Messaging

Before you begin

Register a QuickBlox account. This is a matter of a few minutes and you will be able to use this account to build your apps.
Configure QuickBlox SDK for your app. Check out our Setup page for more details.
Create a user session to be able to use QuickBlox functionality. See our Authentication page to learn how to do it.
Connect to the Chat server. See our Connection page to learn how to do it.
Create a dialog. See our Dialogs page to learn how to do it.

Visit our Key Concepts page to get an overall understanding of the most important QuickBlox concepts.

Subscribe message events

To add the listener to receive messages in real-time, use the addDialogMessageListener() method. The listener enables the app to listen to the incoming message.

QBChatService chatService = QBChatService.getInstance();
QBIncomingMessagesManager incomingMessagesManager = chatService.getIncomingMessagesManager();

incomingMessagesManager.addDialogMessageListener(new QBChatDialogMessageListener() {
    @Override
    public void processMessage(String dialogId, QBChatMessage chatMessage, Integer senderId) {

    }

    @Override
    public void processError(String dialogId, QBChatException exception, QBChatMessage chatMessage, Integer senderId) {

    }
});

val chatService = QBChatService.getInstance()
val incomingMessagesManager = chatService.incomingMessagesManager

incomingMessagesManager.addDialogMessageListener(object : QBChatDialogMessageListener {
    override fun processMessage(dialogId: String?, chatMessage: QBChatMessage?, senderId: Int?) {

    }

    override fun processError(dialogId: String?, exception: QBChatException?, chatMessage: QBChatMessage?, senderId: Int?) {

    }
})

You can add a message listener for a particular dialog if needed.

privateDialog.addMessageListener(new QBChatDialogMessageListener() {
    @Override
    public void processMessage(String dialogId, QBChatMessage chatMessage, Integer senderId) {

    }

    @Override
    public void processError(String dialogId, QBChatException exception, QBChatMessage chatMessage, Integer senderId) {

    }
});

privateDialog.addMessageListener(object : QBChatDialogMessageListener {
    override fun processMessage(dialogId: String?, qbChatMessage: QBChatMessage?, senderId: Int?) {

    }

    override fun processError(dialogId: String?, e: QBChatException?, qbChatMessage: QBChatMessage?, senderId: Int?) {

    }
})

Send text message

To send a message to a private, group or public dialog, use the code snippet below.

QBChatMessage chatMessage = new QBChatMessage();
chatMessage.setBody("Hello QuickBlox!");
chatMessage.setSaveToHistory(true);

// if you want to use this feature without callbacks:
//try{
//    privateDialog.sendMessage(chatMessage);
//} catch (SmackException.NotConnectedException e) {
//
//}

dialog.sendMessage(chatMessage, new QBEntityCallback<Void>() {
    @Override
    public void onSuccess(Void aVoid, Bundle bundle) {

    }

    @Override
    public void onError(QBResponseException exception) {

    }
});

val chatMessage = QBChatMessage()
chatMessage.body = "Hello QuickBlox!"
chatMessage.setSaveToHistory(true)

// If you want to use this feature without callbacks:
//try{
//    privateDialog.sendMessage(chatMessage);
//} catch (SmackException.NotConnectedException e) {
//
//}

dialog.sendMessage(chatMessage, object : QBEntityCallback<Void> {
    override fun onSuccess(aVoid: Void?, bundle: Bundle?) {

    }

    override fun onError(exception: QBResponseException?) {

    }
})

📘
You need to join the group and public dialog by calling the join() method before you start chatting in a dialog. Once the dialog is joined, you can receive/send messages. See this section to learn how to join the dialog.

There are two ways to send any message to any dialog:

Synchronous.

QBChatMessage chatMessage = new QBChatMessage();
chatMessage.setBody("Hello QuickBlox!");
chatMessage.setSaveToHistory(true);

try {
    dialog.sendMessage(chatMessage);
} catch (SmackException.NotConnectedException exception) {

}

val chatMessage = QBChatMessage()
chatMessage.body = "Hello QuickBlox!"
chatMessage.setSaveToHistory(true)

try {
    dialog.sendMessage(chatMessage)
} catch (exception: SmackException.NotConnectedException) {

}

Asynchronous.

QBChatMessage chatMessage = new QBChatMessage();
chatMessage.setBody("Hello QuickBlox!");
chatMessage.setSaveToHistory(true);

dialog.sendMessage(chatMessage, new QBEntityCallback<Void>() {
    @Override
    public void onSuccess(Void aVoid, Bundle bundle) {

    }

    @Override
    public void onError(QBResponseException exception) {

    }
});

val chatMessage = QBChatMessage()
chatMessage.body = "Hello QuickBlox!"
chatMessage.setSaveToHistory(true)

dialog.sendMessage(chatMessage, object : QBEntityCallback<Void> {
    override fun onSuccess(aVoid: Void?, bundle: Bundle?) {

    }

    override fun onError(e: QBResponseException?) {

    }
})

You can use the most convenient for you, according to your application logic.

📘
Make sure to set the saveToHistory as true to save the message on the server. If the saveToHistory is set as false, the message won't be saved on the server. However, the message will be delivered to the user in either case.

Send message with attachment

Chat attachments are supported by the content API. In order to send a chat attachment, you need to upload the file to QuickBlox cloud storage and obtain a link to the file (file UID). Then you need to include this UID into the chat message and send it.

File filePhoto = new File("image.png");
boolean fileIsPublic = false;
String [] tags = new String[]{"tag_1", "tag_2"};

QBContent.uploadFileTask(filePhoto, fileIsPublic, String.valueOf(tags), new QBProgressCallback() {
    @Override
    public void onProgressUpdate(int i) {
        // i - progress in percents
    }
}).performAsync(new QBEntityCallback<QBFile>() {
    @Override
    public void onSuccess(QBFile file, Bundle bundle) {
        // create a message
        QBChatMessage chatMessage = new QBChatMessage();
        chatMessage.setSaveToHistory(true); // save a message to history

        // attach a photo
        QBAttachment attachment = new QBAttachment("photo");
        attachment.setId(file.getId().toString());
        chatMessage.addAttachment(attachment);

        // send the message
        // ...
    }

    @Override
    public void onError(QBResponseException exception) {
        // error
    }
});

val filePhoto = File("image.png")
val fileIsPublic = false
val tags = arrayOf("tag_1", "tag_2")

QBContent.uploadFileTask(filePhoto, fileIsPublic, tags.toString()) {
    // i - progress in percents
}.performAsync(object : QBEntityCallback<QBFile> {
    override fun onSuccess(file: QBFile?, bundle: Bundle?) {
        // create a message
        val chatMessage = QBChatMessage()
        chatMessage.setSaveToHistory(true) // Save a message to history

        // attach a photo
        val attachment = QBAttachment("photo")
        attachment.id = file.id.toString()
        chatMessage.addAttachment(attachment)

        // send the message
        // ...
    }

    override fun onError(exception: QBResponseException?) {
        // error
    }
})

The same flow is supported on the message receiver's side. When you receive a message with an attachment, you need to get the file UID, and then download the file from the cloud storage.

// QBChatDialogMessageListener
@Override
public void processMessage(String dialogId, QBChatMessage chatMessage, Integer integer) {
    // count of attachments might be more than one
    for (QBAttachment attachment : chatMessage.getAttachments()) {
        String fileId = attachment.getId();

        // download a file
        QBContent.downloadFile(fileId).performAsync(new QBEntityCallback<InputStream>() {
            @Override
            public void onSuccess(InputStream inputStream, Bundle bundle) {
                // process file
            }

            @Override
            public void onError(QBResponseException exception) {

            }
        });
    }
}

// QBChatDialogMessageListener 
override fun processMessage(dialogId: String, chatMessage: QBChatMessage, integer: Int?) {
    // count of attachments might be more than one
    for (attachment in qbChatMessage.attachments) {
        val fileId = attachment.id

        // download a file
        QBContent.downloadFile(fileId).performAsync(object : QBEntityCallback<InputStream> {
            override fun onSuccess(inputStream: InputStream?, bundle: Bundle?) {
                // process file
            }

            override fun onError(exception: QBResponseException?) {

            }
        })
    }
}

Send message with extra data

You have an option to extend the message with additional fields. Specify one or more key-value items in the message. Using these items, you can implement the ability for a user to send self-location information to another user or notification messages signifying that a user has left a group, etc.

QBChatMessage chatMessage = new QBChatMessage();
chatMessage.setSaveToHistory(true);
chatMessage.setBody("How are you today?");
chatMessage.setProperty("customParam1", "book");
chatMessage.setProperty("customParam2", "21");
        
qbChatDialog.sendMessage(chatMessage, new QBEntityCallback<Void>() {
    @Override
    public void onSuccess(Void void, Bundle bundle) {
                
    }

    @Override
    public void onError(QBResponseException exception) {

    }
});

val chatMessage = QBChatMessage()
chatMessage.setSaveToHistory(true)
chatMessage.isMarkable = true
chatMessage.body = "How are you today?"
chatMessage.setProperty("customParam1", "book")
chatMessage.setProperty("customParam2", "21")

qbChatDialog.sendMessage(chatMessage, object : QBEntityCallback<Void> {
    override fun onSuccess(aVoid: Void?, bundle: Bundle?) {

    }

    override fun onError(exception: QBResponseException?) {

    }
})

Argument	Required	Description
qbChatMessage	yes	Specifies message fields that should be set.

Set the following fields of the qbChatMessage:

Field	Required	Description
saveToHistory	no	Specifies if the message will be saved on the server. Set the `saveToHistory` as `true` to save the message on the server.
body	no	A message text.
property	no	Extra data. Specify any key-value pairs. In each pair, the key and value are both string values.

Retrieve chat history

Every dialog stores its chat history that you can retrieve using the getDialogMessages() method. The request below will return messages for a specific dialog limited to the 100 dialogs on the page.

QBMessageGetBuilder messageGetBuilder = new QBMessageGetBuilder();
messageGetBuilder.setLimit(100);

// if you want to retrieve messages using filtering:
//messageGetBuilder.gte("date_sent", "508087800");
//messageGetBuilder.lte("date_sent", "1170720000");
//messageGetBuilder.markAsRead(false);

QBRestChatService.getDialogMessages(chatDialog, messageGetBuilder).performAsync(new QBEntityCallback<ArrayList<QBChatMessage>>() {
    @Override
    public void onSuccess(ArrayList<QBChatMessage> chatMessages, Bundle bundle) {

    }

    @Override
    public void onError(QBResponseException exception) {

    }
});

val messageGetBuilder = QBMessageGetBuilder()
messageGetBuilder.limit = 100

// If you want to retrieve messages using filtering:
//messageGetBuilder.gte("date_sent", "508087800")
//messageGetBuilder.lte("date_sent", "1170720000")
//messageGetBuilder.markAsRead(false)

QBRestChatService.getDialogMessages(chatDialog, messageGetBuilder).performAsync(object : QBEntityCallback<ArrayList<QBChatMessage>> {
    override fun onSuccess(chatMessages: ArrayList<QBChatMessage>?, bundle: Bundle?) {

    }

    override fun onError(exception: QBResponseException?) {

    }
})

🚧
If you want to mark all retrieved chat messages as a read, set the markAsRead parameter as true. If you decide not to mark chat messages as read, just set markAsRead parameter as false.

If you want to retrieve only messages updated after some specific date time and order the search results, you can apply operators. This is useful if you cache messages somehow and do not want to obtain the whole list of messages on every app start. Thus, you can apply search and sort operators to list messages on the page so that it is easier to view specific messages. The operators are set in the QBMessageGetBuilder class.

If you want to get a paginated list of messages from the server, you can set the following pagination parameters in the QBMessageGetBuilder class.

Pagination parameter	Description
skip	Skip N records in search results. Useful for pagination. Default (if not specified): 0.
limit	Limit search results to N records. Useful for pagination. Default value: 100.

Search operators

You can use search operators to search for the exact data that you need.

Search operators	Applicable to types	Applicable to fields	Description
lt(field, searchValue)	number, string, date	date_sent, sender_id, recipient_id, updated_at	Less Than operator.
lte(field, searchValue)	number, string, date	date_sent, sender_id, recipient_id, updated_at	Less Than or Equal to operator.
gt(field, searchValue)	number, string, date	date_sent, sender_id, recipient_id, updated_at	Greater Than operator.
gte(field, searchValue)	number, string, date	date_sent, sender_id, recipient_id, updated_at	Greater Than or Equal to operator.
ne(field, searchValue)	number, string, date	_id, message, date_sent, sender_id, recipient_id	Not Equal to operator.
in(field, searchValue)	number, string, date	date_sent, sender_id, recipient_id	IN array operator.
nin(field, searchValue)	number, string, date	date_sent, sender_id, recipient_id	Not IN array operator.
or(field, searchValue)	number, string, date	date_sent, sender_id, recipient_id	All records that contain a value 1 or value 2.
ctn(field, searchValue)	string	message	All records that contain a particular substring.

Sort operators

You can use sort operators to order the search results.

Sort operator	Applicable to types	Description
sortAsc(field)	All types	Search results will be sorted in ascending order by the specified field.
sortDesc(field)	All types	Search results will be sorted in descending order by the specified field.

Update message

To update a message text , use the updateMessage() method below.

QBMessageUpdateBuilder messageUpdateBuilder = new QBMessageUpdateBuilder();
messageUpdateBuilder.updateText("Updated message body string");

// if you want to mark message as Delivered or Read on the server
//messageUpdateBuilder.markDelivered();
//messageUpdateBuilder.markRead();

QBRestChatService.updateMessage(message.getId(), message.getDialogId(), messageUpdateBuilder).performAsync(new QBEntityCallback<Void>() {
    @Override
    public void onSuccess(Void aVoid, Bundle bundle) {

    }

    @Override 
    public void onError(QBResponseException exception) {

    }
});

val messageUpdateBuilder = QBMessageUpdateBuilder()
messageUpdateBuilder.updateText("Updated message body string")

// If you want to mark message as Delivered or Read on the server
//messageUpdateBuilder.markDelivered();
//messageUpdateBuilder.markRead();

QBRestChatService.updateMessage(message.id, message.dialogId, messageUpdateBuilder).performAsync(object : QBEntityCallback<Void> {
    override fun onSuccess(aVoid: Void?, bundle: Bundle?) {

    }

    override fun onError(exception: QBResponseException?) {

    }
})

📘
You can also use the updateMessage() method to mark message as delivered or read on the server. As a result, the ID of the user who has received the message or read it will be added to the array of delivered_ids/read_ids field, in the message model. However, the server won't notify the sender with delivery or read receipt that informs about the change in the message model.

Delete message

Any user in the occupantIDs can delete a message from the dialog. As a result, the message will be deleted from the current user history, without affecting the histories of other users.

The owner of the dialog can completely remove messages from all users' histories. This is achieved by setting the forceDelete parameter to true.

Set<String> messagesIds = new HashSet<>();
messagesIds.add("456abcdefg9876lmnop23qrst");
messagesIds.add("456gfedcba5432ponml09xyz0");

boolean forceDelete = false;

QBRestChatService.deleteMessages(messagesIds, forceDelete).performAsync(new QBEntityCallback<Void>() {
    @Override
    public void onSuccess(Void aVoid, Bundle bundle) {

    }

    @Override
    public void onError(QBResponseException exception) {

    }
});

val messagesIds = HashSet<String>()
messagesIds.add("456abcdefg9876lmnop23qrst")
messagesIds.add("456gfedcba5432ponml09xyz0")

val forceDelete = false

QBRestChatService.deleteMessages(messagesIds, forceDelete).performAsync(object : QBEntityCallback<Void> {
    override fun onSuccess(aVoid: Void?, bundle: Bundle?) {

    }

    override fun onError(exception: QBResponseException?) {

    }
})

Argument	Required	Description
messagesIDs	yes	A set of strings with messages IDs.
forceDelete	yes	A boolean parameter. Delete message for everyone. Set it as `true` to perform. Only the owner can do it.

Check if a message is sent

The message is considered as sent if it has been delivered to the server. To get to know that a message has been delivered to the server, make sure to enable a stream management before connecting to the Chat server. See this section to learn how to enable the stream management.

Thus, to track the event when your message becomes sent, use the QBChatDialogMessageSentListener.

QBChatDialogMessageSentListener messageSentListener = new QBChatDialogMessageSentListener() {
    @Override
    public void processMessageSent(String dialogId, QBChatMessage chatMessage) {

    }

    @Override
    public void processMessageFailed(String dialogId, QBChatMessage chatMessage) {

    }
};

chatDialog.addMessageSentListener(messageSentListener);

val messageSentListener = object : QBChatDialogMessageSentListener {
    override fun processMessageSent(dialogId: String?, chatMessage: QBChatMessage?) {

    }

    override fun processMessageFailed(dialogId: String?, chatMessage: QBChatMessage?) {

    }
}

chatDialog.addMessageSentListener(messageSentListener)

🚧
You should enable Stream Management before you do the chatService.login() because the Stream Management is initialized while Chat login is performed.
The Stream Management defines an extension for active management of a stream between a client and server, including features for stanza acknowledgments.

Mark message as delivered

As a sender, you may want to be informed that a message has been successfully delivered to the recipient. The mark-as-delivered functionality allows to notify the sender about message delivery.

To track the event when the message has been delivered to the user, use the QBMessageStatusListener().

QBMessageStatusesManager messageStatusesManager = QBChatService.getInstance().getMessageStatusesManager();
messageStatusesManager.addMessageStatusListener(new QBMessageStatusListener() {
    @Override
    public void processMessageDelivered(String messageId, String dialogId, Integer userId) {

    }
});

val messageStatusesManager = QBChatService.getInstance().messageStatusesManager
messageStatusesManager.addMessageStatusListener(object : QBMessageStatusListener {
    override fun processMessageDelivered(messageId: String?, dialogId: String?, userId: Int?) {

    }
})

Use the deliverMessage() method to mark a message as delivered. As a result, the server will notify a sender about the delivery receipt.

// to manually notify the server that the message has been delivered to you
try {
    dialog.deliverMessage(message);
} catch (XMPPException | SmackException.NotConnectedException e) {

}

// to manually notify the server that the message has delivered to you
try {
    dialog.deliverMessage(message)
} catch (e: XMPPException) {

} catch (e: SmackException.NotConnectedException) {
    
}

A message can be marked as delivered automatically by the server once a message is successfully delivered to the recipient. Set the markable as true using the sendMessage() method if you want, as a sender, to receive message delivery receipts from other recipients. Thus, the markable parameter enables the sender to request the delivery receipt. It also enables the recipient to confirm the message delivery. However, if markable is false or omitted, then you can notify a sender about the delivery receipt using the deliverMessage() method.

QBChatMessage chatMessage = new QBChatMessage();
chatMessage.setBody("This is your message body");
chatMessage.setMarkable(true); // to be markable as delivered
chatMessage.setSaveToHistory(true); // to be saved in chat history

qbChatDialog.sendMessage(chatMessage, new QBEntityCallback<Void>() {
    @Override
    public void onSuccess(Void aVoid, Bundle bundle) {
        // message successfully sent
    }

    @Override
    public void onError(QBResponseException exception) {
        // message Sending Error
    }
});

val qbChatMessage = QBChatMessage()
qbChatMessage.body = "This is your message body"
qbChatMessage.isMarkable = true //To be markable as delivered
qbChatMessage.setSaveToHistory(true) // To be saved in chat history

qbChatDialog.sendMessage(qbChatMessage, object : QBEntityCallback<Void> {
    override fun onSuccess(aVoid: Void?, p1: Bundle?) {
        // message successfully sent
    }

    override fun onError(exception: QBResponseException?) {
        // message Sending Error
    }
})

📘
Make sure to understand, that marking-as-delivered operation just confirms the fact of message delivery. The message acquires the delivered status when the message delivered event is received.
When a message is marked as delivered, the IDs of users who have received the message are stored in the message model, on the server. Thus, you can request a chat history from the server to get to know who received the message using the getDialogMessages() method. See this section to learn how to retrieve chat history.

Mark message as read

As a sender, you may want to be informed that a message has been read by the recipient. The mark-as-read functionality allows to notify the sender that a message has been read.

To track the event when the message has been read by the user, use the QBMessageStatusListener().

QBMessageStatusesManager messageStatusesManager = QBChatService.getInstance().getMessageStatusesManager();
messageStatusesManager.addMessageStatusListener(new QBMessageStatusListener() {
    @Override
    public void processMessageRead(String messageId, String dialogId, Integer userId) {

    }
});

val messageStatusesManager = QBChatService.getInstance().messageStatusesManager
messageStatusesManager.addMessageStatusListener(object : QBMessageStatusListener {
    override fun processMessageRead(messageId: String?, dialogId: String?, userId: Int?) {

    }
})

Use the readMessage() method to mark a message as read. As a result, the server will notify a sender about the read receipt.

// to notify the server about displaying message to the user
try {
    dialog.readMessage(message);
} catch (XMPPException | SmackException.NotConnectedException exception) {

}

// to notify the server about displaying message to the user
try {
    dialog.readMessage(message)
} catch (exception: XMPPException) {

} catch (exception: SmackException.NotConnectedException) {

}

📘
When a message is marked as read, the IDs of users who have read the message are stored in the message model, on the server. Thus, you can request a chat history from the server to get to know who read the message using the getDialogMessages() method. See this section to learn how to retrieve chat history.

Send typing indicators

You may want, as a sender, to let the recipient know that you are typing the message or have stopped typing the message. Use typing indicators as a form of chat-specific presence. Typing indicators allow to indicate if users are typing messages in a dialog at the moment.

There are the following typing notifications supported.

typing. The user is composing a message. The user is actively interacting with a message input interface specific to this chat session (e.g. by typing in the input area of a chat window).
stopped. The user had been composing but now has stopped. The user has been composing but has not interacted with the message input interface for a short period of time (e.g. 30 seconds).

To track the event when the sender is typing the message, use the QBChatDialogTypingListener().

QBChatDialogTypingListener typingListener = new QBChatDialogTypingListener() {
    @Override
    public void processUserIsTyping(String dialogId, Integer userId) {

    }
};

dialog.addIsTypingListener(typingListener);

val typingListener = object : QBChatDialogTypingListener {
    override fun processUserIsTyping(dialogId: String?, userId: Int?) {

    }
}

dialog.addIsTypingListener(typingListener)

To track the event when the sender has stopped typing the message, use the QBChatDialogTypingListener().

QBChatDialogTypingListener typingListener = new QBChatDialogTypingListener() {
    @Override
    public void processUserStopTyping(String dialogId, Integer userId) {

    }
};

dialog.addIsTypingListener(typingListener);

val typingListener = object : QBChatDialogTypingListener {
    override fun processUserStopTyping(dialogId: String?, userId: Int?) {

    }
}

dialog.addIsTypingListener(typingListener)

To notify a recipient that a sender is typing the message, use the sendIsTyping() method.

// when user starts typing in the message input field
try {
    dialog.sendIsTypingNotification();
} catch (XMPPException | SmackException.NotConnectedException exception) {

}

// When user starts typing in the message input field
try {
    dialog.sendIsTypingNotification()
} catch (exception: XMPPException) {

} catch (exception: SmackException.NotConnectedException) {

To notify a recipient that a sender had been composing a message but now has stopped, use the sendStopTypingNotification() method.

// when the user stops typing and not interact with message input field
try {
    dialog.sendStopTypingNotification();
} catch (XMPPException | SmackException.NotConnectedException exception) {

}

// When the user stops typing and not interact with message input field
try {
    dialog.sendStopTypingNotification()
} catch (exception: XMPPException) {

} catch (exception: SmackException.NotConnectedException) {

Send system messages

There is a way to send system messages to other users about some events. For example, a system message can be sent when a user has joined or left a group dialog. These messages are handled over a separate channel and are not be mixed up with regular chat messages. Thus, they are handled by the QBSystemMessageListener listener. See how to add the listener in the snippet below.

System messages are also not shown in the dialog history and, consequently, are not stored on the server. This means that these messages will be delivered only to online users. Send system messages using the sendSystemMessage() method.

private QBSystemMessagesManager systemMessagesManager;
private QBSystemMessageListener systemMessageListener;
 
void setSystemMessagesManager() {
    systemMessagesListener = new QBSystemMessageListener(){
        @Override
        public void processMessage(QBChatMessage chatMessage) {
            // new System Message Received
        }

        @Override
        public void processError(QBChatException exception, QBChatMessage chatMessage) {
            // new System Message Received with Exception
        }
    };
    systemMessagesManager = QBChatService.getInstance().getSystemMessagesManager();
    systemMessagesManager.addSystemMessageListener(systemMessagesListener);
}

void sendSystemMessage(QBChatDialog chatDialog, Integer opponentId) {
    QBChatMessage chatMessage = new QBChatMessage();

    chatMessage.setDialogId(chatDialog.getDialogId());
    chatMessage.setRecipientId(opponentId);

    chatMessage.setProperty("custom_property_1", "custom_value_1");
    chatMessage.setProperty("custom_property_2", "custom_value_2");
    chatMessage.setProperty("custom_property_3", "custom_value_3");

    try {
        systemMessagesManager.sendSystemMessage(chatMessage);
    } catch (SmackException.NotConnectedException exception) {
        exception.printStackTrace();
    }
}

private lateinit var systemMessagesListener: QBSystemMessageListener
private lateinit var systemMessagesManager: QBSystemMessagesManager
    
fun setSystemMessagesManager() {
    systemMessagesListener = object : QBSystemMessageListener {
        override fun processMessage(chatMessage: QBChatMessage) {
            // new System Message Received
    }

        override fun processError(exception: QBChatException, chatMessage: QBChatMessage) {
            // new System Message Received with Exception
        }
    }
    systemMessagesManager = QBChatService.getInstance().systemMessagesManager
    systemMessagesManager.addSystemMessageListener(systemMessagesListener)
}

fun sendSystemMessage(qbChatDialog: chatDialog, opponentId: Int?) {
    val chatMessage = QBChatMessage()

    chatMessage.dialogId = chatDialog.dialogId
    chatMessage.recipientId = opponentId

    chatMessage.setProperty("custom_property_1", "custom_value_1")
    chatMessage.setProperty("custom_property_2", "custom_value_2")
    chatMessage.setProperty("custom_property_3", "custom_value_3")

    try {
        systemMessagesManager.sendSystemMessage(chatMessage)
    } catch (exception: SmackException.NotConnectedException) {
        exception.printStackTrace()
    }
}

Argument	Description
qbChatMessage	Specifies system message fields that should be set.

Set the following fields of the qbChatMessage:

Field	Required	Description
recipientId	yes	ID of the recipient.
dialogId	no	ID of the dialog.
property	no	Extra data. Specify any key-value pairs. In each pair, the key and value are both string values.