- IBM Websphere. They started in 2006 and aggresively moved their code on OSGi. Obviously it helped that IBM has committed itself to OSGi since day -1.
- Oracle WebLogic. Formerly known as BEA weblogic. BEA was one of the first companies public touting the advantages of OSGi, clearing the road for others.
- Paremus Infiniflow. Paremus has pioneered the use of OSGi in highly distributed application servers allowing the system to scale to unprecendented heights.
- ProSyst ModuleFusion. ProSyst is the key provider of OSGi technology in the embedded worlds but originated from the development of a J2EE server. They are now back in this market with an offering based completely on OSGi.
- Redhat JBoss. JBoss already worked with a microkernel approach but recognized the advantages of a standard two years ago.
- SAP Netweaver. Well, they are not yet based on OSGi, but they clearly see their future based on the OSGi specifications and are becoming more and more active in the OSGi Alliance.
- SpringSource Application Platform. The company that simplified Enterprise development with their Spring Framework decided to create their own offering in the application server market completely based on the OSGi specifications.
- Sun Glassfish. And last, but definitely not least, Sun decided to use OSGi in the JEE reference implementation Glassfish. They clearly take OSGi extremely serious nowadays since they also hired Richard S. Hall. It is so good to see Sun back at the OSGi Alliance.
As said, this list is impressive by any measure. It is a clear indication that the OSGi specifications are mature and robust. Application servers are highly strategic products for companies; no fortune 500 company bets the house on something that is not highly reliable. Even better, most people know how painful it can be to move non-modular code the strong modularity that the OSGi Framework enforces in runtime. The fact that the key software firms in our industry has made this move signals that the advantages of strong modularity are more than worth this pain.
What does this mean for application developers? Interestingly enough, several application platforms based on OSGi do not expose the OSGi APIs for application developers. The companies that really embrace OSGi are SpringSource, ProSyst, Paremus, and Jonas. IBM, Oracle, and Redhat use the advantages themselves but do not (yet?) allow their customers to use them. However, I expect (and hope) that this will change over time. Why? Because for the first time you can now create middleware libaries that can be deployed on all major application servers without having to worry about implementation differences. I expect this possibility to become too attractive to ignore in the next few years, but today, some of the major vendors exclude this possibility. We'll see what will happen.
It is kind of bizarre that a technology developed for home automation ten years ago now ends up as the state of the art foundation of the servers that run the web. However, there is no time to sit on our laurels. This is a major milestone on the road to building applications from components, the vision I have been chasing all my working life.