$post = new Post(
  new PostId(9),
  'Hello World',
  'Your first post',
  new User(
      new UserId(1),
      'Post Author'
  ),
  [
      new Comment(
          new CommentId(1000),
          'Have no fear, sers, your king is safe.',
          new User(new UserId(2), 'Barristan Selmy'),
          [
              'created_at' => (new DateTime('2015/07/18 12:13:00'))->format('c'),
              'accepted_at' => (new DateTime('2015/07/19 00:00:00'))->format('c'),
          ]
      ),
  ]
);

use NilPortugues\Api\Mapping\Mapper;

$mappings = [
    [
        'class' => Post::class,
        'alias' => 'Message',
        'aliased_properties' => [
            'author' => 'author',
            'title' => 'headline',
            'content' => 'body',
        ],
        'hide_properties' => [

        ],
        'id_properties' => [
            'postId',
        ],
        'urls' => [
            'self' => 'http://example.com/posts/{postId}',
            'comments' => 'http://example.com/posts/{postId}/comments'
        ],
        // (Optional)
        'relationships' => [
            'author' => [ //this key must match with the property or alias of the same name in Post class.
                'related' => 'http://example.com/posts/{postId}/author',
                'self' => 'http://example.com/posts/{postId}/relationships/author',
            ]
        ],
    ],
    [
        'class' => PostId::class,
        'alias' => '',
        'aliased_properties' => [],
        'hide_properties' => [],
        'id_properties' => [
            'postId',
        ],
        'urls' => [
            'self' => 'http://example.com/posts/{postId}',
         ],
         'relationships' => [
              'comment' => [ //this key must match with the property or alias of the same name in PostId class.
                 'self' => 'http://example.com/posts/{postId}/relationships/comments',
              ],
            ],
        ],
    ],
    [
        'class' => User::class,
        'alias' => '',
        'aliased_properties' => [],
        'hide_properties' => [],
        'id_properties' => [
            'userId',
        ],
        'urls' => [
            'self' => 'http://example.com/users/{userId}',
            'friends' => 'http://example.com/users/{userId}/friends',
            'comments' => 'http://example.com/users/{userId}/comments',
        ],
    ],
    [
        'class' => UserId::class,
        'alias' => '',
        'aliased_properties' => [],
        'hide_properties' => [],
        'id_properties' => [
            'userId',
        ],
        'urls' => [
            'self' => 'http://example.com/users/{userId}',
            'friends' => 'http://example.com/users/{userId}/friends',
            'comments' => 'http://example.com/users/{userId}/comments',
        ],
    ],
    [
        'class' => Comment::class,
        'alias' => '',
        'aliased_properties' => [],
        'hide_properties' => [],
        'id_properties' => [
            'commentId',
        ],
        'urls' => [
            'self' => 'http://example.com/comments/{commentId}',
        ],
        'relationships' => [
            'post' => [ //this key must match with the property or alias of the same name in Commend class.
                'self' => 'http://example.com/posts/{postId}/relationships/comments',
            ]
        ],
    ],
    [
        'class' => CommentId::class,
        'alias' => '',
        'aliased_properties' => [],
        'hide_properties' => [],
        'id_properties' => [
            'commentId',
        ],
        'urls' => [
            'self' => 'http://example.com/comments/{commentId}',
        ],
        'relationships' => [
            'post' => [ //this key must match with the property or alias of the same name in CommendId class.
                'self' => 'http://example.com/posts/{postId}/relationships/comments',
            ]
        ],
    ],
];

$mapper = new Mapper($mappings);

use NilPortugues\Api\JsonApi\JsonApiTransformer;
use NilPortugues\Api\JsonApi\Http\Message\Response;
use NilPortugues\Serializer\DeepCopySerializer;

$transformer = new JsonApiTransformer($mapper);

//Output transformation
$serializer = new DeepCopySerializer($transformer);
$serializer->setSelfUrl('http://example.com/posts/9');
$serializer->setNextUrl('http://example.com/posts/10');
$serializer->addMeta('author',[['name' => 'Nil Portugués Calderó', 'email' => '[email protected]']]);

$output = $serializer->serialize($post);

//PSR7 Response with headers and content.
$response = new Response($output);

header(
    sprintf(
        'HTTP/%s %s %s',
        $response->getProtocolVersion(),
        $response->getStatusCode(),
        $response->getReasonPhrase()
    )
);
foreach($response->getHeaders() as $header => $values) {
    header(sprintf("%s:%s\n", $header, implode(', ', $values)));
}

echo $response->getBody();

namespace NilPortugues\Api\JsonApi\Http\Message;

final class Request
{
    public function __construct(ServerRequestInterface $request) { ... }
    public function getQueryParam($name, $default = null) { ... }
    public function getIncludedRelationships($baseRelationshipPath) { ... }
    public function getSortFields() { ... }
    public function getAttribute($name, $default = null) { ... }
    public function getSortDirection() { ... }
    public function getPageNumber() { ... }
    public function getPageLimit() { ... }
    public function getPageOffset() { ... }
    public function getPageSize() { ... }
    public function getPageCursor() { ... }
    public function getFilters() { ... }
}