There is a requirement to suggest best integration approach between TM and decentralized multiple EWM systems.
TM is in S/4HANA embedded and EWM is on 9.4 version all decentralized in separate instances.
Should we go for Point to Point (WS/RM) or go for a CPI in between TM and EWM?
What are the pros and cons with P2P compared with CPI
Which approach can have better routing and monitoring.
Which approach is more scalable?
You need to use LDAP integration to communicate with decentralized EWM systems. AS&R is available for embedded systems only, at least for now.
Unless you really need to map any data in LDAP messages, you don't need CPI or any other middleware between TM and EWM(s). You can route LDAP messages to the right EWM instance with logical receiver determination based on receiving logical system - refer to the attachment in the note 1978857 - WS/RM Integration Guide for SAP Transportation Management, page 27.