AJAX driven simple chat

AJAX driven simple chat is a PHP class that can be used to implement a simple Web based chat system that uses AJAX to update the chat dialog display area without reloading the whole page. The class generates a page with a Web form to submit each chat line that the users type. The chat lines are sent to the server using a XMLHttpRequest object. The chat lines are received by a server side script that uses the class to store what each user entered, and the class responds by outputting the chat text to be displayed in the users' browsers.