TCP socket programing and multithreading in java

Question

I want to send and receive data between three computers using a TCP socket in Java

• The first computer takes the data from the keyboard and sends it to the second computer.
• The second computer takes the data from the first and sends it to the third computer.

My question is: Can I implement the TCP socket program in the second computer (which receives data from the first computer and sends it to the third at the same time) without using multithreading?

Answer 1

Yes you can. (but it's probably stupid)

Just bind a port and listen on it on server 2. Server 1 connects to server 2 and sends data. Server 2 reads data, connects to server 3 and sends him data, on same thread.

Without multithreading, you can either read input from server 1 either send data to server 3. Moreover, you can handle data from server 1 only one by one. The program will work slowly (no faster as it can be with multithreading).

Answer 2

You should make machine 2 as server which will listen on some fixed ip:port. Make machine 1 and 3 as client which will connect to machine 2 on fixed ip:port.

Regarding multithreading, you can make your server thread less by using poll/select. Please refer to link Is there epoll equivalent in Java? which explains poll/select better.