Pub Sub Workflow

patterns

This workflow models one publisher notifying many subscribers of events.

Full FlowZap Code

Publisher { # Publisher
n1: circle label:"Start"
n2: rectangle label:"Create message payload"
n3: rectangle label:"Serialize to JSON"
n4: rectangle label:"Publish to topic"
n5: circle label:"End"
n1.handle(right) -> n2.handle(left)
n2.handle(right) -> n3.handle(left)
n3.handle(bottom) -> MessageBroker.n6.handle(top) [label="Publish"]
n4.handle(right) -> n5.handle(left)
}
MessageBroker { # Message Broker
n6: rectangle label:"Receive message"
n7: rectangle label:"Validate message schema"
n8: diamond label:"Topic exists?"
n9: rectangle label:"Store in topic partition"
n10: rectangle label:"Create topic"
n11: rectangle label:"Notify 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(right) -> n9.handle(top)
n11.handle(bottom) -> Subscriber.n12.handle(top) [label="Deliver"]
n11.handle(top) -> Publisher.n4.handle(bottom) [label="ACK"]
}
Subscriber { # Subscriber
n12: rectangle label:"Receive notification"
n13: rectangle label:"Fetch message from topic"
n14: rectangle label:"Deserialize payload"
n15: diamond label:"Processing successful?"
n16: rectangle label:"Acknowledge message"
n17: rectangle label:"Negative acknowledge"
n18: rectangle label:"Update consumer offset"
n12.handle(right) -> n13.handle(left)
n13.handle(right) -> n14.handle(left)
n14.handle(right) -> n15.handle(left)
n15.handle(right) -> n16.handle(left) [label="Yes"]
n15.handle(bottom) -> n17.handle(top) [label="No"]
n16.handle(right) -> n18.handle(left)
n17.handle(top) -> n13.handle(bottom) [label="Retry"]
n18.handle(top) -> Publisher.n5.handle(bottom) [label="Complete"]
}