场景2：计算编排

1、组件风格链配置示例

定义组件

@Slf4j
@Component("a")
public class ACom implements TaskComponent {
    @Override
    public void run(FlowContext context, Node node) {
        log.info("ACom");
    }
}

@Slf4j
@Component("b")
public class BCom implements TaskComponent {
    @Override
    public void run(FlowContext context, Node node) {
        log.info("BCom");
    }
}

@Slf4j
@Component("c")
public class CCom implements TaskComponent {
    @Override
    public void run(FlowContext context, Node node) {
        log.info("CCom");
    }
}

计算编排链（以下示例，使用了简化模式）

# demo.chain.yml
id: "c1"
title: "计算编排"
layout:
  - { type: "start"}
  - { task: "@a"}
  - { task: "@b"}
  - { task: "@c"}
  - { type: "end"}

2、简单脚本风格链配置示例

# demo.chain.yml
id: "c1"
title: "计算编排"
layout:
  - { type: "start"}
  - { task: 'System.out.println("ACom");'}
  - { task: 'System.out.println("BCom");'}
  - { task: 'System.out.println("CCom");'}
  - { type: "end"}

3、复杂脚本风格链配置示例

使用 $ 符号（或者定制其它识别符），从链的元信息里引用配置内容作为脚本。

# demo.chain.yml
id: "c1"
title: "计算编排"
layout:
  - { type: "start"}
  - { task: '$script1'}
  - { task: '$script2'}
  - { task: '$script3'}
  - { type: "end"}
meta:
  script1: |
    if(user.id == 0) {
        return;
    }
    System.out.println("ACom");
  script2: |
    System.out.println("BCom");
  script3: |
    System.out.println("CCom");

需要驱动定制后支持。（v3.1.3 后，将默认支持）

@Component
public class SimpleFlowDriverEx extends SimpleFlowDriver {
    @Override
    protected void tryAsScriptTask(FlowContext context, Task task, String description) throws Throwable {
        //按脚本运行
        if (description.startsWith("$")) {
            String metaName = description.substring(1);
            description = (String) getDepthMeta(task.getNode().getChain().getMetas(), metaName);

            if (Utils.isEmpty(description)) {
                throw new FlowException("Chain meta not found: " + metaName);
            }
        }
        
        super.tryAsScriptTask(context, task, description);
    }
}