事件溯源工作流
patterns
事件溯源模式，包括事件捕获、事件存储持久化、聚合重建、快照优化以及时间点状态查询。
完整 FlowZap 代码
Command { # Command Handler
n1: circle label:"Start"
n2: rectangle label:"Receive command"
n3: rectangle label:"Validate command"
n4: rectangle label:"Query current state"
n5: circle label:"End"
n1.handle(right) -> n2.handle(left)
n2.handle(right) -> n3.handle(left)
n3.handle(bottom) -> EventStore.n6.handle(top) [label="Process"]
n4.handle(right) -> n5.handle(left)
}
EventStore { # Event Store
n6: rectangle label:"Load aggregate events"
n7: rectangle label:"Replay to build state"
n8: diamond label:"Command valid for state?"
n9: rectangle label:"Create new event"
n10: rectangle label:"Reject command"
n11: rectangle label:"Append to event stream"
n12: rectangle label:"Publish to subscribers"
n6.handle(right) -> n7.handle(left)
n7.handle(right) -> n8.handle(left)
n8.handle(right) -> n9.handle(left) [label="Yes"]
n8.handle(bottom) -> n10.handle(top) [label="No"]
n9.handle(right) -> n11.handle(left)
n10.handle(top) -> Command.n4.handle(bottom) [label="Invalid"]
n11.handle(right) -> n12.handle(left)
n12.handle(bottom) -> Projection.n13.handle(top) [label="Notify"]
}
Projection { # Read Model Projection
n13: rectangle label:"Receive event notification"
n14: rectangle label:"Update read model"
n15: diamond label:"Projection type?"
n16: rectangle label:"Update SQL database"
n17: rectangle label:"Update search index"
n18: rectangle label:"Acknowledge processing"
n13.handle(right) -> n14.handle(left)
n14.handle(right) -> n15.handle(left)
n15.handle(right) -> n16.handle(left) [label="Database"]
n15.handle(bottom) -> n17.handle(top) [label="Search"]
n16.handle(right) -> n18.handle(left)
n17.handle(right) -> n18.handle(top)
n18.handle(top) -> Command.n4.handle(bottom) [label="Complete"]
}