Presence Events

PubNub triggers presence events as users come online or go offline from the application.

Clients can receive these events directly or use webhooks to keep a user's online/offline status up to date. Use these events to keep track of active/inactive users and the total occupancy of the channel.

Presence webhooks

PubNub can invoke a REST endpoint on your server when presence events occur. For more information, refer to Presence Webhooks.

Presence Event Types

There are five main types of presence events:

joinFires when a user subscribes to a channel.
leaveFires when a user unsubscribes from a channel.
timeoutFires when a connection to a channel is lost and the subscriber hasn't been seen in 300 seconds.
state-changeFires anytime the user's state is changed.
intervalFires in interval mode to provide an occupancy count and optionally include delta changes.

Adding Presence Listeners

The Event listener and its handlers are briefly mentioned in the Application Setup section. Receiving the Presence events requires a Presence handler in the listener. Presence events will be received in this handler for all channels on which the client is subscribed and has enabled Presence events. In this handler, you have the following data available to you:

User ID / UUID

User ID is also referred to as UUID/uuid in some APIs and server responses but holds the value of the userId parameter you set during initialization.

Event DataDescription
actionThe Presence event action type: join, leave, timeout, state-change, interval
channelThe channel on which the Presence action happened
occupancyThe total number of subscribers on the channel when the event occurred
uuidThe User ID of the client that published the message
timetokenThe timetoken when the Presence action took place (when PubNub published the event)
dataThe state of the client that changed
subscriptionThe channel group or wildcard subscription pattern that the channel belongs to (if applicable)
presence: function(event) {
var action = event.action;
var channelName =;
var occupancy = event.occupancy;
var eventTimetoken = event.timetoken;
var occupantUserId = event.uuid;
var state = event.state;
var subscribeManager = event.subscription;

Subscribing to Presence Channel

Once you've added presence listeners, call subscribe with the withPresence flag enabled to receive presence events. Your client will now start receiving presence events in real time as users join and leave channels.

When you enable the withPresence flag, the SDK automatically subscribes you to presence channels. These channels are sister channels where presence events are published by PubNub. If you don't wish to subscribe to all presence channels in your list, you can subscribe to individual channels by appending pnpres to the channel name. For example, the presence channel for ch1 is ch1-pnpres.

channels: ["chats.room1", "chats.room2"],
withPresence: true

If you want to subscribe to a bunch of channels at once but you only want to listen for presence events on some of them, you'll invoke two separate subscribe requests.

// do listen for presence events for these channels
channels: ["chats.team1", "chats.dept5"],
withPresence: true

// do not listen for presence events for these channels
pubnub.subscribe({channels: ["alerts.system", "alerts.team1"]});

Presence Event Modes

The channel presence mode indicates when presence events are triggered for that channel. There are two modes: announce and interval. The mode is determined by the occupancy count (total actively subscribed clients on that channel) in relation to the Presence Announce Max setting on the Admin Portal.

This feature prevents high occupancy channels from becoming too noisy with presence events. If you require the announce mode to be in effect past 100 occupants, please contact PubNub Support.

Announce Mode

If the channel occupancy is less than the Announce Max setting (defaults to 20), the channel is in announce mode. In this mode, join, leave, timeout and state-change events are sent to subscribed clients as and when they're triggered.

User ID / UUID

User ID is also referred to as UUID/uuid in some APIs and server responses but holds the value of the userId parameter you set during initialization.

"action": "join",
"channel": "chats.room1",
"subscribedChannel": "chats.room1-pnpres",
"timetoken": "15119466699655811",
"occupancy": 2,
"uuid": "user123",
"timestamp": 1511946669

Interval Mode

When a channel's occupancy exceeds the Announce Max setting, the channel goes into interval mode. In this mode, the join, leave, timeout events are replaced by an interval event which is sent every few seconds with the total occupancy on the channel. The Interval setting is also configurable for the settings page.

Triggering state-change events

The state-change events are always triggered regardless of which presence mode is active on a channel.

Presence Deltas

Additionally, you can enable the Presence Deltas setting from the Admin Portal. When this flag is enabled, interval events will also include a list of clients (User IDs) that joined, left or timed-out since the last interval event. The following is a simple representation of a Presence Delta event payload.

"action": "interval",
"channel": "chats.megachat",
"occupancy": 27,
"join": ["user123","user88"],
"leave": ["user20", "user11", "user14"],
"timeout": ["user42"],
"subscribedChannel": "chats.megachat-pnpres",
"timestamp": 1511947739,
"timetoken": "15119477396210903"

If a Presence Delta payload exceeds 32KB, the here_now_refresh flag indicates that you should use the Here Now API if you wish to retrieve the list of client User IDs that may have triggered a join, leave or timeout since the last interval.

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