On which ports Java Connector listens ?

Hey,

How is listening for RFC connections handled in Java Connector (as in Business Connector) when server registers itself in R/3 as a Program ID ?

Is there a TCP/IP port listener (a listening TCP/IP socket) or maybe the JCo RFC library opens a TCP/IP connection to the R/3 and keeps it alive ? If a TCP/IP port is open, what number is it

Please help, this is urgent. I tried to find some information in the documentation - nothing. I also tried to setUp a listener using Business Connector and watch the open ports, but having two listeners for different servers i saw only one port open beside the HTTP port of Business Connector and this port number was not meainingful.

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regards

Marcin