【正文】 request. However, you can design your Web page to target a specific browser, such as Microsoft Inter Explorer 6, and take advantage of the features of that browser. supports mobile controls for Webenabled devices such as cellular phones, handheld puters, and personal digital assistants (PDAs). Web pages are pletely objectoriented. Within Web pages you can work with HTML elements using properties, methods, and events. The page framework removes the implementation details of the separation of client and server inherent in Webbased applications by presenting a unified model for responding to client events in code that runs at the server. The framework also automatically maintains the state of a page and the controls on that page during the page processing life cycle. The page and controls framework also enables you to encapsulate mon UI functionality in easytouse, reusable controls. Controls are written once, can be used in many pages, and are integrated into the Web page that they are placed in during rendering. The page and controls framework also provides features to control the overall look and feel of your Web site via themes and skins. You can define themes and skins and then apply them at a page level or at a control level. In addition to themes, you can define master pages that you use to create a consistent layout for the pages in your application. A single master page defines the layout and standard behavior that you want for all the pages (or a group of pages) in your application. You can then create individual content pages that contain the pagespecific content you want to display. When users request the content pages, they merge with the master page to produce output that bines the layout of the master page with the content from the content page. All code is piled, which enables strong typing, performance optimizations, and early binding, among other benefits. Once the code has been 15 piled, the mon language runtime further piles code to native code, providing improved performance. includes a piler that will pile all your application ponents including pages and controls into an assembly that the hosting environment can then use to service user requests. In addition to the security features of .NET, provides an advanced security infrastructure for authenticating and authorizing user access as well as performing other securityrelated tasks. You can authenticate users using Windows authentication supplied by IIS, or you can manage authentication using your own user database using forms authentication and membership. Additionally, you can manage the authorization to the capabilities and information of your Web application using Windows groups or your own custom role database using roles. You can easily remove, add to, or replace these schemes depending upon the needs of your application. always runs with a particular Windows identity so you can secure your application using Windows capabilities such as NTFS Access Control Lists (ACLs), database permissions, and so on. For more information on the identity of , provides intrinsic state management functionality that enables you to store information between page requests, such as customer information or the contents of a shopping cart. You can save and manage applicationspecific, sessionspecific, pagespecific, userspecific, and developerdefined information. This information can be independent of any controls on the page. offers distributed state facilities, which enable you to manage state information across multiple instances of the same application on one puter or on several puters. applications use a configuration system that enables you to define configuration settings for your Web server, for a Web site, or for individual 16 applications. You can make configuration settings at the time your applications are deployed and can add or revise configuration settings at any time with minimal impact on operational Web applications and servers. configuration settings are stored in XMLbased files. Because these XML files are ASCII text files, it is simple to make configuration changes to your Web applications. You can extend the configuration scheme to suit your requirements. includes features that enable you to monitor health and performance of your application. health monitoring enables reporting of key events that provide information about the health of an application and about error conditions. These events show a bination of diagnostics and monitoring characteristics and offer a high degree of flexibility in terms of what is logged and how it is logged. supports two groups of performance counters accessible to your applications: ? The system performance counter group ? The application performance counter group takes advantage of the runtime debugging infrastructure to provide crosslanguage and crossputer debugging support. You can debug both managed and unmanaged objects, as well as all languages supported by the mon language runtime and script languages. In addition, the page framework provides a trace mode that enables you to insert instrumentation messages into your Web pages. supports XML Web services. An XML Web service is a ponent containing business functionality that enables applications to exchange information across firewalls using standards like HTTP and XML messaging. XML Web services are not tied to a particular ponent technology or objectcalling convention. As a result, programs written in any language, using any ponent model, and running on any operating system can access XML Web services. 17 includes an extensible hosting environment that controls the life cycle of an application from when a user first accesses a resource (such as a page) in the application to