问题
I don't know how to subscribe to changes in DynamoDB database. Let me show an example: User A sends a message (which is saved in the database) to User B and in the User B's app the message automatically appears.
I know this is possible with recently released AWS AppSync, but I couldn't integrate it with Ionic (which I am using). However, there must be an alternative since AWS AppSync was released only at the end of 2017/beginning of 2018.
I've also seen something called Streams in DynamoDB but not sure if that's what I need.
回答1:
DynamoDB Streams is designed specifically for capturing/subscribing to table activity. You can set up a Lambda Function with your notification logic to process the stream and send notifications accordingly.
来源：https://stackoverflow.com/questions/51495112/how-to-subscribe-to-changes-in-dynamodb