Camunda External Task Embedded Client as Spring Boot Starter

Spring Boot Starter provides embedded client to fast handling of external tasks for Camunda BPM. An embedded client opens up a different way to handle external tasks than camunda-bpm-spring-boot-starter-external-task-client. It works on top of thrown historical events to avoid long polling when using the FetchAndLock API.

Getting Started

Dependency

Maven:

<dependency>
  <groupId>io.github.omarchenko4j</groupId>
  <artifactId>camunda-bpm-spring-boot-starter-external-task-embedded-client</artifactId>
  <version>0.3.0</version>
</dependency>

Gradle:

compile("io.github.omarchenko4j:camunda-bpm-spring-boot-starter-external-task-embedded-client:0.3.0")

Example

We have the following process:

Implement external task handlers:

2.1 With manually locking and completing an external task:

@Slf4j
@Component
@ExternalTaskTopicName("scoreProvider") // Specifies the topic name of external task.
public class ScoreProviderExternalTaskHandler extends AbstractExternalTaskHandler {
    @Override
    public void handle(ExternalTask externalTask) {
        String externalTaskId = externalTask.getId();
        
        externalTaskService.lock(externalTaskId, "WORKER", TimeUnit.SECONDS.toMillis(5)); // Manual lock.
        
        log.info("Some logic of score provider.");
        
        externalTaskService.complete(externalTaskId, "WORKER"); // Manual complete.
    }
}

2.2 Without manually locking but with manually completing an external task:

@Slf4j
@Component
@ExternalTaskTopicName("loanGranter")
public class LoanGranterExternalTaskHandler extends ExternalTaskLockingHandler {
    public LoanGranterExternalTaskHandler() {
        super("WORKER", TimeUnit.SECONDS.toMillis(5));
    }
    
    @Override
    protected void handleAfterLocking(ExternalTask externalTask) {
        log.info("Some logic of loan granter.");
        
        externalTaskService.complete(externalTask.getId(), workerId); // Manual complete.
    }
}

2.3 Without manually locking and completing an external task:

@Slf4j
@Component
@ExternalTaskTopicName("requestRejecter")
public class RequestRejecterExternalTaskHandler extends ExternalTaskCompletingHandler {
    public RequestRejecterExternalTaskHandler() {
        super("WORKER", TimeUnit.SECONDS.toMillis(5));
    }
    
    @Override
    protected void handleBeforeCompleting(ExternalTask externalTask) {
        log.info("Some logic of request rejecter.");
    }
}

Start a process instance. It works!

License

Camunda External Task Embedded Client is Open Source software released under the Apache 2.0 license.