ASP.NET
ASP.NET is a web application framework developed and marketed by Microsoft to allow programmers to build dynamic web sites, web applications and web services. It was first released in January 2002 with version 1.0 of the .NET Framework, and is the successor to Microsoft's Active Server Pages (ASP) technology. ASP.NET is built on the Common Language Runtime (CLR), allowing programmers to write ASP.NET code using any supported .NET language. The ASP.NET SOAP extension framework allows ASP.NET components to process SOAP messages.
History
After the release of Internet Information Services 4.0 in 1997, Microsoft began researching possibilities for a new web application model that would solve common complaints about ASP, especially with regard to separation of presentation and content and being able to write "clean" code. Mark Anders, a manager on the IIS team, and Scott Guthrie, who had joined Microsoft in 1997 after graduating from Duke University, were tasked with determining what that model would look like. The initial design was developed over the course of two months by Anders and Guthrie, and Guthrie coded the initial prototypes during the Christmas holidays in 1997.
The initial prototype was called "XSP"; Guthrie explained in a 2007 interview that, "People would always ask what the X stood for. At the time it really didn't stand for anything. XML started with that; XSLT started with that. Everything cool seemed to start with an X, so that's what we originally named it."The initial prototype of XSP was done using Java, but it was soon decided to build the new platform on top of the Common Language Runtime (CLR), as it offered an object-oriented programming environment, garbage collection and other features that were seen as desirable features that Microsoft's Component Object Model platform didn't support. Guthrie described this decision as a "huge risk", as the success of their new web development platform would be tied to the success of the CLR, which, like XSP, was still in the early stages of development, so much so that the XSP team was the first team at Microsoft to target the CLR.
With the move to the Commo
n Language Runtime, XSP was re-implemented in C# (known internally as "Project Cool" but kept secret from the public), and renamed to ASP+, as by this point the new platform was seen as being the successor to Active Server Pages, and the intention was to provide an easy migration path for ASP developers.
Note that this sample uses code "inline", as opposed to code-behind.
<%@ Page Language="C#" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script runat="server">
protected void Page_Load(object sender, EventArgs e)
{
Label1.Text = DateTime.Now.ToLongDateString();
}
</script>
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title>Sample page</title>
</head>
<body>
<form id="form1" runat="server">
<div>
The current time is: <asp:Label runat="server" id="Label1" />
</div>
</form>
</body>
</html>
Code-behind model
It is recommended by Microsoft for dealing with dynamic program code to use the code-behind model, which places this code in a separate file or in a specially designated script tag. Code-behind files typically have names like MyPage.aspx.cs or MyPage.aspx.vb (same filename as the ASPX file, with the final extension denoting the page language). This practice is automatic in Microsoft Visual Studio and other IDEs. When using this style of programming, the developer writes code to respond to different events, like the page being loaded, or a control being clicked, rather than a procedural walk through the document.
ASP.NET's code-behind model marks a departure from Classic ASP in that it encourages developers to build applications with separation of presentation and content in mind. In theory, this would allow a web designer, for example, to focus on the design markup with less potential for disturbing the programming code that drives it. This is similar to the separation of the controller from the view in model-view-controller frameworks.
Example
<%@ Page Language="C#" CodeFile="SampleCodeBehind.aspx.cs" Inherits="Website.SampleCodeBehind"
AutoEventWireup="true" %>
The above tag is placed at the beginning of the ASPX file. The CodeFile property of the @ Page directive specifies the file (.cs or .vb) acting as the code-behind while the Inherits property specifies the Class the Page derives from. In this example, the @ Page directive is included in SampleCodeBehind.aspx, then SampleCodeBehind.aspx.cs acts as the code-behind for this page:
using System;
namespace Website
{
public partial class SampleCodeBehind : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
// ...
}
}
}
In this case, the Page_Load() method is called every time the ASPX page is requested. The programmer can implement event handlers at several stages of the page execution process to perform processing.
