As VLOOKUP only match the first row I will show who to use arrays, FILTER, JOIN and ARRAY_CONSTRAIN to get around this limitation. Lets assume we have a table of…
Server Sent Events (SSE) is a HTML5 standard that allows pushing events from the server to the client. I think it is unfortunate that most people think of Web Sockets…
When I first heard about Elixir at Øredev 2012 I thought it was nice, but I didn't really get it. I remember thinking than Elixir was like Ruby for the…
I have been experimenting with event sourcing in Clojure (and in Java), but previously I simply used an in-memory store. In this post I'll describe how to use Greg Young's EventStore from Clojure.
I wanted to investigate how to implement something similar to my previous Event Sourcing examples but this time using Datomic. In particular, I wanted to keep the way commands are implemented in the domain, the way commands could be executed asynchronously and aggregates for consistency.
During a discussion around some of the code examples in Vaugn Vernon's book Implementing Domain Driven Design we got stuck at what first appeared to be a tiny detail: where…
Berlin Buzzwords feels more like a festival than a normal conference. You get these wristbands that you should wear for a few days and being held at a brewery there…
The four of us recently visited the Confess, CONference For Enterprise Software Solutions, in Vienna. It was located at the Messe Wien Exhibition & Congress Center which was a nice…
At our recent talk at Confess 2013 in Vienna there were several developers working with mobile devices in the audience. This is great as the purpose of hypermedia in the API is to make life simpler for client developers. However, after the talk several of them raised issues regarding the high latency and low bandwidth of mobile phones. In this post I will try to address both these concerns.
In this blog post I implement the same rock-paper-scissors domain using what I hope is idiomatic Clojure. By using immutable datastructures I show that snapshots of aggregate state is really nothing special and snapshotting should be implemented as a cache.
I have been following the excellent BTW podcast and thinking a lot about CQRS and Event Sourcing. Inspired by Greg Youngs lecture on Functional Programming with DDD I have tried…
Three of us recently visited Scandinavian Developer Conference in Gothenburg. Being backend developers we liked the Big Data track the most, but we also managed to see some good presentations about collaboration and web technology.
Transitioning from Java to Scala was simplified by the fact that you could still write something similar to your old style Java code in Scala and then start learning the functional way and all other cool things available in Scala. When learning Clojure this threshold is higher as the language is so different than Java. However, by using records and protocols you should be able to do things in a similar way that you are already used to and then transition into more idiomatic Clojure.
When we talk about creating RESTful services using hypermedia we often get into discussions why the links are necessary. Why not simply publish a list of available URI:s and the client can code directly using these links? Won't there be much overhead in putting links into every response? In this blogpost we will try to explain why we think a hypermedia API is useful.
We are using the @Indexed annotation in Morphia and when we changed to @Indexed(unique=true) we were first surprised when nothing happened. Our first thought was that this might be a…