No, inflow is for one-way communication. JCA is about making EIS resouces available to J2EE components, not the other way around. For that the EIS integration would use the standard J2EE client apis.
If you read the spec, you will see that the message interface can be anything you like
including having a return value
public interface MyMessageListener
ReturnType onRequest(MyRequest request);
Also with jca 1.5 it is possible for a resource adapter to invoke either directly
or using the workmanager (if you want transaction inflow) on an EJB (e.g. an SLSB)
NOTE: Being a newbie does not excuse you from reading the specs before posting
frivilous questions. We are not here so you don't have to do your own work.
Here is a good example of inbound resource adapter.
I have executed it and it works fine.
Here is another for outbound resource adapter.
Hope this helps.