Why asp.net session is expired sooner than its timeout?

Question

I have an Asp.net webservice. It has method M1. M1 creates a folder for each session. When a session is expired, I delete that folder in global.asax using the following code

Answer 1

Have a look at this post, I believe your problem may be similar:

• Client sends a cookie with a Session Id for an expired session
• Server creates a new session, reusing the id sent by the client
• If the request does not access session, the session is immediately abandoned.

Does your WebMethod actually access Session state? If not, try adding an access to a dummy session variable.

Update:

These lines of code in Global.asax solve the problem:

 void Session_Start(object sender, EventArgs e)
 {
     Session["dummy"] = "dummy session for solving immediate session expire";
 }

Update 2

Personally I wouldn't do the directory creation in Session_Start; instead I'd have a method called something like EnsureMyPacksFolder which the app is required to call before any attempt to access the folder. This would look something like the following, avoids the need for a "dummy" Session variable, and means the folder is only created if and when it is actually needed.

Global.asax:

void Session_Start(object sender, EventArgs e)
{
     // No code needed in Session_Start
}

void Session_End(object sender, EventArgs e)
{
    if (Session["MyPacksFolder"] != null)
    {
        // Folder has been created, delete it
        // ... add code to delete folder as above
    }
}

Somewhere else:

public static void EnsureMyPacksFolder()
{
    if (Session["MyPacksFolder"] == null)
    {
        // Add code to create MyPacksFolder that was previously in Session_Start

        Session["MyPacksFolder"] = true;
    }
}

Answer 2

If you are creating and deleting folder under your web service path, iis immediatly restarts. Take a look on this post.

Answer 3

Did you add the following to your WebMethods?

[WebMethod (EnableSession = true)]