function getToken($server_service,$username,$password) {
/**
	get a REST web API token from magento (we mimic the following console curl command)
	curl -X POST "http://domain.com/magento/index.php/rest/V1/integration/admin/token" \
	-H "Content-Type:application/json" -d '{"username":"admin", "password":"admin123"}'
 *
 * @param string $server_service 	- server name and service to connect to
 * @param string $username 			- authorized user 
 * @param string $username 			- password for authorized user 
 */
	$endpoint = $server_service.'/V1/integration/admin/token';
	$credentials = json_encode(array('username' => $username, 'password' => $password));
																	   
	$ch = curl_init($endpoint); 				# create new cURL resource
	curl_setopt($ch, CURLOPT_CUSTOMREQUEST, 'POST');
	curl_setopt($ch, CURLOPT_POSTFIELDS, $credentials);
	curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
	curl_setopt($ch, CURLOPT_HTTPHEADER, array(
		'Content-Type: application/json',
		'Content-Length: ' . strlen($credentials))
	);  
	$token = curl_exec($ch);
	// Check for errors and return any error message
	$curlError = "";							# no error
	if(curl_errno($ch) != 0) {
		$errno = curl_errno($ch);
		$error_message = curl_strerror($errno);
		$curlError = "cURL error ({$errno}): {$error_message}";
	}
	curl_close($ch);
	return array($curlError,$token);
}

function updateProduct($server_service,$sku,$updates,$headers) {
/**
 * update a products existing attributes 
 * reference: http://devdocs.magento.com/swagger/index.html#!/catalogProductRepositoryV1
    (we mimic this curl console command)
	curl -X PUT "http://domain.com/magento/index.php/rest/V1/products/24-MB01" \
	-d '{"product" : {"price": 12345}}' -H "Content-Type:application/json" \
	-H "Authorization: Bearer omcv3y5pydj4iemrfjnrhenay6nqb3vf" 
 *
 * @param string $server_service 	- server name and service to connect to
 * @param string $sku 				- sku of the product to be updated 
 * @param array  $updates 			- array of the individual columns be updated 
 * @param array  $headers 			- the curl header 
 */

	$endpoint = $server_service.'/V1/products/'.$sku;
	$productUpdates = json_encode(array('product' => $updates));
	$ch = curl_init();							# create new cURL resource
	curl_setopt($ch, CURLOPT_URL, $endpoint);
	curl_setopt($ch, CURLOPT_CUSTOMREQUEST, "PUT");
	curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);
	curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
	curl_setopt($ch, CURLINFO_HEADER_OUT, true);
	curl_setopt($ch, CURLOPT_POSTFIELDS,$productUpdates);
	curl_exec($ch);
	// Check for errors and return any error message
	$curlError = "";							# no error
	if(curl_errno($ch) != 0) {
		$errno = curl_errno($ch);
		$error_message = curl_strerror($errno);
		$curlError = "cURL error ({$errno}): {$error_message}";
	}
	$requestHeaders = curl_getinfo($ch)['request_header'];	# just for info
	curl_close($ch);
	return array($curlError,$requestHeaders);
}