Camunda ServiceTask

一：Java class

Java class实现JavaDelegate接口，只需要配置类的全限定名即可，不需要被Spring容器管理。

public class JavaClassServiceTask implements JavaDelegate {
    @Override
    public void execute(DelegateExecution execution) throws Exception {
        System.out.println("JavaClassServiceTask");
        String currentActivityId = execution.getCurrentActivityId();
        execution.setVariable(currentActivityId, "ok");
    }
}

二：Delegate expression

实现JavaDelegate接口，配置成Bean的名字即可。

@Service
public class DelegateExpressionServiceTask implements JavaDelegate {
    @Override
    public void execute(DelegateExecution execution) throws Exception {
        System.out.println(execution.getVariable("JavaClass"));
        System.out.println("DelegateExpressionServiceTask");
    }
}

三：Expression

配置成普通的方法调用，可以是任意类的任意方法，方法的返回值会赋值给Result variable变量，该变量可以从下一个节点获取。

@Service
public class ExpressionServiceTask {

    public boolean execute(DelegateExecution execution) {
        System.out.println("ExpressionServiceTask");
        return true;
    }
}

四：External

@Configuration
public class CamundaHandlerConfig {

    @Bean
    @ExternalTaskSubscription(topicName = "java_external_task_topic",
            processDefinitionKeyIn = {"ServiceTaskProcess"},
            lockDuration = 5000)
    public ExternalTaskHandler externalTaskHandler() {
        return (ExternalTask externalTask, ExternalTaskService externalTaskService) -> {
            boolean expressionResult = (boolean)externalTask.getVariable("expressionResult");
            // 处理业务逻辑...
            if (!expressionResult) {
                externalTaskService.handleFailure(externalTask, "error msg...", "error detail...", 0, 5000);
            }
            Map<String, Object> variables = new HashMap<>();
            variables.put("result", 1);
            externalTaskService.complete(externalTask, variables);
        };
    }
}

# pip3 install camunda-external-task-client-python3
# pip3 install pydantic

from camunda.external_task.external_task import ExternalTask, TaskResult
from camunda.external_task.external_task_worker import ExternalTaskWorker

default_config = {
    "maxTasks": 1,  # 一次只拉一个任务，这样多实例处理就不会所有任务被一个实例锁住
    "lockDuration": 10000,  # 锁任务的时间
    "asyncResponseTimeout": 30000,
    "retries": 0,
    "retryTimeout": 5000,
    "sleepSeconds": 30000,  # 每次拉取的间隔时间
    "auth_basic": {"username": "admin", "password": "123456"}
}


def handle_task(task: ExternalTask) -> TaskResult:
    result = task.get_variable("result")
    if result:
        return task.failure(error_message="error_message",
                            error_details="error_details 如异常堆栈信息",
                            max_retries=0, retry_timeout=5000)
    return task.complete()


if __name__ == '__main__':
    worker = ExternalTaskWorker(worker_id="python-client",
                                base_url="http://localhost:8080/engine-rest",
                                config=default_config).subscribe("python_external_task_topic", handle_task)

五：运行

1. 启动工作流引擎
2. 启动Java客户端
3. 启动Python客户端

repositoryService.createDeployment()
       .name("服务任务流程")
       .addClasspathResource("bpmn/service_task.bpmn")
       .deploy();

identityService.setAuthenticatedUserId("huihui");
ProcessInstance processInstance = runtimeService.startProcessInstanceByKey("ServiceTaskProcess");
System.out.println("processInstance=" + processInstance.getId());

五：连接器

<dependency>
   <groupId>org.camunda.bpm</groupId>
   <artifactId>camunda-engine-plugin-connect</artifactId>
   <version>${camunda.spring-boot.version}</version>
</dependency>
<dependency>
   <groupId>org.camunda.connect</groupId>
   <artifactId>camunda-connect-connectors-all</artifactId>
   <version>1.5.6</version>
</dependency>

public class HttpConnectorConfigurator implements ConnectorConfigurator<HttpConnector> {
    public Class<HttpConnector> getConnectorClass() {
        return HttpConnector.class;
    }

    public void configure(HttpConnector connector) {
        CloseableHttpClient client = HttpClients.custom()
                .setMaxConnPerRoute(10)
                .setMaxConnTotal(200)
                .build();
        ((AbstractHttpConnector) connector).setHttpClient(client);
    }
}

在文件src/main/resources/META-INF/services/org.camunda.connect.spi.ConnectorConfigurator中配置以下完全限制类。

com.example.camunda.config.HttpConnectorConfigurator