main.aspx.cs

this is the file to chat in web

using System;
using System.Data;
using System.Data.SqlClient;
using System.Configuration;
using System.Collections;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;

[AjaxPro.AjaxNamespace("AjaxProChat")]
    public partial class main : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {
		    // Register Ajax.NET methods from this class
		    AjaxPro.Utility.RegisterTypeForAjax(typeof(main));
			if (!IsPostBack)
			{
				// Show the login user name
                //Page.User property--get the  info of the user who sends out the page request
				lblUsername.Text = User.Identity.Name;
			}

        }
		/// <summary>
        /// Get the online user list
		/// </summary>
        /// <returns>online user DataSet</returns>
        [AjaxPro.AjaxMethod]
        public  DataSet GetOnlineUserList()
		{

            //to hold the returned DataSet
			DataSet ds = new DataSet();

			//the data connection
            string strConnection = ConfigurationManager.ConnectionStrings["msn_Data_ConnStr"].ConnectionString;
            SqlConnection conn = new SqlConnection(strConnection);

			// SQL command
			SqlCommand cmd = conn.CreateCommand();
			cmd.CommandText = "SELECT username, nickname FROM users WHERE status = 1 AND username <> '"
				+ User.Identity.Name + "'";

			try
			{
				// fill in the friend messages into the DataSet
				SqlDataAdapter da = new SqlDataAdapter(cmd);
				da.Fill(ds);
			}
			catch (SqlException)
			{
			}
			finally
			{
				conn.Close();
			}

			return ds;
		}

		/// <summary>
		/// Obtain the changing times inside table users
		/// </summary>
        /// <returns>The changing times inside table users</returns>
        [AjaxPro.AjaxMethod]
        public  int StatusChanged()
		{
			// to hold the returned value
			int iRet = 0;

            // Obtain the database connection string from the file web.config
            string strConnection = ConfigurationManager.ConnectionStrings["msn_Data_ConnStr"].ConnectionString;
            SqlConnection conn = new SqlConnection(strConnection);

            // SQL command
			SqlCommand cmd = conn.CreateCommand();
			cmd.CommandText = "SELECT UsersChanged FROM global_info";

			try
			{
                //open the data connection
				conn.Open();

				// get the value of field UsersChanged
                //execute the query and return the value in the first line and the first column 
                //from inside the result DataSet--ignore all the others
                iRet = Convert.ToInt32(cmd.ExecuteScalar());
			}
			catch (SqlException)
			{
			}
			finally
			{
				//close the database connection
				conn.Close();
			}

			return iRet;
		}

		/// <summary>
		/// Check the user status
		/// </summary>
		/// <returns></returns>
        [AjaxPro.AjaxMethod]
        public  int CheckStatus()
		{
            //to hold the returned value
			int iRet = 0;

            //Obtain the database connection string from the file web.config
            string strConnection = ConfigurationManager.ConnectionStrings["msn_Data_ConnStr"].ConnectionString;
            SqlConnection conn = new SqlConnection(strConnection);

            // SQL command
			SqlCommand cmd = conn.CreateCommand();
			cmd.CommandText = "SELECT status FROM users WHERE username = '" +
                User.Identity.Name + "'";

			try
			{
                // open the data connection
				conn.Open();

				// return the current user related value of field status
				iRet = Convert.ToInt32(cmd.ExecuteScalar());
			}
			catch (SqlException)
			{
			}
			finally
			{
                // close the database connection
				conn.Close();
			}

			return iRet;
		}

        /// <summary>
        /// Get the most recent messages
        /// </summary>
        /// <returns>The most recent messages related DataSet</returns>
        [AjaxPro.AjaxMethod]
        public DataSet mainGetNewMessage()
		{
            //to hold the returned DataSet
			DataSet ds = new DataSet();

            //Obtain the database connection string from the file web.config and set up the connection
            SqlConnection conn = new SqlConnection(ConfigurationManager.ConnectionStrings["msn_Data_ConnStr"].ConnectionString);

			// SQL command
			SqlCommand cmd = conn.CreateCommand();
            cmd.CommandText = string.Format("GetNewMessage '{0}'", User.Identity.Name);

			// the data adapter
			SqlDataAdapter da = new SqlDataAdapter(cmd);

			try
			{
				//fill the messages into the DataSet
				da.Fill(ds);
			}
			catch (SqlException)
			{
			}
			finally
			{
                //close the database connection
				conn.Close();
			}

			return ds;
		}

		/// <summary>
		///Set the user status
		/// </summary>
		/// <param name="strUsername">user name</param>
		/// <param name="iStatus">status value</param>
		/// <returns>whether the query is successful</returns>
        [AjaxPro.AjaxMethod]
        public  int SetUserStatus(string strUsername, int iStatus)
		{
			//to hold the returned value
			int iRet = 0;

            //Obtain the database connection string from the file web.config and set up the connection
            string strConnection = ConfigurationManager.ConnectionStrings["msn_Data_ConnStr"].ConnectionString;
            SqlConnection conn = new SqlConnection(strConnection);

			// SQL command
			SqlCommand cmd = conn.CreateCommand();
			cmd.CommandText = string.Format(
				"UPDATE users SET status = {0} WHERE username='{1}'",
				iStatus, strUsername
				);

			try
			{
                //open the data connection
				conn.Open();

				// execute the SQL command-- set the user's status
				iRet = cmd.ExecuteNonQuery();
			}
			catch (SqlException)
			{
			}
			finally
			{
                //close the database connection
				conn.Close();
			}

			return iRet;
		}

        protected void lblExit_Click(object sender, EventArgs e)
        {
            //Obtain the database connection string from the file web.config and set up the connection
            string strConnection = ConfigurationManager.ConnectionStrings["msn_Data_ConnStr"].ConnectionString;
            SqlConnection conn = new SqlConnection(strConnection);

            // SQL command
            SqlCommand cmd = conn.CreateCommand();
            cmd.CommandText = string.Format("UserLogout '{0}'", User.Identity.Name);

            try
            {
                //open the data connection
                conn.Open();

                // execute the SQL command--logout
                cmd.ExecuteNonQuery();
            }
            catch (SqlException)
            {
            }
            finally
            {
                //close the database connection
                conn.Close();
            }

            //logout
            FormsAuthentication.SignOut();

            // redirect to the login page
            Response.Redirect("Login.aspx");
        }
    }