We all know the joke about distributed systems right? There are only two hard problems in distributed systems: 2. Exactly-once delivery 1. Guaranteed order of messages 2. Exactly-once delivery — Mathias Verraes (@mathiasverraes) August 14, 2015 (btw you should go follow Mathias if you don’t already) 1 Exactly-once delivery defined First of all: Exactly-once delivery guarantee is the guarantee that a message can be delivered to a recipient once, and only once.
This is the second blog post in a short series about Consistency I love the two generals problem. I am mesmerized by its simplicity and impossibility. And I believe nothing has shaped my professional life more than this problem. Back in 2008 I had not yet worked with any major distributed systems, and most of my work was with systems which involved heavy aspects of custom electronics; one could say I was into IoT before IoT was a thing.
This is the first blog in a short series about Consistency When I decided to start my blog again, I created a poll about what should I write first. The reason was that I have gathered material about 2-3 subjects which I liked and wanted to speak about, but I wasn’t sure which one to start with. More people voted than I expected, but the decision was a tie between what different types of events would be helpful to recognise in an Event Sourced system, and Distributed consistency.