Helper library for GCM HTTP server operations — see GCM Server for more information.
| Constants | Constants used on GCM service communication. | 
| Message | GCM message. | 
| Message.Builder | |
| MulticastResult | Result of a GCM multicast message request . | 
| MulticastResult.Builder | |
| Result | Result of a GCM message request that returned HTTP status code 200. | 
| Result.Builder | |
| Sender | Helper class to send messages to the GCM service using an API Key. | 
| InvalidRequestException | Exception thrown when GCM returned an error due to an invalid request. |