$context  = stream_context_create(array('ssl' => array('header' => 'Accept: application/xml')));
$url = 'https://kosekayalar-1.dia.com.tr/b2c_xml?key=6ixVFCSWNOO2HnU9Ljct';

$xml = file_get_contents($url, false, $context);
$xml = simplexml_load_string($xml);

foreach($xml->product as $product){
    $stok_kodu = $product->stok_kodu;
    $title = $product->title;
    $description = $product->description;
    $keywords = $product->keywords;
    $stok_miktari = $product->stok_miktari;
    echo "Stok Kodu: $stok_kodu<br>Title: $title<br>Description: $description<br>Keywords: $keywords<br>Stok Miktarı: $stok_miktari";
}