XEP-0280: Message Carbons

XEP-0280: Message Carbons allows you to tell the server to fork a message to all connected resources of a user.

This if useful if you want all your connected resources to stay in sync with each other.

Enabling Message Carbons for Your Session

If you want to make use of Message Carbons, you must first tell it the server:

MessageCarbonsManager messageCarbonsManager = xmppClient.getManager(MessageCarbonsManager.class);
messageCarbonsManager.enableCarbons();

Your server now copies all inbound and outbound chat messages to all connected resources.

Get Outbound Copies of a Message

Let's say, you enabled Message Carbons for your resource A and your other resource B sends a message to one of your contacts, resource A should then receive a copy of B's message.

You can get the original sent message by checking for the Sent extension:

MessageCarbons.Sent sent = message.getExtension(MessageCarbons.Sent.class);
if (sent != null) {
    Forwarded forwardedMessage = sent.getForwardedMessage();
    Stanza stanza = forwardedMessage.getStanza();
    if (stanza instanceof Message) {
        Message originalSentMessage = (Message) stanza;
        // This is the original message, which has been sent by another resource.
    }
}

Get Inbound Copies of a Message

Similarly, if your resource B receives a message (to its full JID), resource A will receive a carbon copy of this message.

You can get the original message (sent to B) by checking for the Received extension:

MessageCarbons.Received received = message.getExtension(MessageCarbons.Received.class);
if (received != null) {
    Forwarded forwardedMessage = received.getForwardedMessage();
    Stanza stanza = forwardedMessage.getStanza();
    if (stanza instanceof Message) {
        Message originalReceivedMessage = (Message) stanza;
        // This is the original message, which has been received by another resource.
    }
}