Is it possible in some cases to
migrate the session data by setting
the session cookie on the user's
browser?
Sure you can. Simply set a new cookie and redirect. You will have to do this server-side. Setting a session cookie client-side will be problematic.
const string sessionStateCookieName = "ASP.NET_SessionId";
string sessionId = "some session id";
HttpCookie cookie = new HttpCookie(sessionStateCookieName, sessionId) { Path = "/", HttpOnly = true };
Response.Cookies.Remove(sessionStateCookieName);
Response.Cookies.Add(cookie);
// force a redirect to complete session switch
Response.Redirect(Request.Path);
You can expand on this. Here is a working example .aspx page. To switch sessions, simply add a url param 'sessionId'.
<%@ Page Language="C#" AutoEventWireup="true" %>
<script runat="server">
// this is the method that does the magic
protected override void OnPreInit(EventArgs e)
{
var sessionId = Request["sessionId"];
if (!string.IsNullOrEmpty(sessionId))
{
// this could be found via reflection if different sessionstate cookie name is used in config
const string sessionStateCookieName = "ASP.NET_SessionId";
HttpCookie cookie = new HttpCookie(sessionStateCookieName, sessionId) { Path = "/", HttpOnly = true };
Response.Cookies.Remove(sessionStateCookieName);
Response.Cookies.Add(cookie);
// force a redirect to complete session switch
Response.Redirect(Request.Path);
}
}
// the rest of this script is just demo code
protected void Page_Load(object sender, EventArgs e)
{
CurrentSessionIdLabel.Text = Session.SessionID;
}
protected void SwitchSessionButton_Click(object sender, EventArgs e)
{
// this is the session we wish to switch to
string switchToSessionId = SessionIdTextBox.Text;
Response.Redirect(Request.Path + "?sessionId=" + Server.UrlEncode(switchToSessionId));
}
</script>
<!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></title>
</head>
<body>
<form id="Form1" runat="server">
<div>
Current SessionId<br />
<asp:Label ID="CurrentSessionIdLabel" runat="server"></asp:Label>
<br />
<br />
<asp:Label ID="Label1" runat="server" Text="Desired SessionId"></asp:Label>
<br />
<asp:TextBox ID="SessionIdTextBox" runat="server"></asp:TextBox>
<br />
<asp:Button ID="SwitchSessionButton" runat="server" Text="Switch Session" OnClick="SwitchSessionButton_Click" />
</div>
</form>
</body>
</html>