add worker template

.gitignore

@@ -9,3 +9,4 @@ buildNumber.properties
 .mvn/timing.properties
 # https://github.com/takari/maven-wrapper#usage-without-binary-jar
 .mvn/wrapper/maven-wrapper.jar
+/.idea/

README.md

@@ -1,2 +1,34 @@
-# zeebe-worker-java-template
-Minimal template for a Zeebe Java worker
+# Zeebe Worker Java Template
+
+Minimal template for a [Zeebe](https://github.com/camunda-cloud/zeebe)
+Java [worker](https://docs.camunda.io/docs/components/concepts/job-workers/). This template adds only the bare minimum
+of dependencies.
+
+If you want something more convenient, have a look
+at [Spring Zeebe](https://github.com/camunda-community-hub/spring-zeebe).
+
+## How to Use
+
+The main method is in `Worker.java`. It requires a couple of environment variables to run.
+
+### Connection Setup
+
+#### Connect to Cluster Camunda Cloud
+
+1. Follow the [Getting Started Guid](https://docs.camunda.io/docs/guides/getting-started/) to create an account, a
+   cluster and client credentials
+2. Use the client credentials to fill the following environment variables:
+    * `ZEEBE_ADDRESS`: Address where your cluster can be reached.
+    * `ZEEBE_CLIENT_ID` and `ZEEBE_CLIENT_SECRET`: Credentials to request a new access token.
+    * `ZEEBE_AUTHORIZATION_SERVER_URL`: A new token can be requested at this address, using the credentials.
+3. Run `Worker`
+
+#### Connect to local Installation
+
+For a local installation (without authentication) you only need to set `ZEEBE_ADDRESS`
+
+### Workflow
+
+Either you deploy `process.bpmn` or you design your own process with a service task with the `greet` job type.
+
+

pom.xml

@@ -0,0 +1,44 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xmlns="http://maven.apache.org/POM/4.0.0"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+
+    <groupId>org.camunda</groupId>
+    <artifactId>zeebe-worker-java-template</artifactId>
+    <version>1.0-SNAPSHOT</version>
+
+    <properties>
+        <maven.compiler.target>1.8</maven.compiler.target>
+        <maven.compiler.source>1.8</maven.compiler.source>
+        <zeebe.version>1.2.9</zeebe.version>
+        <junit.jupiter.version>5.8.1</junit.jupiter.version>
+    </properties>
+
+    <dependencies>
+        <dependency>
+            <groupId>io.camunda</groupId>
+            <artifactId>zeebe-client-java</artifactId>
+            <version>${zeebe.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>io.zeebe</groupId>
+            <artifactId>zeebe-worker-java-testutils</artifactId>
+            <version>${zeebe.version}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter-engine</artifactId>
+            <version>${junit.jupiter.version}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter-api</artifactId>
+            <version>${junit.jupiter.version}</version>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+
+</project>

process.bpmn

@@ -0,0 +1,47 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<bpmn:definitions xmlns:bpmn="http://www.omg.org/spec/BPMN/20100524/MODEL" xmlns:bpmndi="http://www.omg.org/spec/BPMN/20100524/DI" xmlns:dc="http://www.omg.org/spec/DD/20100524/DC" xmlns:zeebe="http://camunda.org/schema/zeebe/1.0" xmlns:di="http://www.omg.org/spec/DD/20100524/DI" xmlns:modeler="http://camunda.org/schema/modeler/1.0" id="Definitions_1shoozx" targetNamespace="http://bpmn.io/schema/bpmn" exporter="Camunda Modeler" exporterVersion="4.11.0" modeler:executionPlatform="Camunda Cloud" modeler:executionPlatformVersion="1.1.0">
+  <bpmn:process id="greet-process" name="Greet" isExecutable="true">
+    <bpmn:startEvent id="start-event" name="start">
+      <bpmn:outgoing>Flow_16yhcf2</bpmn:outgoing>
+    </bpmn:startEvent>
+    <bpmn:sequenceFlow id="Flow_16yhcf2" sourceRef="start-event" targetRef="greet-task" />
+    <bpmn:serviceTask id="greet-task" name="Greet Task">
+      <bpmn:extensionElements>
+        <zeebe:taskDefinition type="greet" />
+      </bpmn:extensionElements>
+      <bpmn:incoming>Flow_16yhcf2</bpmn:incoming>
+      <bpmn:outgoing>Flow_1b2mrjt</bpmn:outgoing>
+    </bpmn:serviceTask>
+    <bpmn:endEvent id="end-event" name="end">
+      <bpmn:incoming>Flow_1b2mrjt</bpmn:incoming>
+    </bpmn:endEvent>
+    <bpmn:sequenceFlow id="Flow_1b2mrjt" sourceRef="greet-task" targetRef="end-event" />
+  </bpmn:process>
+  <bpmndi:BPMNDiagram id="BPMNDiagram_1">
+    <bpmndi:BPMNPlane id="BPMNPlane_1" bpmnElement="greet-process">
+      <bpmndi:BPMNEdge id="Flow_16yhcf2_di" bpmnElement="Flow_16yhcf2">
+        <di:waypoint x="215" y="117" />
+        <di:waypoint x="270" y="117" />
+      </bpmndi:BPMNEdge>
+      <bpmndi:BPMNEdge id="Flow_1b2mrjt_di" bpmnElement="Flow_1b2mrjt">
+        <di:waypoint x="370" y="117" />
+        <di:waypoint x="432" y="117" />
+      </bpmndi:BPMNEdge>
+      <bpmndi:BPMNShape id="_BPMNShape_StartEvent_2" bpmnElement="start-event">
+        <dc:Bounds x="179" y="99" width="36" height="36" />
+        <bpmndi:BPMNLabel>
+          <dc:Bounds x="186" y="142" width="22" height="14" />
+        </bpmndi:BPMNLabel>
+      </bpmndi:BPMNShape>
+      <bpmndi:BPMNShape id="Activity_1gst4kg_di" bpmnElement="greet-task">
+        <dc:Bounds x="270" y="77" width="100" height="80" />
+      </bpmndi:BPMNShape>
+      <bpmndi:BPMNShape id="Event_0ryqdq5_di" bpmnElement="end-event">
+        <dc:Bounds x="432" y="99" width="36" height="36" />
+        <bpmndi:BPMNLabel>
+          <dc:Bounds x="441" y="142" width="19" height="14" />
+        </bpmndi:BPMNLabel>
+      </bpmndi:BPMNShape>
+    </bpmndi:BPMNPlane>
+  </bpmndi:BPMNDiagram>
+</bpmn:definitions>

src/main/java/Worker.java

@@ -0,0 +1,90 @@
+import io.camunda.zeebe.client.ZeebeClient;
+import io.camunda.zeebe.client.api.worker.JobWorker;
+
+import java.util.Map;
+import java.util.concurrent.CountDownLatch;
+
+/**
+ * Example application that connects to a cluster on Camunda Cloud, or a locally deployed cluster.
+ *
+ * <p>When connecting to a cluster in Camunda Cloud, this application assumes that the following
+ * environment variables are set:
+ *
+ * <ul>
+ *   <li>ZEEBE_ADDRESS
+ *   <li>ZEEBE_CLIENT_ID (implicitly required by {@code ZeebeClient} if authorization is enabled)
+ *   <li>ZEEBE_CLIENT_SECRET (implicitly required by {@code ZeebeClient} if authorization is enabled)
+ *   <li>ZEEBE_AUTHORIZATION_SERVER_URL (implicitly required by {@code ZeebeClient} if authorization is enabled)
+ * </ul>
+ *
+ * <p><strong>Hint:</strong> When you create client credentials in Camunda Cloud you have the option
+ * to download a file with above lines filled out for you.
+ *
+ * <p>When connecting to a local cluster, you only need to set {@code ZEEBE_ADDRESS}.
+ * This application also assumes that authentication is disabled for a locally deployed clusterL
+ */
+public class Worker {
+
+    private static final String JOB_TYPE = "greet";
+
+    public static void main(String[] args) throws InterruptedException {
+        System.out.println("Starting worker...");
+
+        final String zeebeAddress = getEnvironmentVariable("ZEEBE_ADDRESS");
+
+        System.out.println("Connecting to " + zeebeAddress);
+        ZeebeClient client = createZeebeClient(zeebeAddress);
+
+        System.out.println("Registering worker for jobType:" + JOB_TYPE);
+        final JobWorker jobWorker = client.newWorker().jobType(JOB_TYPE).handler(new WorkerJobHandler()).open();
+
+        final CountDownLatch countDownLatch = new CountDownLatch(1);
+
+        Runtime.getRuntime().addShutdownHook(
+                new Thread(() -> {
+
+                    System.out.println("Closing worker for jobType:" + JOB_TYPE);
+                    jobWorker.close();
+
+                    System.out.println("Closing client connected to " + zeebeAddress);
+                    client.close();
+
+                    System.out.println("Worker Shutdown Complete");
+                    countDownLatch.countDown();
+                })
+        );
+
+        countDownLatch.await();
+    }
+
+    private static ZeebeClient createZeebeClient(String gatewayAddress) {
+        if (gatewayAddress.contains("zeebe.camunda.io")) {
+            checkEnvVars("ZEEBE_CLIENT_ID", "ZEEBE_CLIENT_SECRET", "ZEEBE_AUTHORIZATION_SERVER_URL");
+            /* Connect to Camunda Cloud Cluster, assumes that credentials are set in environment variables.
+             * See JavaDoc on class level for details
+             */
+            return ZeebeClient.newClientBuilder().gatewayAddress(gatewayAddress).build();
+        } else {
+            // connect to local deployment; assumes that authentication is disabled
+            return ZeebeClient.newClientBuilder().gatewayAddress(gatewayAddress).usePlaintext().build();
+        }
+    }
+
+    private static String getEnvironmentVariable(final String key) {
+        checkEnvVars(key);
+
+        final Map<String, String> envVars = System.getenv();
+
+        return envVars.get(key);
+    }
+
+    private static void checkEnvVars(String... keys) {
+        final Map<String, String> envVars = System.getenv();
+
+        for (String key : keys) {
+            if (!envVars.containsKey(key)) {
+                throw new IllegalStateException("Unable to find mandatory environment variable " + key);
+            }
+        }
+    }
+}

src/main/java/WorkerJobHandler.java

@@ -0,0 +1,18 @@
+import io.camunda.zeebe.client.api.response.ActivatedJob;
+import io.camunda.zeebe.client.api.worker.JobClient;
+import io.camunda.zeebe.client.api.worker.JobHandler;
+
+import java.util.Collections;
+
+public class WorkerJobHandler implements JobHandler {
+
+    @Override
+    public void handle(JobClient client, ActivatedJob job) {
+        final String greeting = job.getCustomHeaders().getOrDefault("greeting", "Hello");
+        final String name = (String) job.getVariablesAsMap().getOrDefault("name", "Zeebe user");
+
+        final String message = String.format("%s %s!", greeting, name);
+
+        client.newCompleteCommand(job.getKey()).variables(Collections.singletonMap("message", message)).send().join();
+    }
+}

src/test/java/WorkerJobHandlerTest.java

@@ -0,0 +1,42 @@
+import org.camunda.community.zeebe.testutils.stubs.ActivatedJobStub;
+import org.camunda.community.zeebe.testutils.stubs.JobClientStub;
+import org.junit.jupiter.api.Test;
+
+import java.util.Collections;
+
+import static org.assertj.core.data.MapEntry.entry;
+import static org.camunda.community.zeebe.testutils.ZeebeWorkerAssertions.assertThat;
+
+class WorkerJobHandlerTest {
+
+    private final WorkerJobHandler sutJubHandler = new WorkerJobHandler();
+
+    @Test
+    public void testDefaultBehavior() {
+        // given
+        final JobClientStub jobClient = new JobClientStub();
+        final ActivatedJobStub activatedJob = jobClient.createActivatedJob();
+
+        // when
+        sutJubHandler.handle(jobClient, activatedJob);
+
+        // then
+        assertThat(activatedJob).completed().extractingOutput().containsOnly(entry("message", "Hello Zeebe user!"));
+    }
+
+    @Test
+    public void testMessageGeneration() {
+        // given
+        final JobClientStub jobClient = new JobClientStub();
+        final ActivatedJobStub activatedJob = jobClient.createActivatedJob();
+
+        activatedJob.setCustomHeaders(Collections.singletonMap("greeting", "Howdy"));
+        activatedJob.setInputVariables(Collections.singletonMap("name", "ladies and gentlemen"));
+
+        // when
+        sutJubHandler.handle(jobClient, activatedJob);
+
+        // then
+        assertThat(activatedJob).completed().extractingOutput().containsOnly(entry("message", "Howdy ladies and gentlemen!"));
+    }
+}