Posts Tagged ‘session’
Prevent Session Timeout in Asp.net
Prevent Session Timeout in Asp.net [VB]
ASP.Net 2.0 [VB]
Inspired by this article from Code Project. [Thanks Ach1lles ]
I slightly modified few things to work for VB and VS2005 environment. The code works perfect and I’m very happy with it.First I created a Module file and created this function.
Public Function KeepAlive() As String
Dim int_MilliSecondsTimeOut As Integer = (HttpContext.Current.Session.Timeout * 60000) - 30000
Dim sScript As New StringBuilder
sScript.Append("<script type='text/javascript'>" & vbNewLine)
'Number Of Reconnects
sScript.Append("var count=0;" & vbNewLine)
'Maximum reconnects Setting
sScript.Append("var max = 6;" & vbNewLine)
sScript.Append("function Reconnect(){" & vbNewLine)
sScript.Append("count++;" & vbNewLine)
sScript.Append("var d = new Date();" & vbNewLine)
sScript.Append("var curr_hour = d.getHours();" & vbNewLine)
sScript.Append("var curr_min = d.getMinutes();" & vbNewLine)
sScript.Append("if (count < max){" & vbNewLine)
sScript.Append("window.status = 'Refreshed ' + count.toString() + ' time(s) [' + curr_hour + ':' + curr_min + ']';" & vbNewLine)
sScript.Append("var img = new Image(1,1);" & vbNewLine)
sScript.Append("img.src = 'http://localhost/myapp/reconnect.aspx';" & vbNewLine)
sScript.Append("}" & vbNewLine)
sScript.Append("}" & vbNewLine)
sScript.Append("window.setInterval('Reconnect()',")
sScript.Append(int_MilliSecondsTimeOut.ToString() & "); //Set to length required" & vbNewLine)
sScript.Append("</script>")
KeepAlive = sScript.ToString
End Function
All this code does is, build a simple javascript function and its called from server side.The works like this,- Gets the current session timeout duration.
– Subtract 30 seconds from it and assign it to MilliSecondsTimeOut variable
– Create a Reconnect() javascript function
– Create a global variable with max value 6
– Get current hour and Min [just for displaying the last refresh time]
– Verify whether count is less than max value (ie 6)
– If so, change the window status with Text
– Create a dummy image and set reconnect.aspx url as its source [this way a call is made to server and it wont session timeout]Create a timer using window.setInterval and assign the MilliSecondsTimeOut value.
[this way this function is called 30 seconds before session timeout]Tha max value (6) can be set to any number. If its 6 then this session timeout is avoided 5 times.
Default session timeout is 20min. 20 * 5 = 100 mins. Which is good for non-secure page.
Then
On the pages where I want to prevent Session Timeout I entered this line.
Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load Try 'dont forget to add this line Page.ClientScript.RegisterClientScriptBlock(Me.GetType, "reconn key", KeepAlive()) If Not Page.IsPostBack Then --- --- --- End If Catch eX as Exception '---- End Try End Sub
Created reconnect.aspx in Visual Studio and deleted the .vb and .designer.vb files.This is the final version of reconnect.aspx
<%@ Page Language="vb" AutoEventWireup="false"%> <%@ OutputCache Location="None" VaryByParam="None" %> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "<a href="http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd" mce_href="http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd</a>"> <html xmlns="<a href="http://www.w3.org/1999/xhtml" mce_href="http://www.w3.org/1999/xhtml">http://www.w3.org/1999/xhtml</a>" > </html>
Note : When you compile the project sometimes, VS2005 complains reconnect.aspx is not in right format.
So I EXCLUDED this file from my project. Now VS 2005 will compile without complaining and the logic will also work.- Happy Programming
Script(s) 