Access a Forms Based SharePoint Site's Web Service

using System;
using System.Collections.Generic;
using System.Text;
using SharePointWebServiceAccess.SPAuthentication;
using SharePointWebServiceAccess.SPList;
using System.Net;
using System.Xml;
using System.Web.Services.Protocols;

namespace SharePointWebServiceAccess
{
    public class SharePointWSManager
    {
        public string QueryToSharePoint(string authenticationWSAddress, string userName, string password, string listWSAddress)
        {
            string response = string.Empty;
            try
            {
                Authentication spAuthentication = new Authentication();
                spAuthentication.Url = authenticationWSAddress;
                spAuthentication.CookieContainer = new CookieContainer();
                Lists spLists = new Lists();
                spLists.Url = listWSAddress;
                //Try to login to SharePoint site with Form based authentication
                LoginResult loginResult = spAuthentication.Login(userName, password);
                Cookie cookie = new Cookie();
                //If login is successfull
                if (loginResult.ErrorCode == LoginErrorCode.NoError)
                {
                    //Get the cookie collection from the authenticatin web service
                    CookieCollection cookies = spAuthentication.CookieContainer.GetCookies(new Uri(spAuthentication.Url));
                    //Get the specific cookie which contains the security token
                    cookie = cookies[loginResult.CookieName];
                    //Initialize the cookie container of the list web service
                    spLists.CookieContainer = new CookieContainer();
                    //set the cookie of list web service to the authenticatio cookie
                    spLists.CookieContainer.Add(cookie);
                    XmlNode responseNode = spLists.GetListCollection();
                    response = responseNode.InnerXml;
                }
            }
            catch (SoapException exp)
            {
                return "SOAP ERROR: " + Environment.NewLine + exp.Message;
            }
            catch (Exception exp)
            {
                return "ERROR: " + Environment.NewLine + exp.Message;
            }
            return response;
        }
    }
}