spring application,ejb Job Trends

spring application jobs – ejb jobs

The new buzz from SpringSource is all about the Spring Application Platform (S2AP) with built-in OSGi support. Basically, SpringSource is getting into the application server space, but as they have always done, they provide a different way of doing things from the traditional J2EE. S2AP is basically an application server but with OSGi enabled – I’m still not sure why they don’t call it an application server.

According to the OSGi Alliance, OSGi is the dynamic module system for Java. It “modularizes” applications into bundles which can be “dynamically” swapped in and out of the runtime environment. I see it as like Maven – but for runtime. The idea is to be able to manage versioning of internal and external bundles (jars) during runtime. By pulling external jars out (from a war or ear file) into a repository, OSGi would massively reduce the size of a deliverable. In the future, I would like to see it with built-in search and automatic download from an online repository. OSGi is in fact a very service-oriented technology. It consists of bundles which contains “services” that you can “publish” to a “registry”. An OSGi-enabled bundle is basically a jar with special information in the manifest that tells what services the bundle exports and what other bundles (and their versions) are dependencies. A bundle would follow a certain lifecyle: where you can install, start, stop, uninstall, and update a bundle in runtime.

In an OSGi environment, a bundle must publish its services and find and bind to other bundles. The plumbing code for doing this is provided by Spring Dynamic Modules. Spring-DM combines Spring and OSGi. It provides a dynamic service model that makes it easier to write Spring applications for deployment in an OSGi environment.

Although all of the leading application servers seem to be moving towards OSGi, Spring seems to be the only one that makes it available to developers instead of only for the operations side. I’m not sure why this is. Maybe someone can let me know.

In conclusion, Spring Application Platform and Spring Dynamic Modules together provide Spring developers the ability to managing versioning in runtime using OSGi. The main idea is to promote faster development by removing the need to redeploy on the application server.