As mentioned before WmRoot is internal only and should never be used, there is no support for it and no guarantee the services will remain as they are in the next release. There are official service for remote invoke in WmPublic ().
For a flexible architecture you should consider using either Soap or Rest services for inter IS communication or (if available) the messaging layer (Broker or Universal messaging) which gives best (and reliable) decoupling.
#Flow-and-Java-services#webMethods#Integration-Server-and-ESB