Which is better approach to send push notification in Kuzzle using hooks or subscription? - kuzzle

Question

I’m using Kuzzle as backend for my realtime chat application.
What is the better approach to sending push notification when user is offline in a mobile chat app?
1. Using custom plugin hooks
// check for every message in chat
this.hooks = {
'document:afterCreate': (request) => {
if (request.input.resource.collection == 'messages') {
let message = request.input.body;
this.context.accessors.sdk.document.get('now', 'user_sessions', message.otherUserId).then((userSession) => {
if (!userSession._source.isOnline) {
userSession._source.devices.forEach(device => {
// send push notification
});
}
})
}
}
}
2. Subscription per user for all users after the Kuzzle server start-up
const app = new Backend('kuzzlebackend')
app.start()
.then(async () => {
// Application started
// Loops through all users and adds their subscriptions to Kuzzle
foreach(user in users) {
app.sdk.realtime.subscribe('now', 'messages', { ‘otherUserId' : user._id }, async (notification: Notification) => {
this.context.accessors.sdk.document.get('now', 'user_sessions', user._id).then((userSession) => {
if (!userSession._source.isOnline) {
userSession._source.devices.forEach(device => {
// send push notification
});
}
})
})
}
})

Answer 1

You should use the hook mechanism on the generic:document:afterWrite event to send notification to offline users when a new message is created.
This event will be triggered every time a document is written with one of the Document controller action, and for the m* action family it you will able to process documents in bulk instead of one by one.