I am coding a vue.js app using web pushes with Firebase Cloud Messaging and I wondered if it was possible to send a web push to a user and in case the user was offline, to somehow store it for later display when the user opens the app again. Is there a principled approach to this problem, i.e. managing web pushes when the end user is offline?
The reason I am asking this is that, so far, all the web push notifications I've committed to FCM server with tokens of offline clients (i.e. desktop browsers) went into oblivion. To be sure, FCM didn't try pushing the notification again when the clients went back online.
For this reason I am considering coding a self-made dispatcher to manage web push for offline clients, but I need to make sure my efforts are worth it.
updated: I am now able to display notifications sent to an offline client after coming back online using appropriate time_to_live values. However, only the latest notification is displayed. How is there any specific reason why?
FCM's default behavior is exactly like that. From the docs:
If the device is not connected to FCM, the message is stored until a connection is established (again respecting the collapse key rules). When a connection is established, FCM delivers all pending messages to the device.
We use FCM to send app notifications. Basically, we want to put a cap on maximum number of notifications that an app user can get in a day. Does FCM have an option where on hitting the cap, the subsequent messages are discarded by FCM and not sent to the user?
FCM is a free service which currently doesn't have any limitations whatsoever when it comes to the count of notifications sent and received.
If you want to enforce a limit of some sort, you would have to enforce this on your implementation (probably server side), by preventing further messages when a specific range is hit.
In general, push notification features are good for letting users know of specific (non-critical) information. I don't get why anyone would limit something when it's already free of use -- unless there's some different cost you're limiting which is directly affected by the push notif service.
I'm trying to understand what I will need to build on my server for Push notifications to work successfully.
My thoughts were:
The phone sends the notify URL to my server
The server stores the information in a Database
A separate process or PHP script will query the database and open continuous looping process for each device. (Each socket will be querying a 3rd party API)
When there is a change detected in the API for that device a push notification will be sent to the device's notify url.
Is this the right method on what needs to be done. Isn't this going to eat up server resources or is it the expected outcome of Push a push notifications server?
I've produced a simple diagram on all this below:
First of all, let's separate the process in the main stages needed for PUSH.
Device subscription.
Send the PUSH
Process the notification on device.
Subscription
For the subscription, your device (more specifically, your App) must call the PUSH api,for enabling PUSH notifications. This call to the push API will give you a URL that uniquely identify the device where your application is installed and running. You should store this URL on your database, the same way you store a user's email, or a user's phone number. No special black magic here. You only use it when you need to send a communication to a user.
Send the PUSH
For the push stuff, the same approach as for email, or SMS messaging here: "One does not simply make an infinite loop and send a message if any change is detected". What you have to do is, just send the PUSH message when your application needs to. So you have the user to which you want to send a message, instead of opening a SMTP connection to send ane mail, just build the PUSH XML Message and call the URL associated with that user. Some things to consider here are:
Network reliability (you need to retry if you can't connect to the server).
Response error code-handling (you don't need to retry if the server tells you that the phone has uninstalled your application, for example).
Scalability. You don't want to send a PUSH message from your PHP code, because you don't know how long it will take for the task to be completed. You have to make this thing asynchronously. So just queue up all the push messages, you can create a separate process (windows service, nodeJS service, cron job, daemon, etc.) to send the PUSH, handle retries and errors and clean the queue.
Process the notification on Device
So now that you are this far, you need to handle the notification on the phone. It depends on the type of PUSH notification that you are sending:
Tile. You will update the image, text and counter of the application tile, if the user has put your application to the start screen. On client side you need nothing to so, as all these parameters are part of your PUSH request.
Toast. This one requires a title, text (limited to some 35 characters more or less) and a relative URL inside of your APP. Your application will be launched (like when you click on a Toast notification from Twitter, for example) using the URI that you specify in the payload. So a bit of data can be already injected here. You may/or may not make a request to your server for new data. It is up to you.
Raw. This one is pretty much silent. Is not seen by the user if your APP is not running. As you might guess, this kind of PUSH is useful to live update your running APP, instead of continuously polling your server, wasting user battery and bandwidth and wasting your server resources. You can send anything (raw bytes or strings) up to the max size of the payload allowed my Microsoft.
If yo have any more questions, don't hesitate to ask.
Bottom line: separate the PUSH sending, make it async, don't you ever forget that...
Your PHP script that continually pings the database for changes...THAT is what will eat up your system resources. Push notifications go hand in hand with Event Driven Programming. This means that ideally, your code shouldn't continuously ping your DB. Rather, when something happens (ie, an "event"), THEN your code does something...like contact your phone via push notification.
Your steps for push notifications are more or less correct, but are incomplete. Step 4: the server contacts the client via the notify url (which you have). Step 5 is that the client then contacts the server to actually pull down the information it needs. That is: The new information is not provided to the client via the notify url. Once the client has its new information, then the program continues as normal (populates a list, downloads skynet, etc.)
Your third step is very wasteful and not practical if your app is installed on more than a few devices.
Instead, each device should be subscribed to types of server updates it cares about. Your server's DB will have a mapping from each type of update you support to the list of notification channel URLs of devices that care about this update type.
When your server detects an update of type X, it would send a notification to all devices subscribed to that type of update.
We have a table containing apns device tokens on our servers and due to unforeseen circumstances lost all data, including backups. In order to send push notifications we need to send device tokens along with message, since we lost all the tokens, is there any way to get them through apple/ application ? I'm pretty clueless on how to proceed further, any help is really appreciated
There is no API that gives you the device tokens for which your app registered to APNS.
Assuming that your app doesn't send the device token to your server every time it is launched, you'll have to release a new version that would send the device token to the server. Then you'll get the device token of every user who installs the updated version and launches the app. You won't recover the tokens of users who don't install the update, but there's nothing you can do about it.
I hope you have better backups next time.
Does anybody know the limits of using the MPNS? I need to know specifically if I can send to MPNS millions of notifications to unique devices (if I ever had) almost all at once (seconds) and how will the MPNS handle it? is it no problem? will MPNS handle the notifications as soon as it can? would the MPNS block my service?
Thanks
The only limit I saw mentioned on MSDN is this :
Authenticated web
services do not have a daily limit on the number of push notifications
they can send. Unauthenticated web services, on the other hand, are
throttled at a rate of 500 push notifications per subscription per
day. For more info, see Setting up an authenticated web service to
send push notifications for Windows Phone.
It's a limit per device per day, and it exists only if you don't setup an authenticated web service.
They don't mention a limit on the number of unique devices.