Domain class
---------------------

File: /application/domain/Book.php

class Book {
   public $id;
   public $title;
   public $release_date;
}

Defining ORM Metadata
---------------------

File: /application/domain/mapping/Book.php

class BookMapper {
   public $table = 'Book';
   public $columns = array(
       'title' => array('name'=>'Title', 'type'=>'string')
   );
}

class BookConstraints {
   public $constraints = array(
       'title' => array('maxSize' => 200)
   );
}

class BookRelationships {
   public $belongsTo = 'Author';
   public $hasMany = array(
       'authors' => 'Author'
   );
}

Repository
---------------------

The Repository pattern offers a mechanism to manage the Book Entity and abstract the persistence away from the Domain object.

$book = new Book();
$book->name = 'ZF in Action';

$repository = new BookRepository();
$repository->setEntity($book);
$repository->setDao(new BookDao());
$repository->setMapper(new BookMapper());
$repository->save();

// Or...
$book = Zf_Orm::new('Book'); // returns an instance of BookRepository
$book->setTitle('ZF in Action'); // EntityManager.getEntity('Book')->$property = $value 
$book->save();

// Or...
$book = Zf_Orm::new('Book', array('title'=>'ZF in Action'));
$book->save();

Dynamic Finders
---------------------

A dynamic finder looks like a method invocation, but the methods themselves don't actually 
exist in any form at the code level.

$book = Zf_Orm::new('Book')->get(1);
$books = Zf_Orm::new('Book')->getAll(1, 2, 3);

Method expressions can also use a boolean operator to combine two criteria:

$book = Zf_Orm::new('Book');
$books = $book->findAllByTitleAndReleaseDate($title, $date);

Relationships
---------------------

$book = Zf_Orm::new('Book')->findByTitle('ZF in Action'); 
$book->addToAuthors(array('name'=>'Matthew');
$book->save();

$book = Zf_Orm::new('Book', array('title'=>'ZF in Action'));
$author->addToBooks($book);
$author->save();

Querying associations
---------------------

$author = Zf_Orm::new('Author')->findByName('Stephen King');
$books = Zf_Orm::new('Book')->findAllByAuthor($author);