Amazon SNS is a managed notification service. It works on a push mechanism: the publisher raises a request to send a message to the subscribers. Figure 13.1 shows us how it works:
Figure 13.1: Introduction to SNS
Reference URL: http://docs.aws.amazon.com/sns/latest/dg/images/sns-how-works.png
First, you need to create an Amazon SNS topic. An SNS topic acts as an access point between the publisher and subscriber applications. The publisher communicates asynchronously with the subscribers using SNS. Subscribers can be an entity such as a Lambda function, SQS, HTTP or HTTPS endpoint, email, or a mobile device that subscribes to an SNS topic for receiving notifications. To receive notifications, subscribers must specify the protocol (that is, HTTP, HTTPS, Email, Email-JSON, Amazon SQS, Application, AWS Lambda, or SMS). When a publisher has new information to share with the subscribers, it publishes a message to the topic. Finally, SNS delivers the message/notification...