var row = new string[3]; 
row[0] = "Liverpool"; 
row[0] = "15";

using System.AddIn.Pipeline;
using System.AddIn.Contract;

namespace CalculatorConract
{
  [AddInContract]
  public interface ICalculatorContract : IContract
  {
      double Operate(string operation, double a, double b);
  }
}

using System;
using CalculatorConract.AddInViews;
using System.AddIn;

namespace CalculatorAddIn
{
   [AddIn]
  public class MyCalculatorAddIn : ICalculator
  {
      public double Operate(string operation, double a, double b)
      {
          throw new NotImplementedException();
      }
  }
}

using System;
using CalculatorConract.AddInViews;
using System.AddIn;

namespace CalculatorAddIn
{
  [AddIn("افزونه یک", Description = "توضیحات", Publisher = "نویسنده", Version = "نگارش یک")]
  public class MyCalculatorAddIn : ICalculator
  {
      public double Operate(string operation, double a, double b)
      {
          switch (operation)
          {
              case "+":
                  return a + b;
              case "-":
                  return a - b;
              case "*":
                  return a * b;
              default:
                  throw new NotSupportedException("عملیات مورد نظر توسط این افزونه پشتیبانی نمی‌شود");
          }
      }
  }
}

using System;
using System.AddIn.Hosting;
using CalculatorConract.HostViews;

namespace Calculator
{
  class Program
  {
      private static ICalculator _calculator;

      static void doOperation()
      {
          Console.WriteLine("1+2: {0}", _calculator.Operate("+", 1, 2));
      }

      static void Main(string[] args)
      {
          //مسیر پوشه ریشه مربوطه به خط لوله افزونه‌ها
          string path = Environment.CurrentDirectory;

          //مشخص سازی مسیر خواندن و کش کردن افزونه‌ها
          AddInStore.Update(path);

          //یافتن افزونه‌هایی سازگار با شرایط قرارداد پروژه
          //در اینجا هیچ افزونه‌ای بارگذاری نمی‌شود
          var addIns = AddInStore.FindAddIns(typeof(ICalculator), path);

          //اگر افزونه‌ای یافت شد
          if (addIns.Count > 0)
          {
              var addIn = addIns[0]; //استفاده از اولین افزونه
              Console.WriteLine("1st addIn: {0}", addIn.Name);

              //فعال سازی افزونه و همچنین مشخص سازی سطح دسترسی آن
              _calculator = addIn.Activate<ICalculator>(AddInSecurityLevel.Intranet);

              //یک نمونه از استفاده آن
              doOperation();
          }

          Console.WriteLine("Press a key...");
          Console.ReadKey();
      }
  }
}

//فعال سازی افزونه و همچنین مشخص سازی سطح دسترسی آن
//همچنین جدا سازی پروسه اجرایی افزونه از هاست
   _calculator = addIn.Activate<ICalculator>(
                  new AddInProcess(),
                  AddInSecurityLevel.Intranet);

using System.Web;
using System.Web.Mvc;
using Microsoft.AspNet.Identity.Owin;
using Users.Infrastructure;

namespace Users.Controllers
{
    public class HomeController : Controller
    {
        private AppUserManager UserManager
        {
            get { return HttpContext.GetOwinContext().GetUserManager<AppUserManager>(); }
        }
        // GET: Home
        public ActionResult Index()
        {
            return View(UserManager.Users);

        }

}

در این مقاله حالت‌هایی را که الگوی طراحی Null Object، قادر به تشخیص آنها نیست را به وسیله الگوی طراحی Special case رفع می‌کنیم.

 الگوی طراحی Special Case 

گاهی از اوقات پیش خواهد آمد که ما تسلیم شده و شیءای را برمی‌گردانیم که خودش نشان دهنده خطاست. اما همه شکست‌ها یکسان نیستند. در ابتدا، کاربر ممکن است واجد شرایط انجام خرید نباشد. اما اگر واجد شرایط باشد، آیتم مورد نظر ممکن است در انبار نباشد. در صورت موجود بودن در انبار، حساب کاربر ممکن است مبلغ کافی نداشته باشد.

بجای برگشت دادن شیء Null در تمام این موارد، ما می‌توانیم نتیجه را اصلاح کنیم و اساسا هر بار یک شیء مختلف را بازگردانیم. اینها هنوز هم نوعی از اشیاء Null هستند؛ ولی اینبار دارای معانی هستند. یکی از انها برای «حساب کاربری ناکافی» است، یکی دیگر برای «سایت در دست تعمیر و نگهداری» است و یا یکی دیگر از آنها «موجود نبودن در انبار» خواهد بود. 

چنین اشیائی به موارد خاص ( Special Case ) اشاره می‌کنند. ما می‌توانیم اشیاء مورد خاص ( Special Case ) را به عنوان نتایج واقعی عملیات بسازیم. فقط اگر تمام بررسی‌های کسب و کار به پایان برسند و عملیات موفقیت آمیز باشد، آنگاه شیء واقعی نتیجه را باز می‌گردانیم.

نمونه‌ای از پیاده سازی موارد خاص

این بخشی از رابط کاربری است که توسط سرویس‌های برنامه کاربردی اجرا می‌شود:

public interface IApplicationServices
{
    ...
    IReceiptViewModel LoggedInUserPurchase(string itemName);
}

لایه نمایش انتظار دارد که لایه نرم افزار یک ویو مدل به خصوصی را برای آن تولید کند. در حال حاضر ما یک سناریوی موفقیت آمیز را داریم که در آن ویو مدل شامل اطلاعات واقعی از خرید است و چندین سناریوی شکست. 

 اگرعملیات خرید با هر کدام از شرایط زیر مواجه شود به شکست می‌انجامد:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Threading;

 class Program
    {
        static int a = 0;
        static int b = 0;
        static Random random = new Random();
        
        static void Main(string[] args)
        {

            Thread obj = new Thread(Division);
            obj.Start();

            Division();
        }

        static void Division()
        {

            for (int i = 0; i <= 500; i++)
            {

                try
                {
                   
                        //Choosing random numbers between 1 to 5
                        a = random.Next(1, 10);
                        b = random.Next(1, 10);


                        //Dividing
                        double ans = a / b;


                        //Reset Variables
                        a = 0;
                        b = 0;

                        Console.WriteLine("Answer : {0} --> {1}", i, ans);
                    
                }
                catch (Exception ex)
                {
                    Console.WriteLine(ex.ToString());
                }
            }
        }
    }

class Program
    {
        static int a = 0;
        static int b = 0;
        static Random random = new Random();
        static readonly object _object = new object();
        static void Main(string[] args)
        {

            Thread obj = new Thread(Division);
            obj.Start();

            Division();
        }

        static void Division()
        {

            for (int i = 0; i <= 500; i++)
            {

                try
                {
                    Monitor.Enter(_object);
                   
                        //Choosing random numbers between 1 to 5
                        a = random.Next(1, 10);
                        b = random.Next(1, 10);


                        //Dividing
                        double ans = a / b;


                        //Reset Variables
                        a = 0;
                        b = 0;

                        Console.WriteLine("Answer : {0} --> {1}", i, ans);
                    Monitor.Exit(_object);

                }
                catch (Exception ex)
                {
                    Console.WriteLine(ex.ToString());
                }
            }
        }
    }

 static void Main()
  { 
    using (var mutex = new Mutex (false, "dotnettips.info Demo"))
    {
     
      if (!mutex.WaitOne (TimeSpan.FromSeconds (3), false))
      {
        Console.WriteLine ("Another app instance is running. Bye!");
        return;
      }
      RunProgram();
    }
  }
 
  static void RunProgram()
  {
    Console.WriteLine ("Running. Press Enter to exit");
    Console.ReadLine();
  }

namespace NHSample1.Domain
{
   public class Product
   {
       public int Id { get; set; }
       public string Name { get; set; }
       public decimal UnitPrice { get; set; }
       public bool Discontinued { get; set; }
   }
}

using FluentNHibernate.Mapping;
using NHSample1.Domain;

namespace NHSample1.Mappings
{
   public class ProductMapping : ClassMap<Product>
   {
       public ProductMapping()
       {
           Not.LazyLoad();
           Id(p => p.Id).GeneratedBy.HiLo("1000");
           Map(p => p.Name).Length(50).Not.Nullable();
           Map(p => p.UnitPrice).Not.Nullable();
           Map(p => p.Discontinued).Not.Nullable();
       }
   }
}

using NUnit.Framework;
using FluentNHibernate.Testing;
using NHSample1.Domain;

namespace UnitTests
{
   [TestFixture]
   public class ProductMapping_Fixture : FixtureBase
   {
       [Test]
       public void can_correctly_map_product()
       {
           new PersistenceSpecification<Product>(Session)
                   .CheckProperty(p => p.Id, 1001)
                   .CheckProperty(p => p.Name, "Apples")
                   .CheckProperty(p => p.UnitPrice, 10.45m)
                   .CheckProperty(p => p.Discontinued, true)
                   .VerifyTheMappings();
       }
   }
}

ProductMapping_Fixture.can_correctly_map_product : Passed
NHibernate: select next_hi from hibernate_unique_key
NHibernate: update hibernate_unique_key set next_hi = @p0 where next_hi = @p1;@p0 = 2, @p1 = 1
NHibernate: INSERT INTO "Product" (Name, UnitPrice, Discontinued, Id) VALUES (@p0, @p1, @p2, @p3);@p0 = 'Apples', @p1 = 10.45, @p2 = True, @p3 = 1001
NHibernate: SELECT product0_.Id as Id1_0_, product0_.Name as Name1_0_, product0_.UnitPrice as UnitPrice1_0_, product0_.Discontinued as Disconti4_1_0_ FROM "Product" product0_ WHERE product0_.Id=@p0;@p0 = 1001

using System;
namespace NHSample1.Domain
{
   public class Employee
   {
       public int Id { set; get; }
       public string LastName { get; set; }
       public string FirstName { get; set; }
   }
}

using NHSample1.Domain;
using FluentNHibernate.Mapping;

namespace NHSample1.Mappings
{
   public class EmployeeMapping : ClassMap<Employee>
   {
       public EmployeeMapping()
       {
           Not.LazyLoad();
           Id(e => e.Id).GeneratedBy.Assigned();
           Map(e => e.LastName).Length(50);
           Map(e => e.FirstName).Length(50);
       }
   }
}

using NUnit.Framework;
using NHSample1.Domain;
using FluentNHibernate.Testing;

namespace UnitTests
{
   [TestFixture]
   public class EmployeeMapping_Fixture : FixtureBase
   {
       [Test]
       public void can_correctly_map_employee()
       {
           new PersistenceSpecification<Employee>(Session)
                   .CheckProperty(p => p.Id, 1001)
                   .CheckProperty(p => p.FirstName, "name1")
                   .CheckProperty(p => p.LastName, "lname1")
                   .VerifyTheMappings();
       }
   }
}

NHibernate: select next_hi from hibernate_unique_key
NHibernate: update hibernate_unique_key set next_hi = @p0 where next_hi = @p1;@p0 = 2, @p1 = 1
NHibernate: INSERT INTO "Employee" (LastName, FirstName, Id) VALUES (@p0, @p1, @p2);@p0 = 'lname1', @p1 = 'name1', @p2 = 1001
NHibernate: SELECT employee0_.Id as Id4_0_, employee0_.LastName as LastName4_0_, employee0_.FirstName as FirstName4_0_ FROM "Employee" employee0_ WHERE employee0_.Id=@p0;@p0 = 1001

namespace NHSample1.Domain
{
   public class OrderItem
   {
       public int Id { get; set; }
       public int Quantity { get; set; }
       public Product Product { get; set; }
   }
}

using FluentNHibernate.Mapping;
using NHSample1.Domain;

namespace NHSample1.Mappings
{
   public class OrderItemMapping : ClassMap<OrderItem>
   {
       public OrderItemMapping()
       {
           Not.LazyLoad();
           Id(oi => oi.Id).GeneratedBy.Assigned();
           Map(oi => oi.Quantity).Not.Nullable();
           References(oi => oi.Product).Not.Nullable();
       }
   }
}

using NUnit.Framework;
using NHSample1.Domain;
using FluentNHibernate.Testing;

namespace UnitTests
{
   [TestFixture]
   public class OrderItemMapping_Fixture : FixtureBase
   {
       [Test]
       public void can_correctly_map_order_item()
       {
           var product = new Product
           {
               Name = "Apples",
               UnitPrice = 4.5m,
               Discontinued = true
           };

           new PersistenceSpecification<OrderItem>(Session)
                       .CheckProperty(p => p.Id, 1)
                       .CheckProperty(p => p.Quantity, 5)
                       .CheckReference(p => p.Product, product)
                       .VerifyTheMappings();
       }
   }
}

using System.Collections;
using NHSample1.Domain;

namespace UnitTests
{
   public class CustomEqualityComparer : IEqualityComparer
   {
       public bool Equals(object x, object y)
       {
           if (ReferenceEquals(x, y)) return true;
           if (x == null || y == null) return false;

           if (x is Product && y is Product)
               return (x as Product).Id == (y as Product).Id;

           if (x is Customer && y is Customer)
               return (x as Customer).Id == (y as Customer).Id;

           if (x is Employee && y is Employee)
               return (x as Employee).Id == (y as Employee).Id;

           if (x is OrderItem && y is OrderItem)
               return (x as OrderItem).Id == (y as OrderItem).Id;
          

           return x.Equals(y);
       }

       public int GetHashCode(object obj)
       {
           //شاید وقتی دیگر
           return obj.GetHashCode();
       }
   }
}

new PersistenceSpecification<OrderItem>(Session, new CustomEqualityComparer())

NHibernate: select next_hi from hibernate_unique_key
NHibernate: update hibernate_unique_key set next_hi = @p0 where next_hi = @p1;@p0 = 2, @p1 = 1
NHibernate: INSERT INTO "Product" (Name, UnitPrice, Discontinued, Id) VALUES (@p0, @p1, @p2, @p3);@p0 = 'Apples', @p1 = 4.5, @p2 = True, @p3 = 1001
NHibernate: INSERT INTO "OrderItem" (Quantity, Product_id, Id) VALUES (@p0, @p1, @p2);@p0 = 5, @p1 = 1001, @p2 = 1
NHibernate: SELECT orderitem0_.Id as Id0_1_, orderitem0_.Quantity as Quantity0_1_, orderitem0_.Product_id as Product3_0_1_, product1_.Id as Id3_0_, product1_.Name as Name3_0_, product1_.UnitPrice as UnitPrice3_0_, product1_.Discontinued as Disconti4_3_0_ FROM "OrderItem" orderitem0_ inner join "Product" product1_ on orderitem0_.Product_id=product1_.Id WHERE orderitem0_.Id=@p0;@p0 = 1

using System;
using System.Collections.Generic;

namespace NHSample1.Domain
{
   public class Order
   {
       public int Id { set; get; }
       public DateTime OrderDate { get; set; }
       public Employee Employee { get; set; }
       public Customer Customer { get; set; }
       public IList<OrderItem> OrderItems { get; set; }
   }
}

using NHSample1.Domain;
using FluentNHibernate.Mapping;

namespace NHSample1.Mappings
{
   public class OrderMapping : ClassMap<Order>
   {
       public OrderMapping()
       {
           Not.LazyLoad();
           Id(o => o.Id).GeneratedBy.GuidComb();
           Map(o => o.OrderDate).Not.Nullable();
           References(o => o.Employee).Not.Nullable();
           References(o => o.Customer).Not.Nullable();
           HasMany(o => o.OrderItems)
               .AsList(index => index.Column("ListIndex").Type<int>());
       }
   }
}

using System;
using System.Collections.Generic;
using NUnit.Framework;
using NHSample1.Domain;
using FluentNHibernate.Testing;

namespace UnitTests
{
   [TestFixture]
   public class OrderMapping_Fixture : FixtureBase
   {
       [Test]
       public void can_correctly_map_an_order()
       {
           {
               var product1 =
                   new Product
                   {
                       Name = "Apples",
                       UnitPrice = 4.5m,
                       Discontinued = true
                   };
               var product2 =
                   new Product
                   {
                       Name = "Pears",
                       UnitPrice = 3.5m,
                       Discontinued = false
                   };

               Session.Save(product1);
               Session.Save(product2);

               var items = new List<OrderItem>
                               {
                                   new OrderItem
                                   {
                                       Id = 1,
                                       Quantity = 100,
                                       Product = product1
                                   },
                                   new OrderItem
                                   {
                                       Id = 2,
                                       Quantity = 200,
                                       Product = product2
                                   }
                               };

               var customer = new Customer
               {
                   FirstName = "Vahid",
                   LastName = "Nasiri",
                   AddressLine1 = "Addr1",
                   AddressLine2 = "Addr2",
                   PostalCode = "1234",
                   City = "Tehran",
                   CountryCode = "IR"
               };

               var employee =
                   new Employee
                   {
                       FirstName = "name1",
                       LastName = "lname1"
                   };


              
               var order = new Order
               {
                   Customer = customer,
                   Employee = employee,
                   OrderDate = DateTime.Today,
                   OrderItems = items
               };

               new PersistenceSpecification<Order>(Session, new CustomEqualityComparer())
                   .CheckProperty(o => o.OrderDate, order.OrderDate)
                   .CheckReference(o => o.Customer, order.Customer)
                   .CheckReference(o => o.Employee, order.Employee)
                   .CheckList(o => o.OrderItems, order.OrderItems)
                   .VerifyTheMappings();
           }
       }
   }
}

OrderMapping_Fixture.can_correctly_map_an_order : Passed
NHibernate: select next_hi from hibernate_unique_key
NHibernate: update hibernate_unique_key set next_hi = @p0 where next_hi = @p1;@p0 = 2, @p1 = 1
NHibernate: select next_hi from hibernate_unique_key
NHibernate: update hibernate_unique_key set next_hi = @p0 where next_hi = @p1;@p0 = 3, @p1 = 2
NHibernate: INSERT INTO "Product" (Name, UnitPrice, Discontinued, Id) VALUES (@p0, @p1, @p2, @p3);@p0 = 'Apples', @p1 = 4.5, @p2 = True, @p3 = 1001
NHibernate: INSERT INTO "Product" (Name, UnitPrice, Discontinued, Id) VALUES (@p0, @p1, @p2, @p3);@p0 = 'Pears', @p1 = 3.5, @p2 = False, @p3 = 1002
NHibernate: INSERT INTO "Customer" (FirstName, LastName, AddressLine1, AddressLine2, PostalCode, City, CountryCode, Id) VALUES (@p0, @p1, @p2, @p3, @p4, @p5, @p6, @p7);@p0 = 'Vahid', @p1 = 'Nasiri', @p2 = 'Addr1', @p3 = 'Addr2', @p4 = '1234', @p5 = 'Tehran', @p6 = 'IR', @p7 = 2002
NHibernate: select next_hi from hibernate_unique_key
NHibernate: update hibernate_unique_key set next_hi = @p0 where next_hi = @p1;@p0 = 4, @p1 = 3
NHibernate: INSERT INTO "Employee" (LastName, FirstName, Id) VALUES (@p0, @p1, @p2);@p0 = 'lname1', @p1 = 'name1', @p2 = 3003
NHibernate: INSERT INTO "OrderItem" (Quantity, Product_id, Id) VALUES (@p0, @p1, @p2);@p0 = 100, @p1 = 1001, @p2 = 1
NHibernate: INSERT INTO "OrderItem" (Quantity, Product_id, Id) VALUES (@p0, @p1, @p2);@p0 = 200, @p1 = 1002, @p2 = 2
NHibernate: INSERT INTO "Order" (OrderDate, Employee_id, Customer_id, Id) VALUES (@p0, @p1, @p2, @p3);@p0 = 2009/10/10 12:00:00 ق.ظ, @p1 = 3003, @p2 = 2002, @p3 = 0
NHibernate: UPDATE "OrderItem" SET Order_id = @p0, ListIndex = @p1 WHERE Id = @p2;@p0 = 0, @p1 = 0, @p2 = 1
NHibernate: UPDATE "OrderItem" SET Order_id = @p0, ListIndex = @p1 WHERE Id = @p2;@p0 = 0, @p1 = 1, @p2 = 2
NHibernate: SELECT order0_.Id as Id1_2_, order0_.OrderDate as OrderDate1_2_, order0_.Employee_id as Employee3_1_2_, order0_.Customer_id as Customer4_1_2_, employee1_.Id as Id4_0_, employee1_.LastName as LastName4_0_, employee1_.FirstName as FirstName4_0_, customer2_.Id as Id2_1_, customer2_.FirstName as FirstName2_1_, customer2_.LastName as LastName2_1_, customer2_.AddressLine1 as AddressL4_2_1_, customer2_.AddressLine2 as AddressL5_2_1_, customer2_.PostalCode as PostalCode2_1_, customer2_.City as City2_1_, customer2_.CountryCode as CountryC8_2_1_ FROM "Order" order0_ inner join "Employee" employee1_ on order0_.Employee_id=employee1_.Id inner join "Customer" customer2_ on order0_.Customer_id=customer2_.Id WHERE order0_.Id=@p0;@p0 = 0
NHibernate: SELECT orderitems0_.Order_id as Order4_2_, orderitems0_.Id as Id2_, orderitems0_.ListIndex as ListIndex2_, orderitems0_.Id as Id0_1_, orderitems0_.Quantity as Quantity0_1_, orderitems0_.Product_id as Product3_0_1_, product1_.Id as Id3_0_, product1_.Name as Name3_0_, product1_.UnitPrice as UnitPrice3_0_, product1_.Discontinued as Disconti4_3_0_ FROM "OrderItem" orderitems0_ inner join "Product" product1_ on orderitems0_.Product_id=product1_.Id WHERE orderitems0_.Order_id=@p0;@p0 = 0

SessionSource.BuildSchema(Session, true);

    drop table if exists "OrderItem"

    drop table if exists "Order"

    drop table if exists "Customer"

    drop table if exists "Product"

    drop table if exists "Employee"

    drop table if exists hibernate_unique_key

    create table "OrderItem" (
        Id INTEGER not null,
       Quantity INTEGER not null,
       Product_id INTEGER not null,
       Order_id INTEGER,
       ListIndex INTEGER,
       primary key (Id)
    )

    create table "Order" (
        Id INTEGER not null,
       OrderDate DATETIME not null,
       Employee_id INTEGER not null,
       Customer_id INTEGER not null,
       primary key (Id)
    )

    create table "Customer" (
        Id INTEGER not null,
       FirstName TEXT not null,
       LastName TEXT not null,
       AddressLine1 TEXT not null,
       AddressLine2 TEXT,
       PostalCode TEXT not null,
       City TEXT not null,
       CountryCode TEXT not null,
       primary key (Id)
    )

    create table "Product" (
        Id INTEGER not null,
       Name TEXT not null,
       UnitPrice NUMERIC not null,
       Discontinued INTEGER not null,
       primary key (Id)
    )

    create table "Employee" (
        Id INTEGER not null,
       LastName TEXT,
       FirstName TEXT,
       primary key (Id)
    )

    create table hibernate_unique_key (
         next_hi INTEGER
    )

           var cfg = Fluently.Configure().Database(
              // SQLiteConfiguration.Standard.ShowSql().InMemory
              MsSqlConfiguration
              .MsSql2008
              .ShowSql()
              .ConnectionString("Data Source=(local);Initial Catalog=testdb2009;Integrated Security = true")
               );

    if exists (select 1 from sys.objects where object_id = OBJECT_ID(N'[FK3EF88858466CFBF7]') AND parent_object_id = OBJECT_ID('[OrderItem]'))
alter table [OrderItem]  drop constraint FK3EF88858466CFBF7


    if exists (select 1 from sys.objects where object_id = OBJECT_ID(N'[FK3EF888589F32DE52]') AND parent_object_id = OBJECT_ID('[OrderItem]'))
alter table [OrderItem]  drop constraint FK3EF888589F32DE52


    if exists (select 1 from sys.objects where object_id = OBJECT_ID(N'[FK3117099B1EBA72BC]') AND parent_object_id = OBJECT_ID('[Order]'))
alter table [Order]  drop constraint FK3117099B1EBA72BC


    if exists (select 1 from sys.objects where object_id = OBJECT_ID(N'[FK3117099BB2F9593A]') AND parent_object_id = OBJECT_ID('[Order]'))
alter table [Order]  drop constraint FK3117099BB2F9593A


    if exists (select * from dbo.sysobjects where id = object_id(N'[OrderItem]') and OBJECTPROPERTY(id, N'IsUserTable') = 1) drop table [OrderItem]

    if exists (select * from dbo.sysobjects where id = object_id(N'[Order]') and OBJECTPROPERTY(id, N'IsUserTable') = 1) drop table [Order]

    if exists (select * from dbo.sysobjects where id = object_id(N'[Customer]') and OBJECTPROPERTY(id, N'IsUserTable') = 1) drop table [Customer]

    if exists (select * from dbo.sysobjects where id = object_id(N'[Product]') and OBJECTPROPERTY(id, N'IsUserTable') = 1) drop table [Product]

    if exists (select * from dbo.sysobjects where id = object_id(N'[Employee]') and OBJECTPROPERTY(id, N'IsUserTable') = 1) drop table [Employee]

    if exists (select * from dbo.sysobjects where id = object_id(N'hibernate_unique_key') and OBJECTPROPERTY(id, N'IsUserTable') = 1) drop table hibernate_unique_key

    create table [OrderItem] (
        Id INT not null,
       Quantity INT not null,
       Product_id INT not null,
       Order_id INT null,
       ListIndex INT null,
       primary key (Id)
    )

    create table [Order] (
        Id INT not null,
       OrderDate DATETIME not null,
       Employee_id INT not null,
       Customer_id INT not null,
       primary key (Id)
    )

    create table [Customer] (
        Id INT not null,
       FirstName NVARCHAR(50) not null,
       LastName NVARCHAR(50) not null,
       AddressLine1 NVARCHAR(50) not null,
       AddressLine2 NVARCHAR(50) null,
       PostalCode NVARCHAR(10) not null,
       City NVARCHAR(50) not null,
       CountryCode NVARCHAR(2) not null,
       primary key (Id)
    )

    create table [Product] (
        Id INT not null,
       Name NVARCHAR(50) not null,
       UnitPrice DECIMAL(19,5) not null,
       Discontinued BIT not null,
       primary key (Id)
    )

    create table [Employee] (
        Id INT not null,
       LastName NVARCHAR(50) null,
       FirstName NVARCHAR(50) null,
       primary key (Id)
    )

    alter table [OrderItem]
        add constraint FK3EF88858466CFBF7
        foreign key (Product_id)
        references [Product]

    alter table [OrderItem]
        add constraint FK3EF888589F32DE52
        foreign key (Order_id)
        references [Order]

    alter table [Order]
        add constraint FK3117099B1EBA72BC
        foreign key (Employee_id)
        references [Employee]

    alter table [Order]
        add constraint FK3117099BB2F9593A
        foreign key (Customer_id)
        references [Customer]

    create table hibernate_unique_key (
         next_hi INT
    )

using System;
using System.Net;

  public class CSiteMonitor
  {
      public struct UrlHeaderInfo
      {
          public DateTime _lastModified;
          public string _statusCode;
          public string _errorMessage;
      }

      /// <summary>
      /// آیا آدرس اینترنتی وارد شده معتبر است؟
      /// </summary>
      /// <param name="url">آدرس مورد نظر جهت بررسی</param>
      /// <returns></returns>
      public static bool IsValidURL(string url)
      {
          try
          {
              Uri uri = new Uri(url);
              return (uri.Scheme == Uri.UriSchemeHttp) || (uri.Scheme == Uri.UriSchemeHttps);
          }
          catch { return false; }
      }
      /// <summary>
      /// آدرس اینترنتی جهت بررسی
      /// </summary>
      /// <param name="url"></param>
      /// <returns></returns>
      /// <exception cref="ArgumentException">آدرس اینترنتی وارد شده معتبر نیست</exception>
      public static UrlHeaderInfo GetSiteHeaderInfo(string url)
      {
          if (!IsValidURL(url))
              throw new ArgumentException("آدرس اینترنتی وارد شده معتبر نیست", "url");

          UrlHeaderInfo hhi = new UrlHeaderInfo { _lastModified = DateTime.Now, _statusCode = "NOK!", _errorMessage = string.Empty };

          HttpWebRequest request = (HttpWebRequest)WebRequest.Create(url);
          //request.Proxy
          request.Method = "HEAD";
          request.AllowAutoRedirect = true;
          request.UserAgent = "Mozilla/5.0 (Windows; U; Windows NT 5.0; ; rv:1.8.0.7) Gecko/20060917 Firefox/1.9.0.1";
          request.Timeout = 1000 * 300;
          request.AutomaticDecompression = DecompressionMethods.GZip | DecompressionMethods.Deflate;
        
          try
          {
              using (HttpWebResponse response = (HttpWebResponse) request.GetResponse())
              {
                  hhi._statusCode = response.StatusCode.ToString();
                  hhi._lastModified = response.LastModified;
              }
          }
          catch (Exception ex)
          {
              hhi._errorMessage = ex.Message;
          }

          return hhi;
      }
  }

CSiteMonitor.UrlHeaderInfo info = CSiteMonitor.GetSiteHeaderInfo("http://www.google.com");
MessageBox.Show(info._statusCode);