ajaxでWebサービスを呼び出す際に注意すべきことは何ですか?

<httpHandlers>
   <remove verb="*" path="*.asmx"/>
   <add verb="*" path="*.asmx" validate="false" type="System.Web.Script.Services.ScriptHandlerFactory, System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35"/>
  </httpHandlers>

<webServices>
   <protocols>
    <add name="HttpPost" />
    <add name="HttpGet" />
   </protocols>
  </webServices>

/// <summary>
  /// UserValidate 的摘要说明
  /// </summary>
  [WebService(Namespace = "http://tempuri.org/")]
  [WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)]
  [System.ComponentModel.ToolboxItem(false)]
  // 若要允许使用 ASP.NET AJAX 从脚本中调用此 Web 服务，请取消对下行的注释。
   [System.Web.Script.Services.ScriptService]
  public class UserValidate : System.Web.Services.WebService
  {
    DFHon.Content.Common.rootPublic rp = new DFHon.Content.Common.rootPublic();
    [WebMethod]
    [ScriptMethod(ResponseFormat = ResponseFormat.Json)]
    public string ValidateUserLogState()
    {
      string result = "";
      HttpCookie cookie = HttpContext.Current.Request.Cookies["DHFonMenberInfo"];
      if (cookie != null)
      {
        string username = System.Web.HttpUtility.UrlDecode(cookie["MenberName"]);
        int ipoint = 0;
        int gpoint = 0;
        try
        {
          DataTable dt = UserBll.ExecuteUserAllInfo(username);

          if (dt.Rows.Count > 0)
          {
            ipoint = int.Parse(dt.Rows[0]["iPoint"].ToString());
            gpoint = int.Parse(dt.Rows[0]["gPoint"].ToString());
          }
        }
        catch
        { }
        result = "{&#39;user&#39;:{&#39;id&#39;:&#39;" + cookie["UserId"] + "&#39;,&#39;name&#39;:&#39;" + username + "&#39;,&#39;message&#39;:&#39;" + rp.getUserMsg(DFHon.Global.CurrentCookie.UserName) + "&#39;,&#39;ipoint&#39;:&#39;" + ipoint.ToString() + "&#39;,&#39;gpoint&#39;:&#39;" + gpoint.ToString() + "&#39;}}";
      }
      else
      {
        result = "{&#39;user&#39;:{&#39;id&#39;:&#39;0&#39;,&#39;name&#39;:&#39;&#39;,&#39;message&#39;:&#39;0&#39;,&#39;ipoint&#39;:&#39;0&#39;,&#39;gpoint&#39;:&#39;0&#39;}}";
      }
      return result;
    }

    [WebMethod]
    [ScriptMethod(ResponseFormat = ResponseFormat.Json)]
    public string UserLogin(string userName, string userPwd)
    {
      string returnVal = "";
      try
      {
        GlobalUserInfo info;
        DFHon.Content.UserLogin _UserLogin = new DFHon.Content.UserLogin();
        EnumLoginState state = _UserLogin.PersonLogin(HttpUtility.UrlDecode(userName), userPwd, out info);
        if (state == EnumLoginState.Succeed)
        {
          DFHon.Global.CurrentCookie.Set(info);
          DFHon.API.PDO.DiscuzNT.PassportLogin.UserLogin(Server.UrlDecode(userName), userPwd, -1);
          int ipoint = 0;
          int gpoint = 0;
          DataTable dt = UserBll.ExecuteUserAllInfo(userName);

          if (dt.Rows.Count > 0)
          {
            ipoint = int.Parse(dt.Rows[0]["iPoint"].ToString());
            gpoint = int.Parse(dt.Rows[0]["gPoint"].ToString());
          }
          returnVal = "{&#39;user&#39;:{&#39;id&#39;:&#39;" + info.UserId.ToString() + "&#39;,&#39;name&#39;:&#39;" + info.UserName + "&#39;,&#39;message&#39;:&#39;" + rp.getUserMsg(userName) + "&#39;,&#39;ipoint&#39;:&#39;" + ipoint.ToString() + "&#39;,&#39;gpoint&#39;:&#39;" + gpoint.ToString() + "&#39;}}";
        }
        else
        {
          int ids = 0;//状态：-2用户被锁定 -1用户名密码错误
          switch (state)
          {
            case EnumLoginState.Err_Locked:
              ids = -2;
              break;
            case EnumLoginState.Err_UserNameOrPwdError:
              ids = -1;
              break;
            default:
              break;
          }
          returnVal = "{&#39;user&#39;:{&#39;id&#39;:&#39;" + ids + "&#39;,&#39;name&#39;:&#39;&#39;,&#39;message&#39;:&#39;0&#39;,&#39;ipoint&#39;:&#39;0&#39;,&#39;gpoint&#39;:&#39;0&#39;}}";
        }
      }
      catch
      {
        returnVal = "{&#39;user&#39;:{&#39;id&#39;:&#39;0&#39;,&#39;name&#39;:&#39;&#39;,&#39;message&#39;:&#39;0&#39;,&#39;ipoint&#39;:&#39;0&#39;,&#39;gpoint&#39;:&#39;0&#39;}}";
      }
      return returnVal;
    }
    [WebMethod]
    public string UserLogout()
    {
      if (HttpContext.Current.Request.Cookies["DHFonMenberInfo"] != null)
      {
        HttpCookie cookie = new HttpCookie("DHFonMenberInfo");
        cookie.Expires = System.DateTime.Now.AddDays(-1);
        cookie.Domain = DFHon.Config.BaseConfig.getV("weblogin");
        HttpContext.Current.Response.AppendCookie(cookie);
      }
      return "1";
    }
    DFHon.Content.user UserBll = new DFHon.Content.user();
    [WebMethod]
    public string ValidateUserEmail(string email)
    {
      string result = "0";//返回的结果 -2邮箱为空 -1邮箱格式不正确 0邮箱存在 1填写正确
      if (string.IsNullOrEmpty(email))
      {
        result = "-2";//邮箱为空
      }
      else if (!IsValidEmail(email))
      {
        result = "-1";//邮箱格式不正确
      }
      else if (UserBll.sel_useremail(email) > 0)
      {
        result = "0";//邮箱存在
      }
      else
      {
        result = "1";//可以注册
      }
      return result;
    }

    [WebMethod]
    public string ValidateUserName(string username)
    {
      string result = "0";//返回值：-1用户名长度为2-16;0用户名存在;1可以注册
      if (username == "" || username == null || username.Length < 2 || username.Length > 16)
      {
        result = "-1";
      }
      else if (UserBll.sel_username(username) != 0)
      {
        result = "0";
      }
      else
      {
        result = "1";
      }
      return result;
    }

    public bool IsValidEmail(string strIn)
    { // Return true if strIn is in valid e-mail format. 
      return System.Text.RegularExpressions.Regex.IsMatch(strIn, @"^([\w-\.]+)@((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.)|(([\w-]+\.)+))([a-zA-Z]{2,4}|[0-9]{1,3})(\]?)$");
    }
  }