Setup and event listeners

All chat applications have a notion of a user. It's important to be able to uniquely identify users as they interact with the PubNub Network. Usually, a user is a human end user—a person using an app to interact with a system (via a laptop, phone, tablet, or kiosk).

You use a User ID to uniquely identify each user on the system. Users can connect from multiple devices, such as phones, tablets, desktops, etc., using the same User ID. If a user is connected from multiple devices simultaneously, they will receive the same messages on each device.

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.

Setup

Start by initializing a PubNub object with publishKey, subscribeKey, and userId as required fields. The userId is a string of maximum 64 characters that represents a user in your application.

Your publish and subscribe keys are available in your PubNub Account. Go to the Admin Portal to create your free account.

userId is required

Setting the userId parameter is required to establish a connection to PubNub, ensure that your billing is accurate, and for other features like presence and storage to work as expected.

JavaScript

const pubnub = new PubNub({
  subscribeKey: "mySubscribeKey",
  publishKey: "myPublishKey",
  userId: "john-doe",
  autoNetworkDetection: true, // enable for non-browser environment automatic reconnection
  restore: true, // enable catchup on missed messages
});

Java

PNConfiguration pnConfiguration = new PNConfiguration();
pnConfiguration.setSubscribeKey("mySubscribeKey");
pnConfiguration.setPublishKey("myPublishKey");
pnConfiguration.setUserId("john-doe");

PubNub pubnub = new PubNub(pnConfiguration);

Swift

let config = PubNubConfiguration(
  publishKey: "myPublishKey",
  subscribeKey: "mySubscribeKey",
  userId: "john-doe"
)

let pubnub = PubNub(configuration: config)

Objective-C

PNConfiguration *pnconfig = [PNConfiguration configurationWithPublishKey:@"myPublishKey"
                                             subscribeKey:@"mySubscribeKey"];
pnconfig.uuid = "john-doe";
self.pubnub = [PubNub clientWithConfiguration:pnconfig];

Add event listeners

Events are received in your app using listeners. These listeners allows a single point to receive messages, signals, and presence events. Each event type has its own handler to receive them where you implement your custom app logic to perform actions on events.

The following handlers are available to you:

Handler	Description
Status	Receives events when the client successfully connects (subscribes), or reconnects (in case of connection issues) to channels.
Message	Receives all messages published to all the channels subscribed by the client. The event payload will contain the published message data, publish timetoken, the User ID of the client that published the message and more.
Signal	Receives all signals that are sent to any channels subscribed by the client. The event payload will contain the signal data, signal timetoken, the User ID of the client that published the message and more.
Presence	Receives all presence events that are triggered on any channels subscribed by the client. The event payload will contain the presence event type (join, leave, timeout, state-change), timetoken of the action, the User ID of the client that caused the event, state data (if applicable) and more.
MessageAction	Receives all events when existing messages are annotated (by an action) for any channels subscribed by the client. The event payload will contain the User ID that acted on the message, message action type (such as an emoji reaction), timetoken of the annotated message, timetoken of the action, action value and more.
Objects	Receives all objects events that are emitted when a channel, channel membership, or user metadata is created, updated or removed.

JavaScript

pubnub.addListener({
    message: function(m) {
        // handle message
        var channelName = m.channel; // The channel to which the message was published
        var channelGroup = m.subscription; // The channel group or wildcard subscription match (if exists)
        var pubTT = m.timetoken; // Publish timetoken
        var msg = m.message; // The Payload
        var publisher = m.publisher; //The Publisher
    },
    presence: function(p) {
        // handle presence
        var action = p.action; // Can be join, leave, state-change, or timeout
        var channelName = p.channel; // The channel to which the message was published
        var occupancy = p.occupancy; // Number of users subscribed to the channel
        var state = p.state; // User State

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Java

// SubscribeCallback is an Abstract Java class. It requires that you
// implement all Abstract methods of the parent class even if you don't
// need all the handler methods.


pubnub.addListener(new SubscribeCallback() {
    // PubNub status
    @Override
    public void status(PubNub pubnub, PNStatus status) {
        switch (status.getOperation()) {
            // combine unsubscribe and subscribe handling for ease of use
            case PNSubscribeOperation:
            case PNUnsubscribeOperation:
                // Note: subscribe statuses never have traditional errors,
                // just categories to represent different issues or successes

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Swift

// Create a new listener instance
let listener = SubscriptionListener()

// Add listener event callbacks
listener.didReceiveSubscription = { event in
  switch event {
  case let .messageReceived(message):
    print("Message Received: \(message) Publisher: \(message.publisher ?? "defaultUserID")")
  case let .connectionStatusChanged(status):
    print("Status Received: \(status)")
  case let .presenceChanged(presence):
    print("Presence Received: \(presence)")
  case let .subscribeError(error):
    print("Subscription Error \(error)")
  default:

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Objective-C

// Listener's class should conform to `PNEventsListener` protocol
// in order to have access to available callbacks.

// Adding listener.
[pubnub addListener:self];

// Callbacks listed below.

- (void)client:(PubNub *)pubnub didReceiveMessage:(PNMessageResult *)message {
    NSString *channel = message.data.channel; // Channel on which the message has been published
    NSString *subscription = message.data.subscription; // Wild-card channel or channel on which PubNub client actually subscribed
    NSNumber *timetoken = message.data.timetoken; // Publish timetoken
    id msg = message.data.message; // Message payload
    NSString *publisher = message.data.publisher; // Message publisher
}

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Unity

pubnub.SubscribeCallback += SubscribeCallbackHandler;

//Handler
void SubscribeCallbackHandler(object sender, EventArgs e) {
    SubscribeEventEventArgs mea = e as SubscribeEventEventArgs;

    if (mea.Status != null) {
        switch (mea.Status.Category) {
            case PNStatusCategory.PNUnexpectedDisconnectCategory:
            case PNStatusCategory.PNTimeoutCategory:
                pubnub.Publish()
                    .Channel("my_channel")
                    .Message("Hello from the PubNub Unity SDK")
                    .Async((result, status) => {
                        if(!status.Error){

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