Sending messages

Messages are the actual packages of data that get published to a channel. Messages can be chat messages, typing on/off events, location updates, emojis, or anything that your application publishes.

For more details on working with messages, refer to Publishing a Message, or head to PubNub Tour for our interactive sample.

The message doesn't have to be formatted as JSON, but it's usually the best choice. Most developers use the JSON format and most PubNub SDKs automatically stringify JSON objects before publishing. Here is an example of a JSON message:

{
  "from": "user123",
  "message": "Hello, how are you?"
}

Refer to Message Specifications for more information about messages.

Sending a message

Use the publish method to publish messages in a channel. You can publish a message as a string, or send any data (JSON data, or an object), as long as the data size is below 32 KiB.

JavaScript

pubnub.publish({
  message: 'Hello World!',
  channel: 'ch-1',
}, (status, response) => {
  // handle status, response
});

Swift

pubnub.publish(
  channel: "ch-1",
  message: ["text": "Hello World!"]
) { result in
  switch result {
  case let .success(response):
    print("Successful Publish Response: \(response)")
  case let .failure(error):
    print("Failed Publish Response: \(error.localizedDescription)")
  }
}

Java

pubNub.publish()
        .message("Hello World!")
        .channel("ch-1")
        .async(new PNCallback<PNPublishResult>() {
            @Override
            public void onResponse(PNPublishResult result, PNStatus status) {
                if (!status.isError()) {
                    // message is sent
                    Long timetoken = result.getTimetoken(); // message timetoken
                }
            }
});

Unity

pubnub.Publish()
    .Channel("ch-1")
    .Message("Hello World")
    .Async((result, status) => {
        if (!status.Error) {
            Debug.Log(result.Timetoken);
        } else {
            Debug.Log(status.Error);
            Debug.Log(status.ErrorData.Info);
        }
    });

Receive messages

If users are subscribed to a channel, listener events are triggered in the SDK when a new message is received in that channel. The message includes the publish payload, the sender's User ID and the timetoken of when the message was published. Refer to Adding a Listener for details on how to add a listener.

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.

The subscribe listener returns an envelope containing a 17-digit precision Unix time (UTC). To convert the timestamp to a UNIX epoch time (in seconds), divide it by 10,000,000. Or, you can use it directly from 17-digit precision time without converting. The format of localeDateTime is something similar to 7/5/2019, 3:58:43 PM.

Don't miss messages

You only receive messages on channels to which you are subscribed. To avoid missing messages, add the message listener before calling subscribe().

JavaScript

pubnub.addListener({
  message: (message) => {
    // handle message
    const channelName = message.channel;
    const channelGroup = message.subscription;
    const publishTimetoken = message.timetoken;
    const msg = message.message;
    const publisher = message.publisher;

    //show time
    const unixTimestamp = message.timetoken / 10000000;
    const gmtDate = new Date(unixTimestamp * 1000);
    const localeDateTime = gmtDate.toLocaleString();
  }
});

Swift

listener.didReceiveMessage = { message in
  print("Message Received: \(message)")

  let messageDate = message.timetoken.timetokenDate
  print("The message was sent at \(messageDate)")
}

Java

pubNub.addListener(new SubscribeCallback() {
    @Override
    public void message(PubNub pubnub, PNMessageResult message) {
        String channel = message.getChannel(); // the channel for which the message belongs
        String channelGroup = message.getSubscription(); // the channel group or wildcard subscription match (if exists)
        Long publishTimetoken = message.getTimetoken(); // publish timetoken
        JsonElement messagePayload = message.getMessage(); // the message payload
        String publisher = message.getPublisher(); // the publisher

        //show message time
        long timetoken = message.getTimetoken() / 10_000L;
        SimpleDateFormat sdf = new SimpleDateFormat("dd MMM yyyy HH:mm:ss");
        Calendar calendar = Calendar.getInstance();
        calendar.setTimeInMillis(timetoken);
        String localDateTime = sdf.format(calendar.getTimeInMillis());

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Unity

pubnub.SubscribeCallback += (sender, e) => {
  SubscribeEventEventArgs mea = e as SubscribeEventEventArgs;
  if (mea.MessageResult != null) {
    Debug.Log("Channel" + mea.MessageResult.Channel); // the channel to which the message belongs
    Debug.Log("Payload" + mea.MessageResult.Payload); // the message payload
    Debug.Log("Publisher Id: " + mea.MessageResult.IssuingClientId); // the publisher
    Debug.Log("Subscription" + mea.MessageResult.Subscription); // the channel group or wildcard subscription match (if exists)
    Debug.Log("Timetoken" + mea.MessageResult.Timetoken); // publish timetoken

    //show message time
    Debug.Log("Channel: " + mea.MessageResult.Channel); // the channel to which the message belongs
    Debug.Log("Payload: " + mea.MessageResult.Payload); // the message payload
    Debug.Log("Publisher Id: " + mea.MessageResult.IssuingClientId); // the publisher
    Debug.Log("Subscription: " + mea.MessageResult.Subscription); // the channel group or wildcard subscription match (if exists)
    Debug.Log("Timetoken: " + mea.MessageResult.Timetoken); // publish timetoken

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Message Events

The following events are generated when messages are received on channels or channel groups that are subscribed by the clients.

{
    "actualChannel": null,
    "channel": "my_channel_1",
    "message": "Hello World!",
    "publisher": "pn-58e1a647-3e8a-4c7f-bfa4-e007ea4b2073",
    "subscribedChannel": "my_channel_1",
    "subscription": null,
    "timetoken": "14966804541029440"
}