With the upcoming end of life (EOL) of Java 5.0. We need to upgrade our enterprise application to work with Java 6. The application can be deployed on both WebLogic, WebSphere & JBoss. (It's up to the customer's choice)
Does anyone have an experience with such an upgrade? What issues should we encounter? What pitfalls we should avoid?
Why, I would follow the JavaSE 6 Adoption Guide!
http://java.sun.com/javase/6/webnotes/adoption/adoptionguide.html
The upgrade usually is pretty straight forward...
Your biggest problem will be with the WebSphere, WebLogic etc.
Are they all certified to run on Java 6.
I am surprised that Java 5 is EOL so quickly - in practice Sun will offer patches for years.
One problem you may encounter is if you use JAXB 2.1. See this link for details.
At my last job, we had to do this; it was put off for a long time. When we got to doing it, it took no time at all in the grand scope of things. A few interfaces expanded to add new functionality, the enum keyword was used and promptly refactored, etc.; nothing major. We supported the same app-servers you do, and they all work just fine with Java6. The whole thing turned out to be something an intern could do.
Can't do anything specific to WebLogic, WebSphere, or JBOSS. You have to include whatever special config each one needs in the distro at all times.
The only way I find I can migrate between app servers without changes is to use Spring. I can move a WAR from Tomcat to WebLogic without issues, but only if I include the META-INF/context.xml for Tomcat and weblogic.xml for WebLogic.