Question

为了了解Axon框架中Saga的实现，我一直关注AxonBank example，并使用了类似这样的代码来开始和结束saga

@Saga
public class MoneyTransferSaga {
    @Inject
    private transient CommandGateway commandGateway;

    private String targetAccount;
    private String transferId;

    @StartSaga
    @SagaEventHandler(associationProperty = "transferId")
    public void on(MoneyTransferRequestedEvent event) {
        System.out.println("Inside start saga for money transfer event");
        targetAccount = event.getTargetAccount();
        transferId = event.getTransferId();
        SagaLifecycle.associateWith("transactionId", transferId);
        System.out.println("## These are the params going into WMC : sourceAccount: " + event.getSourceAccount()
                + " transferID: " + transferId + " event.getAmount: " + event.getAmount());
        commandGateway.send(new WithdrawMoneyCommand(event.getSourceAccount(), transferId, event.getAmount()),
                new CommandCallback<WithdrawMoneyCommand, Object>() {
                    @Override
                    public void onSuccess(CommandMessage<? extends WithdrawMoneyCommand> commandMessage,
                            Object result) {

                    }

                    @Override
                    public void onFailure(CommandMessage<? extends WithdrawMoneyCommand> commandMessage,
                            Throwable cause) {
                        System.out.println("On failure of withdraw money command inside saga ");
                        System.out.println("###################### Cause of failure = " + cause);
                        commandGateway.send(new CancelMoneyTransferCommand(event.getTransferId()));
                    }
                });
    }

    @SagaEventHandler(associationProperty = "transactionId")
    public void on(MoneyWithdrawnEvent event) {
        System.out.println("Inside saga event handler for monney withdrawnevent");
        commandGateway.send(new DepositMoneyCommand(targetAccount, event.getTransactionId(), event.getAmount()),
                LoggingCallback.INSTANCE);
    }

    @SagaEventHandler(associationProperty = "transactionId")
    public void on(MoneyDepositedEvent event) {
        System.out.println("Inside saga event handler for money deposited event");
        commandGateway.send(new CompleteMoneyTransferCommand(transferId), LoggingCallback.INSTANCE);
    }

    @EndSaga
    @SagaEventHandler(associationProperty = "transferId")
    public void on(MoneyTransferCompletedEvent event) {
        System.out.println("Inside Endsaga for money transfer complete event");
    }

    @SagaEventHandler(associationProperty = "transferId")
    public void on(MoneyTransferCancelledEvent event) {
        end();
    }
}

通过REST API进行转帐后，所有这些代码都将执行，因为我可以看到我的日志已打印到控制台，所有交易都存储在帐户表中。

所有条目也都存在于domain_event_entry中，但是saga_entry和association_value_entry表仍然为空，无论事务是成功还是失败。

最初，我认为这可能是由于错误配置的saga存储，所以我用MongoSagaStore配置了saga存储，但Saga的集合仍然为空。

那么我是否在这里丢失了一些东西，或者在完成传奇之后轴突只是从这些表中删除了数据？

Answer 1

AxonFramework结束后，它将自动从其存储中删除Saga条目，包括所有关联。因此，您只会在那里看到活动实例的信息。

在示例应用程序中，所有总线组件都使用“ Simple ...”实现，这基本上意味着所有活动都在同一线程中执行。因此，一旦收到OK或NotOK，Saga的所有活动也将结束。如果要用“异步”或“分布式”实现替换它们，则不再是这种情况。整个过程完成之前，您将返回OK。

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