Info on ESS for HCM Ehp5

Dears,

I've been asked to add the ESS package for our HCM system, release ERP 605 latest stack (Abap only).

In older releases to use the ESS I remember was required a J2EE instance were to deploy the ESS packages.

Somewhere over the network I read that starting from EHP5 the webdympro architecture is changed and the J2EE instance could not be required anymore.

BUt it's not clear for me if it's mandatory to setup a separate Abap instance or I could use the Abap instance of the HCM system itself.

Any advise on this issue ? Which is better ?

Regards