What changes do I need to make when migrating my application from JBoss to GlassFish?

Try running GLASSFISH_HOME/bin/verifier on your application to
understand its level of Java EE portability. Also see the section about migrating from JBoss to GlassFish in the Migration Guide for GlassFish. Other resources are also available as part of the Migrate to GlassFish project.