Master Pages - Examining the Markup Emitted by the ScriptManager Control
Over the past several years, more and more developers have been building AJAX-enabled web applications. An AJAX-enabled website uses a number of related web technologies to offer a more responsive user experience. Creating AJAX-enabled ASP.NET applications is amazingly easy thanks to Microsoft’s ASP.NET AJAX framework. ASP.NET AJAX is built into ASP.NET 3.5 and Visual Studio 2008; it is also available as a separate download for ASP.NET 2.0 applications.
When building AJAX-enabled web pages with the ASP.NET AJAX framework, you must add precisely one ScriptManager control to each and every page that uses the framework. As its name implies, the ScriptManager manages the client-side script used in AJAX-enabled web pages. At a minimum, the ScriptManager emits HTML that instructs the browser to download the JavaScript files that makeup the ASP.NET AJAX Client Library. It can also be used to register custom JavaScript files, script-enabled web services, and custom application service functionality.
If your site uses master pages (as it should), you do not necessarily need to add a ScriptManager control to every single content page; rather, you can add a ScriptManager control to the master page. This tutorial shows how to add the ScriptManager control to the master page. It also looks at how to use the ScriptManagerProxy control to register custom scripts and script services in a specific content page.
Examining the Markup Emitted by the ScriptManager Control
The ScriptManager control emits markup that instructs the browser to download the JavaScript files that makeup the ASP.NET AJAX Client Library. It also adds a bit of inline JavaScript to the page that initializes this library. The following markup shows the content that is added to the rendered output of a page that includes a ScriptManager control:
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The tags instruct the browser to download and execute the JavaScript file at url. The ScriptManager emits three such tags; one references the file WebResource.axd, while the other two reference the file ScriptResource.axd. These files do not actually exist as files in your website. Instead, when a request for either one of these files arrives at the web server, the ASP.NET engine examines the querystring and returns the appropriate JavaScript content. The script provided by these three external JavaScript files constitute the ASP.NET AJAX framework’s Client Library. The other
Tags: .NET, Ajax, Master Page, ScriptManager
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