TechJava

On Wednesday, August 27th I visited a presentation about Apache Maven 2. I will describe in short here what I have learned from that event and what you might want to know for your decision if you read more about Maven 2 or not. I will not repeat the basics or advanced features of Maven 2 here, it has been done a million times elsewhere.

Maven 2 is often compared with Apache Ant. Sometimes it is seen as an extension to Ant. This is wrong. So, what’s the difference? Ant is a build tool, meaning you can build your projects with it. Maven is a “project management and comprehension tool”. Project management is actually focussing the technical part, is does not include Gantt diagrams or things like that. What is does include is a description of the technical part of your project, including a source repository, dependencies, documentation, developers and so on. What is the advantage of this?

• Project setup is easier now. No searching for required libs, setting build paths, dealing with other weird stuff
• Project comprehension is easier. The information about the project, the Project Object Model (POM) is human readable. That’s for a reason. Especially in larger projects this seems to be useful to me.
• Changes in projects are tracked easier. Someone includes a new library? All the colleagues’ builds are broken. You have to communicate somehow to your team mates that they have to use that lib. With maven, just check in the new pom file, which includes the new dependency. All your colleagues will get it automatically from the repository you have in your company (hopefully).
• Release management and integration in CI systems comes out-of-the-box. You have all you need to do that. Simply.

Granted, you can do a lot of those with Ant if you are good at it. But with Maven 2 it is a lot easier. As Maven 2 brings a standard project layout, projects not only look similar in their structure every time but they can build in support for a lot of things this way. The pom files are very short compared to Ant build scripts doing the same and more readable. Granted again, you can make your own Ant script containing standard targets you use in every project. You split your Ant files in project specific and general parts. Your project specific part is very short then. Then you did just what the creators of Maven did. Congratulations, you are a smart guy.

I am not saying that all your problems are solved by using it. Maven 2 has some weaknesses as far as I can tell from my limited experience with it. I heard from a participant that the automatic dependency resolving does not work all the time. Normally, Maven would resolve all transitive dependencies from all libs. If lib A is dependent on lib B and you include A in your project, the description of A includes the dependency. Maven will include B, too. I don’t know if that is a failure of maven or the guy who told me about it. AFAIK it needs time to get into it, I often encountered behaviour I didn’t expect. But that was because of my lack of understanding of Maven 2, not because of Maven 2 itself. So, the disadvantage is the same as with every new tool. You need time to learn doing stuff with it, and unfortunately you need to fail sometimes to learn from your mistakes.

BTW, Maven 2 is open source. Everyone who misses something or wants something to get better is welcomed to get into the dev team of Maven 2. One of  those points would be the beloved documentation which has great potential for improvement.

Hope this helps integrating Maven 2 into your understanding of the software development world.

The vacation time of most people is over, so it is time to meet and discuss a little. A good opportunity to do this will be given on September 1st in Roxie, Hamburg during the Eclipse Stammtisch. The event name translates into regular’s table and indicates a regularity of the happening. Even if the upcoming event is only the second in series I expect to meet many people after the great feedback after the last one.

Details:

• When: Monday, September 1st, 19:00 CET
• Where: Roxie, Hamburg, Germany
• Directions: http://www.roxie-hamburg.com/roxieway.htm
• Who’s comming: Doodle Poll

See you next Monday.

The Java User Group Hamburg (JUG-HH) organizes another event at Lehmanns Bookstore in Hamburg. This time the subject of the talk is build management and project automation with help of an open-source tool called Maven. Maven is a software project management and comprehension tool. Based on the concept of a project object model (POM), Maven can manage a project’s build, reporting and documentation from a central piece of information.

On June 16th another Eclipse Demo Camp took place in Hamburg. Organized by Peter Friese of itemis and Martin Lippert of it-agile, Eclipse enthusiasts and presenters met in a former coffee exchange in the harbor of Hamburg, the so called “Hafencity”.

The evening started with an interesting preview of Xtext 2.0 by Sven Efftinge (also itemis). Xtext 2.0 is rewritten from scratch and provides better performance than its predecessor. The current plan for release is about October 2008. The talk was followed by a presentation given by Matthias Lübken (akquinet it-agile) who demostrated how to use the google web toolkit (GWT) in conjunction with serverside Equinox framework. Matthias talked about some of the tweaks which are necessary in order to get the two working together and also showed a little live demo. He was followed by Stefan Reichert of Lufthansa Systems who introduced his ‘wicked shell’ for Eclipse. This handy tool started as tech-demo how to bind an external process to a SWT widget. Finally, it turned into a command line, shell, bash… integration for Eclipse – featuring code completion and history. Reginald Stadlbauer (CEO froglogic) showed how to automize GUI testing of GWT and other Java based GUIs using froglogics Squish. Squish offers scripting languages like Perl, Python or JavaScript to the user to automatize application gui testing. The tool, not an Eclipse application itself, is currently rewritten and will feature full Eclipse integration sometime soon. Finally, Frank Zimmermann (Prof. at the Nordakademie) and two of his students Stefan Tanck and Henning Banneitz showed how model-driven software development (MDSD) using oAWs XText can be used to generate adapters for SAP SI in order to transform EDIFACT messages to XML and back. Unfortunately, a talk about Spring dynamic modules with OSGi was not held, the presenter Gerd Wütherich (independant consulting) was ill.

Apart from the interesting talks, it was nice to see many familiar faces, which attended the Eclipse Demo Camp in Hamburg at the end of 2007. The Eclipse Demo Camp seems to build a community. Thanks to the organizers for enabling this great event.

Yesterday, the first “Eclipse Stammtisch Hamburg” took place in Bolero in Ottensen. It was a full success, about 50 people were there. I was glad to see people I known from Eclipse Democamp again. I liked the location, having a separated room, big enough for another 50 people. I spoke with Ralph on the intended frequency of the event – it could be good to have it four times a year.
The rest of the pictures can be seen in my FlickR gallery.