ASMX webservice第一次连接ORACLE数据库时超时

我写了一个c#应用程序，它与部署在另一台机器上的(ASMX) web服务通信。webservice连接到位于第三层的后端数据库并对其执行操作。

应用程序中的所有DB操作都是从一个名为DataLayerFunctor的静态类调用的。下面是该类的一个片段:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using WebserviceTest.DataLayer;
using WebserviceTest.SecurityLayer;
using SettingsAlias = WebserviceTest.Properties;
namespace WebserviceTest
{
    public static class DataLayerFunctor
    {
        public static MyWebserviceReference.Service1 myWebService;
        private static string HOST = "192.168.1.100";
        private static string PORT = "1521";
        private static string DATABASE = "orcl";
        private static string USERNAME = "MY_USER";
        private static string PASSWORD = "123";
        private static string ORACLE_CONNECTION_STRING = "Data Source=(DESCRIPTION=(ADDRESS_LIST=(ADDRESS=(PROTOCOL=TCP)(HOST={0})(PORT={1})))(CONNECT_DATA=(SERVER=DEDICATED)(SERVICE_NAME={2})));Users Id={3};Password={4};";
        public static List<UserGroup> UserGroupsList { get; set; }
        public static List<Role> RolesList { get; set; }
        public static Dictionary<UserGroup,Role> GroupsToRoles { get; set; }
        static DataLayerFunctor()
        {
            HOST = CryptoServices.DecryptText(SettingsAlias.Settings.Default.HOST,CryptoServices.DEFAULT_KEY) ?? HOST;
            PORT = CryptoServices.DecryptText(SettingsAlias.Settings.Default.PORT,CryptoServices.DEFAULT_KEY )?? PORT;
            DATABASE = CryptoServices.DecryptText(SettingsAlias.Settings.Default.DATABASE,CryptoServices.DEFAULT_KEY) ?? DATABASE;
            USERNAME = CryptoServices.DecryptText(SettingsAlias.Settings.Default.USER_NAME,CryptoServices.DEFAULT_KEY) ?? USERNAME;
            PASSWORD = CryptoServices.DecryptText(SettingsAlias.Settings.Default.PASSWORD,CryptoServices.DEFAULT_KEY) ?? PASSWORD;
            ORACLE_CONNECTION_STRING = SettingsAlias.Settings.Default.ORACLE_CONNECTION_STRING ?? ORACLE_CONNECTION_STRING;
            HOST = "192.168.1.6";
            PORT = "1521";
            DATABASE = "orcl";
            USERNAME = "ALAMAL_BANK";
            PASSWORD = "123";

            myWebService = new MyWebserviceReference.Service1();
            myWebService.Url = "http://192.168.1.6/MyWebservice/Service1.asmx";
            //myWebService.Url = CryptoServices.DecryptText(SettingsAlias.Settings.Default.WebserviceURL,CryptoServices.DEFAULT_KEY);
            myWebService.Timeout = 36000;            
            //Load enumeration tables
            LoadGroupsToRoles();
        }
        public static void LoadGroupsToRoles() {
            string query = "SELECT * FROM GROUPS_TO_ROLES";
            DataTable groupsToRoles = myWebService.GetTableParamOracle(query, HOST, PORT, DATABASE, USERNAME, PASSWORD);
            GroupsToRoles = new Dictionary<UserGroup, Role>();
            foreach (DataRow groupsToRolesRow in groupsToRoles.Rows)
            {
                Role role = RolesList.First((i) => i.RoleId == groupsToRolesRow["ROLE_ID_FK"] as long?);
                UserGroup userGroup = UserGroupsList.First((i) => i.GroupId == groupsToRolesRow["GROUP_ID_FK"] as long?);
                GroupsToRoles.Add(userGroup, role);
            }
        }
    }
}

问题是第一次连接数据库总是失败。所以，我需要重新运行应用程序，以获得连接，这是不可接受的应用程序部署时。另一件事是，连接会在几分钟后重置。我怎样才能保持联系?

我正在使用:
ORACLE 11g DB
ODP。净
c# 4
SOAP的Webservice

Webservice代码:

public class Service1 : System.Web.Services.WebService
{
logger.LogCreator _log = new logger.LogCreator(@"C:'GDW_logs");
public static long DataTableCounter = 1;
string oracleConnection = "Data Source=(DESCRIPTION=(ADDRESS_LIST=(ADDRESS=(PROTOCOL=TCP)(HOST={0})(PORT={1})))(CONNECT_DATA=(SERVER=DEDICATED)(SERVICE_NAME={2})));User Id={3};Password={4};";                
    [WebMethod]
    public DataTable GetTableParamOracle(string sqltext, string host, string port, string database, string username, string password)
    {
        OracleConnection SQLConnection = new OracleConnection(string.Format(oracleConnection, host, port, database, username, password));
        OracleDataAdapter dad = new OracleDataAdapter(sqltext, SQLConnection);
        DataTable dtb = new DataTable("DataTable" + (DataTableCounter++));
        SQLConnection.Open();
        try
        {
            dad.Fill(dtb);
        }
        catch (Exception ex)
        {
            _log.WriteLine(ex.Message);
        }
        finally
        {
            SQLConnection.Close();
        }

        return dtb;
    }
}