Home » Author Archives: Jos Dirksen

Author Archives: Jos Dirksen

Easy validation in Scala using Scalaz, Readers and ValidationNel

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I’m working on a new book for Packt which shows how you can use various Scala frameworks to create REST services. For this book I’m looking at the following list of frameworks: Finch, Unfiltered, Scalatra, Spray and Akka-HTTP (reactive streams). While writing the chapters on Finch and Unfiltered I really liked the way these two frameworks handled validation. They both ...

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Backpressure in action with websockets and akka-streams

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So in the previous article I showed how you could create a websocket server using akka-streams. In this follow up article we’ll look a bit closer on how backpressure works with websockets (and probably any TCP based protocol on top of akka). To show you this we’ll use the same setup as we did in the article on visualizing backpressure. ...

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Migrate sonar data from old to new sonar version

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At my current project we were setting up a new buildserver. One of the things we had to do was move an old sonar implementation running on top of H2 to a new version running on Oracle. The problem was that just migrating the data is nearly impossible to do when you start with H2, and when the versions were ...

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Using Go to build a REST service on top of mongoDB

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I’ve been following go (go-lang) for a while now and finally had some time to experiment with it a bit more. In this post we’ll create a simple HTTP server that uses mongoDB as a backend and provides a very basic REST API. In the rest of this article I assume you’ve got a go environment setup and working. If ...

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Scala snippets 2: List symbol magic

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The following other snippets are also available: Scala snippets 1: Folding In scala every symbol can be a function, so overloading operators (which isn’t really overloading, since operators are already methods) is very easy and is something which you see in many libraries. In this snippet we’ll just explore a couple of the overloaded methods that make working with lists ...

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ReactiveMongo with Akka, Scala and websockets

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I was looking for a simple websocket server for one of my projects to test some stuff with reactive mongo. When looking around, though, I couldn’t really find a simple basic implementation without including a complete framework. Finally I stumbled upon one of Typesage activtor projects: http://typesafe.com/activator/template/akka-spray-websocket. Even though the name implies that spray is required, it actually uses websocket ...

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Scala snippets 1: Folding

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Coming from a Java background, Scala provides lots of nice features and libraries that allow you to create nice and concise code. Wrapping your head around these concepts though, can be hard. In this short series of articles I’ll walk through some of the concepts behind scala, and show you how you can use the various concepts. There is no ...

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