Spring offers many namespaces for the XML Application Context configuration to make your life a lot easier. Although not often needed, it is easy to create your own namespaces and provide custom elements. It makes configuration easier. However, I noticed that the some of the IDE support is lost. By chance, I found an undocumented […]
The new axon incubator and the google app engine project
Some time ago we started adding modules or classes to axon that were not really the core of the system. The most important one of them is a MongoDB based event store. The amount of testing of this module was not as high as the other parts. It has not yet been tested in a […]
Android basics – Applying some UI patterns
When I started with my Android application, I had the idea to create a home screen and an action bar just like one of the Android developers described in a blog item. I was really helped by the source code of the Google I/O Schedule app. In this post I will explain how I used […]
Lucene indexing gains concurrency
Imagine you are a Kindergarten teacher and a whole bunch of kids are playing with lego. Suddenly it’s almost 4pm and the big mess needs to be cleaned up, so you ask each kid to pick up one lego brick and put it in your hands. They all run around, bringing bricks to you one […]
Axon Framework 1.0 released!
It has been an exciting year. Little over a year ago, I started developing a framework to make it easier for developers to implement a highly scalable en extensible architecture. The first public Axon release (0.3) came out in April 2010, and was far from feature complete. Now, almost a year later, Axon has proven […]
Using Google Geocoding API with Geocoder
I was looking for a way to retrieve latitude and longitude for a given address. I thought that Google could provide me with a solution and eventually it did. First I was looking at the Google Data API, but found that some parts were deprecated and not supported anymore. The Google Geocoding API, that is […]
How to cluster Seinfeld episodes with Mahout
This february I gave a talk on Mahout clustering at FOSDEM 2011 where I demonstrated how to cluster Seinfeld episodes. A few people wanted to know how to run this example so I write up a short blog about it. In just a few minutes you can run the Seinfeld demo on your own machine.
Gimme all resources you have – I can use them!
Exploiting full IO and CPU concurrency when indexing with Apache Lucene During the last year Apache Lucene has been improved an extreme amount with outstanding improvements such as 100 times faster FuzzyQueries, new Term-Dictionary implementation, enhanced Segment-Merging and the famous Flexible-Indexing API. Recently I started working on another fundamental change referred to as DocumentsWriterPerThread, an […]
Debugging the dreaded “SEVERE: Error listenerStart” and “SEVERE: Error filterStart” tomcat error messages
Just a quick post that I hope might benefit others. If you have been developing web applications on tomcat for a while you have likely come the two error messages mentioned in the title: SEVERE: Error listenerStart and SEVERE: Error filterStart. SEVERE: Error listenerStart Occurs when an exception is thrown in the contextInitialized method of a ServletContextListener […]
Getting GWT to work with Servlet 3 Async Requests
For one of our projects, we use a GWT client that needs to be updated in near-real time (< 1 second delay) when something relevant happens on the server. There are multiple ways of doing it, but I tried to get it working with the new Servlet 3 feature: Asynchronous Http Request handling. Read on […]