Google Cloud Messaging - We've Come a Long Way- Google Developers Blog

This post details the evolution of Google Cloud Messaging (GCM), highlighting its journey from its initial release to becoming a robust platform for sending messages to applications on Android, iOS, and Chrome. It discusses the technical challenges and solutions in scaling GCM to handle billions of messages daily, including improvements in reliability, latency, and developer experience. The post also touches upon the transition towards Firebase Cloud Messaging (FCM) as the successor to GCM.