PHP replicaSet connection

rs.php

<?php
  // connecting to mongood.com cluster
  $m = new Mongo("mongodb://mongo1.mongood.com:27017,mongo2.mongood.com:27017,mongo3.mongood.com:27017", array("replicaSet" => "cluster"));
  var_dump($m);
  $db = $m->selectDB('my_database');
  $db->authenticate("my_login", "my_password");
  $collection = new MongoCollection($db, 'my_collection');
  $cursor = $collection->find();
  foreach ($cursor as $doc) {
    var_dump($doc);
  }
?>