A very simple client in Groovy (sending and listening for message)

import tigase.jaxmpp.core.client.BareJID
import tigase.jaxmpp.core.client.JID
import tigase.jaxmpp.core.client.SessionObject
import tigase.jaxmpp.core.client.exceptions.JaxmppException
import tigase.jaxmpp.core.client.xmpp.modules.chat.Chat
import tigase.jaxmpp.core.client.xmpp.modules.chat.MessageModule
import tigase.jaxmpp.core.client.xmpp.stanzas.Message
import tigase.jaxmpp.j2se.Jaxmpp

final Jaxmpp contact = new Jaxmpp()

tigase.jaxmpp.j2se.Presence.initialize(contact);

contact.getModulesManager().register(new MessageModule());

contact.getProperties().setUserProperty(SessionObject.USER_BARE_JID, BareJID.bareJIDInstance("admin@atlantiscity"))
contact.getProperties().setUserProperty(SessionObject.PASSWORD, "admin")

contact.getEventBus().addHandler(MessageModule.MessageReceivedHandler.MessageReceivedEvent.class,
        new MessageModule.MessageReceivedHandler() {

            @Override
            public void onMessageReceived(SessionObject sessionObject, Chat chat, Message stanza) {
                System.out.println("message: " + stanza.getBody());
            }
        });

println("Loging in...");

contact.login(true)

if (contact.isConnected()) {
    contact.getModule(MessageModule.class).sendMessage(JID.jidInstance("tigase1@atlantiscity"), "Test", "This is a test")

    Thread.sleep(1 * 10 * 1000)

    contact.disconnect()
}