Sending information to a specific client, so the data of the client must be cached in the backend.
I tried to use Redis to solve the problem, but SocketIOClient cannot be serialized.
I am trying to use Redisson to store UUID in Redis, but I created two SocketIOServers, the client connects to one of the servers, the data is not synchronized, and the size of one of the servers is 0.
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We want to track each users turn usage seperately. I inspected Turn Rest API, AFAIU it is just used to authorize the user which already exists in Coturn db. This is the point I couldn't realize exactly. I can use an ice server list which includes different username-credential peers. But I must have initialized these username-credential peers on coturn db before. Am I right? If I am right, I do not have an idea how to do this. Detection of user's request to use turn from frontend -> Should generate credentials like this CoTURN: How to use TURN REST API? which I am already achieved -> if this is a new user, my backend should go to my EC2 instance and run "turnadmin create user command" somehow -> then I will let the WebRTC connection - > then track the usage of specific user and send it back to my backend somehow.
Is this a true scenario? If not, how should it be? Is there another way to manage multiple users and their data usage? Any help would be appreciated.
AFAIU to get the stats data, we must use redis database. I tried to used it, I displayed the traffic data (with psubscribe turn/realm//user//allocation//traffic ) but the other subscribe events have never worked ( psubscribe turn/realm//user//allocation//traffic/peer or psubscribe turn/realm//user//allocation/*/total_traffic even if the allocation is deleted). So, I tried to get past traffic data from redis db but I couldn't find how. At redis, KEYS * command gives just "status" events.
Even if I get these traffic data, I couldn't realize how to use it with multi users. Currently in our project we have one user(in terms of coturn) and other users are using turn over this user.
BTW we tried to track the usage where we created peer connection object from RTCPeerConnection interface. I realized that incoming bytes are lower than the redis output. So I think there is a loss and I think I should calculate it from turn side.
Currently, I have a project with public transport vehicles, I have to poll the GTFS-RT standard every x seconds and then I will receive the latest data for all vehicles. So to send this to the frontend I am using Redis Pub/Sub with WebSockets.
Currently, however I just publish all the vehicles to redis regardless of any changes. This causes the frontend to re-render everything => slows down the front-end client. I want to actually only publish whenever changes are made to the vehicles. Doing that however means that new listeners would miss out on vehicles. So I would have to persist the latest data for every vehicle.
My question is - is this achievable by replacing Redis Pub/Sub with Redis Streams and then always deleting the current message if another message appears? If that is possible how would I do that? With Pub/Sub I thought about just making a channel for every vehicle and letting the client listen to all the channels, as can be done with pattern matching, but it wouldn't solve the problem of persistence, so what would be the best approach to tackle this problem?
Is there an API point or whatever other queryable source where I can get the total queued data?:
setting up a little dataflow in NiFi to monitor NiFi itself sounds sketchy, but if it's a common practice, let's be it. Anyway, I cannot find the API endpoint to get that total
Note: I have a single NiFi instance: I don't have nor will implement S2S reporting since I am on a single instance, single node NiFi setup
The Site-to-Site Reporting tasks were developed because they work for clustered, standalone, and multiple instances thereof. You'd just need to put an Input Port on your canvas and have the reporting task send to that.
An alternative as of NiFi 1.10.0 (via NIFI-6780) is to get the nifi-sql-reporting-nar and use QueryNiFiReportingTask, you can use a SQL query to get the metrics you want. That uses a RecordSinkService controller service to determine how to send the results, there are various implementations such as Site-to-Site, Kafka, Database, etc. The NAR is not included in the standard NiFi distribution due to size constraints, but you can get the latest version (1.11.4) here, or change the URL to match your NiFi version.
#jonayreyes You can find information about how to get queue data from NiFi API Here:
NiFi Rest API - FlowFile Count Monitoring
I'm new at Redis. I'm designing a pub/sub mechanism, in which there's a specific channel for every client (business client) that has at least one user (browser) connected. Those users then receive information of the client to which they belong.
I need Redis because I have a distributed system, so there exists a backend which pushes data to the corresponding client channels and then exists a webapp which has it's own server (multiple instances) that holds the users connections (websockets).
Resuming:
The backend is the publisher and webapp server is the subscriber
A Client has multiple Users
One channel per Client with at least 1 User connected
If Client doesn't have connected Users, then no channel exists
Backend pushes data to every existing Client channel
Webapp Server consumes data only from the Client channels that correspond to the Users connected to itself.
So, in order to reduce work, from my Backend I don't want to push data to Clients that don't have Users connected. So it seems that I need way to share the list of connected Users from my Webapp to my Backend, so that the Backend can decide which Clients data push to Redis. The obvious solution to share that piece of data would be the same Redis instance.
My approach is to have a key in Redis with something like this:
[USERS: User1/ClientA/WebappServer1, User2/ClientB/WebappServer1,
User3/ClientA/WebappServer2]
So here comes my question...
How can I overcome stale data if for example one of my Webapps nodes crashes and it doesn't have the chance to remove the list of connected Users to it from Redis?
Thanks a lot!
Firstly, good luck with the overall project - sounds challenging and fun :)
I'd use a slightly different design to keep track of my users - have each Client/Webapp maintain a set (possibly sorted with login time as score) of their users. Set a TTL for the set and have the client/webapp reset it periodically, or it will expire if the owning process crashes.
I understand that, roughly speaking, Trello uses Redis for a transient data store.
Is anyone able to elaborate further on the part it plays in the application?
We use Redis on Trello for ephemeral data that we would be okay with losing. We do not persist the data in Redis to disk, and we use it allkeys-lru, so we only store things there can be kicked out at any time with only very minor inconvenience to users (e.g. momentarily seeing an incorrect user status). That being said, we give it more than 5x the space it needs to store its actual working set and choose from 10 keys for expiry, so we really never see anything get kicked out that we're using.
It's our pubsub server. When a user does something to a board or a card, we want to send a message with that delta to all websocket-connected clients that are subscribed to the object that changed, so all of our Node processes are subscribed to a pubsub channel that propagates those messages, and they propagate that out to the appropriately permissioned and subscribed websockets.
We SORT OF use it to back socket.io, but since we only use the websockets, and since socket.io is too chatty to scale like we need it to at the moment, we have a patch that disables all but the one channel that is necessary to us.
For our users who don't have websockets, we have to keep a list of the actions that have happened on each object channel since the user's last poll request. For that we use a list which we cap at the most recent 100 elements, and an auxilary counter of how many elements have been added to the list since it was created. So when we're answering a poll request from such a browser, we can check the last element it reports that it has seen, and only send down any messages that have been added to the queue since then. So that gets a poll request down to just a permissions check and a single Redis key check in most cases, which is very fast.
We store some ephemeral data about the active status of connected users in Redis, because that data changes frequently and it is not necessary to persist it to disk.
We store short-lived keys to support OAuth logins in Redis.
We love Redis; once you have an instance of it up and running, you want to use it for all kinds of things. The only real trouble we have had with it is with slow-consuming clients eating up the available space.
We use MongoDB for our more traditional database needs.
Trello uses Redis with Socket.IO (RedisStore) for scaling, with the following two features:
key-value store, to set and get values for a connected client
as a pub-sub service
Resources:
Look at the code for RedisStore in Socket.IO here: https://github.com/LearnBoost/socket.io/blob/master/lib/stores/redis.js
Example of Socket.IO with RedisStore: http://www.ranu.com.ar/2011/11/redisstore-and-rooms-with-socketio.html