Why Event Sourced Systems Often Succeed Despite Common FAILURES

•Download as PPTX, PDF•

1 like•678 views

I have given literally hundreds of talks on what makes them great but I don't think I have ever discussed previously the common failures :O I have had many discussions with teams and people recently who have had failures and I think a talk discussing the DOWNSIDES of such systems would make for a good talk ... especially coming from me as I have hundreds of talks on their POSITIVE aspects.

Technology

Why Event Sourced Systems …
FAIL
Greg Young

Purchase Order
Line Items (n)
Shipping Information

Cart Created
3 Items
Added
Shipping
Information
Added

Cart Created
3 Items
Added
1Item
Removed
Shipping
Information
Added

And … then tried to generalize
their failures to the idea as a
whole.

What are problems people have
run into?
Are they valid?

Issue #1 : The vast majority are
its … different …
Or FUD

If you have not built many
similar systems and have years
of production operation under
your belt …
You … are not an expert.

Identified issues?
Let’s take them real to imagined …

OK this is … non-trivial.
Really its … non-trivial …
This is more complicated than many people like to recognize.

Versioning takes experience to learn.
Its … different.

Issue #3: Modelling is different.
Well yeah. Functional programming is also different.
Certainly we can chalk this up as … different. Not an … issue.

Issue #4: Eventual Consistency
This is what most spend time on …
For some utterly #$%^ing bizarre reason..

“Their main complaint is that they add a
salesperson to a customer, but they don`t see the
change taking effect. The list of salespeople does
not contain the latest change. ”
See! CQRS is a failure …
But…

I have literally used this slide for more than a decade and it is … CQRS

So …
Well … just … don’t?!
Why not just transactionally update?
There are tradeoffs but what are you gaining with eventual consistency?

But … what are the …
benefits?
Preferring eventual consistency with read models is not … random.

The benefit is being able to have
THREE or FIVE read models!
Maybe one document, one 1nf in SQL (reporting), one as a graph?!
Maybe some are in London, some are in Hong Kong, and some in NYC?!

But I could transactionally
write to three?!

Geographic Distribution is
often a primary … goal

What if …
I included the written
version/position with my query?
I would just return a retry-after …

Version Version
Include version!!!
Include version!!!

Almost all of my … eventual
consistency issues … go away.
Not all but the vast majority

As with anything there is much
imposter syndrome and … FUD.
Most of it is BS.

Similar to Why Event Sourced Systems Often Succeed Despite Common FAILURES

The alignmentAlberto Brandolini

Scottish Ruby Conference 2014michaelag1971

Dark Matter, Public Health, and Scientific ComputingGreg Wilson

iOS Test-Driven DevelopmentPablo Villar

How To Run a 5 Whys (With Humans, Not Robots)Dan Milstein

What lies beneathAlberto Brandolini

“Don’t Repeat Yourself”: 4 Process Street Features to Keep Work DRYLizzyManz

Chaos Engineering Without Observability ... Is Just ChaosCharity Majors

Pair Programming - Be the best pair you can be.David Morgantini

Let's interfaceChristian Heilmann

The sweet spotAlberto Brandolini

Flow based-1994getdownload

E4IT STARTER - MODULE 11.pdfAnna Gandrabura

How good is your software development team ?Kinshuk Adhikary

Distributed Teams and Eclipsebfitzpat

C programming guide newKuntal Bhowmick

"Startups, comment gérer une équipe de développeurs" par Laurent CerveauTheFamily

(E book pdf) thinking in patterns with javaRaffaella D'angelo

Binary crosswordsLaurent Cerveau

Improve Testing with a Zone DefenseTechWell

Similar to Why Event Sourced Systems Often Succeed Despite Common FAILURES (20)

The alignment

Scottish Ruby Conference 2014

Dark Matter, Public Health, and Scientific Computing

iOS Test-Driven Development

How To Run a 5 Whys (With Humans, Not Robots)

What lies beneath

“Don’t Repeat Yourself”: 4 Process Street Features to Keep Work DRY

Chaos Engineering Without Observability ... Is Just Chaos

Pair Programming - Be the best pair you can be.

Let's interface

The sweet spot

Flow based-1994

E4IT STARTER - MODULE 11.pdf

How good is your software development team ?

Distributed Teams and Eclipse

C programming guide new

"Startups, comment gérer une équipe de développeurs" par Laurent Cerveau

(E book pdf) thinking in patterns with java

Binary crosswords

Improve Testing with a Zone Defense

Recently uploaded

Raspberry Pi 5: Challenges and Solutions in Bringing up an OpenGL/Vulkan Driv...Igalia

Boost PC performance: How more available memory can improve productivityPrincipled Technologies

How to Troubleshoot Apps for the Modern Connected WorkerThousandEyes

Boost Fertility New Invention Ups Success Rates.pdfsudhanshuwaghmare1

Finology Group – Insurtech Innovation Award 2024The Digital Insurer

Powerful Google developer tools for immediate impact! (2023-24 C)wesley chun

A Call to Action for Generative AI in 2024Results

Bajaj Allianz Life Insurance Company - Insurer Innovation Award 2024The Digital Insurer

08448380779 Call Girls In Civil Lines Women Seeking MenDelhi Call girls

08448380779 Call Girls In Greater Kailash - I Women Seeking MenDelhi Call girls

The 7 Things I Know About Cyber Security After 25 Years | April 2024Rafal Los

A Year of the Servo Reboot: Where Are We Now?Igalia

Apidays Singapore 2024 - Building Digital Trust in a Digital Economy by Veron...apidays

Histor y of HAM Radio presentation slidevu2urc

Presentation on how to chat with PDF using ChatGPT code interpreternaman860154

CNv6 Instructor Chapter 6 Quality of Servicegiselly40

The Codex of Business Writing Software for Real-World Solutions 2.pptxMalak Abu Hammad

Driving Behavioral Change for Information Management through Data-Driven Gree...Enterprise Knowledge

[2024]Digital Global Overview Report 2024 Meltwater.pdfhans926745

GenCyber Cyber Security Day PresentationMichael W. Hawkins

Recently uploaded (20)

Raspberry Pi 5: Challenges and Solutions in Bringing up an OpenGL/Vulkan Driv...

Boost PC performance: How more available memory can improve productivity

How to Troubleshoot Apps for the Modern Connected Worker

Boost Fertility New Invention Ups Success Rates.pdf

Finology Group – Insurtech Innovation Award 2024

Powerful Google developer tools for immediate impact! (2023-24 C)

A Call to Action for Generative AI in 2024

Bajaj Allianz Life Insurance Company - Insurer Innovation Award 2024

08448380779 Call Girls In Civil Lines Women Seeking Men

08448380779 Call Girls In Greater Kailash - I Women Seeking Men

The 7 Things I Know About Cyber Security After 25 Years | April 2024

A Year of the Servo Reboot: Where Are We Now?

Apidays Singapore 2024 - Building Digital Trust in a Digital Economy by Veron...

Histor y of HAM Radio presentation slide

Presentation on how to chat with PDF using ChatGPT code interpreter

CNv6 Instructor Chapter 6 Quality of Service

The Codex of Business Writing Software for Real-World Solutions 2.pptx

Driving Behavioral Change for Information Management through Data-Driven Gree...

[2024]Digital Global Overview Report 2024 Meltwater.pdf

GenCyber Cyber Security Day Presentation

Why Event Sourced Systems Often Succeed Despite Common FAILURES

1. Why Event Sourced Systems … FAIL Greg Young

3. Quick Intro What is Event Sourcing?

5. Purchase Order Line Items (n) Shipping Information

6. Cart Created 3 Items Added Shipping Information Added

8. Cart Created 3 Items Added 1Item Removed Shipping Information Added

10. But … many have … failed.

11. And … then tried to generalize their failures to the idea as a whole.

12. What are problems people have run into? Are they valid?

13. Issue #1 : The vast majority are its … different … Or FUD

14.

15. If you have not built many similar systems and have years of production operation under your belt … You … are not an expert.

16.

17. But …

18. Identified issues? Let’s take them real to imagined …

19. Issue #2 : Versioning

20. OK this is … non-trivial. Really its … non-trivial … This is more complicated than many people like to recognize.

21. Versioning is Easy!

22. Versioning takes experience to learn. Its … different.

23. Issue #3: Modelling is different. Well yeah. Functional programming is also different. Certainly we can chalk this up as … different. Not an … issue.

24. Issue #4: Eventual Consistency This is what most spend time on … For some utterly #$%^ing bizarre reason..

25.

26. “Their main complaint is that they add a salesperson to a customer, but they don`t see the change taking effect. The list of salespeople does not contain the latest change. ” See! CQRS is a failure … But…

27. I have literally used this slide for more than a decade and it is … CQRS

28. So … Well … just … don’t?! Why not just transactionally update? There are tradeoffs but what are you gaining with eventual consistency?

29. But … what are the … benefits? Preferring eventual consistency with read models is not … random.

30. One?!?!

31. The benefit is being able to have THREE or FIVE read models! Maybe one document, one 1nf in SQL (reporting), one as a graph?! Maybe some are in London, some are in Hong Kong, and some in NYC?!

32. But I could transactionally write to three?!

33. And …

34. Geographic Distribution is often a primary … goal

35. You can hide it …

36. You can hide it …

37. What if … I included the written version/position with my query? I would just return a retry-after …

38. Version Version Include version!!! Include version!!!

39. Almost all of my … eventual consistency issues … go away. Not all but the vast majority

40. Really.

41. As with anything there is much imposter syndrome and … FUD. Most of it is BS.

42. Want to know why the projects failed?