The advantages with creating a JCA connector is so that you can create a pooled, managed resource that can take part in a JTA (transaction). And integrates better with EJB, supports security, etc.
For simple resources, such as read-only look up services, I would advise creating an MBean instead.
Just wonder how did you solve your problem ?
I have the same question currently and trying to find out if JCA will be
suitable thing for EPP connection management.
Would using JCA work for accessing an external EIS. For example, lets say you are registrar (godaddy) that must communicate with a registry (verisign) using their predefined protocol (EPP). Is it possible to use JCA and create a connection adapter that can use their predefined protocol to communicate with the registry? Am I totally going the wrong direction on this?