I've tried the Chapter 6 - Gab Project.
And I've implemented session attachment to BOSH.
But I'm having problem with multiple chat windows/tabs in my browser.
When a user send message to someone, the message that him/her sent will not be broadcast to another windows/tabs.
I've try to manipulate a user to send message to him/herself like this:

var myOwnMessage = $msg({to: myJid, "type": "chat"}).c('body').t(body).up().c('active', {xmlns: "http://jabber.org/protocol/chatstates"});
Chat.connection.send(myOwnMessage);

but the message seems not delivered.
What should I do to accomplish this task?
Thanks in advance :)

You need to send the message to the bare JID instead of the full JID. A full JID will deliver the message only to a particular resource. A bare JID will deliver it to the account's session manager, which will deliver it to one or more full JIDs. Most servers will deliver it to the highest priority level and to all sessions tied with that priority level.