Introduction
The Global.asax, also known as the ASP.NET application file, is located in the
root directory of an ASP.NET application. This file contains code that is
executed in response to application-level and session-level events raised by
ASP.NET or by HTTP modules. You can also define 'objects' with application-wide
or session-wide scope in the Global.asax file. These events and objects declared
in the Global.asax are applied to all resources in that web application. The
Global.asax is an optional file. If a user requests the Global.asax file, the
request is rejected.
About Global.asax page
Adding a Global.asax to your web project is quiet simple. Open Visual Studio
2005 or 2008 > Create a new website > Go to the Solution Explorer > Add New Item
> Global Application Class > Add.
Now we will have three Application Event Handlers and two Session Event
Handlers.
Here is the list of Application Event Handlers:
Sub
Application_Start(ByVal sender
As Object,
ByVal e As
EventArgs)
'
Code that runs on application startup
End
Sub
Sub
Application_End(ByVal sender
As Object,
ByVal e As
EventArgs)
'
Code that runs on application shutdown
End
Sub
Sub
Application_Error(ByVal sender
As Object,
ByVal e As
EventArgs)
'
Code that runs when an unhandled error occurs
End
Sub
Here
is the list of Session Event Handlers:
Sub
Session_Start(ByVal sender
As Object,
ByVal e As
EventArgs)
'
Code that runs when a new session is started
End
Sub
Sub
Session_End(ByVal sender
As Object,
ByVal e As
EventArgs)
'
Code that runs when a session ends.
' Note: The Session_End event is raised only when the sessionstate mode
' is set to InProc in the Web.config file. If session mode is set to StateServer
' or SQLServer, the event is not raised.
End
Sub
Note: About Session Event Handlers will learn in next article.
Application Event Handlers
Application_Start():
It gets fired when the first resource is requested from the web server and the
web application starts.
Application_End():
It gets fired when the web application ends.
Application_Error():
It gets fired when an error occurs.
Working with Global.asax file
<%@
Application Language="VB"
%>
<script
runat="server">
Sub Application_Start(ByVal
sender As Object,
ByVal e As
EventArgs)
Application("HitCount") = 0
' Code that runs on application startup
End Sub
Sub Application_End(ByVal
sender As Object,
ByVal e As
EventArgs)
' Code that runs on application shutdown
End Sub
Sub Application_Error(ByVal
sender As Object,
ByVal e As
EventArgs)
' Code that runs when an unhandled error
occurs
End Sub
Sub Session_Start(ByVal
sender As Object,
ByVal e As
EventArgs)
' Code that runs when a new session is started
End Sub
Sub Session_End(ByVal
sender As Object,
ByVal e As
EventArgs)
' Code that runs when a session ends.
' Note: The Session_End event is raised
only when the sessionstate mode
' is set to InProc in the Web.config
file. If session mode is set to StateServer
' or SQLServer, the event is not
raised.
End Sub
</script>
Working with Default.aspx file
<%@
Page Language="VB"
AutoEventWireup="false"
CodeFile="Default.aspx.vb"
Inherits="_Default"
%>
<!DOCTYPE
html PUBLIC
"-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html
xmlns="http://www.w3.org/1999/xhtml"
>
<head
runat="server">
<title>Create
and Use Application Level Events in ASP.Net</title>
</head>
<body>
<form
id="form1"
runat="server">
<div>
<strong>
Total Hits:
</strong>
<asp:Label
ID="Label1"
runat="server"
Text="Label"
Width="247px"
Font-Size="Large"
ForeColor="Red">
</asp:Label>
</div>
</form>
</body>
</html>
Working with Default.aspx.vb file
Protected
Sub Page_Load(ByVal
sender As Object,
ByVal e As
System.EventArgs) Handles
Me.Load
Application("HitCount") = Application("HitCount")
+ 1
Label1.Text = Application("HitCount")
End
Sub
HAVE A HAPPY CODING!