Slides from my talk at Eureg JUG Aachen in February 2018. You can find the recoding here: https://youtu.be/hS-4hjeFjt0. Code is available: http://github.com/flowing/flowing-retail and https://github.com/flowing/flowing-retail/tree/master/payment-rest.

1. The 7 sins of workflow
mail@bernd-ruecker.com | @berndruecker
Co-founder & Developer Advocate

2. The 7 sins of workflow
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https://blog.bernd-ruecker.com/

3. What is workflow*?
* Workflow Automation

4. The obvious use case
for workflow automation:
Human task management

5. Tasklists and task forms
…

6. A simple workflow example
Human task
management
Service
collaboration
Events , e.g.
timers
* Modeled in BPMN
= ISO Standard for modeling and execution

7. More realistic examples

8. Service collaboration

9. Distributed systems
Challenges of
asynchronicity
Distributed
Transactions
Communication
is complex

10. Communication
is complex
Challenge #1:

11. Photo by Tookapic, available under Creative Commons CC0 1.0 license.

12. „There was an error
while sending your
boarding pass“

13. 3D-
Barcode
Generator
Output
Mgmt
Check-In
Web-UI
Me
Example

14. Check-in
3D-
Barcode
Generator
Web-UI
Me
Output
Mgmt
Circuit breaker

15. „There was an error
while sending your
boarding pass“

16. Check-in
3D-
Barcode
Generator
Web-UI
Me
Output
Mgmt
Stateful
Retry
Current situation (pretty bad)

17. Check-in
3D-
Barcode
Generator
Web-UI
Me
Output
Mgmt
Stateful
Retry
Possible situation (pretty good)
The failure
never leaves
this scope!

18. Workflow automation can do

19. Challenge #2:
Challenges of
asynchronicity

20. Check-in
3D-
Barcode
Generator
Web-UI
Me
Output
Mgmt
Asynchronous communication
You need to
monitor
timeouts

21. Check-in
3D-
Barcode
Generator
Web-UI
Me
Output
Mgmt
Remember…
The failure
never leaves
this scope!

22. Workflow…

23. Workflow…

24. Challenge #3:
Distributed
Transactions
Distributed
Transactions

25. Business transactions (sometimes called Saga pattern)
Compensation

26. Compensation
Saga-Pattern
Manigfold Use Cases for Workflow Automation
Business
short running
(milliseconds)
potentially long running long running
IT
Automation of
business processes
(STP, Human Task
Management,
BPM)
Business
Transactions
Communication in
distributed systems
Decision
Automation
Order / Application Management
Invoice Management / Billing
Inbound / Outbound Management
Approval
Stateful retries
Correlate asynchronous responses / events
Sequence of decoupled service calls
Timeouts
Approval
Fraud check
Risk check
Fee calculation
Motivated by
Microservice
Orchestration

27. Decision Automation

28. Let‘s simply build
this ourselves…*
* how hard can it be…

30. Death by properties panel
OK – let‘s buy it from
this guy. Low-code
sounds great…*
* what‘s the worst thing
that can happen…

31. The 7 sins of workflow
Zero-code suites
Homegrown
engine
No engine Wrong engine
4
6
5
7

32. …
There are lightweight and open source
workflow engines or state machines
available. Leverage them!

33. Live hacking

36. Before mapping processes
explicitly with BPMN, the truth was
buried in the code and nobody
knew what was going on.
Jimmy Floyd, 24 Hour Fitnesse
„

39. Living documentation

40. Executable specifications

41. The 7 sins of workflow
Zero-code suites
Homegrown
engine
No engine Wrong engine
4
6
5
7

42. The 7 sins of workflow
Zero-code suites
Homegrown
engine
No engine Wrong engine
4
6
5
Stakeholders
habitat violation

43. The 7 sins of workflow
Zero-code suites
Homegrown
engine
No engine Wrong engine
6
5
Granularity
bloopers
Stakeholders
habitat violation

44. Example

45. The 7 sins of workflow
Zero-code suites
Homegrown
engine
Granularity
bloopers
Over engineering
No engine Wrong engine Wrong usage
6
Stakeholders
habitat violation

46. The 7 sins of workflow
Zero-code suites
Homegrown
engine
Granularity
bloopers
BPM monolith
Over engineering
No engine Wrong engine Wrong usage
Stakeholders
habitat violation

47. BPM architecture - the traditional view
BPM This is an Anti-Pattern in
microservice architectures!

48. Photo by born1945, available under Creative Commons BY 2.0 license.

49. Workflows live inside service boundaries
In DDD:
Bounded
Contexts

50. Workflows live inside service boundaries
The
busines process as
first class citizen

51. Finally!

52. Event-driven example
InventoryPaymentOrder ShippingCheckout Monitor
https://github.com/flowing/flowing-retail/
Human
Tasks
H2 H2

53. Live

54. Manigfold architecture options
https://blog.bernd-ruecker.com/architecture-options-to-run-a-workflow-engine-6c2419902d91

55. Manigfold architecture options
https://blog.bernd-ruecker.com/architecture-options-to-run-a-workflow-engine-6c2419902d91

56. Manigfold architecture options
https://blog.bernd-ruecker.com/architecture-options-to-run-a-workflow-engine-6c2419902d91

57. Manigfold architecture options
https://blog.bernd-ruecker.com/architecture-options-to-run-a-workflow-engine-6c2419902d91

58. Manigfold architecture options
https://blog.bernd-ruecker.com/architecture-options-to-run-a-workflow-engine-6c2419902d91

59. Manigfold architecture options
https://blog.bernd-ruecker.com/architecture-options-to-run-a-workflow-engine-6c2419902d91

60. New kid on the block
https://zeebe.io/
Zeebe
Broker
Your
application
Binary (MsgPack)
Support streaming & batching
Client
Horiziontally
scalable
Append only log / event sourcing

61. Summary: How to avoid the 7 sins?
• Use a lightweight workflow engine or
state machine
• Use it properly – as a state machine
(state, timeouts, retrying, message
correlation & deduplication,
compensation)
• Do not model everything
• Leverage BizDevOps & embrace visibility
• Slice your processes fitting your contexts
(monolith vs. microservices)
• Avoid over-engineering (enterprise-wide
xyz, abstractions, …)

62. Thank you!

63. Code:
https://github.com/berndruecker
Slides:
https://bernd-ruecker.com
Blog:
https://blog.bernd-ruecker.com
Feedback:
https://bernd-ruecker.com/feedback