Exploring Cats Effect
In two previous articles we explored how you can use ZIO to easily create programs in a type-safe manner: Exploring ZIO - Part I Exploring ZIO - Part I...
posts
Exploring ZIO - Part II - ZStream and modules
In the previous article we looked at the basics of ZIO. In this part we’re going to extend on that example and add the following: ZStream integration: we...
Exploring ZIO - Part I
I’ve done a lot of Kotlin for the last two years, and have mainly followed Scala and done some pet projects. Since a lot of interesting stuff has been going ...
Running a minimal Kafka instance on K8S
A couple of days ago I ran into an issue with our hosted Kafka environment, and we had to give a demo. So I was looking for a quick way to run a simple ephem...
My 10 goto terminal commands
There are a lot of useful terminal/shell commands which can make your live a lot easier. I do a lot of backend development, and there is a set of commands wh...
Getting started with Rust - part 2
In the previous article I started experimenting with Rust and build a very simple extension to git, which helps me remember the most recent branches I’ve bee...
Getting started with Rust - part 1
I decided to look a bit into Rust. I’ve been hearing great things about it, the community seems to be (mostly) very inviting and open, and the language in it...
Running puppeteer headless with extensions in docker
Puppeteer (https://github.com/puppeteer/puppeteer) is a great way to write scrapers, integration tests, or automate boring tasks and web forms. For a lot of ...
Setting up a simple Kafka cluster with docker for testing
In this short article we’ll have a quick look at how to set up a Kafka cluster locally, which can be easily accessed from outside of the docker container. ...
Scala/Kotlin developer learning Haskell - Part 2 - Monad Transformers
In the previous article learning haskell part 1 I walked through the steps I took to get a very simple and basic REST endpoint up and running. All that wen...
Scala/Kotlin developer learning Haskell - Part 1 - Rest endpoint with JSON
I’ve been doing scala and FP for a while now, and during that time I’ve tried a couple of times to pickup haskell as well. What I noticed was that I knew to...
Getting started with FP in Kotlin and Arrow: Typeclasses
I’ve recently made the effort to try and pick up Kotlin (again). The last couple of years I’ve been doing mostly scala work (with some other languages in b...
All (150+) learning three.js third edition examples online
A couple of months ago the third edtion of my book on learning three.js was released: View on Packt. Just as for the previous examples I’ve put all the examp...
D3.js: Devoxx presentation 2017
I just noticed that I never published the D3.js presentation I gave last year on Devoxx. So a bit late, but you can find the video for that presentation belo...
10 Practical Kubernetes Tips for Day to Day Kubernetes usage
A couple of years ago I wrote a number of articles on how to work with docker. Since that time a lot has changed in the docker and container world. Docker ha...
Three.js: Devoxx presentation 2018
Hi everyone,
Voronoi Fractal with D3.js
I’ve been very busy the last couple of months. Started a new project at Philips, started writing on D3.js for Packt, and besides that participating in two st...
Dynamic component loading with Angular2: replace $compile
Note that this has become outdated… again. But it has become part of the standard Angular distribution. Please look at the latest angular documentation here:...
Analyzing swearing in movies Part 1: Swears per minute
In this short article I’d like to explain the process I took to create some simple D3.js visualizations based on the number of swears per minute in movies. I...
First steps with Angular 2: 8 cool features
I’ve been doing some work the last couple of weeks with Angular2. I really like it. Not just because it uses typescript, but also because it feels really nat...
Scalaz features for everyday usage part 3: State Monad, Writer Monad and lenses
In this article in the mini series on Scalaz, we'll look at a couple of additional monads and patterns available in Scalaz. Once again, we'll look at stuff t...
Getting started with scala-native
This is just a quick recollection of the steps I've taken to get my own helloworld running using scala-native. I haven't really started looking at scala-nati...
Render 3D Star Wars: The Force Awakens models in Blender and Three.js
Recently video copilot released a free set of high-definition professional grade 3D models (which you can download for yourself from here). This model pack, ...
Service Discovery with Docker and Consul: part 2
So, welcome to the second part of the series on using Consul for service discovey together with docker. In this second article we'll look at how you can use ...
Scalaz features for everyday usage part 2: Monad Transformers and the Reader Monad
For the second article of the "Scalaz features for everyday usage" we'll look at the subject of Monad transformers and the Reader monad.Let's start with Mona...
Service Discovery with Docker and Consul: part 1
During the last year I've become a big fan of using Consul for all things related to service discovery. If you're doing microservices you've probably ran int...
Presentation: Service discovery in a microservice architecture
I recently gave a presentation on how you can use Consul (http://consul.io) for all your service discovery needs in a microservice architecture. The present...
Developing Scala in Atom with Ensime
When I began Java software development way back in the time of Java 1.3 I remember using JDeveloper for a time, before switching to the early versions of Ecl...
Website scraping using Selenium, Docker and Chrome with Extensions.
For a specific project we needed a quick way to get the content of a specific URL and check whether a word was present in the text there. If all we had to s...
Create a Slack Docker proxy in Go - Part 2
In the previous article we had a look at how you could easily create a slack-docker-proxy using go and a couple of small libraries. In this second article we...
Create a Slack Docker proxy in Go - Part 1
Last year I had the opportunity to work with lots of cool tools and technologies. A couple of those were go, slack and docker. We pretty much use slack for a...
10 Practical Docker Tips for Day to Day Docker usage
I’ve had the opportunity to setup a complete new docker based microservice architecture at my current job, so since everyone is sharing their docker tips and...
Akka Typed Actors: Exploring the receptionist pattern
In this article we’ll explore another of Akka-Typed patterns. This time we’ll show you how you can use the receptionist patterns. This is the third and last ...
Two-way SSL (client certificates) with Scalatest
At work we recently added the option to authenticate machine to machine communication using client certificates (two-way ssl). While this was relatively easy...
Akka Typed Actors: Exploring the receiver pattern
In the previous article we looked at some of the basic features provided by Akka Typed. In this article and the next one we’ll look a bit closer at some more...
Akka Typed: First steps with typed actors in Scala
With the release of Akka 2.4.0 a couple of weeks ago the experimental Akka Typed module was added. With Akka Typed it is possible to create and interact with...
Listen to notifications from Postgresql with Scala
In the past I’ve written a couple of articles (Building a REST service in Scala with Akka HTTP, Akka Streams and reactive mongo and ReactiveMongo with Akka, ...
Scala typeclass explained: Implement a String.read function
In this short article I’d like to explain how you can use the typeclass pattern in Scala to implement adhoc polymorphism. We won’t go into too much theoretic...
Easy validation in Scala using Scalaz, Readers and ValidationNel
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...
Exploring the HTML5 Web Audio API: Filters
03-07-2015 Update: Updated the example, it now works with the latest versions of Chrome and Firefox With the Web Audio API you can have advanced audio pro...
Backpressure in action with websockets and akka-streams
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 bac...
Create a reactive websocket server with akka-streams
In the previous article we looked at how backpressure works when working with akka-streams. Akka also uses akka-streams as the base for akka-http, with which...
Visualizing back pressure and reactive streams with akka-streams, statsd, grafana and influxdb
Currently reactive programming is getting more and more attentions. With reactive programming it is possible to easily create resilient, scalable and fault t...
Migrate sonar data from old to new sonar version
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...
Creating an Angular.js application without JavaScript: Scala.js
In my day job I work a lot with Angular.js. And while this is a great framework, sometimes I do miss the type-safety and advanced features of languages such ...
Using Go to build a REST service on top of mongoDB
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 ...
All 80+ recipes from Three.js Cookbook online
About a month ago my third book on Three.js got released: Three.js Cookbook. This book has 80+ recipes on how to accomplish common tasks in Three.js. On this...
Building a REST service in Scala with Akka HTTP, Akka Streams and reactive mongo
At the end of last year I wrote a couple of articles that showed how you can use Spray.io to create a Scala based REST service () and how to create a websock...
Scala snippets 4: Pimp my library pattern with type classes.
I wanted to write an article on the fun parts of scalaz, but thought it would be best to first look a bit closer at the type classes system provided by scala...
Scala snippets 3: Lists together with Map, flatmap, zip and reduce
You can’t really talk about scala without going into the details of the Map, flatMap, zip and reduce functions. With these functions it is very easy to proce...
Scala snippets 2: List symbol magic
The following snippets are available: Scala snippets 1: Folding Scala snippets 2: List symbol magic Scala snippets 3: Lists together with Map, flatmap,...
Scala snippets 1: Folding
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 t...
ReactiveMongo with Akka, Scala and websockets
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 fin...
Use reactive streams API to combine akka-streams with rxJava
Just a quick article this time, since I’m still experimenting with this stuff. There is a lot of talk around reactive programming. In Java 8 we’ve got the St...
First steps with REST, Spray and Scala
On this site you can already find a couple of articles on how to do REST with a multiple of different frameworks. You can find an old one on Play, some on Sc...
Access information from GeoTIFF using Java
I’m always very interested in combining information from various open data sources together. The last couple of weeks I’ve been working with GIS related info...
Widgets and dashboard with Atlasboard, Node.js and d3.js
So it’s been a while since I added something to this blog. I’ve been very busy with work and at the same time finishing up my second book on Three.js. For ou...
Create global precipitation (rain) visualizations with HTML5, Canvas, and open data
I’m currently working on my next book for Three.js and one of the chapters deals with visualizing open data. When looking around for data that I could use, I...
Browser to browser communication with Vert.x, websockets and HTML5
I’ve been playing around with Vert.x for a couple of weeks and I’m really starting to like the simplicity of the framework. With very little configuration yo...
Win a Free Copy of Packt’s Learning Three.js: The JavaScript 3D Library for WebGL
We are pleased to announce that we are organizing a giveaway especially for you. All you need to do is just comment below the post and win a free copy of Lea...
Capture Canvas and WebGL output as video using websockets
About a month ago I got the request to create a video from one of the WebGL demos on this site (the rotating earth cube, showing population density). So, of ...
All 109 Examples from my book on Three.js for Three.js version r63
A couple of months ago my book on Three.js was published by packt (which you can buy from here: Learning Three.js: The JavaScript 3D Library for WebGL). All ...
Create a simpe RESTful service with vert.x 2.0, RxJava and mongoDB
A new article after an hiatus of almost half a year. In this article we’ll have quick look at how you can get started with vert.x and more interestingly how ...
The Truth About HTML5
I work for Malmberg, which is a publisher of educational content. Within our company we have a lot of very interactive content that is currently made availab...
Movie color analysis with XBMC, Boblight, Java and D3.js
It’s been a while since I blogged, but it has been a rather busy time. Lots of big projects at work that need my complete attention, and lots of personal stu...
Quickly create GUI for javascript variables with dat.GUI
I’m currently working on a book for Three.js. This book contains lots and lots of examples that show off the various features of this great library. I want r...
Chrome and Firefox: Desktop Notifications
Just a short article this time, since I’m kind of swamped with work and the start of a new book on Three.js I’m writing for Packt. In this article we’ll very...
CPI Interactive index (15 years) created with Angular.js, bootstrap and d3.js
Long time since I posted anything. But it’s been a busy time with the holidays a new job and a week of snowboarding :) So after this short hiatus a quick art...
HTML5: Server-sent events with Angular.js, Node.js and Express.js
I was playing around with Node.js and Express.js and happened to run across an article on server-sent events. Server-sent events is a W3C specification that ...
Drag and Drop with AngularJS using jQuery UI
In the last couple of weeks I’ve started working with AngularJS. AngularJS is a great simple framework that allows you to create complete web-apps in javascr...
Tutorial: Node.js and Express.js - Part I - Getting started
A couple of months ago a wrote a series of tutorials on scalatra. In this article, and a couple of follow ups, I’ll do the same for Node.js together with Exp...
HAL 9000 Soundboard with HTML5, Canvas and HTML5 Audio
In the last month I’ve been experimenting with the Web Audio API. Currently I’m looking at how you can use this API to create robot sounds and was looking fo...
Use COLOURlovers top patterns as random background for you web application
A couple of days ago I stumbled on the COLOURlovers site from the Android Play Store. This site provides a whole lot of beautiful patterns, colors and palett...
Copy and paste images into your browser using W3C Clipboard API
Just a quick article about the Clipboard API and how you can use this to quickly add copy and paste support for your applications. The clipboard API is a bi...
Exploring the HTML5 Web Audio: visualizing sound
If you’ve read some of my other articles on this blog you probably know I’m a fan of HTML5. With HTML5 we get all this interesting functionality, directly in...
HTML5: Use the pointer lock API to restrict mouse movement to an element
In this article we’ll look a bit closer at one of the new web APIs that recently has landed in Chrome: the pointer lock API (http://www.w3.org/TR/pointerlock...
Tutorial: Getting started with scala and scalatra - Part IV
Welcome to the last part of this series of tutorials on scala and scalatra. In this part we’ll look at how you can use Akka to handle your requests using an ...
Record audio using webrtc in chrome and speech recognition with websockets
There are many different web api standards that are turning the web browser into a complete application platform. With websockets we get nice asynchronous co...
Deep dive into chrome web intents
In a previous article I already wrote about the web intents API. At that time the web intents feature was very experimental, but already usuable. In this art...
Tutorial: Getting started with scala and scalatra - Part III
This post is the third on a series of articles I’m writing on scalatra. In “part I” we created the initial environment, and in “part II” we created the first...
Access the Twitter REST API (v1.1) from Scala and Java using signpost
If you’ve read some other articles on this blog you might know that I like creating visualizations of various datasets. I’ve just started a small project whe...
Hot code replace for scala / scalatra with free JRebel
One of the (many) advantages of working with the Play framework is that you can start the server and have your changes automatically reloaded. This makes dev...
Tutorial: Getting started with scala and scalatra - Part II
In the previous part of the tutorial we created a simple application from scratch and setup Eclipse so we could edit the scala files for scalatra. In this se...
Tutorial: Getting started with scala and scalatra - Part I
In this series of tutorials we’re going to look a bit closer at scalatra. Scalatra is a lightweight scala based micro-web framework, that can be used to crea...
HTML5: Render urban population growth on a 3D world globe with Three.js and canvas
In this article I’ll once again look at data / geo visualization with Three.js. This time I’ll show you how you can plot the urban population growth over the...
HTML5: Render open data on a 3D world globe with Three.js
With Three.js it’s very easy to create 3D objects and render these using WebGL. In a couple of previous articles I already showed how you can create 3D maps ...
Remote opera debugging on android
The final article on remote debugging web applications on mobile devices shows how you can do this using Opera Mobile. With Opera Mobile you can easily debug...
Remote firefox debugging on android
In the previous article I wrote about remote debugging web applications using chrome on Android. If you don’t want to use chrome or you want to test and debu...
Remote chrome debugging on android
With the latest versions of chrome debugging web apps running on smartphones and tablets has become a lot easier. This article shows you how to setup the req...
Motion controlled space invaders using webrtc and canvas
TL;DR: Play the game here (requires current Chrome, Opera of Firefox with webrtc enabled): Motion controlled space invaders A couple of days ago I ran acros...
Euro debt and financial crisis visualized with timeline using d3.js and Three.js
n a couple of recent articles I’ve been using Three.js and d3.js to create 3D maps and visualize metrics. In the last week I combined a couple of these techn...
Three.js: render real world terrain from heightmap using open data
Three.js is a great library for creating 3D objects and animations. In a couple of previous articles I explored this library a bit and in one of those exampl...
Render geographic information in 3D with Three.js and D3.js
The last couple of days I’ve been playing around with three.js and geo information. I wanted to be able to render map/geo data (e.g. in geojson format) insid...
Create complex Word (.docx) documents programatically with docx4j
A couple of months ago I needed to create a dynamic Word document with a number of tables and paragraphs. In the past I’ve used POI for this, but I’ve found ...
HTML5 geolocation API to measure speed and heading of your car
In this article we’ll show you how you can use the W3C geolocation API to measure the speed and the heading of your car while driving. This article further u...
HTML5: Web intents to share information between web apps
If you’ve read any of my other articles you’re probably aware that I really like this whole “browser as the platform” concept. We can easily communicate with...
Compress PDF in Mac using command line (for free)
Compressing a PDF in Mac is very easy and doesn’t require any of the commercial tools out there. This isn’t an area I normally blog about, but when I needed ...
HTML5: Access Battery status through javascript
Update 19-01-2014: Well the adoption rate is very small. Firefox still supports this, but support has still not landed in Chrome (see here: https://code.goog...
Three.js tutorial: example with webgl, canvas and webworkers
In this tutorial we’ll look at how you can use three.js to render a 3D map of an image using webgl on a canvas element. In this example we’ll rasterize an im...
Adjust colors of your page based on the lighting of the room with HTML5, webrtc and a webcam
Most modern laptops automatically dim the screen when the light conditions in the room change. If there is a lot of light, the screen normally increases in b...
Stop labeling everything as an impedance mismatch!
I recently ran across an article that was talking (again) about the Object-Relational mismatch. And just like in many articles this mismatch is called the O...
HTML5: Remotely vibrate a phone with morse code using web sockets and the vibrate API.
In my last couple of blog posts I showed you can use a couple of the new HTML5 related APIs (webrtc, web workers, device orientation) directly from your brow...
HTML5: Easily parallelize jobs using web workers and a threadpool
I’ve been experimenting with web workers and the various browser implementations. Most of the articles I’ve seen show an example where a single worker thread...
Presentation: From REST to HATEOAS
Yesterday I gave a presentation at JPoint’s meetingpoint on how to get your API or service from using the basic REST principles such as verbs and resources t...
Partial image manipulation with canvas and webworkers
In my previous article I showed how to use box2d-web and deviceorientation to rol around a set of circles using standard HTML5 APIs. My initial goal of that ...
HTML5: Combining physics engine (box2dWeb) with DeviceOrientation
When the first smartphones came out, they all had the traditional labyrinth applications. Application where you had to move a ball around a certain path by t...
Access WSO2 Registry programatically
When you have many services it is a good thing to register them somewhere so your consumers can easily find them, see what they are about, determine whether ...
Using SPDY and HTTP transparently using Netty
Most people have already heard about SPDY, the protocol, from google, proposed as a replacement for the aging HTTP protocol. Webservers are browsers are slow...
Binary websockets with Play 2.0 and Scala (and a bit op JavaCV/OpenCV)
In a recent article I showed how you can use webrtc, canvas and websockets together to create a face detection application whose frontend runs completely in ...
Face detection using HTML5, javascript, webrtc, websockets, Jetty and OpenCV
Through HTML5 and the corresponding standards, modern browsers get more standarized features with every release. Most people have heard of websockets that al...
Connect to RabbitMQ (AMQP) using Scala, Play and Akka
In this article we’ll look at how you can connect from Scala to RabbitMQ so you can support the AMQP protocol from your applications. In this example I’ll us...
Election site part 1: Basics with Knockout.js, Bootstrap and d3.js
This article shows how you can use knockout.js, Twitter’s Bootstrap and d3.js together to create a javascript application that creates visually pleasing grap...
How to use SPDY with Jetty
SPDY is a new protocol proposed by Google as a new protocol for the web. SPDY is compatible with HTTP but tries to reduce web page loading by using compressi...
Protect a REST service using HMAC (Play 2.0)
When you talk about security for REST based APIs, people often point to HTTPS. With HTTPS you can easily protect your services from prying eyes using methods...
How to analyze Java SSL errors
In my recent projects I’ve had to do a lot with certificates, java and HTTPS with client-side authentication. In most of these projects, either during testin...
Play 2.0: Akka, Rest, Json and dependencies
I’ve been diving more and more into scala the last couple of months. Scala together with the “Play Framework” provides you with a very effective and quick de...
Embedded Jetty with client certificates
Every time I start with an embedded Jetty server, I can’t find any up to date documentation and have to mess around with old, obsolete and deprecated documen...
Client certificates with HTTPClient 4
I just wrote a small post on how to setup Jetty to support client-side certificates (http://www.smartjava.org/content/embedded-jetty-client-certificates). To...
How should REST services be documented?
REST has become the standard way of creating APIs and exposing resources on the internet. Traditional web services (using SOAP and various sets of WS-* stand...
Using Querulous with Scala on postgresql
I’ve started diving deeper into scala and as a language I’m starting to like it. Combine it with the Play framework and you’ve got a nice, statically typed, ...
Maven and wildcard exclusions
Once in a while I run into the problem where I don’t want to exclude a single dependency from a maven dependency, but all dependencies. For instance I recent...
Embedded Jetty, Vaadin and Weld
When I develop web applications I like to be able to quickly start them from Eclipse without having to rely on all kinds of heavy-weight tomcat or glassfish ...
Using d3.js to visualize GIS
I've been playing around with d3.js a bit the last couple of days and it's a great little javascript library to visualize information. I needed a simple li...
Mule and WSO2 Registry integration
In this two part article we’ll look at how we can use the WSO2 registry (http://wso2.com/products/governance-registry/) as the service repository for service...
First steps with Mule 3.0
Been a while since I looked at the new versions of Mule, so took some time this weekend to look at the new version of Mule. After a rather unexpected small d...