Architecture Weekly #96 - 10th October 2022

Oskar Dudycz

Oct 10

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Welcome to the new week!

I’ve heard a few times that Event Sourcing is hard to test. I’m not sure where this myth comes from; maybe from mixing it with event streaming. Event Sourcing logic is pretty straightforward. We’re getting the list of events recorded for a specific entity (e.g. bank account), building the current state from them and running business logic based on it. As a result, we’re getting either a new event or a list of events. We can think about business logic as a pure function and just verify if, for the defined inputs (state + command) we’re getting the expected result (event or error). In my last article, I explained in detail how to do that:

Oskar Dudycz - Testing business logic in Event Sourcing, and beyond!

Check new goodies to my small testing library Ogooreck, in which I added helpers to cut the boilerplate of testing business logic (not only event-sourced one).

Tests are great, but nowadays, not all we can verify before production. I wrote once that I tested on production and am not ashamed of it. In the distributed world, we can be certain about one thing: there will always be something that’s not working. We need to embrace that and make our systems resilient to failure. Check more in:

That’s also why I like the Event-Driven approach, as it helps with that. It won’t help us to avoid failure, but it will enable us to manage it and be prepared for the worst. Of course, it may also introduce accidental complexity, so it’s always worth questioning what we read. InfoQ released a new eMag about the streaming pipelines:

The InfoQ eMag: Modern Data Architectures, Pipelines, & Streams

Check also the new Kafka release notes. The Kafka team is pushing for the removal of Zookeeper. On a bigger scale, everything is custom. Kafka provided their implementation of the Raft protocol, called KRaft and aimed to remove the dependency for Zookeeper. It served them well, but they decided they wanted to have more control, fewer moving pieces and make it more fine-tuned to their needs. Read:

Confluent - What’s New in Apache Kafka 3.3

Speaking of the design. Most of the architects I know come from the backend or operations. We tend to ignore the UI and UX as something that’s maybe nice but not so important. That too often leads to building the iceberg, where we’re trying to hide too much underwater instead of delivering more to users. Check the nice summary about the UI and UX in:

Miklos Philips - Design Principles: why a design works

From the industry news, read more about the not-great time for NFTs and Metaverse. I’ve heard that “future is now”. It seems that not quite yet.

Have you thought about watching Star Wars on the terminal? I bet you did. See it:

Abhishek Prakash - Watch Star Wars In Linux Terminal via Telnet

Check, also other links!

Cheers
Oskar

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