Weblogic Server is one of the best commercial Application Server around. Likewise JBoss Application Server is one of best in open source. Lately it has been seen that companies are moving from Weblogic to JBoss primarily to save on license cost as they want to reduce their expense foot print in light of the not so great economy.
The porting process can be complex or relatively easy, all depends of complexity of the app and how much proprietary technologies have been used instead of J2EE specs and lot of other factors. As such its better to consult people who have done this porting to get to know their story first hand and see how can you apply that knowhow to your case. The following are some of the basic questions to ask someone (person/team) who has done a successful porting of an Application built on Weblogic Server to
JBoss Application Server.<!>
1) What is the approach you followed, did some proof of concept (took some module of application/ one of the applications and tried to migrate and see challenges) and went ahead or directly worked on migration project?.
2) What are the challenges you faced?
3) what are the possible time lines expected for the migration? how long it took for you to migrate?
4) What the changes expected with JDK? Did you upgrade to JDK 1.6 from JDK 1.4 or any JDK changes you did when you migrated?
5) What are the vendor specific changes you had to do ( converting weblogic specific configurations/calls to the code to Jboss and adding new configurations/doing code changes specific to Jboss?
6) Any database specific changes expected (drivers or libraries or configuration changes)? which database are you using currently?
7) Any J2EE specification that was supported by Weblogic but not supported in JBoss?
8) What are the run time issues you encountered?
9) Did you find any compatibility issue with any third party OSS library?
Carefully review these and lot more questions and apply to you case to evaluate feasibility, complexity, issues, effort etc. required before you go any further with the porting decision.