how to exchange session or cookie variables betwee

I have two webmethod i have used session variable to exchange the username variable between two webmethods but its displaying null in second webmethod ,can we use cookie as alternate to session to store and retrieve username

[WebMethod(EnableSession = true)]
    [ScriptMethod(ResponseFormat = ResponseFormat.Json)]
    public bool SubmitList1(string username )
    {
       Session["User_Name"] = username;
      .........
        .......

     }
[WebMethod(EnableSession = true)]
    [ScriptMethod(ResponseFormat = ResponseFormat.Json)]
    public bool addresslisting( string keyword)
    {

       string username = Context.Session["User_Name"].ToString();
        ........
          .........
    }

Disclaimer: I think that a web service that relies on Session state is just plain WRONG since a web service should be stateless. However:

At http://msdn.microsoft.com/en-us/library/aa480509.aspx you can read about how to use ASP.NET Session in a web service:

Make sure that /configuration/system.web/sessionState in web.config is configured properly to enable session state
Make sure that uses the web service has a cookie container where the ASP.NET session cookie can be stored. If the client is from a web browser (e.g. ajax call) this usually works out of the box, but if you are building a standalone client, you have to do some more work, see the link above.

All in all: a bad design decision gives you more work than necessary (sorry for rubbing it in).

I think you should redesign you web service so that you either always send username and password in all methods or add a login method that gives the client a token that is sent with each web service request.