Transaction Isolation in ADO.NET Entity Framework

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Data.Objects;
using System.Transactions;

namespace EFTransactionExample.Models
{
    class ApplicationModel
    {
        // Get all the information for the employees
        public IEnumerable<Employee> GetEmployeeInformation()
        {
            EmployeeSalaryEntities context = new EmployeeSalaryEntities();
            return context.Employees.AsEnumerable<Employee>();
        }

        // Set an employee's salary to a value
        public void SetEmployeeSalary(int employeeID,
            string employeeName, int salary)
        {
            EmployeeSalaryEntities context = new EmployeeSalaryEntities();
            var employee = context.Employees.Where(e => e.ID == employeeID)
                .SingleOrDefault<Employee>();

            if (employee == null)
            {
                employee = new Employee()
                {
                    ID = employeeID,
                    Name = employeeName,
                    Salary = salary
                };

                context.Employees.AddObject(employee);
            }
            employee.Salary = salary;
            context.SaveChanges(SaveOptions.AcceptAllChangesAfterSave);
        }

        public void RaiseEmployeeSalaryNonSerialized(int employeeID, int amount)
        {
            // Read employee information
            EmployeeSalaryEntities context = new EmployeeSalaryEntities();
            var employee = context.Employees.Where(e => e.ID == employeeID)
                .Single<Employee>();

            // sleep a while
            System.Threading.Thread.Sleep(5000);

            // Update the salary
            employee.Salary = employee.Salary + amount;
            context.SaveChanges(SaveOptions.AcceptAllChangesAfterSave);
        }

        public void RaiseEmployeeSalarySerialized(int employeeID, int amount)
        {
            TransactionOptions options = new TransactionOptions();
            options.IsolationLevel = IsolationLevel.Serializable;
            using (TransactionScope scope
                = new TransactionScope(TransactionScopeOption.Required, options))
            using (EmployeeSalaryEntities context = new EmployeeSalaryEntities())
            {
                // Open the database connection explicitly
                context.Connection.Open();

                // Read employee information
                var employee = context.Employees.Where(e => e.ID == employeeID)
                    .Single<Employee>();

                // sleep a while
                System.Threading.Thread.Sleep(5000);

                // Update the salary
                employee.Salary = employee.Salary + amount;
                context.SaveChanges(SaveOptions.AcceptAllChangesAfterSave);

                scope.Complete();
            }
        }
    }
}