Status migration AS2 → AS4
Peppol migrated to AS4 as the mandatory transport protocol as of February 1st, 2020. The support of AS2 will be gracefully faded out. Personally I wouldn't recommend to start new Peppol AS2 projects.
See phase4 as an AS4 solution that can send and receive Peppol Messages: https://github.com/phax/phase4