Friday, June 26, 2009

ObjektSpektrum-Article on Agility & Architecture

Together with my colleague Stefan Roock I wrote an article on building architectures in an agile way for the current issue of the German ObjektSpektrum magazine. The article is part of a controversy with Thomas Lieder about how to incrementally build architectures in agile projects.

In the introductory part of the controversy we talk about the basics of agile methods and the goal of keeping a flat cost curve for features over a long period of time. To achieve this goal we need to change and refactor the software all the time. This is an integral part of agile software development. We learned that its not possible to foresee the future and therefore decided to design only the next steps - and refactor, if we learn over time and find better designs if new requirements appear. This is quite clear on the low-level of individual classes and nicely supported by test-driven development and refactoring tools.

If we use the same argumentation for the architecture of a project, the discussions get a lot more controversy. People don't believe that it is easy to change and refactor the architecture of a system incrementally and flexible over time. We found this discussion often times quite unstructured and using the term architecture in various flavors and meanings. To ease the discussion about agile architectures we divide between the basic architectural style and the concrete architecture of a concrete system. Our opinion is that the basic architectural style is hard to change over time (for example changing a system from a standalone-rich-client application into a multi-user app-server-based system could be quite hard). In contrast to this we believe that changing the concrete architecture and structure of a system could be done incrementally and agile over time. This is obviously not true for every application. They need to be build from ground-up for flexibility and change. But how to build a system that is easier to change over time, even on the architectural level?

From our point of view, there are three fundamental characteristics of design you need to remember every day to build flexible architectures: understandable, loosely coupled and free of redundance. There are many well-known design principles that helps you to build such systems. Keep them in mind, build loosely coupled components, think about good APIs between them - and you are on the right track to build flexible applications and flexible architectures.

Incremental Design at SEACON 2009

A few days ago I gave a short talk on Incremental Design at SEACON 2009, a new buzzword-free conference in Hamburg, Germany. Aside of the fact that this was the first conference in my beautiful home town (and only 15min away from home), I enjoyed to meet a lot of people there. I also made up a few slides for my talk, which you can now download as PDF (in German):
And last but not least I used my new presentation tool called Session Five for the first time. Was absolutely great!

Friday, June 12, 2009

"OSGi on the Server"-Talk at JAOO 2009 in Aarhus

I am invited to the JAOO 2009 conference in Aarhus, Denmark, to talk in the “Java-Now” track about “OSGi on the Server”. I am pretty excited to join the folks at JAOO since I heard a lot of good things about this conference and the program already sounds quite interesting. Hope to meet a lot of interesting people there!