There are two approaches we can follow while creating an Application Page in SharePoint.

One is Inline Approach

·         Create a new default.aspx page rename it to HelloWorldAppPage.aspx

·         Put the following markup in it

<%@ Page Language=”C#” MasterPageFile=”~/_layouts/application.master” Inherits=”Microsoft.SharePoint.WebControls.LayoutsPageBase” %>

<asp:Content ID=”Main” ContentPlaceHolderID=”PlaceHolderMain” runat=”server”>

  <asp:Label Text=”Hello World” runat=”server” ></asp:Label>

</asp:Content>

·         Every application page is an content page in SharePoint. And here to have same look and feel as the other application pages we have specified the application.master as the masterpagefile.

·         Inherits attribute of the Page directive refers to LayoutsPageBase class from which the application pages inherit.

·         We have than used a content server control that would be referring to the PlaceHolderMain content place holder inside the application.master page.

·         Than we have simple added a label control that would be displaying hello world.

·         Now go to your 12 hive i.e. C:Program FilesCommon FilesMicrosoft Sharedweb server extensions12TEMPLATELAYOUTS and create a folder (MyHelloWorld) over there and put the HelloWorldAppPage.aspx over there.

·         We could have directly placed the aspx page to layouts folder but than from better organization perspective we have created a folder and kept the aspx page inside it.

·         Now the page is available to all the SharePoint sites.

http://servername:port/_layouts/MyHelloWorld/HelloWorldAppPage.aspx

Another is code behind approach.

·         The easiest way is to first create a Asp.NET Web site project.

·         Add a class library project to the solution (GCL)

·         Delete class1.cs and copy the default.aspx.cs page from asp.net web site project to the class library project.

·         Delete the default.aspx.cs from the website.

·         Add reference to System.Web and Microsoft.SharePoint.dll  in your class library project

·         Put the following code in the _Default

public partial class _Default : LayoutsPageBase

{

    protected Label Label1;

    protected void Page_Load(object sender, EventArgs e)

    {

        Label1.Text = “Hello World Code Behind”;

 

    }

}

·         Sign the assembly and put it in GAC.

·         Get the public key token.

·         In the default.aspx page replace and put the following markup to use the assembly.

<%@ Page Language=”C#” MasterPageFile=”~/_layouts/application.master”

 Inherits=”_Default,GCL, Version=1.0.0.0,Culture=neutral,PublicKeyToken=16391a8a7c882343″ %>

<asp:Content ID=”Main” ContentPlaceHolderID=”PlaceHolderMain” runat=”server”>

  <asp:Label ID=”Label1″ Text=”Hello World” runat=”server” ></asp:Label>

</asp:Content>

·         Put default.aspx to the  layouts folder or your custom folder inside it.

That’ s it !!