Benefits of using MQTT vs another push notification service for android?

Hey guys, I am new to android development and I am curious on what is the "best" or most customary way to enable push notifications on an android app from a server.

i have been reading online and have see开发者_JAVA百科n two major ways that people implement push notifications service are with MQTT and C2DM. Can anyone please elaborate on these or other services that are available that are the best solution to implementing push notifications.

i have been using MQTT in my RnD and so far looks good, but the question now is it has some limitation of clients 1032 if im not mistaken? so i guess that i need to know more.

about c2dm i will study that later on.