[HttpPost]
public HttpResponseMessage AddEmployee([FromBody]Employee employee)
{
    if (ModelState.IsValid)
    {
         _employeeService.AddEmployee(employee);
         _employeeService.SaveEmployee();

         return new HttpResponseMessage(HttpStatusCode.OK);
    }

         return Request.CreateErrorResponse(HttpStatusCode.BadRequest, ModelState);
}

public void AddEmployee(Employee employee)
{
     _employeeRepository.Add(employee);
}

public class UnitOfWork : IUnitOfWork
    {
        private readonly IDbFactory dbFactory;
        private MyAppEntities dbContext;

        public UnitOfWork(IDbFactory dbFactory)
        {
            this.dbFactory = dbFactory;
        }

        public MyAppEntities DbContext
        {
            get { return dbContext ?? (dbContext = dbFactory.Init()); }
        }

        public void Commit()
        {
            DbContext.Commit();
        }
    }

    public interface IUnitOfWork
    {
        void Commit();
    }