Be careful with requests and responses when using the Serverless Framework in Java

Serverless Framework / Notes on implementation in AWS / Java.

API Gateway and Lambda do not work with the code generated by the template as it is, and it does not work! !!

For example, create a project with the following command.

sls create --template aws-java-maven --path serverless

Then the following Java file is created.

Handler.java

package hello;

import java.io.IOException;

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

public class Handler implements RequestHandler<Request, Response> {

	@Override
	public Response handleRequest(Request input, Context context) {
		return new Response("Go Serverless v1.0! Your function executed successfully!", input);
	}

}

But if this method is executed through API Gateway, it won't work. Because the following JSON is passed (partially modified).

{
  "httpMethod" : "POST",
  "requestContext" : {
    "httpMethod" : "POST",
    "accountId" : "*******",
    "apiId" : "*******",
    "resourceId" : "******",
    "identity" : {
      "userAgent" : "Apache-HttpClient\/4.5.x (Java\/1.8.0_112)",
      "userArn" : "arn:aws:iam::******:user\/****",
      "caller" : "***************",
      "cognitoAuthenticationProvider" : null,
      "cognitoIdentityId" : null,
      "accessKey" : "******************",
      "accountId" : "*****************",
      "sourceIp" : "test-invoke-source-ip",
      "apiKey" : "test-invoke-api-key",
      "cognitoAuthenticationType" : null,
      "cognitoIdentityPoolId" : null,
      "user" : "*******************"
    },
    "requestId" : "test-invoke-request",
    "stage" : "test-invoke-stage",
    "resourcePath" : "\/hello"
  },
  "resource" : "\/hello",
  "pathParameters" : null,
  "isBase64Encoded" : false,
  "headers" : null,
  "path" : "\/hello",
  "stageVariables" : null,
  "queryStringParameters" : null,
  "body" : "{\n    \"key1\": \"hoge\",\n    \"key2\": 120\n}"
}

What I really want is the last `body` property part.

It means that you need to write a program that extracts this.

Not only the request but also the response does not work as it is. It seems that the response object needs three properties: `statusCode```, headers```, and `` body```.

~~ I will provide a sample solution to deal with this area. aws-serverless-java-sample ~~

(Fixed June 24, 2018) The AWS SDK has a corresponding solution, so I'll rewrite it.

When AWS provides a library called aws-lambda-java-events and connects Lambda to various services Request and response types are defined.

The types of requests and responses passed when connecting to API Gateway are as follows.

• APIGatewayProxyRequestEvent
• APIGatewayProxyResponseEvent

Since the body is a String type, the effort of JSON encode / decode remains, but it should still be much easier to code.