版本：latest

事务案例

案例说明

购买商品是很常见的业务场景，一般涉及购买方账户扣减，以及商家库存扣减，和订单生成。该案例为了简化实现，不生成订单。

整个业务逻辑由2个聚合根(微服务)构成:

仓储服务: 对给定的商品扣除仓储数量。
账户服务: 从用户账户中扣除余额。

show

该案例使用的是TCC+Saga模式。

更多的事务模式请参见：PhoenixIQ/phoenix-samples/shopping

command/event定义

Phoenix支持 protostuff 和 javaBean 协议进行序列化，可以通过以下配置进行指定，设定值分别为:proto_stuff和java

quantex.phoenix.server.default-serializer: java

这里使用javaBean序列化协议进行示范。

事务服务相关事件

@Getter
@AllArgsConstructor
public class BuyGoodsCmd implements Serializable {
    private static final long serialVersionUID = -8667685124103764667L;
    private String            accountCode;
    private String            goodsCode;
    private long              qty;
    private double            price;
}

账户服务相关事件

@Getter
@AllArgsConstructor
public class AccountTryCmd implements Serializable {
    private static final long serialVersionUID = 4778468915465985552L;
    private String accountCode;
    private double frozenAmt;
}

@Getter
@AllArgsConstructor
public class AccountConfirmCmd implements Serializable {
    private static final long serialVersionUID = 6915539313674995272L;
    private String accountCode;
    private double frozenAmt;
}

@Getter
@AllArgsConstructor
public class AccountCancelCmd implements Serializable {
    private static final long serialVersionUID = 3086192070311956483L;
    private String accountCode;
    private double frozenAmt;
}

@Getter
@Setter
@AllArgsConstructor
public class AccountTryOkEvent implements Serializable {
    private static final long serialVersionUID = 1525408241428571363L;
    private String accountCode;
    private double frozenAmt;
}

@Getter
@Setter
@AllArgsConstructor
public class AccountTryFailEvent implements Serializable {
    private static final long serialVersionUID = -8352616962272592136L;
    private String accountCode;
    private double frozenAmt;
    private String remark;
}

@Getter
@Setter
@AllArgsConstructor
public class AccountConfirmOkEvent implements Serializable {
    private static final long serialVersionUID = -6789245872360028227L;
    private String accountCode;
    private double frozenAmt;
}

@Getter
@Setter
@AllArgsConstructor
public class AccountCancelOkEvent implements Serializable {
    private static final long serialVersionUID = -1017410771260579937L;
    private String accountCode;
    private double frozenAmt;
}

仓储服务相关事件

@Getter
@AllArgsConstructor
public class GoodsSellCmd implements Serializable {
    private static final long serialVersionUID = -4615713736312293797L;
    private String goodsCode;
    private long   qty;
}

@Getter
@AllArgsConstructor
public class GoodsSellCompensateCmd implements Serializable {
    private static final long serialVersionUID = -1797830080849363235L;
    private String goodsCode;
    private long   qty;
}

@Getter
@Setter
@AllArgsConstructor
public class GoodsSellOkEvent implements Serializable {
    private static final long serialVersionUID = 873406977804359197L;
    private String goodsCode;
    private long   qty;
}

@Getter
@Setter
@AllArgsConstructor
public class GoodsSellFailEvent implements Serializable {
    private static final long serialVersionUID = 4825942818190006297L;
    private String goodsCode;
    private long   qty;
    private String remark;
}

@Getter
@Setter
@AllArgsConstructor
public class GoodsSellCompensateOkEvent implements Serializable {
    private static final long serialVersionUID = 3256345453720913064L;
    private String goodsCode;
    private long   qty;
}

定义事务聚合根

事务聚合根在接收到购买命令时，分别返回账户服务TCC和仓储服务Saga的命令给到事务状态机，事务状态机会发送并协调驱动达到最终状态。

事务聚合根可以独立运行，也可以和实体聚合根一起运行。独立运行的情况下，设置targetTopic为实体聚合根的Topic，这里为了方便就设置为空串""代表和实体聚合根集成运行。

事务聚合根的具体定义规则请参考上文事务聚合根定义

@TransactionAggregateAnnotation(aggregateRootType = "ShoppingAggregateSagaTcc")
public class ShoppingAggregateSagaTcc implements Serializable {
    private static final long serialVersionUID = 7007603076743033374L;
    private BuyGoodsCmd       request;
    private String            remark           = "";

    // 事务聚合根入口
    @TransactionStart
    public TransactionReturn act(BuyGoodsCmd request) {
        this.request = request;
        double frozenAmt = request.getQty() * request.getPrice();
        return TransactionReturn
            .builder()
            .addAction(
                TccAction.builder().tryCmd(new AccountTryCmd(request.getAccountCode(), frozenAmt))
                    .confirmCmd(new AccountConfirmCmd(request.getAccountCode(), frozenAmt))
                    .cancelCmd(new AccountCancelCmd(request.getAccountCode(), frozenAmt)).targetTopic("")
                    .subTransId(UUID.randomUUID().toString()).tryMaxRetryNum(2).confirmRetryNum(3).cancelRetryNum(3)
                    .build())
            .addAction(
                SagaAction.builder().targetTopic("").tiCmd(new GoodsSellCmd(request.getGoodsCode(), request.getQty()))
                    .ciCmd(new GoodsSellCompensateCmd(request.getGoodsCode(), request.getQty())).tiMaxRetryNum(2)
                    .ciMaxRetryNum(2).subTransId(UUID.randomUUID().toString()).build()).build();
    }

    // ... on method (处理返回的结果)
    
    // 事务结束调用的方法，返回结果事件
    public TransactionFinishReturn onFinish() {
        return TransactionFinishReturn.builder()
                .retMessage("response message")
                .data(new ResponseEvent())
                .build();
    }
    
}

定义实体聚合根

实体聚合根中对 Command 的处理需要遵循 SAGA 或 TCC 规范，具体的定义规则可以参考实体聚合根定义

@EntityAggregateAnnotation(aggregateRootType = "AccountAggregate")
public class AccountAggregate implements Serializable {
    private static final long serialVersionUID = 1989248847513267951L;
    private double            amt;
    private double            frozenAmt;
    
    @CommandHandler(aggregateRootId = "accountCode")
    public ActReturn act(AccountTryCmd cmd) {
        if (amt - frozenAmt > cmd.getFrozenAmt()) {
            return ActReturn.builder().retCode(RetCode.SUCCESS)
                .event(new AccountTryOkEvent(cmd.getAccountCode(), cmd.getFrozenAmt())).build();
        } else {
            String retMessage = String.format("资金可用不足，剩余:%f, 当前需要冻结:%f", amt - frozenAmt, cmd.getFrozenAmt());
            return ActReturn.builder().retCode(RetCode.FAIL).retMessage(retMessage)
                .event(new AccountTryFailEvent(cmd.getAccountCode(), cmd.getFrozenAmt(), retMessage)).build();
        }
    }

    public void on(AccountTryOkEvent event) {
        frozenAmt += event.getFrozenAmt();
    }

    public void on(AccountTryFailEvent event) { }

    @CommandHandler(aggregateRootId = "accountCode")
    public ActReturn act(AccountConfirmCmd cmd) {
        return ActReturn.builder().retCode(RetCode.SUCCESS)
            .event(new AccountConfirmOkEvent(cmd.getAccountCode(), cmd.getFrozenAmt())).build();
    }

    public void on(AccountConfirmOkEvent event) {
        amt -= event.getFrozenAmt();
        frozenAmt -= event.getFrozenAmt();
    }

    @CommandHandler(aggregateRootId = "accountCode")
    public ActReturn act(AccountCancelCmd cmd) {
        return ActReturn.builder().retCode(RetCode.SUCCESS)
            .event(new AccountCancelOkEvent(cmd.getAccountCode(), cmd.getFrozenAmt())).build();
    }

    public void on(AccountCancelOkEvent event) {
        frozenAmt -= event.getFrozenAmt();
    }
}

@EntityAggregateAnnotation(aggregateRootType = "GoodsTcc")
public class GoodsAggregate implements Serializable {
    private static final long serialVersionUID = -6111851668488622895L;
    private long              qty;
    private long              frozenQty;

    @CommandHandler(aggregateRootId = "goodsCode")
    public ActReturn act(GoodsSellCmd cmd) {
        if (cmd.getQty() < 0) {
            throw new RuntimeException("数不能小于0");
        }
        if (qty > cmd.getQty()) {
            return ActReturn.builder().retCode(RetCode.SUCCESS)
                .event(new GoodsSellOkEvent(cmd.getGoodsCode(), cmd.getQty())).build();
        } else {
            String ret = String.format("余额不足，剩余:%d, 当前需要:%d", qty, cmd.getQty());
            return ActReturn.builder().retCode(RetCode.FAIL).retMessage(ret)
                .event(new GoodsSellFailEvent(cmd.getGoodsCode(), cmd.getQty(), ret)).build();
        }
    }

    public void on(GoodsSellOkEvent event) {
        qty -= event.getQty();
    }

    public void on(GoodsSellFailEvent event) { }

    @CommandHandler(aggregateRootId = "goodsCode")
    public ActReturn act(GoodsSellCompensateCmd cmd) {
        return ActReturn.builder().retCode(RetCode.SUCCESS)
            .event(new GoodsSellCompensateOkEvent(cmd.getGoodsCode(), cmd.getQty())).build();
    }

    public void on(GoodsSellCompensateOkEvent event) {
        qty += event.getQty();
    }
}

完整的案例请参考：PhoenixIQ/phoenix-samples/shopping

案例说明​

command/event定义​

定义事务聚合根​

定义实体聚合根​

案例说明

command/event定义

定义事务聚合根

定义实体聚合根