DDD Weekly: Issue #16

Enabling Retroactive Computing Through Event Sourcing [pdf] Michael Müller. We examine how retroaction can be applied to event-sourced systems and discuss conceptual considerations. Furthermore, we demonstrate how different architectures can be used to provide retroaction and describe the prototypical implementation of an appropriate programming model.

MediatR Pipeline Examples [blog] Jimmy Bogard. Whether you have specific or generic needs, a mediator pipeline can be a great place to apply domain-centric behaviors to all requests, or only matching requests based on generics rules, across your entire application.

Answering a Question [video] Greg Young. A response to a question on the DDD/CQRS mailing list: “I’m struggling withe a temporal aspect of my domain… I have persons that can become members of a group… memberships can be scheduled, reschedule, or cancelled…” Greg explains modeling temporality in a domain by thinking in terms of loops, sending messages to oneself, and keeping state within messages.

Kafka Event Sourcing with Neha Narkhede [podcast] Neha Narkhede interviewed by Jeff Meyerson. When Neha Narkhede was at LinkedIn, she helped develop Kafka, which was deployed at LinkedIn to help solve this very problem. Using Kafka as an event queue, LinkedIn adopted the CQRS architectural pattern together with event sourcing. Neha explains how to use Kafka for event sourcing and how related software patterns are improving the architectures of companies like Netflix and Uber.

Handling Eventual Consistency in JVM Microservices with Event Sourcing [video] Chris Richardson, Kenny Bastani. Presentation at JavaOne 2016. Provides an overview of event sourcing, the problem with microservices, transactions and queries, using events to maintain consistency, event sourcing in a microservice architecture, and implementing queries with CQRS.

An Architecture with CQRS and Event Sourcing [video] Eugen Paraschiv. Presentation at Voxxed Days Bucharest. Talks about why to use event sourcing, what projections are, where does Spring fit in, and microservices.

Harnessing Domain Driven Design [presentation slides] Gayathri Thiyagarajan, Andrew Harmel.