I previously blogged about shell scripting JSON with Node.js. In this post, I’ll demonstrate how to achieve the same thing with jsawk. The way these things go, I didn’t find out about jsawk until after I wrote my post about shell scripting with Node. It’s good to know both 
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Jsawk, as the name implies, aims to be for json what awk is for structured plain text. It’s rather useful, as it saves a lot of setup/boilerplate compared to the node.js scripts I’ve shown before.
I’m currently in a project team working on an application that stores much of its data in CouchDB. One of the lovely things about Couch is its RESTful API. It’s all simple HTTP and JSON, easy to understand and easy to program to.
One aspect where this interface isn’t so readily accessible is in shell scripting. There’s curl to handle all the HTTP stuff we could ever need, but to transform a JSON structure or extract information from it proved less straightforward. We can cover simple cases with grep and awk, but JSON is complex enough that we (or, well, I) wouldn’t want to. If the documents were XML, we could have used xpath and xslt to do our heavy lifting. There is to my knowledge no equivalent to xmlstarlet for JSON to reliably handle these chores.
We solved our shell scripting problem and the solution is dead obvious, Read more
What is NodeJS?
The NodeJS five-word sales pitch from their own website is “Evented I/O for V8 Javascript”. We’ll get to what that means exactly in the How. NodeJS, in a few more words, is a server-side application framework with a focus on high concurrent performance. Applications written for Node run in a single-threaded, event-based process.
Node is an open source project initially conceived and developed by Ryan Dahl in early 2009, and has been in active development ever since. Joyent, Dahl’s employer, is backing and sponsoring the project.
Before we go in-depth, let’s explain what’s probably the core point of NodeJS – event-based I/O.
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Tonight in one of our knowledge exchange sessions, one of my colleagues challenged us to writing a TagCloud in JavaScript. He had prepared a nice setup with a server producing twitter hashtags over a WebSocket to the browser and using Processing.js to produce a graphical representation of the tags zooming by on twitter. Since he had already done all the heavy lifting in integrating all these fancy new frameworks, what was left to do, you might ask. Well, we still needed to implement the algorithm to count the number of tags on the continuous stream, sorting this list on the bases of the counts and making sure the system wouldn’t run out of memory by removing less used tags in some smart way. His point to all of this was, that although JavaScript is being prophesized in some circles as the new-old-new language of the future, writing and testing a non-trivial algorithm in it is a big challenge.
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Last friday we had a techrally at Xebia. We could pick our subject: MongoDB or Websockets or Canvas. I teamed up with Albert. There also was another websockets team consisting of Mischa, Ron and Frank.
We decided to use Jetty for websockets. No particual reason to pick Jetty, we both heard it did something with websockets and in the end it was an easier solution than the other team picked (jWebSocket).
Since we only had a few hours we were in quite a hurry, but in the end it was so simple we had time to write a blog, listen to Dan North and Albert even redid everthing and more in Python. Read more
Last Friday, one week ago, the Software Development Day was at Xebia, the first one for me as I started at Xebia this year. As written by Iwein there was some discussion about the use of Javascript started by yours truly. Should we do all UI related functionality in Javascript? Do we do throw away our knowledge, tools and best practices we know when we start coding Javascript? Why should we code in Javascript using the browser as some sort of Virtual Machine, if in fact we want to create desktop application?
After being away from the GIS world for a while, I started working on a new project replacing the current used software by an open source alternative. The first small application that needed to be made was for an emergency phone call center to show the position of the caller on a map. After that a few prototypes should prove that it was doable to replace the current software stack by open source alternatives.
In this blog I will describe the tools used, a few of the problems I ran into and of course the solutions to the problems which involve coding and communication 
The tools used where a Java based server called Geoserver and a client side JavaScript library called OpenLayers.
One of the challenges we are facing in our project is connecting antique display devices to the brand new travel information system we are building. If you have traveled by train in the Netherlands you are familiar with them: large displays with booklets for destinations and departure times. It contains a number of booklets which are controlled by a stepper engine. The devices are called CTA’s, were developed in the eighties and are a solid piece of engineering. Behind the track indicator, which doubles as a door, is a temperature control for the heating, a power socket for connecting electrical equipment, a telephone socket and a connector for testing. Oh yes, did I mention it is heavy?
One of the challenges we are facing in our project is connecting antique display devices to the brand new travel information system we are building. If you have traveled by train in the Netherlands you are familiar with them: large displays with booklets for destinations and departure times. It contains a number of booklets which are controlled by a stepper engine. The devices are called CTA’s, were developed in the eighties and are a solid piece of engineering. Behind the track indicator, which doubles as a door, is a temperature control for the heating, a power socket for connecting electrical equipment, a telephone socket and a connector for testing. Oh yes, did I mention it is heavy?
I was trying to learn Adobe AIR and was looking for some good set of learning resources. I found the book “Adobe AIR for Javascript Developers” from Oreilly by and started reading it online. A cool book, the authors have done great job on presenting the topics as an easilit readable pocket guide. Soon after reading this book, i felt i got the right resource i want for now.
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