| CurlFactoryInterface |
| CurlFactory | Creates curl resources from a request |
| CurlHandler | HTTP handler that uses cURL easy handles as a transport layer. |
| CurlMultiHandler | Returns an asynchronous response using curl_multi_* functions. |
| MockHandler | Handler that returns responses or throw exceptions from a queue. |
| Proxy | Provides basic proxies for handlers. |
| StreamHandler | HTTP handler that uses PHP's HTTP stream wrapper. |