internal class Person
{
  string firstName = "Jane";
  string lastName = "Doe";
  int id;
 
  internal Person(string fname, string lname)
  {
    this.firstname = fname;
    this.lastname = lname;
  }

  internal int Id
  {
    get { return this.id; }
    set { this.id = value; }
  }

  internal string FirstName
  {
    get { return this.firstName; }
    set { this.firstName = value; }
  }

  internal string LastName
  {
    get { return this.lastName; }
    set { this.lastName = value; }
  }
}

internal class Broker
{
  internal void GenerateAndStore()
  {
    List<Person> list = new List<Person>();
    list.Add(new Person());
    list.Add(new Person("John", "Smith"));

    PersonDAO dao = new PersonDAO();
    dao.Save(list);
  }
}

internal class PersonDAO
{
  internal void Save(List<Person> list)
  {
    //open session to database
    ISession session = factory.OpenSession();
    //store objects in database
    session.SaveOrUpdateCopy(collection); [color=blue]<-- DOES NOT WORK[/color]
    //close session
    session.Close();
  }

  //this method works like a charme
  internal List<Person> GetAllPersons()
  {
    //open session to database
    ISession session = factory.OpenSession();
    //get objects from database
    List<Person> list = session.CreateCriteria(typeof (Person)).List<Person>();
    //close session
    session.Close();
  }
}

<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2">
   <class name="MyNameSpace.Person, MyAssembly" table="persons">
      <id name="Id" column="id" type="System.Int32">
         <generator class="increment" />
      </id>
      <property name="FirstName" column="firstname" />
      <property name="LastName" column="lastname" />
   </class>
</hibernate-mapping>

internal void Save(List<Person> list) {
         using(ISession session = factory.OpenSession()){
            foreach(Person lifeForm in list){
               session.Save(lifeForm);
            }
            session.Flush();
         }
      }