ASP.NET

Microsoft ASP.NET is a free technology that allows programmers to create dynamic web applications. ASP.NET can be used to create anything from small, personal websites through to large, enterprise-class web applications. All you need to get started with ASP.NET is the free .NET Framework and the free Visual Web Developer. Get the Essential Downloads, and start today.



Microsoft Asp.net

Performance

ASP.NET aims for the overall performance benefits value over other value based script-based technologies (including Classic ASP) by compiling the server-side code to one or more DLL files on the web server.[1] This compilation happens automatically the first time a page is requested (which means the developer need not perform a separate compilation step for pages). This feature provides the ease of development offered by scripting languages with the performance benefits of a compiled binary. However, the compilation might cause a noticeable delay to the web user when the newly-edited page is first requested from the web server.
The ASPX and other resource files are placed in a virtual host on an Internet Information Services server (or other compatible ASP.NET servers; see Other Implementations, below). The first time a client requests a page, the .NET framework parses and compiles the file(s) into a .NET assembly and sends the response; subsequent requests are served from the DLL files. By default ASP.NET will compile the entire site in batches of 1000 files upon first request. If the compilation delay is causing problems, the batch size or the compilation strategy may be tweaked.
Developers can also choose to pre-compile their code before deployment, eliminating the need for just-in-time compilation in a production environment.
[edit]Extension

Microsoft has released some extension frameworks that plug into ASP.NET and extend its functionality. Some of them are:
ASP.NET AJAX
An extension with both client-side as well as server-side components for writing ASP.NET pages that incorporate AJAX functionality.
ASP.NET MVC Framework
An extension to author ASP.NET pages using the MVC architecture.
[edit]ASP.NET compared to ASP Classic

ASP.NET attempts to simplify developers' transition from Windows application development to web development by offering the ability to build pages composed of controls similar to a Windows user interface. A web control, such as a button or label, functions in very much the same way as its Windows counterpart: code can assign its properties and respond to its events. Controls know how to render themselves: whereas Windows controls draw themselves to the screen, web controls produce segments of HTML and JavaScript which form part of the resulting page sent to the end-user's browser.
ASP.NET encourages the programmer to develop applications using an event-driven GUI model, rather than in conventional web-scripting environments like ASP and PHP. The framework attempts to combine existing technologies such as JavaScript with internal components like "ViewState" to bring persistent (inter-request) state to the inherently stateless web environment.
Other differences compared to ASP classic are:
Compiled code means applications run faster with more design-time errors trapped at the development stage.
Significantly improved run-time error handling, making use of exception handling using try-catch blocks.
Similar metaphors to Microsoft Windows applications such as controls and events.
An extensive set of controls and class libraries allows the rapid building of applications, plus user-defined controls allow commonly-used web template, such as menus. Layout of these controls on a page is easier because most of it can be done visually in most editors.
ASP.NET leverages the multi-language capabilities of the .NET Common Language Runtime, allowing web pages to be coded in VB.NET, C#, J#, Delphi.NET, Chrome etc.
Ability to cache the whole page or just parts of it to improve performance.
Ability to use the code-behind development model to separate business logic from presentation.
If an ASP.NET application leaks memory, the ASP.NET runtime unloads the AppDomain hosting the erring application and reloads the application in a new AppDomain.
Session state in ASP.NET can be saved in a Microsoft SQL Server database or in a separate process running on the same machine as the web server or on a different machine. That way session values are not lost when the web server is reset or the ASP.NET worker process is recycled.
Versions of ASP.NET prior to 2.0 were criticized for their lack of standards compliance. The generated HTML and JavaScript sent to the client browser would not always validate against W3C/ECMA standards. In addition, the framework's browser detection feature sometimes incorrectly identified web browsers other than Microsoft's own Internet Explorer as "downlevel" and returned HTML/JavaScript to these clients with some of the features removed, or sometimes crippled or broken. However, in version 2.0, all controls generate valid HTML 4.0, XHTML 1.0 (the default) or XHTML 1.1 output, depending on the site configuration. Detection of standards-compliant web browsers is more robust and support for Cascading Style Sheets is more extensive.
Web Server Controls: these are controls introduced by ASP.NET for providing the UI for the web form. These controls are state managed controls and are WYSIWYG controls.
[edit]Criticism

On IIS 6.0 and lower, pages written using different versions of the ASP framework can't share Session State without the use of third-party libraries. This criticism does not apply to ASP.NET and ASP applications running side by side on IIS 7. With IIS 7, modules may be run in an integrated pipeline that allows modules written in any language to be executed for any request.[2][citation needed]
ASP.NET 2.0 Web Forms produces markup that passes W3C validation, but it is debatable as to whether this increases accessibility, one of the benefits of a semantic XHTML page + CSS representation. Several controls, such as the Login controls and the Wizard control, use HTML tables for layout by default. Microsoft has solved this problem by releasing the ASP.NET 2.0 CSS Control Adapters, a free add-on that produces compliant accessible XHTML+CSS markup.