Question

I want to store a sequence input of number separate by comma (1,2,3,4…)
into a session object

And my code is:

string items = string.Empty;

protected void Button1_Click(object sender, EventArgs e)
    {
                    fillitem(TextBox1.Text);
                    showsession();
    }

      void fillitem(string par1)
        {
            if (Session["itemvar"] != null)
            {
                items = Session["itemvar"].ToString();
                Session["itemvar"] = null;
            }

            items += par1 + ",";
            Session["itemvar"] = items;
        }     


 void showsession()
    {
            string itempp = string.Empty;
            if (Session["itemvar"] != null)
            {
                itempp = Session["itemvar"].ToString();
                int indexOfkoma = itempp.LastIndexOf(",", StringComparison.OrdinalIgnoreCase);

                if (indexOfkoma != -1)
                {
                    itempp = itempp.Substring(0, indexOfkoma);

                }
            }
            Label1.Text = itempp;

    }

The code is running wel on my local. But when I publish on the server, the session object returns strange results like below transaction:

Button1_Click Event 1 Result :
Session[“itemvar”] Return : 1

Button1_Click Event 2 Result :
Session[“itemvar”] Return : 2 —-> The correct result should return: 1,2

Button1_Click Event 3 Result :
Session[“itemvar”] Return : 1,3 —-> The correct result should return: 1,2,3

Button1_Click Event 4 Result :
Session[“itemvar”] Return : 2,4 —-> The correct result should return: 1,2,3,4

Any idea, what is the cause of these strange behavior?

Answer 1

The behavior you are seeing could be caused by using In-Process Session State (default on IIS) in a web farm configuration.

Your requests in such a case would actually be serviced by different application servers(each with its own session).

Configure Out-of-Process Session State to solve this problem in a web farm scenario.