Smack is a library for communicating with XMPP servers to perform
instant messaging and chat.

Smack Key Advantages

Extremely simple to use, yet powerful API. Sending a text message to a user
can be accomplished in three lines of code:

XMPPConnection connection = new XMPPConnection("jabber.org");
connection.login("mtucker", "password");
connection.createChat("jsmith@jivesoftware.com").sendMessage("Howdy!");

Doesn't force you to code at the packet level, as other libraries do. Smack provides
intelligent higher level constructs such as the Chat and GroupChat
classes, which let you program more efficiently.

Does not require that you're familiar with the XMPP XML format, or even that you're familiar with XML.

Provides easy machine to machine communication. Smack lets you set any number of properties on
each message, including properties that are Java objects.

Open Source under the Apache License, which means you can incorporate Smack into your commercial or
non-commercial applications.