Saga 编排模式架构

Architecture

Saga 编排架构图，中央编排器协调跨订单、库存和支付服务的多步骤分布式事务，具有专用的补偿链用于失败时的回滚。该模板模拟基于编排的 Saga 模式，单个协调器管理事务生命周期并在任何步骤失败时触发补偿操作。对于实施不使用两阶段提交的可靠分布式事务的架构师至关重要。

下载 .fz 文件

完整 FlowZap 代码

Orchestrator { # Saga Orchestrator
n1: circle label:"Start Saga"
n2: rectangle label:"Create Saga Instance"
n3: rectangle label:"Execute Step 1: Create Order"
n4: rectangle label:"Execute Step 2: Reserve Inventory"
n5: rectangle label:"Execute Step 3: Process Payment"
n6: diamond label:"All Steps Succeeded?"
n7: rectangle label:"Mark Saga Complete"
n8: rectangle label:"Begin Compensation"
n9: circle label:"Saga Finished"
n1.handle(right) -> n2.handle(left)
n2.handle(right) -> n3.handle(left) [label="Initialize"]
n3.handle(right) -> n4.handle(left) [label="Step 1 OK"]
n4.handle(right) -> n5.handle(left) [label="Step 2 OK"]
n5.handle(right) -> n6.handle(left)
n6.handle(right) -> n7.handle(left) [label="Yes"]
n6.handle(bottom) -> n8.handle(top) [label="No"]
n7.handle(right) -> n9.handle(left)
n8.handle(bottom) -> Compensation.n16.handle(top) [label="Rollback"]
n3.handle(bottom) -> OrderService.n10.handle(top) [label="Command"]
n4.handle(bottom) -> InventoryService.n12.handle(top) [label="Command"]
n5.handle(bottom) -> PaymentService.n14.handle(top) [label="Command"]
}
OrderService { # Order Service
n10: rectangle label:"Create Order Record"
n11: rectangle label:"Return Order ID"
n10.handle(right) -> n11.handle(left) [label="Persisted"]
n11.handle(top) -> Orchestrator.n4.handle(bottom) [label="Success"]
}
InventoryService { # Inventory Service
n12: rectangle label:"Reserve Stock Items"
n13: rectangle label:"Return Reservation ID"
n12.handle(right) -> n13.handle(left) [label="Reserved"]
n13.handle(top) -> Orchestrator.n5.handle(bottom) [label="Success"]
}
PaymentService { # Payment Service
n14: rectangle label:"Charge Payment Method"
n15: rectangle label:"Return Transaction ID"
n14.handle(right) -> n15.handle(left) [label="Charged"]
n15.handle(top) -> Orchestrator.n6.handle(bottom) [label="Result"]
}
Compensation { # Compensation Steps
n16: rectangle label:"Reverse Payment"
n17: rectangle label:"Release Inventory"
n18: rectangle label:"Cancel Order"
n19: circle label:"Saga Rolled Back"
n16.handle(right) -> n17.handle(left) [label="Refund"]
n17.handle(right) -> n18.handle(left) [label="Unreserve"]
n18.handle(right) -> n19.handle(left) [label="Cancelled"]
}

为什么需要这个工作流？

Distributed transactions across microservices cannot use traditional ACID transactions because each service owns its own database. The saga orchestration pattern uses a central coordinator to manage the transaction lifecycle, executing steps sequentially and triggering compensating actions when any step fails.

工作原理

Step 1: The saga orchestrator creates a new saga instance and begins executing steps.
Step 2: Step 1: The Order Service creates an order record and returns the order ID.
Step 3: Step 2: The Inventory Service reserves stock items for the order.
Step 4: Step 3: The Payment Service charges the customer payment method.
Step 5: If all steps succeed, the saga is marked complete.
Step 6: If any step fails, the compensation chain reverses all previously completed steps in reverse order.

替代方案

Two-phase commit provides strong consistency but blocks resources and does not scale. Choreography-based sagas avoid the central coordinator but are harder to monitor. This template shows the orchestration approach with explicit compensation.

Key Facts

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