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BS 娄猪
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What makes AJAX-based clients unique is that the client contains page-specific control logic embedded as JavaScript technology. The page interacts with the JavaScript technology based on events such as the document being loaded, a mouse click, focus changes, or even a timer. AJAX interactions allow for a clear separation of presentation logic from the data. An HTML page can pull in bite-size pieces of data as needed rather than reloading the whole page every time a change needs to be displayed. AJAX will require a different server-side architecture to support this interaction model. Traditionally, server-side web applications have focused on generating HTML documents for every client event resulting in a call to the server. The clients would then refresh and re-render the complete HTML page for each response. Rich web applications focus on a client fetching an HTML document that acts as a template or container into which to inject content, based on client events using XML data retrieved from a server-side component.——是什么使得基于AJAX的客户端如此独特？那就是客户端所嵌入的页面特定的控制逻辑、这些控制逻辑以JavaScript代码的形式存在。页面与JavaScript的交互建立在事件的基础上（比如文档加载事件、鼠标点击事件、焦点变化事件、甚至一个时钟事件）。AJAX清楚的将表示逻辑和数据分离开来、一个HTML网页能够在需要的时候获取以比特为单位的数据片段！这不同于以前的有一点变化就必须刷新整个页面的做法。同时AJAX也需要一种完全不同的服务端架构来支持这种交互模式。以前的传统服务端WEB应用专注于为每一个客户端的每一次请求生成HTML页面、每一次客户端接到响应都要刷新和重新渲染整个页面。而我们所谈的WEB应用专注于客户端把HTML文档当作模版或容器、客户端向这个容器中插入内容、作到这些的原理就是每当客户端发生事件、客户端都可以向服务端发出请求并使用服务端返回的XML数据。
