AWS Lambda and S3 integration using AWS Java Sdk

Question

I am trying to develop a AWS lambda function which is triggered when a file shows up in a specific s3 bucket. I am trying to follow the examples from AWS Lambda documentation, using aws-java-sdk-lambda 1.11.192, aws-java-sdk-s3 1.11.192. But, unfortunately the these examples use RequestHandler which is deprecated in the latest version of the jar.

My code is similar to this example

package example;

import java.net.URLDecoder;

import com.amazonaws.services.lambda.runtime.Context;
import com.amazonaws.services.lambda.runtime.RequestHandler;
import com.amazonaws.services.lambda.runtime.events.S3Event;
import com.amazonaws.services.s3.AmazonS3;
import com.amazonaws.services.s3.AmazonS3Client;
import com.amazonaws.services.s3.event.S3EventNotification.S3EventNotificationRecord;

public class S3GetTextBody implements RequestHandler<S3Event, String> {

public String handleRequest(S3Event s3event, Context context) {
    try {
        S3EventNotificationRecord record = s3event.getRecords().get(0);

        // Retrieve the bucket & key for the uploaded S3 object that
        // caused this Lambda function to be triggered
        String bkt = record.getS3().getBucket().getName();
        String key = record.getS3().getObject().getKey().replace('+', ' ');
        key = URLDecoder.decode(key, "UTF-8");

        // Read the source file as text
        AmazonS3 s3Client = new AmazonS3Client();
        String body = s3Client.getObjectAsString(bkt, key);
        System.out.println("Body: " + body);
        return "ok";
    } catch (Exception e) {
        System.err.println("Exception: " + e);
        return "error";
    }

  }
}

The current version of the aws sdk for lambda doesn't contain -

import com.amazonaws.services.lambda.runtime.Context;
import com.amazonaws.services.lambda.runtime.RequestHandler;
import com.amazonaws.services.lambda.runtime.events.S3Event;

What are my alternatives? How can I achieve similar functionality using the newer versions of their sdk.

Answer 1

You aren't required to implement the RequestHandler interface provided in their helper library. Any method will work provided the input and output parameters can be serialized properly.

See this article for more detail.

If you want to use their helper library, use the following dependency coordinates:

<groupId>com.amazonaws</groupId>
<artifactId>aws-lambda-java-core</artifactId>
<version>1.1.0</version>

And for the S3 event helper:

<groupId>com.amazonaws</groupId>
<artifactId>aws-lambda-java-events</artifactId>
<version>1.3.0</version>

It's not located within their main aws-java-sdk but instead has its own repository.