Life’s an ocean with too much commotion

Monday I went to Javapolis in the Metropolis Business Lounge in Antwerp. It’s a yearly event with several conferences, talks, workshops and BOF’s of projects related to Java. Personally I’m not a Java web framework lover. It’s hard to choose which framework you will need for your kind of web application, and knowing one specific framework doesn’t mean you know them all, on the contrary.

Monday morning I went to see Maurice Naftalin talking about Java Generics and Collections. Maurice also contributed in writing the O’Reilly book with the corresponding name. Although I was familiar with using generics in Java, I’ve learned some nifty tricks to have more exceptions detected at compilation time. The second part of his talk, Collections, was less interesting for me. He went pretty fast over all available collections and their performance. I’ve made a quick reference card with all available collections and for which purpose they can be used, together with their performance for every action (add/remove, select, iterate).

In the afternoon I went to see Google API’s by Dick Wall. He talked about the Google library which extends Generics and Collections. They kindly introduce closures (which is the main reason why I started to program in Ruby a year ago) by specifying filter functions in code blocks. These filter functions allow to manipulate the contents of collections, without having to know how to iterate over a collection. With the use of Generics you avoid having ClassCastExceptions in these inner filter functions. The second part of his talk was about the Google webservices. They use Atom feeds for transporting webservice contents. These Atom feeds can be controlled directly by XML or via a Google library. It’s pretty straightforward.

After the Google API’s talk, I went to see jBPM and Hudson, a continuous integration tool. jBPM gives you the ability to define workflows in Java. Every node needs some input and gives some output, based on the output you can let it direct to a next concept. The talk was given by someone who has implemented a jBPM workflow for a project, but she failed to explain the concept and how it’s all composed and executed. She just explained what it did for her project and showed some graphics which gave no meaning outside her project’s context.

Hudson was promising, because I googled it before I went to the talk. I’m looking for a continuous integration tool that can have distributions for kinds of software that needs a specific environment for getting it build. Triggering remote builds can be done via various ways. They all use SSH remote commands for executing a command or script that builds specific software on a machine. This means that the connection needs to be open while it’s building. Output of the build command is constantly send over the SSH connection. I’m looking for a client/server tool where the remote execution task is given to the client tool which executes a certain task. When the task is completed, the results (logs, artifacts, …) can be pushed to the server and can be processed and displayed. The main developer of Hudson, Kohsuke Kawaguchi, didn’t know exactly how it was done, but it was something with SSH…

Summarized, it wasn’t a thrown away day, I got a free T-shirt (apparently everyone got a XL sized T-shirt), and I learned some new things about the cores of Java.

By the way, you can see recordings of most of the talks on Parleys.