TAILIEUCHUNG - ASP.NET 4 Unleased - p 171

Tầm nhìn Ajax là một công nghệ phía máy chủ cho các ứng dụng web xây dựng. Hầu như tất cả các công việc xảy ra trên máy chủ web và không phải là trình duyệt web. Bất cứ khi nào bạn thực hiện một hành động trong một trang , chẳng hạn như cách nhấn vào một nút hoặc sắp xếp một trang GridView, toàn bộ phải được đăng lại cho máy chủ web. | 1674 CHAPTER 38 Using Server-Side AJAX The Ajax Vision is a server-side technology for building web applications. Almost all the work happens on the web server and not the web browser. Whenever you perform an action in an page such as clicking a button or sorting a GridView the entire page must be posted back to the web server. Any significant action on a page results in a postback. If you think about it this is incredibly inefficient. When you perform a postback in an page the entire page must be transported across the Internet from browser to server. Next the .NET class that corresponds to the page must re-render the entire page again from scratch. Finally the finished page must be sent back across the Internet to the browser. This whole long slow agonizing process must occur even if you are updating a tiny section of the page. Using a server-side technology such as results in a bad user experience. Every time a user performs some action on a page the universe temporarily freezes. Whenever you perform a postback the browser locks the page jumps and the users must wait patiently twiddling their thumbs while the page is reconstructed. All of us have grown accustomed to this awful user experience however we would never design our desktop applications in the same way. When the members of the team invented in the late 1990s there was good reason to embrace the server side. Getting a page that was written in JavaScript to work consistently across different browsers and even across different versions of the same browser was difficult. The server side was safe and reliable. However we ve reached a tipping point. Web developers are discovering that if they want to build truly great applications they need to leave the safety of the server side and enter the wilds of the client side. Today s popular web applications such as Facebook Google Gmail and YouTube all rely heavily on Ajax-based functionality. An Ajax .

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