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Overview

This sample demonstrates how to build and deploy a Java-based microservice as an Event Trigger in SAP Cloud Platform, Kyma runtime using CloudEvents SDK.

The sample uses the CloudEvents SDK to deserialize events. Kyma eventing dispatches the CloudEvents v1, so the v1 library of CloudEvents SDK is used.

The order.created event from SAP Commerce Cloud is used as an example of a trigger.

java-event-trigger

This sample demonstrates how to:

  • Set up the development Namespace in the Kyma runtime.
  • Configure kubectl to use the KUBECONFIG file downloaded from the Kyma runtime.
  • Set up Event Triggers in the Kyma runtime.
  • Create and deploy a Spring Boot application to handle the event using the CloudEvents SDK library.
  • Configure the Spring Boot application to use the Event Trigger.
  • Use kubectl to verify the state.
  • Observe the logs using kubectl.

Prerequisites

Steps

Configure Kyma

  1. Create a new dev Namespace: new-namepace

  2. Bind your application to the Namespace:

  • Navigate to Applications/Systems: Go to Applications/Systems

  • Select the SAP Commerce Cloud system: select commerce cloud

  • Create a Binding to the dev Namespace: create binding

  1. Create a ServiceInstance for the Commerce Events:

  • Navigate to your Namespace: navigate

  • Navigate to the Service Catalog tab and select the bounded SAP Commerce Cloud system: catalog

  • Choose the SAP Commerce Cloud - Events as the ServicePlan: events service plan

  • Create the ServiceInstance: add create instance

After creating the ServiceInstance, the events can be consumed by Functions and microservices deployed in the dev Namespace.

Configure the application

Event Trigger is implemented as a Spring Boot application using gradle as a build tool.

  • The CloudEvents library is added as a dependency to build.gradle.
implementation('io.cloudevents:cloudevents-api:1.3.0')
  • A Plain Old Java Object (POJO) is defined for the order.created event.

The POJO reflects the order.created event definition which you can access from the Service Catalog.

order-created

public class OrderCreated {
    private String orderCode;

    public String getOrderCode() {
        return orderCode;
    }

    public void setOrderCode(String orderCode) {
        this.orderCode = orderCode;
    }

    @Override
    public String toString() {
        return "OrderCreated{" +
                "orderCode='" + orderCode + '\'' +
                '}';
    }
}
  • The controller logic unmarshalls the event payload using the CloudEvent SDK APIs.
@PostMapping(consumes = MediaType.APPLICATION_JSON_VALUE)
    public void eventTrigger(@RequestHeader Map<String, Object> headers, @RequestBody String payload) {
        CloudEvent<AttributesImpl, OrderCreated> cloudEvent =
                Unmarshallers.binary(OrderCreated.class)
                        .withHeaders(() -> headers)
                        .withPayload(() -> payload)
                        .unmarshal();
        System.out.println(cloudEvent.getAttributes());
        System.out.println(cloudEvent.getData());

        //Implement your business extension logic here
    }

Prepare for deployment

  • Configure the KUBECONFIG file:

    • Download the KUBECONFIG file for the Kyma runtime: download kubeconfig

    • Set kubectl to use the KUBECONFIG file:

      export KUBECONFIG={path-to-kubeconfig}

  • Build and push the image to the Docker repository:

    DOCKER_ACCOUNT={your-docker-account} make push-image

  • Update the image name in the Kubernetes Deployment. Refer to the standard Kubernetes Deployment and Service definitions.

Kubernetes Deployment

This section details out deploying the application and event trigger as standard Kubernetes resources.

To deploy as Helm chart, please refer to Helm Chart Deployment

Deploy the application

  • Deploy the application as a Kubernetes Service.

    kubectl -n dev apply -f ./k8s/deployment.yaml

  • Verify that the Pods are up and running:

    kubectl -n dev get po

The expected result shows that the Pod for the sample-event-trigger-java Deployment is running:

  NAME                                         READY   STATUS    RESTARTS   AGE
  default-broker-filter-766bb5bf5f-llnvk       2/2     Running   2          5h1m
  default-broker-ingress-55b8794cb4-62q48      2/2     Running   2          5h1m
  dev-gateway-554dc9bd4b-mvxtk                 2/2     Running   0          5h1m
  sample-event-trigger-java-68f8dfd98c-mnpdv   2/2     Running   0          15s

Configure the Event Trigger

  • Create the Event Trigger to receive the order.created event from the source. The source is the connected SAP Commerce Cloud system.
apiVersion: eventing.knative.dev/v1alpha1
kind: Trigger
metadata:
  name: sample-event-trigger-java
spec:
  broker: default
  filter:
    attributes:
      eventtypeversion: v1
      source: mp-gaurav-10-mock-commerce  # name of the application/system
      type: order.created # event type
  subscriber:
    ref:
      apiVersion: v1
      kind: Service
      name: sample-event-trigger-java
kubectl -n dev apply -f ./k8s/event-trigger.yaml
  • Verify that the Trigger is correctly deployed:
kubectl -n dev get trigger
NAME                        READY   REASON   BROKER    SUBSCRIBER_URI                                            AGE
sample-event-trigger-java   True             default   http://sample-event-trigger-java.dev.svc.cluster.local/   13s

Helm Chart Deployment

A Helm Chart definition is also available for developers to try out.

Must Haves

Helm install

To install the helm chart in dev namespace, run

helm install kymaapp ../helm-charts/sample-event-trigger-java --set image.repository=gabbi/sample-event-trigger-java:0.0.1 --set trigger.source=mp-mock-commerce-2 --set trigger.eventType=order.created -n dev

To verify, the installed chart

helm -n dev ls
NAME            NAMESPACE       REVISION        UPDATED                                 STATUS          CHART                           APP VERSION
dev-gateway     dev             1               2020-09-14 17:34:58.607853163 +0000 UTC deployed        gateway-0.0.1
kymaapp         dev             1               2020-09-14 20:20:03.464428 +0200 CEST   deployed        sample-event-trigger-java-0.1.0 1.16.0

Try it out

  • Simulate the event from the SAP Solution. For the purpose of this tutorial, use the mock to simulate the order.created event.

    • Go to Remote APIs. It lists all registered APIs and Events. mock-remote

    • Navigate to SAP Commerce Cloud - Events and send the order.created event. send-event

  • Observe the logs using kubectl:

    kubectl -n dev logs deploy/sample-event-trigger-java -c sample-event-trigger-java

The expected logs look as follows:

2020-06-19 17:45:12.092  INFO 8 --- [nio-8080-exec-1] o.s.web.servlet.DispatcherServlet        : Completed initialization in 6 ms
AttibutesImpl [id=e2174d4a-29b5-47da-b212-e87735ed08f8, source=mp-gaurav-10-mock-commerce, specversion=1.0, type=order.created, datacontenttype=application/json, dataschema=null, subject=null, time=2020-06-19T17:45Z]
Optional[OrderCreated{orderCode='76272727'}]

Cleanup

Delete the created resources:

kubectl -n dev delete -f ./k8s/

or, for helm

helm del kymaapp -n dev