I was facing that problem in php class, so i have done this using CURL, You can get your stores products, orders and coupon.
here is the code.
$username = 'your username';
$password = 'your key';
$url = ' your store url';
$product_url = $url.'/api/v2/products.json';
$curl = curl_init();
curl_setopt($curl, CURLOPT_URL, $product_url);
curl_setopt($curl, CURLOPT_FOLLOWLOCATION, 1);
curl_setopt($curl, CURLOPT_RETURNTRANSFER, 1);
curl_setopt($curl, CURLOPT_SSL_VERIFYPEER, false);
curl_setopt($curl, CURLOPT_USERPWD, $username . ":" . $password);
curl_setopt($curl, CURLOPT_HTTPAUTH, CURLAUTH_BASIC);
curl_setopt($curl, CURLOPT_ENCODING, "");
$curlData = curl_exec($curl);
curl_close($curl);
//returning retrieved feed
$product_rec = json_decode($curlData);
echo '<pre>';
print_r($product_rec);
now for orders use
$order_url = $url.'/api/v2/orders.json';