I am make chat feature with Flutter and Firestore backend.
Every message is new document in Firestore collection with UID and text field. Chat is 1:1 and random so no know who user will talk to before enter chat. DocID in chat collection are all auto-id.
I have read can use topics to manage send notification. This should be easier than use individual device fcm token.
Anyone know how to implement use topic for this random 1:1 chat app?
You can definitely use a separate topic for each 1:1 conversation, for example with the naming scheme I described here: Best way to manage Chat channels in Firebase. But there are some things to consider which, as Doug already pointed out in his comment, leads most developers to not solely use FCM for their chat apps.
For example: FCM topics are not secured. This means that anyone who finds out the topic ID can subscribe to it, and thus overhear the 1:1 conversation. And while you can generate topics that are hard to guess, you should not rely on not knowing the topic ID as a security mechanism.
Another reason to consider alternatives is that FCM messages are transient: once they are delivered there is no longer any trace of them. With your current Firestore implementation you can query the database to get all messages to show, while with a pure FCM implementation you will have to build your own database (if that is required for your app).
For these reasons most chat apps I know of use a combination of FCM (for push notifications) and an online database (for persistence) as their backend services.
I found Frank's comment really interesting about the "sorted userID composed key". I would probably use that as the chat key in the database (realtime/firestore), however, for the notifications I think I would still use a topic for each user - this way I would be able to avoid notifying the user who posted the message. If that wouldn't be an issue, then just go for just one topic per chatroom.
Also mentioning Frank, I would probably use extra keys in all topic names to make them really difficult to guess. (but add that later so you don't get distracted with non core stuff)
In this answer you have an example of how to post the notifications with a onCreate trigger to a topic (from a functions backend).
In the flutter code, you can use subscribeToTopic from the firebase_messaging plugin to start listening to a topic.
Note: if your app will support user log-off [probably it will :)], then you'll also have to delete the token in the device to avoid receiving notifications from the last logged user.
Related
I've incorporated Firebase Cloud Messaging into my app. After messing around, I kind of understood the premise of how it operates. So, as a result, I structured my code so that when users sign up the FCM token is stored. After creating two accounts, I realise both FCM tokens for the user were the same.
Looked online and sorted this issue, and now I can refresh the token on launch, and still append the new FCM token when users initially sign up.
So now, I ask the question - Users are created with a fcmToken field (which I can refer to in my code), however, due to the fact a new token is generated on launch each time does this render the token(s) stored for each user useless? Or can I still push to the specific user using the fcmToken?
I've looked online, but can't seem to find an answer.
FCM tokens don't uniquely identify an individual end user. They identify a specific installation of an app on a specific device. When sending with that token, it doesn't matter who is signed in to the app (or if anyone is signed in at all) - the app will still receive it and need to figure out what to do with it. It's up to you to decide what to do with that message, given the sign-in state of the user. If you expect that your app could have multiple users sharing a single app on a single device, then you will probably want to send something in the payload to determine who that message was intended for, if necessary.
#doug great answer, but there's a common implementation problem when people share a device, so please add a warning, something like: often only the last logged in user should receive push notifications, otherwise he could see messages from the person who was logged in before. your backend should not only store all the devices a user is logged in, but also for each device who the last active user is and check this upon sending a push. the question whether you receive push or not when logged out is a common topic, too.
Is there a way to secure validate subscriptions to topics? For example, is it possible to limit topic Test to a specific user with ID XXXXX? Is this possible with Cloud Functions?
firebaser here
To be able to subscribe to a topic, you currently need to know two things: the FCM token/instance ID of the app instance, and the path/name of the topic to subscribe to.
Knowing these two allows one to subscribe to the topic from any client. There currently is no public API to limit who can subscribe to what topics. So if you need to guarantee that the message is only delivered to authorized app instances, you should not use topics and instead delivery to each FCM token/instance ID directly from your own (server-side) code.
This request comes along regularly though, so I recommend that you file a feature request to add your vote.
Does Firebase Cloud Messaging provide any way for a user to retrieve old messages? From the documentation, it looks like messages are thrown away once the client receives them.
I ask because I'm looking to build an IM functionality in my app, and a user needs to be able to see past messages when he closes the app and then opens it again.
Update from the comments here:
Unfortunately this just got worse as of 20 Nov 2017 when FCM Diagnostics was removed from Google Play Console. "I understand that FCM Diagnostics was critical to you in troubleshooting FCM messages but unfortunately this has been deprecated. Rest assured that we are working on something better that should allow a lot more insight into what went wrong during message delivery, but we can’t share any timelines. I’ll share your concern internally and continue to work to get this new feature out.
FCM's main purpose is for Push Notifications. So to answer directly, No. FCM doesn't keep track of the message you send for you. There is a diagnostics and statistics tool you can use, but I don't think this is the one you're looking for.
IMHO, it's the developer's responsibility to keep track of the details they need. In your scenario, you would be needing a database to store the message details themselves, wherein you can make use of Firebase Realtime Database. There's actually a sample Codelab about creating a simple chat app using Firebase here.
Documentation for topic messages for FCM says the following two points
Just wanted to know what is this excessive number of topics? Any approximate value to it? Also, the documentation doesn't say anything about creation of topics. How to create/delete a topic?
Another question -
Document says it takes time to show the topic on firebase console, so, we can't send notifications unless the topic is visible on firebase console (even programmatically)?
Thanks in advance
For future questions, please limit yourself to a single question per post. But here are the answers that I know (or a fairly educated guess):
The limit on the number of topics a client can subscribe to is to counter abuse. It is not a documented value.
A topic is auto-created when a client subscribes to it.
There is no API to delete a topic. It will automatically disappears when nobody is subscribed to it anymore.
You can only send notifications from the console once the topic shows up. You can send notifications from your app server using the Firebase Cloud Messaging API at any moment.
I know that Firebase has recently added support for Push Notifications and while this is a great thing, I only seem to be able to send push notifications manually via the Notifications Panel.
What I'd like to do is to send push notifications within a user scope...Let me explain that. Each User in my App has an account and then each user can join a group. Within this group the user can perform tasks and has a list of chores to do. Now when certain tasks are due for example I want to remind the user of doing it with a push notification. For 1-10 I might be able to pull this off manually, but is there a way to dynamically based on the data in the Database send out Push Notifications?
I know that certain Push Notifications can be created using the Analytics tool such as "Hey you have not visited for 3 days, please come back whatever"... but I'd like to register push notifications such as "I just created a task, this task needs to be done within 3 days. Remind me in 3 days if the task is still not done".
Is this possible with Firebase or do I need to have my own server connecting to Firebase and handling those events?
-xCoder
You need to implement FCM in your client and in a server. Let me put this straight:
First, you need that your client, or app, to register into FCM and get a FCM token that will be used to identify that device uniquely.
Then, store that token wherever you like. It can be into firebase database or other server you may like. I recommend you to store it into firebase if you are using it as a database for your users; that's my case.
Also, you need to implement a http or xmpp server in order to send FCM messages to your registered devices containing the data you are interested in. For example, you can implement a Google App Engine endpoint (can be done with Android Studio and Java) that is quite simple or a NodeJS module, depending on your preferred language.
If you are using Firebase as database you can connect from your server with the appropriate SDK and get the FCM tokens you want from your users, and then send the message to those with data. Don't forget to secure your serve.
The way you implement your server algorithm to send FCM messages depends on your app purposes.
Hope it is clear enough for you. Also you can find all the documentation with a short video that explains the general structure here: https://firebase.google.com/docs/cloud-messaging
You can use cloud functions to trigger on any create, update or delete operation in your database and in the trigger event, you can choose to send in FCM push notifications to the devices of your choice.
Here is the documentation regarding the use and structure of a cloud function: https://firebase.google.com/docs/firestore/extend-with-functions
Hope this helps!