If TCP/IP is what you mean, you will be required to create a socket listener (probebaly using java sockets). There are quite a few samples on the internet that demonstrate the use of java sockets to send and receive data.
IP based communication can mean a lot of things. So, you probably should try to understand your partner’s requirements in greater detail. HTTP, FTP, SMTP and HTTPS are all protocols that are a layer above TCP/UDP (which in turn are a layer above IP) in the protocol stack.
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