NEWBIE: Upgrading from Spring 1.9

[IpiRon]

I'm a Spring newbie so if this is wrong forum let me know. I've inherited a java web app that is about 12 years old. It is a propietary 'framework'. At some point Spring 1.9 was included and used only for IoC/DI. I would like to bring it into the proper century (2.5 or 3.x). Unfortunately, I can not convert everything at once and then retest. Is there anyway to run two different versions of Spring simultaneously?

Namely I want to:

1. Develop new Web app functionality with Spring MVC and Spring SQL.
2. Have the old proprietary functionality continue with IoC/DI with 1.9.
3. Possibly migrate old functionality to new version as required. (This will be a low volume activity).

Can anyone elucidate or point me in an appropriate direction?

Thanks in advance!

[Marten Deinum]

Is there anyway to run two different versions of Spring simultaneously?

NEVER mix different versions of a library unless you want to spend a lot of time debugging strange issues, classloading/classcast exceptions. So no...

In general Spring is a drop-in replacement, so I first upgrade to a newer version and fix those cases which don't work. All the old stuff still works as it did since the beginning of spring (more-or-less).