AWS DynamoDB trigger using Lambda in JAVA

Question

I am trying to trigger an AWS lambda function written in Java, on dynamodb stream events. Amazon has a guide for the same, using NodeJS here http://docs.aws.amazon.com/lambd

Answer 1

Create a handler that takes an InputStream, read in the contents of the InputStream (which is just JSON) and then deserialize it to get the data that you need.

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import com.amazonaws.services.lambda.runtime.Context; 

public class MyHandler {    
    public void handler(InputStream inputStream, OutputStream outputStream, Context context) throws IOException {           
        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        int letter;        
        while((letter = inputStream.read()) != -1)
        {
            baos.write(letter);                     
        }        

        //Send the contents of baos to a JSON deserializer ...          
    }      
}

It's a bit cumbersome, but as far as I'm aware AWS doesn't currently provide a higher level Java lambda interface for consuming DynamoDB Streams. I have a full blown example here with details on how I deserialized the stream of JSON to get Java objects for the data.