SWF：如何从子工作流向父工作流发出信号？

Question

我正在尝试向我的父工作流发出信号以更新其状态变量。父工作流 id 被传递给子工作流的 execute 方法。

@Autowired
private AmazonSimpleWorkflowClient swfClient;
@Autowired
private String swfDomain;

private ParentWorkflowClientExternalFactory clientExternalFactory = new ParentWorkflowClientExternalFactoryImpl(swfClient, swfDomain);

@Override
public Promise<String> childActivityMethod(String parentWorkflowId) {
    ParentWorkflowClientExternal clientExternal = clientExternalFactory.getClient(parentWorkflowId);
    clientExternal.updateState(...);
}

但是，这会在 SWF 代码中引发 NullPointerException（AmazonSimpleWorkflow 为空）：

["java.lang.NullPointerException",{"cause":null,"stackTrace":[{"methodName":"signalWorkflowExecution","fileName":"GenericWorkflowClientExternalImpl.java","lineNumber":87,"className":"com.amazonaws.services.simpleworkflow.flow.worker.GenericWorkflowClientExternalImpl","nativeMethod":false},{"methodName":"signalWorkflowExecution","fileName":"DynamicWorkflowClientExternalImpl.java","lineNumber":167,"className":"com.amazonaws.services.simpleworkflow.flow.DynamicWorkflowClientExternalImpl","nativeMethod":false},...

当我初始化不带参数的ClientExternalFactory 时：

private ParentWorkflowClientExternalFactory clientExternalFactory = new ParentWorkflowClientExternalFactoryImpl();

抛出的异常是：The required property genericClient is null. It could be caused by instantiating the factory through the default constructor instead of the one that takes service and domain arguments.

ParentWorkflow#updateState 这样做：

private MyWorkflowState state;

// This method has @Signal in the interface.
@Override
public void updateState(MyWorkflowState newState) {
    state = newState;
}

有什么建议吗？

Answer 1

从工作流界面生成了两种类型的客户端。内部的和外部的。内部预计将在工作流代码中使用，而外部代码将在工作流之外使用（例如来自 Web 服务器）。 您正在尝试在不受支持的工作流中使用外部客户端。请改用内部客户端（使用 ParentWorkflowClientFactory 创建）。请参阅Flow Development Guide 了解更多信息。