<%@ WebService Language="C#" Class="SessionStateExample" %>

using System.Web.Services;

public class SessionStateExample : WebService
{
  [WebMethod(EnableSession=true)]
  public void SetSession(string key, string item)
  {
    Session[key] = item;
  }

  [WebMethod(EnableSession=true)]
  public string GetSession(string key)
  {
    return Session[key].ToString();
  }
}