Mirko Jahn

I admit it: “Using OSGi for the first time isn’t as fun as any of the hip new scripting languages.” Actually, it can be quite painful – especially in the beginning. You’re forced to think about things you actually don’t want to – or better put – you thought you don’t want to. The good news is that there is tooling support (like: BND, maven-bundle-plugin or Eclipse PDE) that can help you getting around most of the time. Unfortunately, there is still the remaining bit, that keeps nagging your brain with the “what could possible have gone wrong”. The one thing that bothered me most about it is that in many cases the steps you need to figure out what’s wrong are the same. It is simple, repetitive work you have to do, mostly only using basic OSGi know how. Also surprisingly simple, there is no tool at hand that can help you going through the necessary steps – well, till ... (more)

Adopting OSGi in Java Application Frameworks: A Case Study

Migration of software systems to the OSGi platform is gaining momentum with wide acceptance of the OSGi technology as the dynamic module system for Java. This transition is of special interest when it comes to popular Java application frameworks, which attract a growing number of Java developers around the world. Although the technical merits of the OSGi platform are broadly recognized, the migration of existing application frameworks is slow due to significant redesign and re-implementation efforts involved. We present an alternative lightweight approach - an adaptation of exist... (more)

Is there a future for software versioning?

Versioning in software is as old as software itself. So, one should assume we are able to handle versions pretty good right? Well, you can’t be more wrong. Versions at the moment – and this holds true for ALL programming languages and concepts I know off – haven’t even remotely been done right till now. You ask why? Well, that’s easy to explain… Currently, versions can only be considered as simple timestamps with a sophisticated syntax. You might be able to read intentions from the provider but further than that they are useless. The syntax of a version theme might indicate some... (more)

The Dynamic Import Issue

After some less OSGi technology centric posts I am now getting back to the meat and will highlight the problems involved with dynamic imports. In well designed OSGi applications the “DynamicImport-Package” header is obsolete should be. Unfortunately not every code is OSGi aware. Actually it is not the missing OSGi awareness that is the core of the problem. It is more the notion of making wrong assumptions on the visibility of classes and the misuse of context class loaders in 90% of the cases I saw. But what is the problem in a concrete example? Well, a common example is JAXB. Y... (more)

Extenders in OSGi - what is all the buzz about?

It feels like recently extenders became extremely fashionable among the OSGi community. Eclipse is using an extender like pattern to track their plugin.xml configurations and Spring DM introduced the plain osgi extender together with a special web extender. It seems like everyone has one lately, but what is all the buzz about and how should or could you use one - and even more important, when should you use one. As always in software development there is no clear black and white answer to this, but this blog post at least tries to shade some light on this topic to help you making... (more)