Sending text messages

Hello All, I hope i have posted this question on the right forum. I want to build a live video chat application in ActionScript 3 and FMS. I am really unsure what is the best alternative to go for, for the users to send text data messages.

I have read tutorials on the the SharedObject.send method and the For the client to speak to the Server. However, i am still no clearer in my mind what the difference is? Please forgive me for the simplicity of this question but i am a newbie could these two alternatives work in a chat application were users are constantly send messages back and forth?