Creating a Java WebStart (JNLP) application

Java WebStart, also called Java Network Launching Protocol (JNLP), allows you to launch Java applications directly from the internet using a webbrowser. In this article we will create a simple application and all configuration files necessary to launch it through Java WebStart. We start with a simple Java program with a GUI: package nl.jansipke.samplegui; import […]

Creating network diagrams with D3.js

D3.js is a JavaScript library for manipulating documents based on data. It can be used for all sorts of visualizations including network diagrams. In this article we will create a network diagram with nodes and directed links between them, visualized by circles and lines with arrowheads. We start with the file index.html that holds the […]

Grep lines before and after matched line

The command grep is really useful for finding matches of a certain word in files or streams. However, until recently I didn’t know how to display lines before and after the matched line(s). Let’s say we have a file named test.txt that contains the following content: ALICE was beginning to get very tired of sitting […]

Temperature graphs

In a previous article we looked at remote measurement of temperature and humidity. Now it is time to show the results of the temperature measurements. First a recap of the setup: Three remote temperature and humidity sensors are located in the living room, the garage and outside. The following graph shows the output of about […]

Programming the Arduino ethernet shield

The Arduino is an open-source electronics prototyping platform based on flexible, easy-to-use hardware and software. It features an IDE that allows you to program the Arduino using a standard USB cable. Several shields exist that extend the functionality of the standard Arduino platform. In the picture above the Arduino is shown on the left and […]

Installing Sun JDK 6 on Ubuntu 10.04

The Sun JDK can be installed on Ubuntu by adding a repository and installing with apt-get. The following works with the latest versions of both at the time of writing: Sun JDK 6 update 20 Ubuntu 10.04 sudo add-apt-repository “deb lucid partner” sudo apt-get update sudo apt-get install sun-java6-jdk If the command add-apt-repository is […]