Java Lambda Workshop

Notes and examples for the Sydney Java Meetup's Lambda Workshop

Workshop Outline

Prerequisites

• Java SE JDK 8 (https://www.oracle.com/technetwork/java/javase/downloads/jdk8-downloads-2133151.html)
• IntelliJ / Eclipse (https://www.jetbrains.com/idea/download)
  • workshop demos done in IntelliJ
• SAM CLI (https://github.com/awslabs/aws-sam-cli/blob/develop/docs/installation.rst)
  • requires Python and Docker
• (Optional) An AWS account to deploy your code to the cloud!
• Enthusiasm!

PART 1

Project Instantiation

• Initialize SAM CLI Java project

  sam init -r java8 -n starry-skies
  

• Run

  cd starry-skies
  mvn clean test    

• Open in IntelliJ for some IDE goodness

    idea .

• Remember to fix the module Java versions if IntelliJ didn't pick them up
• Build the package

    mvn package

At this point we should have an uber-jar in starry-skies/target/HelloWorld-1.0.jar.

Running locally

• Run the service:

  sam local start-api

• Start a browser: http://127.0.0.1:3000/hello

Debugging it locally

• Add a 'remote' debug configuration in IntelliJ / equivalent Eclipse

• Put a breakpoint in App::handler

• Run the service:

  sam local start-api -d 9292

• Start a browser:

  http://127.0.0.1:3000/hello

  (the local lambda will pause waiting for you to attach a debugger)

BREAK

Take a break for questions and getting everyone up to the same place.

PART 2

A Little Style

Let's upgrade the default SAM CLI implementation with some generics and stronger typing.

Functionality

Let's make our function do something fun!

BREAK

PART 3

Cloud Deployment

Let's deploy our functions to AWS cloud and invoke them from the browser.

Cloud Monitoring

Let's add some metrics to our function and show them on a dashboard.

private void writeMetric(String name, double value) {
    try {
        final AmazonCloudWatch cw =
                AmazonCloudWatchClientBuilder.defaultClient();

        MetricDatum datum = new MetricDatum()
                .withMetricName(name)
                .withUnit(StandardUnit.Milliseconds)
                .withValue(value);

        PutMetricDataRequest request = new PutMetricDataRequest()
                .withNamespace("VISUALISING_PERFORMANCE")
                .withMetricData(datum);

        PutMetricDataResult putMetricDataResult = cw.putMetricData(request);
        System.out.println(putMetricDataResult.getSdkResponseMetadata());

    } catch (Exception e) {
        System.out.println("Failed to write CloudWatch metric." + e.getMessage());
        e.printStackTrace();
    }
}