Another flavour of microservices’ integration — In my last post, I discussed Event-Carried State Transfer as a way to integrate microservices and examined its benefits and drawbacks. In this post, I want to demonstrate a slight variation of this approach I have seen implemented. Below is the traditional Event-Carried State Transfer diagram I used in my…

Good or Bad? — Event-Carried State Transfer is an event-based integration approach where events carry all the information consumers need to perform their functions. There are benefits to using this approach: No temporal coupling to producers No unnecessary load on producers to request more information Reduced latency when processing

Embracing Behavioural Coupling — In a previous post, I discussed how I inherited a communication microservice that relied on Event-based integration and how that resulted in a leaky abstraction where the communication microservice has knowledge of all e-mail triggering events from all the microservices in our system. I mentioned that a byproduct of this…

Or glorified data caches Read models are materialized views of denormalised data, mostly serving user interfaces but could also be used to provide data for other microservices. They are usually formed using data from a single microservice and live within that microservice’s boundary. …

How I shared streams to split an aggregate and why. With most DDD projects, you try to understand the problem domain as best as possible before modelling the solution domain and starting the implementation. Now, in an ideal world, you’d be given access to domain experts and allowed time to…

Exceptions, Cancellation, Idempotency and Isolation — This is a continuation of the last post in this series about design considerations in Sagas. Other posts in this series: Sagas — Part 1: An Introduction Sagas — Part 2: Sagas in Distributed System Sagas — Part 2b: Sagas in Distributed Systems Continued Sagas — Part 3: Choreography Instead? Sagas — Part 4: Design…

When Events are Passive-Aggressive Commands — I worked on a microservices system for a banking client a few years ago and inherited a “Communication” microservice that sends e-mails. Event-based architecture and choreography were all the rage then, so it was applied everywhere, including integration with this microservice. Event-based integration gives you low coupling, which is a…

Sagas — Part 1: An Introduction Sagas — Part 2: Sagas in Distributed System Sagas — Part 2b: Sagas in Distributed Systems Continued Sagas — Part 3: Choreography Instead? In previous posts in this series, I have introduced Sagas, given an example of a Saga in distributed systems and talked…

When to Choose Choreography — Sagas — Part 1: An Introduction Sagas — Part 2: Sagas in Distributed System Sagas — Part 2b: Sagas in Distributed Systems Continued Part 1 of this series detailed when I’d choose Orchestration over Choreography and why. …