namespace NHSample3.Domain
{
  public class Car
  {
      public virtual int Id { get; set; }
      public virtual string Name { get; set; }
      public virtual string Color { get; set; }
  }
}

using System.Collections.Generic;

namespace NHSample3.Domain
{
  public class Parking
  {
      public virtual int Id { get; set; }
      public virtual string Name { get; set; }
      public virtual string Location { get; set; }
      public virtual IList<Car> Cars { get; set; }

      public Parking()
      {
          Cars = new List<Car>();
      }
  }
}

using FluentNHibernate.Automapping;
using FluentNHibernate.Cfg;
using FluentNHibernate.Cfg.Db;
using NHibernate.Tool.hbm2ddl;

namespace NHSessionManager
{
  public class Config
  {
      public static FluentConfiguration GetConfig()
      {
          return
            Fluently.Configure()
                    .Database(
                       MsSqlConfiguration
                         .MsSql2008
                         .ConnectionString(x => x.FromConnectionStringWithKey("DbConnectionString"))                         
                        )
                      .ExposeConfiguration(
                           x => x.SetProperty("current_session_context_class", "managed_web")
                       )
                      .Mappings(
                        m => m.AutoMappings.Add(
                           new AutoPersistenceModel()
                               .Where(x => x.Namespace.EndsWith("Domain"))                               
                               .AddEntityAssembly(typeof(NHSample3.Domain.Car).Assembly))
                               );
      }

      public static void CreateDb()
      {
          bool script = false;//آیا خروجی در کنسول هم نمایش داده شود
          bool export = true;//آیا بر روی دیتابیس هم اجرا شود            
          bool dropTables = false;//آیا جداول موجود دراپ شوند
          new SchemaExport(GetConfig().BuildConfiguration()).Execute(script, export, dropTables);
      }
  }
}

<connectionStrings>
  <!--NHSessionManager-->
  <add name="DbConnectionString"
         connectionString="Data Source=(local);Initial Catalog=HelloNHibernate;Integrated Security = true" />
</connectionStrings>

using NHibernate;

namespace NHSessionManager
{
  /// <summary>
  /// lazy, lock-free, thread-safe singleton
  /// </summary>
  public class SingletonCore
  {
      private readonly ISessionFactory _sessionFactory;

      SingletonCore()
      {
          _sessionFactory = Config.GetConfig().BuildSessionFactory();
      }

      public static SingletonCore Instance
      {
          get
          {
              return Nested.instance;
          }
      }

      public static ISession GetCurrentSession()
      {
          return Instance._sessionFactory.GetCurrentSession();
      }

      public static ISessionFactory SessionFactory
      {
          get { return Instance._sessionFactory; }
      }

      class Nested
      {
          // Explicit static constructor to tell C# compiler
          // not to mark type as beforefieldinit
          static Nested()
          {
          }

          internal static readonly SingletonCore instance = new SingletonCore();
      }
  }
}

using System;
using System.Web;
using NHibernate;
using NHibernate.Context;

namespace NHSessionManager
{
  public class SessionModule : IHttpModule
  {
      public void Dispose()
      { }

      public void Init(HttpApplication context)
      {
          if (context == null)
              throw new ArgumentNullException("context");

          context.BeginRequest += Application_BeginRequest;
          context.EndRequest += Application_EndRequest;
      }

      private void Application_BeginRequest(object sender, EventArgs e)
      {
          ISession session = SingletonCore.SessionFactory.OpenSession();
          ManagedWebSessionContext.Bind(HttpContext.Current, session);
          session.BeginTransaction();
      }

      private void Application_EndRequest(object sender, EventArgs e)
      {
          ISession session = ManagedWebSessionContext.Unbind(
              HttpContext.Current, SingletonCore.SessionFactory);
          if (session == null) return;

          try
          {
              if (session.Transaction != null &&
                  !session.Transaction.WasCommitted &&
                  !session.Transaction.WasRolledBack)
              {
                  session.Transaction.Commit();
              }
              else
              {
                  session.Flush();
              }
          }
          catch (Exception)
          {
              session.Transaction.Rollback();
          }
          finally
          {
              if (session != null && session.IsOpen)
              {
                  session.Close();
                  session.Dispose();
              }
          }
      }
  }
}

  <httpModules>
    <!--NHSessionManager-->
    <add name="SessionModule" type="NHSessionManager.SessionModule"/>
  </httpModules>

using System.Linq;
using NHibernate;
using NHibernate.Linq;
using NHSample3.Domain;

namespace NHSample3
{
  public class ParkingContext : NHibernateContext
  {
      public ParkingContext(ISession session)
          : base(session)
      { }

      public IOrderedQueryable<Car> Cars
      {
          get { return Session.Linq<Car>(); }
      }

      public IOrderedQueryable<Parking> Parkings
      {
          get { return Session.Linq<Parking>(); }
      }
  }
}

using System;
using System.Collections.Generic;
using System.Linq;
using NHibernate;
using NHSample3.Domain;
using NHSessionManager;

namespace NHSample3
{
  public partial class _Default : System.Web.UI.Page
  {
      protected void Page_Load(object sender, EventArgs e)
      {
          //ایجاد دیتابیس در صورت نیاز
          //Config.CreateDb();

          //ثبت یک سری رکورد در دیتابیس
          ISession session = SingletonCore.GetCurrentSession();

          Car car1 = new Car() { Name = "رنو", Color = "مشکلی" };
          session.Save(car1);
          Car car2 = new Car() { Name = "پژو", Color = "سفید" };
          session.Save(car2);

          Parking parking1 = new Parking()
          {
              Location = "آدرس پارکینگ مورد نظر",
              Name = "پارکینگ یک",
              Cars = new List<Car> { car1, car2 }
          };

          session.Save(parking1);

          //نمایش حاصل در یک گرید ویوو
          ParkingContext db = new ParkingContext(session);
          var query = from x in db.Cars select new { CarName = x.Name, CarColor = x.Color };
          GridView1.DataSource = query.ToList();
          GridView1.DataBind();
      }
  }
}

static void InitStructureMap()
{
            ObjectFactory.Initialize(x =>
            {
                x.For<IUnitOfWork>().HybridHttpOrThreadLocalScoped().Use<MyContext>();
                x.Scan(scan =>
                {
                    scan.AssemblyContainingType<INewsService>();
                    scan.WithDefaultConventions();
                });
                
            });

            ControllerBuilder.Current.SetControllerFactory(new StructureMapControllerFactory());
            var container = ObjectFactory.Container;
            GlobalConfiguration.Configuration.Services
                .Replace(typeof(IHttpControllerActivator),
                new StructureMapHttpControllerActivator(container));
            
}

public ActionResult EditSave(IEnumerable<HttpPostedFileBase> files, int referid)
       {
           // OASEntities db = new OASEntities();
           // The Name of the Upload component is "files"
           if (files != null)
           {
 
 
               int i =(int)db.letterdatas.Where(x => x.referletid == referid).Max(p => p.seq);
               foreach (var file in files)
               {
                   bool failtestsize = false;
                   if (file.ContentLength > 5096000) failtestsize = true;
                   if (failtestsize) return Content(new Exception("خطا : حجم فایل ارسالی بیش از حد مجاز می‌باشد").Message);
                 //  System.Threading.Thread.Sleep(2000);
                   var xi = db.letterdatas.Where(x => x.referletid == referid).Count();
                   if (xi > 4) return Content(new Exception("خطا : تعداد فایلهای ارسالی بیش از حد مجاز می‌باشد").Message);
 
 
                   i++;
                    
                  
                   var fileName = Path.GetFileName(file.FileName);
 
 
                 
                   byte[] filedata = new byte[file.ContentLength];
                   Stream st = file.InputStream;
                   st.Read(filedata, 0, file.ContentLength);
                   var letterdata = new letterdata
                   {
                       data = filedata,
                       extention = Path.GetExtension(file.FileName),
                       filename = fileName,
                       seq = i,
                       referletid = referid,
                       templetguid = null,
                       fileid = Guid.NewGuid(),
                       userid = db.users.Where(x => x.username == User.Identity.Name).Select(x => x.userid).FirstOrDefault()
 
 
                   };
                   db.letterdatas.Add(letterdata);
                   db.SaveChanges();
                  
               }
               
           }
            
           return Content("");
       }

int i =(int)db.letterdatas.Where(x => x.referletid == referid).Max(p => p.seq);
var xi = db.letterdatas.Where(x => x.referletid == referid).Count();

In summary, the most important issues here are:

• The Aggregate’s main task is to protect invariants (business rules, the boundary of immediate consistency)
• In a multi-threaded environment, when multiple threads are running simultaneously on the same Aggregate, a business rule may be broken
• A way to solve concurrency conflicts is to use Pessimistic or Optimistic concurrency techniques
• Pessimistic Concurrency involves the use of a database transaction and a locking mechanism. In this way, requests are processed one after the other, so basically concurrency is lost and it can lead to deadlocks.
• Optimistic Concurrency technique is based on versioning database records and checking whether the previously loaded version has not been changed by another thread.
• Entity Framework Core supports Optimistic Concurrency. Pessimistic Concurrency is not supported
• The Aggregate must always be treated and versioned as a single unit
• Domain events are an indicator, that state was changed so Aggregate version should be changed as well 

public class AggregateRootBase : Entity, IAggregateRoot
{
    private int _versionId;

    public void IncreaseVersion()
    {
        _versionId++;
    }
}

internal sealed class OrderEntityTypeConfiguration : IEntityTypeConfiguration<Order>
{
    public void Configure(EntityTypeBuilder<Order> builder)
    {
        builder.Property("_versionId").HasColumnName("VersionId").IsConcurrencyToken();
 
        //...
    }
}

var order = await _ordersContext.Orders.FindAsync(orderId);
order.AddOrderLine(request.ProductCode); 
var domainEvents = DomainEventsHelper.GetAllDomainEvents(order);
if (domainEvents.Any())
{
    order.IncreaseVersion();
}
await _ordersContext.SaveChangesAsync();

var Cities =from c in Cities
Select new {Id=c.Id, Name=c.Name}; 
return Json(Cities  , JsonRequestBehavior.AllowGet); 

using System.Data;
using System.IO;
using OfficeOpenXml;
using OfficeOpenXml.Drawing.Chart;
using OfficeOpenXml.Style;
using OfficeOpenXml.Table;

namespace EPPlusTest
{
  class Program
  {
      static void Main(string[] args)
      {
          var newFile = new FileInfo("Test.xlsx");
          if (newFile.Exists)
          {
              newFile.Delete();
          }

          //ایجاد یک سری اطلاعات دلخواه
          var table = createDt();

          using (var package = new ExcelPackage(newFile))
          {
              // اضافه کردن یک ورک شیت جدید
              ExcelWorksheet worksheet = package.Workbook.Worksheets.Add("مخارج");             

              //اضافه کردن یک جدول جدید از دیتاتیبل دریافتی
              worksheet.Cells["A1"].LoadFromDataTable(table, true, TableStyles.Dark9);

              //نمایش جمع ستون هزینه‌های ماه‌ها
              var tbl = worksheet.Tables[0];
              //زیر آخرین ردیف یک سطر اضافه می‌کند
              tbl.ShowTotal = true;
              //فرمول نحوه‌ی محاسبه جمع ستون انتساب داده می‌شود
              tbl.Columns[1].TotalsRowFunction = RowFunctions.Sum;

              //تعیین عرض ستون‌های جدول
              worksheet.Column(1).Width = 14;
              worksheet.Column(2).Width = 12;

              //تنظیم متن هدر
              worksheet.HeaderFooter.oddHeader.CenteredText = "مثالی از نحوه‌ی استفاده از ایی پی پلاس";              

              //می‌خواهیم سرستون‌ها در وسط ستون قرار گیرند
              worksheet.Cells["A1"].Style.HorizontalAlignment = ExcelHorizontalAlignment.Center;
              worksheet.Cells["B1"].Style.HorizontalAlignment = ExcelHorizontalAlignment.Center;

              //افزودن یک نمودار جدید به شیت جاری
              var chart = worksheet.Drawings.AddChart("chart1", eChartType.Pie3D);
              chart.Title.Text = "نمودار هزینه‌های سال";
              chart.SetPosition(Row: 2, RowOffsetPixels: 5, Column: 3, ColumnOffsetPixels: 5);
              chart.SetSize(PixelWidth: 320, PixelHeight: 360);
              chart.Series.Add("B2:B13", "A2:A13");
              chart.Style = eChartStyle.Style26;

              //تنظیم یک سری خواص فایل نهایی
              package.Workbook.Properties.Title = "مثالی از ایی پی پلاس";
              package.Workbook.Properties.Author = "وحید";
              package.Workbook.Properties.Subject = "ایجاد فایل اکسل بدون نرم افزار اکسل";

              //تنظیم نحوه‌ی نمایش فایل زمانیکه در نرم افزار اکسل گشوده می‌شود
              worksheet.View.PageLayoutView = true;
              worksheet.View.RightToLeft = true;

              // ذخیر سازی کلیه موارد اعمالی در فایل
              package.Save();
          }
      }

      private static DataTable createDt()
      {
          var table = new DataTable("مخارج");
          table.Columns.Add("ماه", typeof(string));
          table.Columns.Add("هزینه", typeof(decimal));

          table.Rows.Add("فروردین", 100);
          table.Rows.Add("اردیبهشت", 250);
          table.Rows.Add("خرداد", 80);
          table.Rows.Add("تیر", 300);
          table.Rows.Add("مرداد", 200);
          table.Rows.Add("شهریور", 150);
          table.Rows.Add("مهر", 250);
          table.Rows.Add("آبان", 200);
          table.Rows.Add("آذر", 400);
          table.Rows.Add("دی", 100);
          table.Rows.Add("بهمن", 130);
          table.Rows.Add("اسفند", 80);
          return table;
      }
  }
}