- http://phpfour.com/php-http-class/
- https://www.formget.com/curl-library-codeigniter/
- https://eureka.ykyuen.info/2011/05/05/php-send-a-soap-request-by-curl/
- http://code.tutsplus.com/tutorials/working-with-restful-services-in-codeigniter-2--net-8814
- http://guzzle.readthedocs.io/en/latest/quickstart.html
- https://www.sitepoint.com/guzzle-php-http-client/
- http://guzzle.readthedocs.io/en/latest/request-options.html#auth
- http://www.pixelite.co.nz/article/guzzle-http-post-authentication-and-form-submission-symfony-20/