RMI is part of jdk and "enables an object on one
Java virtual machine to invoke methods on an object in another Java virtual machine". It allows point to point communication between 2 Java applications and provides no message persistence.
Tibco is a message
exchange server. It provides much more than just point to point communication.
You should analyze if your application can be redesigned to use RMI instead of Tibco and if this is true then there's no point in using Tibco.