There are no programmatic changes required to migrate from version 5.x to version 6.x. This article describes features that are available after migration.
When you migrate between releases of WebSphere Application Server Version 5.x and later and you are using a database for session persistence, you can share the session database table between releases. For example, if you are accessing applications that are on WebSphere Application Server version 5.x you can share the session id with applications running on Version 6.x.