Saga 编舞模式架构

Architecture

Saga 编舞架构图，订单、支付和库存服务通过领域事件协调而无需中央编排器，每个服务发布和订阅驱动事务前进或触发补偿的事件。该模板模拟去中心化的 Saga 方法，服务自主响应事件，减少单点故障但增加了跟踪 Saga 状态的复杂性。适合偏好服务自治而非集中控制的团队。

下载 .fz 文件

完整 FlowZap 代码

OrderService { # Order Service
n1: circle label:"Place Order"
n2: rectangle label:"Create Pending Order"
n3: rectangle label:"Emit OrderCreated"
n4: rectangle label:"Listen for Saga Events"
n5: diamond label:"Saga Outcome?"
n6: rectangle label:"Confirm Order"
n7: rectangle label:"Cancel Order"
n1.handle(right) -> n2.handle(left)
n2.handle(right) -> n3.handle(left) [label="Pending"]
n3.handle(bottom) -> EventBus.n8.handle(top) [label="Publish"]
n4.handle(right) -> n5.handle(left)
n5.handle(right) -> n6.handle(left) [label="Success"]
n5.handle(bottom) -> n7.handle(top) [label="Failure"]
}
EventBus { # Event Bus
n8: rectangle label:"OrderCreated Topic"
n9: rectangle label:"PaymentProcessed Topic"
n10: rectangle label:"InventoryReserved Topic"
n11: rectangle label:"PaymentFailed Topic"
n8.handle(bottom) -> PaymentService.n12.handle(top) [label="Subscribe"]
n9.handle(bottom) -> InventoryService.n15.handle(top) [label="Subscribe"]
n10.handle(top) -> OrderService.n4.handle(bottom) [label="Notify Success"]
n11.handle(top) -> OrderService.n4.handle(bottom) [label="Notify Failure"]
}
PaymentService { # Payment Service
n12: rectangle label:"Process Payment"
n13: diamond label:"Payment OK?"
n14: rectangle label:"Emit PaymentProcessed"
n18: rectangle label:"Emit PaymentFailed"
n12.handle(right) -> n13.handle(left)
n13.handle(right) -> n14.handle(left) [label="Success"]
n13.handle(bottom) -> n18.handle(top) [label="Declined"]
n14.handle(top) -> EventBus.n9.handle(bottom) [label="Publish"]
n18.handle(top) -> EventBus.n11.handle(bottom) [label="Publish"]
}
InventoryService { # Inventory Service
n15: rectangle label:"Reserve Inventory"
n16: rectangle label:"Emit InventoryReserved"
n17: rectangle label:"Compensate: Release Stock"
n15.handle(right) -> n16.handle(left) [label="Reserved"]
n16.handle(top) -> EventBus.n10.handle(bottom) [label="Publish"]
n17.handle(top) -> EventBus.n11.handle(bottom) [label="On PaymentFailed"]
}

为什么需要这个工作流？

Orchestration-based sagas create a central coordinator that becomes a single point of failure and a deployment bottleneck. Choreography distributes saga logic across participating services, where each service autonomously publishes and subscribes to events—enabling fully independent deployment and eliminating the coordinator dependency.

工作原理

Step 1: The Order Service creates a pending order and publishes an OrderCreated event.
Step 2: The Payment Service subscribes to OrderCreated, processes payment, and publishes PaymentProcessed or PaymentFailed.
Step 3: The Inventory Service subscribes to PaymentProcessed and reserves stock.
Step 4: On successful reservation, InventoryReserved is published, completing the saga.
Step 5: If payment fails, PaymentFailed triggers compensation in the Inventory Service.
Step 6: The Order Service listens for all outcome events to update the final order status.

替代方案

Orchestration provides better visibility and easier debugging. Process managers offer a middle ground between pure choreography and orchestration. This template shows the fully decentralized choreography approach.

Key Facts

Template Name	Saga 编舞模式架构
Category	Architecture
Steps	6 workflow steps
Format	FlowZap Code (.fz file)