currently i'am developing a react app where user can post and comment and like a post.
so i did everything but there is one more thing that i want to do which is getting notification after user
Post or maybe comment and so on..
so let say i have a table called 'posts' in the database (PostgreSQL) and when user called "A" create post ,that post inserted into the database and then i want to receive a notification which Said that the user "A" created a post with the ID of that post and i think the main idea here is to watch the table of posts and whenever a new raw inserted a notification fire.
i searched many sources and find that i can use Pusher ,web-socket but to be honest i can't make a decision without figuring out the best way to achieve that.
So How i can get notified hence a new row inserted into the table "posts" ?
Thank you in advance.
Postgres has LISTEN/NOTIFY that you could use in conjunction with an on-insert trigger on the posts table.
Some process can then be listening for those notifications and figure out whom to send the notification to (via whichever transport you choose).
However, I think you might be better off adding a concrete table for notifications, so the user can see notifications that occurred when they weren't connected to the notification transport.
Related
I am trying to build a web app where users can receive notifications if their posts get likes. This functionality is actually working but the notification component renders only when the page reloads. But I want it to re-render the notification component as soon as there is a change that occurs with it. I am trying to make this work with SocketIO both in client and server but it feels like there should be a way easier way to solve this issue. How?
One way to achieve this is to use server-sent events (SSE), which can be seen as a uni-directional
and simplified version of WebSocket (only server can send data to clients). You might need route param or query string so that users can connect to different channels.
If it doesn't have to be so real-time (i.e. receiving notifications 1 minute after somebody liked the post is okay), you could also try (long)polling.
However, since post-like table may contain a huge amount of data, constantly querying it is expected to result in bad performance on the server. Also, adding an extra column to mark if the user has been notified about a specific like is trivial.
A possible workaround might be to create a new table, say pending-like-notification, which is used to stored all pending like notifications. Whenever a post is liked, we insert a new record into this table.
Therefore, when a user tries to query if any of his posts is liked recently, in the backend we lookup this table instead of the post-like table, and delete the selected rows after the user has been notified so that the amount of data in this table can stay low (hopefully).
All in all, in this scenario, I think SSE and WebSocket will be better choices.
MERN stack
In my app, you can follow users and when those users make a post, you should get a notification.
Currently, my User model has an array that lists all the users they're following as well as users who are following them:
users_you_follow: [ <object_ids>... ],
users_who_follow_you: [ <object_ids>... ]
My current idea looks something like this:
When a user makes a post in the frontend, we pass in the array of users_who_follow_you as well as the post details into the backend.
Then, using mongoose, parse the users_who_follow_you and find the users with the same ID's.
Finally, within that User model, I would store the post details along with some other metadata.
Then in the frontend, I would have a setInterval call to check if there are any new notifications.
This method although might work seems very server intense with all the API calls to check notifications. Is there a better way around this?
I currently don't know how to start on this process. From my research, some people said to use websockets while others say web workers.
What would be the best way to achieve something like this?
A very similar system to compare it to would be StackOverflows inbox thing. If a user comments on your post, the header/navbar shows a notification without having you to refresh your screen.
Thank you.
I am developing Social network type of application in node.js and MongoDB.
I want to add a functionality such as -
If user A has followed user B then when user B post something it should automatically come to user A on his wall!
Approach 1- This is what I have research till now
Create a channel of user B and all the other user subscribe to that channel and when user B post something then emit that with socket.io on all the subscribers.
so for this approach, we are thinking to create a channel when the new user signup every time.
But the problem is -
is this feasible approach as for how do I know which channel is which user or is there a way to store the channel in MongoDB.
if I create too many channels will that crash my server?
Approach 2 -
Another Approach that I have got is
Look up the followers of the source user in your database.
And emit feeds to all the followers using socket.io
How to scale this if I have got 100 followers of each user and when everytime user post, will searching in a Database creates an overhead.
Using Redis caching would be better to store followers?
And instead of checking the followers-
find that from Redis and emit the msg using socket.io
Approach 3 -
I have heard the name of Redis pub/sub but not able to find how it will work in my application.
Please suggest some best standards for creating something like this!
And if above approaches are fine can you pls suggest me the flow for that or how do I create a code for that!
I would be great if you provide me an example.
I think you can use Approach 2, but you must create a queue (redis queue or rabbitMQ) to do that.
I mean when you create a post, it must push to queue to push message to 100, 1000 follower in your DB.
I am building a buy and sell website that is built on MEAN stack. Im planning to use socket.io. So here's how my website will work
User will register and login
They can post an item either buy/sell
Other users can offer to the post (i'll use socket.io on this so that the user who posted the item will have a notification)
The poster will have an option to view the current offers, then they will choose who'll they accept.
Once they accept the offer, both the Poster and the User who offered will have a communication both of them (Chat room)
So when the poster accepted the offer of the customer, it will open a chat for them to communicate. So here's my question, i will use socket io rooms. Once the poster accepts the offer, both of them will join the room (so i'll generate a room for them and automatically join them) then this room will be saved to the MongoDB, then every message they'll send, it will be saved to the database. So that they can see the history of their message even though they logout.
Is this the best method?
Create a room for both of them (saved to DB)
Saved to database everytime they send a message to each other
Query the database when they login for list of the rooms the user has joined so that they could see the messages they have
That would probably be the best way to do it. Here is a similar question is there a good way to save socket.io message history it shows how to save the message history.
You do not have to save the messages, but if you would like to be able to see messages later, you should save every message to a database. If you do not save every message to a database, when you reload the page all previous messages will disappear.
If you want a free database, mongoLab will host small mongoose databases for free. Here is a good tutorial showing how to use mongoLab, it does not use socket.io, but it will probably be very easy to implement it.
Hope this helps! Feel free to ask any questions below.
I have running on NodeJs/MongoDB and Android/HTML client where people are able to follow posts, I store their ids in an array of followers in the post's document.
I want to implement a notification feature when a new comment comes I want to notify all the followers.
So, I have looked across the web but I couldn't get one tutorial where I understood exactly how things work.
I have seen many recommend the Redis Pub/Sub, but from what I have read Redis is a in-memory database, so I was thinking, I could create a channel in Redis with the post's Id, when the user follows that post I would subscribe him to the channel, then when a new comment comes i just publish to the channel. Is this how it works?? If so, then how about when the user goes off then comes back in later, And how about when there are many posts, won't Redis clear the channel then I wouldn't be able to send the notification to all the followers?
I think I'm understanding it all wrong,I'd appreciate your help. How exactly can I be able to send a notification to all followers?