Programming

Installing Apache Libcloud on CentOS

Apache Libcloud is a standard Python library that abstracts away differences among multiple cloud provider APIs. At the moment it can be used to manage four different kinds of cloud services: servers, storage, loadbalancers and DNS. Here are the steps

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

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

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

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

Measuring temperature and humidity with a JeeNode

In a previous article we looked at the Arduino. Now we will look at an (almost) Arduino compatible clone, the JeeNode. It is a bit smaller and cheaper than the original version and operates at 3.3V instead of 5V. This

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

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