Migrating from Pusher to PubSub Without Changing Your Code

Most realtime migrations are painful because the client library changes. This one isn't: PubSub speaks the Pusher protocol, so the same pusher-js you already ship keeps working. What changes is where it connects.

What actually changes

A standard Pusher setup points at Pusher's cluster. To move to PubSub you override the host:

import Pusher from "pusher-js";

const pusher = new Pusher(appKey, {
  wsHost: "pubsub.nextmark.ae",
  wsPort: 443,
  forceTLS: true,
  enabledTransports: ["ws", "wss"],
  cluster: "mt1",
});

cluster is still required by pusher-js even though PubSub ignores it — leave it set to anything.

Authenticating private and presence channels

Private and presence channels need a signature. Point the library at your PubSub endpoints:

const pusher = new Pusher(appKey, {
  wsHost: "pubsub.nextmark.ae",
  wsPort: 443,
  forceTLS: true,
  cluster: "mt1",
  userAuthentication: {
    endpoint: "https://pubsub.nextmark.ae/api/authorize",
    transport: "ajax",
    headers: { "X-APP-Key": appKey },
  },
  channelAuthorization: {
    endpoint: "https://pubsub.nextmark.ae/api/channels/authorize",
    transport: "ajax",
    headersProvider: () => ({
      Authorization: `Bearer ${token}`,
      "X-APP-Key": appKey,
    }),
  },
});

The authorize endpoint checks that the channel user is permitted to join that channel before signing, so access control stays on your side.

What stays identical

• Subscribing and binding. pusher.subscribe("orders") and channel.bind("updated", handler) are unchanged.
• Channel types. Public, private and presence channels behave the same way.
• Server publishing. The HTTP trigger API is Pusher-compatible, so server SDKs and signed requests work as-is.
• Client events. client- prefixed events on private channels still work where your plan allows them.

Verifying the switch

1. Point a staging build at PubSub and watch the connection succeed in the browser console with enableLogging: true.
2. Subscribe to a private channel and confirm the authorize endpoint returns a signature rather than a 403.
3. Publish a test event from your backend and confirm it arrives.

If all three pass, the migration is done — there is no second phase.

Why teams in the Gulf do this

PubSub runs from Dubai. For users in the UAE and wider GCC that typically means sub-50ms delivery instead of 200ms or more spent routing to a European or US cluster, and it keeps data inside the UAE for applications with local residency requirements.