The Application Object

The Application object is a built-in ASP.NET object that represents an instance of the ASP.NET application. It includes all the methods and collections related to the application.When the first user calls an ASP.NET file, the application is started and an Application object is created. Once the Application object is created, it can share information throughout the application. The object remains until the application is shut down. The Application object stores and maintain values through variables. Variables can have two level of scope:

Page Level Variables: Page Level variables are used while the page is being processed. After the page is processed, the variables are destroyed and the associated resources are released.

Code Snippet:


String user_name="Mak"; Response.write("Hello "+user_name);


Object Level Variables: Object Level variables and their values can be accessed across pages. There are two types of Object Level variables:

		Application Level variables are used to share common information across multiple users.
		Session Level variables are used to pass information from one page to another for a particular user.

Example:

Global.asax

protected void Application_Start(object sender, EventArgs e) { Application["count"] = 0; } protected void Session_Start(object sender, EventArgs e) { Response.Write("Session Started"+"<br />"); Application["count"] = Convert.ToInt32(Application["count"]) + 1; } protected void Application_BeginRequest(object sender, EventArgs e) { Response.Write("Application Request Begins" + "<br />"); } protected void Application_EndRequest(object sender, EventArgs e) { Response.Write("Application Request ends"); } protected void Application_AuthenticateRequest(object sender, EventArgs e) { } protected void Application_Error(object sender, EventArgs e) { } protected void Session_End(object sender, EventArgs e) { Response.Write("Session Ended"); } protected void Application_End(object sender, EventArgs e) { }

ApplicationObj.aspx

<script language="C#" runat="server"> protected void Page_Load(object sender, EventArgs e) { Response.Write("Visitor Number:" + Application["count"] + <br>); } </script>

When the user starts the application, the Application_Start event is fired.

Output:

Application Request Begins Session Started Visitor Number:1 Application Request ends

If user refresh the page, the counter is not incremented as shown below.

Application Request Begins Visitor Number:1 Application Request ends

If .aspx page is loaded in a new browser window, the counter is incremented by one as shown below.

Application Request Begins Session Started Visitor Number:2 Application Request ends

An application variable retains the value assigned to it until the application is shut down.