Spring framework has been an unofficial standard for buliding java based enterprise applications. SpringSource, the company that developed Spring framework recently launched SpringSource dm Server, a completely modular, OSGi-based Java server to run enterprise Java applications. dm server brings simplicity to both developers and operations team.
Since I am a developer, I will start with advantages of have a OSGi based application server. I did play around with the dm server release 1.0. The startup time for the server is very small (15 seconds with my web web applications installed). Major advantage would be the deloyment of new application do not need a server restart. This reduce the development team's development,deplyment and test cycle and provide a platform for Agile development. SpringSource Tool Suite, the IDE from SpringSource is very tighly coupled with the server. My first application and its deployment was seamless. Even though the server supports deployment of application as war file, the company has come up with a different strategy to bundle the application. The application development is also bit different. Application is more OSGi oriented and most of your application's configuration goes into the manifest file and not into web.xml
Onto operations team, they can forget application server restarts on each deployment. Keeping tack of all the lbraries are easy and the server is very configurable. But these are the statements all the other server's boast about right? But other application servers do not provide the flexibity that dm server provides. I would say the server is still young. Currently, the server do not support clustering. But when you have these features built-in, with other features like capability to run EJBs and other java enterprise component it would be great.
The dm Server
The dm server is build on Eclipse Equinox and based on SpringSource Dynamic Module Kernel (dm-kernel). The kernel provides a modular tomcat, spring and other OSGi based technologies. The server is licensed under GPLv3 but some components are EPL and spring framework is licensed under Apache software license. You are free to download the server and its tightly integrated IDE from SpringSource. I would say all J2EE developers should have a look at this server and its programming model.
SpringSource and Its business perspective
Look at all other application server providers: IBM,JBoss,Oracle (Weblogic) or even Apache. All have their own application sotfware stack like Seam of Jboss, ADF of Oracle. Spring framework had the application stack but didn't have a complete product range – Application server and IDE. And now they have it! But the difference they brought in is that they didn't follow the same arhitecture as other companines. They brought in OSGi technoloy into main stream java enterprice basically. With the evolution of dm server, I am sure there will not lot of stuff pushed into OSGi. SpringSource have already recommed new features for OSGi. Now, they have a whole range of product to sell: application server,IDE and of course support for spring framework.
Some developers using Spring are not so happy with how SpringSource handle the support (as far as I understood from the forums). But I see that they have a business model in place to compete with other application servers.
Now, thats one perspective. The other part is, SpringSource being asquired by Microsoft. I don't see much news on it except in InfoQ. In an interview with Rod Johnson and InfoQ they talk about how SpringSource and Microsoft team are working on integrating spring into Windows products like Office, Visual Studio and the OS itself. Will Windows 7 have Spring pre installed? What will its main contribution be to the OS? We still have time to find out!