At least a few Web pages now tout dynamic content. In other words, the content of the Web page changes to match real-world events. In most cases, these Web pages rely on advanced programming techniques and client-side components to do their job. In all cases of true dynamic (or live) content, the client and server require several features as listed below:
The server component must generate events based on a real-world occurrence. For example, when the price of a stock changes, the server-side component monitoring that price will generate an event.
The client application must provide some means for accepting the event. It must listen for the server’s call.
The server must provide some means to detect live connections ...