SCC horizontal scaling. Target a specific user on another node.

[ayberkanilatsiz]

Hi, Vertical scaling works fine with scc-state and scc-broker.

Publish clients emitting are working awsome but i have problem. I want emit inbox to user which is connect other server.

I want to emit inbox to User B from Socket Cluster X. I know User B socket id.

I did scServer.clients[socketId].emit('inbox', inbox);. It works on only single cluster but now
i get TypeError: Cannot read property 'emit' of undefined

[MegaGM]

You get the error because there is indeed no socket with such socketID in the scServer.clients object on SC X. Since the UserB is connected to SC Y, it should be in the scServer.clients on SC Y. Although that is not related much to the information which should help you implement what you need.

You said you want to deliver a message from a socketcluster-node-1 to a specific user (client, socket) which is connected to another node, let's say socketcluster-node-2.

[MegaGM]

Essentially you want to deliver a message:

1. From any part of your application
   server-side JS, client-side JS, client-side with client written in any other language, external apps like Redis, AMQP, MQTT, etc.

2. To a specific user which might have multiple opened tabs, maybe uses a phone, a laptop and a PC at the same time. In other words, the user might be connected to multiple workers on the same node or on multiple nodes simultaneously.

If that's the case, you could let SocketCluster handle it for you. How?

• User Bob which is connected to node-1, subscribes to a channel, let's say bob-private-channel.
• User Alice, which is connected to node-2 via her phone, and to node-X via her laptop, subscribes to a channel alice-private-channel.

That's it! Now you can publish a message to Bob or to Alice from anywhere, where you have .publish() method.

// in a worker on socketcluster-node-1
const payload = {text: 'Hello Alice!'}
scServer.exchange.publish('alice-private-channel', payload)

In this example the payload from a worker on node-1 will be automagically (via scc-broker-client and scc-broker) delivered to node-2 and node-X, and pointed to the exact same workers, which Alice is connected to. Hence her phone and laptop will get the payload accordingly, since they're both subscribed to the alice-private-channel. Just like that:

socket.subscribe('alice-private-channel').watch(handleDirectMessage)

function handleDirectMessage(payload) {
  console.info(payload.text) // => Hello Alice!
}

Well, deeply thinking, strictly speaking, the payload won't be "delivered to workers". It'll be rather published to a channel and might be consumed by subscribers.

You definitely would like to read SocketCluster Design Patterns for Chat
And, of course, the docs https://socketcluster.io/#!/docs
Feel free to ask any questions in the Gitter chat room

[ayberkanilatsiz]

@MegaGM it works like a charm! Thankss =)

[happilymarrieddad]

You can assign each user to their own channel (i.e. subscribe(user.id.toString())) and then send emails/messages to that channel. That's essentially what we do for chat messages that are direct messages.

[ayberkanilatsiz]

I use it for direct message and it works. It's for inboxes it means place where you show the profiles that the member is already chatting.