- The document discusses using microservices and event-driven architecture together with orchestration. It notes that while events allow for loose coupling, tracking logical flows across services can become difficult. - An order handling example is presented to illustrate challenges like a payment service needing to know all possible events that could trigger a payment. This calls for introducing an order service to handle event-command transformation and orchestration across services. - The document argues that modern lightweight workflow engines can be embedded within microservices to enable orchestration without introducing a centralized point of control. This allows logical flows to be modeled and changes to be made without affecting individual services.

1. @berndruecker#VoxxedVienna
Because your business is
more complex than *
* Some big video streaming company
bernd.ruecker@camunda.com
With thoughts from http://flowing.io
@berndruecker | @martinschimak

2. FAMGA

3. FANG

4. Tech stack
https://www.slideshare.net/RaminForood/platform-data-technologies-at-netflix
No
orchestration.

5. Orchestration

7. Netflix recognized challenges in orchestration

8. Let‘s do some groundwork before we
dive into orchestration…

9. System complexity increases dramatically
Warehouse
System
Logistics
Platform
Taxi
System
Travel
Platform
Insurance
System
Insurance
Platform
Heating with
temperature
sensor
Smart Heating
(Cloud
controlled)
…
…

10. Helpful paradigms
Microservices Event Driven & Reactive Domain Driven Design

11. Microservices
• Independent components
• Independent deployments
• Decoupling between components
• Dedicated teams to fight conways law
• Autonomy of technology decisions
• Avoid horizontal team boundaries
• New DevOps paradigms
Microservice
Microservice
Microservice
Monolith
A
B
C
A
B
C

12. Event driven microservices
Microservice Microservice Microservice
A B C
Eventbus

13. Communication via events
Microservice Microservice
A C
Eventbus
Event
event name
payload
no receipient

14. Communication via Events
Microservice Microservice
A C
Eventbus
Event
Does not
know
about C
Does not
know
about A

15. Compare to SOA
Service Service
A C
ESB
„smart endpoints
and dumb pipes”

16. Value proposition: fight conway, keep agility and ease changes
Microservice Microservice
A C
Eventbus

17. Yeah.

18. Example: Simple order handling

19. pay receive
shipment
place
order
I want to buy this!
I am happy!

20. Sample Microservices
Inventory Service
Handles Stock,
Reserviations and
physical handling
of goods
Payment Service Handles Payment
Shipping Service
Manage
shipments &
labels for logistic
providers

21. Eventflow
Order
Placed
Payment
Received
Goods
Picked
Goods
Shipped
InventoryPayment ShippingShop

22. Implementation

23. Let‘s zoom in the payment service
Payment Service
order
placed
payment
received

24. Let‘s zoom in the payment service
Payment Service
order
placed
payment
received
The payment service
has to listen to
„order placed“ event

25. De-coupling?
Payment Service
order
placed
service
fullfilled
…
Whenever a new service requires
payment, the payment has to be
changed
Payment has to know all possible
events that trigger a payment
subscription
confirmed

26. Martin Fowler also recognized
Event notification is nice because it implies a low level of
coupling, and is pretty simple to set up. It can become
problematic, however, if there really is a logical flow
that runs over various event notifications. The
problem is that it can be hard to see such a flow as it's
not explicit in any program text. Often the only way to
figure out this flow is from monitoring a live system.
This can make it hard to debug and modify such a flow.
The danger is that it's very easy to make nicely
decoupled systems with event notification, without
realizing that you're losing sight of that larger-scale
flow, and thus set yourself up for trouble in future years
https://martinfowler.com/articles/201701-event-driven.html

27. Event Command Transformation
Payment Service
do
payment
order
placed Transformation
Command
Something has to happen
in the future
1 recipient
Event
Something has happend
in the past
0..n recipients

28. This calls for an order service
Payment service
do
payment
order
placed Order service

29. Microservices
Inventory service
Payment service
Order service
Does event
command
transformation
for orders
Shipping service

30. Event Command Transformation
do
payment
order
placed
Order
Service
payment
received
pick
goods
goods
picked
ship
goods
goods
shipped
order
delivered
Order
Service
Order
Service
Order
Service

31. Smeels like a
central ESB?
http://apsblog.burtongroup.com/2009/01/soa-is-dead-long-live-services.html

32. No! Far from it!
Inventory service
Payment service
Order service
Might be
implemented in
simple Java
Shipping service

33. Order service does the orchestration

34. Implementation (with event command transformation)

35. Some things in life are slow
do
payment
order
placed
payment
received
pick
goods
goods
picked
ship
goods
goods
shipped
order
delivered
Order
Service
Long
Running
Long
Running
Long
Running
Long
Running

36. You also have to handle state.

37. Bernd Rücker
Co-founder Camunda
> 10+ years workflow
http://bernd-ruecker.com/
bernd.ruecker@camunda.com
Camunda
Open source vendor
Berlin + San Francisco
> 60 employees
No venture capital
www.camunda.org

38. The 7 sins of workflow and Java
Homegrown
engine
No engine Wrong engine
4
6
5
7
All sins: http://blog.bernd-ruecker.com/
Zero-code suites
Wrong usage

39. ToolsState Visibility
[ Orchestration | Workflow | BPM ] Engine

40. Order example in BPMN*
*BPMN = ISO standard for modeling and execution
in this
context
means:

41. Payment example

42. Paymentservice
Orchestration is part of the microservices!
Orderservice
Eventbus

43. It does not have to be one monlithic process
Hint: This might work well if your company is structured to
have this one clear process owner for this process.

44. Microservice vs. BPM community

45. Requirement: lightweight and embeddable engine
Engine must be
• easy to use
• developer friendly
also in the scope of microservices
• technically
• license model
Payment service
Order service
engine
engine
…
…
…
…
engine

46. Yes – that‘s possible!

47. Live
Demo

48. Architecture
Inventory
service
Payment
service
Order
service
Shipping
service
H2
Shop Monitor
Camunda
Webapp
on Tomcat
for demo in single Java VM for simplicity

49. Screenshots

50. Screenshots

51. And synchronous communication?

52. Communication between Microservices
Microservice Microservice
Microservice
A B
C
e.g. REST
You need to handle
outtages (wait, retry, …)

53. Change scenarios

54. We want to reserve
goods even before we
received the payment.

55. Changes
Inventory service
Payment service
Order service
Shipping service
must provide
reservation
servicereserve goods at
right moment

56. BPMN

57. Changes
Inventory service
Payment service
Order service
Shipping service
must provide
reservation
servicereserve goods at
right moment
Listen to goods
reserved instead
of order created.
Listen to order
created.
With event command
transformation
Without

58. VIP customers can
order with invoice
(and pay later)

59. Required changes
Inventory service
Payment service
Order service
Shipping service
Invoice service
skip payment, but
add open invoice

60. Responsibility of order service

61. Required changes
Inventory service
Payment service
Order service
Shipping service
Invoice service
skip payment, but
add open invoice
Listen to order
created VIP or
payment received
(non VIP).
Listen to order
created (VIP).

62. We need more cool
stuff – can BPMN do
this?

63. Compensation
…in case of errors in
error handling pay the
money back to the
customer

64. Timeouts
…after two weeks
pricing is not binding
any more

65. When a customer
cancels, we want to
win him back!

66. Required changes
Inventory service
Payment service
Order service
Shipping service
Listen to
appropriate
events, no change
anywhere else
Winback service
BPM monolith

67. Summary
• Microservices and event driven
architecture go well together
• You need an event command
transformation
• If the translation is stateful,
consider using an appropriate
engine
• Modern lightweight engines
foster and not hinder these
architectures

68. Is it for me?
Isn‘t all of that just for FANG?

69. With thoughts from http://flowing.io
@berndruecker | @martinschimak

70. https://github.com/flowing

71. Slides online at http://bernd-ruecker.com

72. Thank you! Any questions?