The Real-Time Web
As you learned in Chapter 11, HTTP is designed around a request-response model. All HTTP communications are initiated by a client making a request to a server. The server then responds to the client with the requested data. In the early days of the web, this model worked because web sites were static HTML pages that linked to other static HTML pages. However, the web has evolved, and sites are no longer just static pages.
Technologies like Ajax have made the web dynamic and data-driven, and enabled a class of web applications that rival native applications. Ajax calls still make HTTP requests, but instead of retrieving ...