any examples or POC's.
you can use Cloud Functions to add such custom functionality...
for example: https://android.jlelse.eu/serverless-notifications-with-cloud-functions-for-firebase-685d7c327cd4
and there are Cloud Datastore Callbacks, which can be used as event triggers. most relevant for Cloud Functions might be the Google Cloud Datastore Node.js Client - in order to connect to the Datastore. here's one of my examples, it is written in AppScript (similar to Node.js), which also connects to a Cloud Datastore, with the service account JSON loaded from Google Drive.
however, in this case the Datastore would need to subsequently trigger an HTTP Trigger or Pub/Sub Trigger and the code behind that trigger could get more data from the Datastore or directly send the Firebase notification.
in Cloud Function there are just triggers for Cloud Storage, while the Pub/Sub (publish/subscribe) triggers can be used for just anything. The Datastore would need to publish whatever event (add/edit/update/delete) - while a Cloud Functions script would need to subscribe these events.
using Firebase as backend might be less effort, because data-change events/triggers are being supported out-of-the-box, without any HTTP interaction or Pub/Sub communication involved.
I am new on firebase cloud functions. I would like to ask a question about always running or self-triggering functions. How can we handle these things? How can we implement always running functions or self-triggering?
Google Cloud Functions are snippets of code that run in response to events that happen somewhere else. Some example events:
a HTTPS URL is accessed, either from application code, or in some other way
a User account is created on Firebase Authentication
a node is written in the Firebase Realtime Database
a message is sent to a Cloud PubSub topic
There is no concept on a forever-running function on Cloud Functions (nor on other, similar Functions-as-a-Service offerings), although it's definitely possible to create a function that gets triggered every minute or so (like a cron job).
As I know currently Cloud Functions doesn't support triggering functions from Firebase.
For now I'm planing to use an basic Engine instance to trigger the functions based on the queue.
Is this the right way to go? or should I trigger the cloud function directly from the clients device after the data is inserted in the db?
thank you
Cloud Functions for Firebase was just launched today! You can use the SDK to trigger cloud functions from your Firebase database, storage bucket, authentication, and analytics events. https://firebase.google.com/docs/functions/