What is the single most compelling reason to migrate to Spring 3 from 2.x

Question

Currently working on a Spring 2.5 web application, looks as if the business has at least a 5+ year plan for it's usage.

There isn't anything in terms of a technology roadmap in place for the app.

Answer 1

Spring 2.5.6 is stable, and working smoothly. Staying with it won't be a mistake.

Spring 3 gives additional features and support for newer JavaEE specifications. I wouldn't say it gives something extraordinary.

Answer 2

I agree with @Bozho's answer. One significant new Spring core feature that isn't mentioned in the page linked is the Expression Language feature, which allows you to do a variety of things in XML wiring files that previously had to be implemented as custom code.

SpringSecurity in 3.0 is a mixed bag. On the one hand, there are new features and improvements to existing ones. On the other hand, they have broken source code compatibility in a lot of areas. People who cannot do everything with the SpringSecurity namespaces and the standard classes may be in for some head scratching, recoding, and in some cases pain.

Answer 3

Spring Roo generates spring 3 based applications. Not immediately applicable to existing apps, but it's great to be able to compare roo's best-practice output, and if you were 3.x based then you could copy roo config / code output into your existing application to get functionality for free.