add example with one worker per class implementing JobHandler

examples/jobworker-interface-example/pom.xml

@@ -0,0 +1,112 @@
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
+  <modelVersion>4.0.0</modelVersion>
+  <groupId>com.camunda.consulting</groupId>
+  <artifactId>zeebe-ejb-example-worker-interface</artifactId>
+  <version>0.0.2-SNAPSHOT</version>
+  <packaging>war</packaging>
+  <name>Zeebe EJB Example Application</name>
+  <description>Zeebe Client running in an Java EE Server</description>
+
+  <properties>
+    <zeebe.version>8.1.0</zeebe.version>
+
+    <maven.compiler.source>11</maven.compiler.source>
+    <maven.compiler.target>11</maven.compiler.target>
+
+    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+    <failOnMissingWebXml>false</failOnMissingWebXml>
+  </properties>
+
+  <dependencies>
+    <dependency>
+      <groupId>org.camunda.community.client</groupId>
+      <artifactId>zeebe-ejb-client</artifactId>
+      <version>0.0.2-SNAPSHOT</version>
+      <exclusions>
+        <exclusion>
+          <groupId>com.fasterxml.jackson.core</groupId>
+          <artifactId>jackson-annotations</artifactId>
+        </exclusion>
+        <exclusion>
+          <groupId>com.fasterxml.jackson.dataformat</groupId>
+          <artifactId>jackson-dataformat-yaml</artifactId>
+        </exclusion>
+        <exclusion>
+          <groupId>com.fasterxml.jackson.core</groupId>
+          <artifactId>jackson-core</artifactId>
+        </exclusion>
+        <exclusion>
+          <groupId>com.fasterxml.jackson.core</groupId>
+          <artifactId>jackson-databind</artifactId>
+        </exclusion>
+      </exclusions>
+    </dependency>
+
+    <dependency>
+      <groupId>com.fasterxml.jackson.dataformat</groupId>
+      <artifactId>jackson-dataformat-yaml</artifactId>
+      <version>2.12.3</version>
+    </dependency>
+
+    <dependency>
+      <groupId>javax</groupId>
+      <artifactId>javaee-api</artifactId>
+      <version>8.0.1</version>
+      <scope>provided</scope>
+    </dependency>
+
+  </dependencies>
+
+  <build>
+    <finalName>${project.artifactId}</finalName>
+    <plugins>
+      <plugin>
+        <groupId>org.apache.maven.plugins</groupId>
+        <artifactId>maven-war-plugin</artifactId>
+        <version>3.3.2</version>
+      </plugin>
+      <plugin>
+        <groupId>org.apache.maven.plugins</groupId>
+        <artifactId>maven-compiler-plugin</artifactId>
+        <version>3.10.1</version>
+      </plugin>
+      <plugin>
+        <artifactId>maven-surefire-plugin</artifactId>
+        <version>2.22.2</version>
+      </plugin>
+      <plugin>
+        <groupId>org.wildfly.plugins</groupId>
+        <artifactId>wildfly-maven-plugin</artifactId>
+        <version>2.0.1.Final</version>
+      </plugin>
+      <plugin>
+        <groupId>org.apache.maven.plugins</groupId>
+        <artifactId>maven-deploy-plugin</artifactId>
+        <version>3.1.0</version>
+        <configuration>
+          <skip>true</skip>
+        </configuration>
+      </plugin>
+      <plugin>
+        <groupId>org.apache.maven.plugins</groupId>
+        <artifactId>maven-release-plugin</artifactId>
+        <version>3.0.0-M7</version>
+        <configuration>
+          <updateDependencies>false</updateDependencies>
+        </configuration>
+      </plugin>
+      <plugin>
+        <groupId>com.diffplug.spotless</groupId>
+        <artifactId>spotless-maven-plugin</artifactId>
+        <version>2.34.0</version>
+        <configuration>
+          <java>
+            <googleJavaFormat>
+            </googleJavaFormat>
+          </java>
+        </configuration>
+      </plugin>            
+    </plugins>
+  </build>
+
+</project>

examples/jobworker-interface-example/src/main/java/org/camunda/consulting/services/CreditCardService.java

@@ -0,0 +1,49 @@
+package org.camunda.consulting.services;
+
+import java.time.LocalDate;
+import javax.ejb.Stateless;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+@Stateless
+public class CreditCardService {
+
+  private static final Logger LOG = LoggerFactory.getLogger(CreditCardService.class);
+
+  public void chargeAmount(String cardNumber, String cvc, String expiryDate, Double amount) {
+    if (!validateExpiryDate(expiryDate)) {
+      throw new RuntimeException(
+          "Invalid expiry date: " + expiryDate + "\nExpiry date must be in the future.");
+    }
+
+    LOG.info(
+        "charging card {} that expires on {} and has cvc {} with amount of {}",
+        cardNumber,
+        expiryDate,
+        cvc,
+        amount);
+
+    LOG.info("payment completed");
+  }
+
+  boolean validateExpiryDate(String expiryDate) {
+    if (expiryDate.length() != 5) {
+      return false;
+    }
+    try {
+      int month = Integer.parseInt(expiryDate.substring(0, 2));
+      int year = Integer.parseInt(expiryDate.substring(3, 5)) + 2000;
+      LocalDate now = LocalDate.now();
+      if (month < 1 || month > 12 || year < now.getYear()) {
+        return false;
+      }
+      if (year > now.getYear() || (year == now.getYear() && month >= now.getMonthValue())) {
+        return true;
+      } else {
+        return false;
+      }
+    } catch (NumberFormatException | IndexOutOfBoundsException e) {
+      return false;
+    }
+  }
+}

examples/jobworker-interface-example/src/main/java/org/camunda/consulting/services/CustomerService.java

@@ -0,0 +1,54 @@
+package org.camunda.consulting.services;
+
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+import javax.ejb.Stateless;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+@Stateless
+public class CustomerService {
+
+  private static final Logger LOG = LoggerFactory.getLogger(CustomerService.class);
+
+  /** The customer credit are the last digits of the customer id */
+  private Pattern pattern = Pattern.compile("(.*?)(\\d*)");
+
+  /**
+   * Deduct the credit for the given customer and the given amount
+   *
+   * @param customerId
+   * @param amount
+   * @return the open order amount
+   */
+  public Double deductCredit(String customerId, Double amount) {
+    Double credit = getCustomerCredit(customerId);
+    Double openAmount;
+    Double deductedCredit;
+    if (credit > amount) {
+      deductedCredit = amount;
+      openAmount = 0.0;
+    } else {
+      openAmount = amount - credit;
+      deductedCredit = credit;
+    }
+    LOG.info("charged {} from the credit, open amount is {}", deductedCredit, openAmount);
+    return openAmount;
+  }
+
+  /**
+   * Get the current customer credit
+   *
+   * @param customerId
+   * @return the current credit of the given customer
+   */
+  public Double getCustomerCredit(String customerId) {
+    Double credit = 0.0;
+    Matcher matcher = pattern.matcher(customerId);
+    if (matcher.matches() && matcher.group(2) != null && matcher.group(2).length() > 0) {
+      credit = Double.valueOf(matcher.group(2));
+    }
+    LOG.info("customer {} has credit of {}", customerId, credit);
+    return credit;
+  }
+}

examples/jobworker-interface-example/src/main/java/org/camunda/consulting/workers/CreditCardWorker.java

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+package org.camunda.consulting.workers;
+
+import javax.enterprise.context.ApplicationScoped;
+import javax.inject.Inject;
+
+import org.camunda.consulting.services.CreditCardService;
+
+import com.camunda.consulting.zeebe_ejb.JobWorker;
+
+import io.camunda.zeebe.client.api.response.ActivatedJob;
+import io.camunda.zeebe.client.api.worker.JobClient;
+import io.camunda.zeebe.client.api.worker.JobHandler;
+
+@ApplicationScoped
+@JobWorker(type = "creditCardCharging" /*, autoComplete = true */)
+public class CreditCardWorker implements JobHandler {
+
+  private CreditCardService creditCardService;
+
+  @Inject
+  public CreditCardWorker(CreditCardService creditCardService) {
+    super();
+    this.creditCardService = creditCardService;
+  }  
+
+  public CreditCardWorker() {
+
+  }
+
+  @Override
+  public void handle(JobClient client, ActivatedJob job) throws Exception {
+    // extract variables from process instance
+    String cardNumber = (String) job.getVariablesAsMap().get("cardNumber");
+    String cvc = (String) job.getVariablesAsMap().get("cvc");
+    String expiryData = (String) job.getVariablesAsMap().get("expiryDate");
+    Double amount = (Double) job.getVariablesAsMap().get("openAmount");
+
+    // execute business logic using the variables
+    if (cvc.equals("789")) {
+      throw new RuntimeException("CVC invalid!");
+    }
+
+    try {
+      creditCardService.chargeAmount(cardNumber, cvc, expiryData, amount);
+    } catch (Exception exc) {
+      client
+          .newThrowErrorCommand(job)
+          .errorCode("chargingError")
+          .errorMessage("We failed to charge credit card with card number " + cardNumber)
+          .send()
+          .join();
+    }
+  }
+
+}

examples/jobworker-interface-example/src/main/java/org/camunda/consulting/workers/CustomerCreditWorker.java

@@ -0,0 +1,62 @@
+package org.camunda.consulting.workers;
+
+import java.util.HashMap;
+import java.util.Map;
+
+import javax.enterprise.context.ApplicationScoped;
+import javax.inject.Inject;
+
+import org.camunda.consulting.services.CustomerService;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import com.camunda.consulting.zeebe_ejb.JobWorker;
+
+import io.camunda.zeebe.client.api.response.ActivatedJob;
+import io.camunda.zeebe.client.api.worker.JobClient;
+import io.camunda.zeebe.client.api.worker.JobHandler;
+
+@ApplicationScoped
+@JobWorker(type = "creditDeduction", autoComplete = false)
+public class CustomerCreditWorker implements JobHandler {
+
+  private static final Logger LOG = LoggerFactory.getLogger(CustomerCreditWorker.class);
+
+  private CustomerService customerService;
+
+  @Inject
+  public CustomerCreditWorker(CustomerService customerService) {
+    super();
+    this.customerService = customerService;
+  }
+
+  public CustomerCreditWorker() {
+
+  }
+
+  @Override
+  public void handle(JobClient client, ActivatedJob job) throws Exception {
+    LOG.info("handler invoked for job {}", job);
+
+    Map<String, Object> resultVariables = creditDeduction(job);
+
+    client.newCompleteCommand(job).variables(resultVariables).send().join();
+    LOG.info("handler completed job {}", job);
+  }
+
+  private Map<String, Object> creditDeduction(ActivatedJob job) {
+    Map<String, Object> variables = job.getVariablesAsMap();
+    String customerId = (String) variables.get("customerId");
+    Double amount = (Double) variables.get("orderTotal");
+
+    // execute business logic using the variables
+    Double openAmount = customerService.deductCredit(customerId, amount);
+    Double customerCredit = customerService.getCustomerCredit(customerId);
+
+    // return the results
+    Map<String, Object> resultVariables = new HashMap<>();
+    resultVariables.put("openAmount", openAmount);
+    resultVariables.put("customerCredit", customerCredit);
+    return resultVariables;
+  }
+}