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Oskar Dudycz - Event-driven Modelling Anti-Patterns - EventCentric 2025

Oskar Dudycz @oskardudycz.bsky.social · 4d

Hip Java coders don't use Impl suffix anymore, they use Default prefix 👌😎

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Oskar Dudycz @oskardudycz.bsky.social · 4d

How to tell that you're using Java without mentioning Java?

I just used DefaultKafkaProducerFactoryCustomizer.

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Reposted by Oskar Dudycz

Oskar Dudycz @oskardudycz.bsky.social · 5d

I packed as many of such cases into our talk and the recording from this year’s @dddeu.bsky.social just arrived: www.youtube.com/watch?v=Lf1M...

I explained the specifics of event modelling (yes, no capital letter, and double l), starting with bad practices and knowing why and how to avoid them

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YouTube video by Aardling

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Oskar Dudycz @oskardudycz.bsky.social · 5d

As you saw here, same here! 😂
bsky.app/profile/did:...

Oskar Dudycz @oskardudycz.bsky.social · 5d

Achievement Unlocked: When you ask LLM to do research while brainstorming, and it asks you back if it can read your own article on this topic 😅

a man wearing glasses and a tie looks serious

Oskar Dudycz @oskardudycz.bsky.social · 5d

ALT: a man wearing glasses and a tie looks serious

media.tenor.com

Dealing with Eventual Consistency and Idempotency in MongoDB projections - Event-Driven.io

Oskar Dudycz @oskardudycz.bsky.social · 5d

Have a look on this article: event-driven.io/en/dealing_w...

It can be helpful on how to deal with some of the issues (I explained there how to use revision to resolve some of them).

Event-Driven by Oskar Dudycz

event-driven.io

Oskar Dudycz @oskardudycz.bsky.social · 5d

If you don't have global ordering then you need to always think on how to correlate and deal with ordering issues (e.g. you got information that someone booked a room, but you didn't yet have even that the profile was created).Then you usually need to create "phantom records" or aggregate data first

Oskar Dudycz @oskardudycz.bsky.social · 5d

It's really useful for the multi-stream projections, which are IMHO one of the killer features of Event Sourcing. So think e.g. dashboard, when you're glueing data from multiple places.

I'd assume to have ordering guarantee on the stream level, but global ordering is useful.

Oskar Dudycz @oskardudycz.bsky.social · 5d

Achievement Unlocked: When you ask LLM to do research while brainstorming, and it asks you back if it can read your own article on this topic 😅

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Oskar Dudycz @oskardudycz.bsky.social · 5d

Btw. about Blumchen and logical replication: if you're using it, then you might not need to store transaction id (as was written in the original article). Logical replication guarantees the ordering respecting commit order (which is not always the same as global architecture ordering).

Oskar Dudycz @oskardudycz.bsky.social · 5d

I agree, but also building your own is a lot of accidental complexity. My general advice is to really hard evaluate existing solutions before doing your own stuff. Especially subscriptions and projections is hard to get proper guarantees.

Let's build event store in one hour! - Event-Driven.io

Reposted by Oskar Dudycz

Lars Hanisch @flensrocker.de · 5d

Spreading my repository everywhere to collect feedback. It's at an early state...

codeberg.org/flensrocker/...

OrleansPlayground

codeberg.org

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Oskar Dudycz @oskardudycz.bsky.social · 5d

Is it a hobby project or a production one? 🙂 (implying: why not Marten? 😅)

You can also check also event-driven.io/en/lets_buil...

And my self-paced kit: github.com/oskardudycz/...

Building a production-grade event store is harder than it seems 🙂 Still, a lot of fun and learning while doing.

Event-Driven by Oskar Dudycz

event-driven.io

Let's build the worst Event Sourcing system! - Oskar Dudycz - NDC London 2024

Oskar Dudycz @oskardudycz.bsky.social · 5d

Or this one about #EventSourcing issues www.youtube.com/watch?v=20zv...

Ah, and drop me your feedback!

8/8

YouTube video by NDC Conferences

Light and Dark Side of the Event-Driven Design • Oskar Dudycz • Devoxx Poland 2021

Oskar Dudycz @oskardudycz.bsky.social · 5d

If you like to understand what you're signing for and learn from anti-patterns, then also check this talk:
www.youtube.com/watch?v=0pYm...

(also you'd see my post-covid prime weight 😆)

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YouTube video by Devoxx Poland

Event modelling anti-patterns explained - Event-Driven.io

Oskar Dudycz @oskardudycz.bsky.social · 5d

Also, as much some of those cases may seem wild, I can assure you that all of those mistakes I either:
- did by myself,
- saw in my projects,
- saw in my client’s project.

Check it out, why learn always from your mistakes?

Learn from mine.

event-driven.io/en/anti-patt...

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Event-Driven by Oskar Dudycz

event-driven.io

Oskar Dudycz @oskardudycz.bsky.social · 5d

I tried to make it both entertaining and educational, bitter and sweet. It is not easy when you’re not a native speaker. There’s a thin line between being funny and being silly.

There’s also a thin line between bad and good practices. And its name is: context.

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Oskar Dudycz @oskardudycz.bsky.social · 5d

I told the story about the project that aimed to modernise legacy software into the event-driven world. In theory, artificial, but in practice, none of the examples were made up. Either I made those mistakes on my own, or I saw them in my projects or helped to fix them for my clients.

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Oskar Dudycz - Event-driven Modelling Anti-Patterns - EventCentric 2025

Oskar Dudycz @oskardudycz.bsky.social · 5d

I packed as many of such cases into our talk and the recording from this year’s @dddeu.bsky.social just arrived: www.youtube.com/watch?v=Lf1M...

I explained the specifics of event modelling (yes, no capital letter, and double l), starting with bad practices and knowing why and how to avoid them

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YouTube video by Aardling

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Oskar Dudycz @oskardudycz.bsky.social · 5d

There’s a wide range of issues in EDA you may be facing, from overfocusing on the state instead of tracking behaviour, to asking others more often than allowing them to tell you what happened, and ending with race conditions and other unpleasant scenarios.

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Oskar Dudycz @oskardudycz.bsky.social · 5d

I’m always saying that with Event-Driven Architectures, the modelling effort pays back.

That goes both ways: the less effort we put in modelling, the more it’ll hurt later.

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Oskar Dudycz @oskardudycz.bsky.social · 5d

I should also probably dig more and give it more love, tho, as always time is a constraint...