The document discusses advanced messaging patterns, particularly focusing on sagas for coordinating long-running processes and how they handle workflows with multiple steps. It also covers polymorphic dispatch for eliminating repetitive code and enabling parallel execution paths, along with message forwarding for processing large data payloads. Additionally, it outlines the importance of handling timeouts and auditing large messages in business processes.

1. Advanced Messaging
Patterns
Donald Belcham

2. Long running processes

3. One process waits
on another process

4. Sometimes the system
is waiting for human
action

5. Sagas

6. Mechanism for
coordinating
multiple
processing
steps

7. Email
happy@face.com
Check email
Follow link
ilikedairyqueen.com/changepassword?id=<guid>
New password
___________
New Saga
ResetId = new GUID
AccountId = happy@face.com

8. Email
happy@face.com
Check email
Follow link
24hr limit
ilikedairyqueen.com/changepassword?id=<guid>
New password
___________
New Saga
ResetId = new GUID
AccountId = happy@face.com
RequestTimeout(24hrs)
Timeout Manager
Runs on a timer
Checks for expired timeouts

9. Saga Traits
- Model time
- Handle long “running”
business processes
- Coordinate workflow
- 2 or more steps required
(including the initial step)

10. Polymorphic
Dispatch

11. class ShipOrder : IUpdatePackaging

12. new ShipOrder()
IHandle<ShipOrder>
IHandle<IUpdatePackaging>

13. Composability

14. class CompleteOrder :
IUpdateSalesDashboard,
IUpdateSalesCommissions
class CancelOrder:
IUpdateSalesDashboard,
IUpdateSalesCommissions

15. Polymorphic Dispatch
- Elimination repetitive code
- Trigger parallel execution
paths

16. Message
Forwarding

17. Moving successfully
completed
messages to
additional endpoints
for more processing

18. new ShipOrder
(Priority = ShipPriority.Urgent)
ShipOrderPrioritizer :
IHandle<ShipOrder>
ShipUrgentOrders:
IHandle<ShipOrder>
ShipStandardOrders:
IHandle<ShipOrder>
ShipBackOrderedOrders:
IHandle<ShipOrder>

19. Auditing

20. Large Message
Payloads

21. Sometimes
messages need
to deal with
large data

23. class ProcessImage {
string Name { get; set; }
DateTime UploadDate { get; set; }
byte[ ] UploadedImage { get; set; }
}

24. Claim
Check
Pattern

25. class ProcessImage {
string Name { get; set; }
DateTime UploadDate { get; set; }
string ImagePath { get; set; }
}
Web Page Controller
Store to disk

26. IHandle<ProcessImage>
Store to disk

27. Sagas (stateful processes)
Polymorphic Dispatch
Message Forwarding
Large Messages

28. Multi-Level Retries
Circuit Breaker
Message Routing
Pub/Sub

29. Thank you
@dbelcham
donald.belcham@particular.net