263. Writing UDP server/client applications

UDP is a protocol built on top of IP. Via UDP, we can send data packets of at most 65,507 bytes (that is, 65,535-byte IP packet size – plus the minimum IP header of 20 bytes – plus the 8-byte UDP header = 65,507 bytes total). In UDP, data packets are seen as individual entities. In other words, no packet is aware of others. Data packets may arrive in any order or may not arrive at all. The sender will not be informed about the lost packets, so it will not know what to resend. Moreover, data packets may arrive too fast or too slow, so processing them may be a real challenge.

While TCP is famous for high-reliability data transmissions, UDP is famous for low-overhead transmissions. So, UDP is more like sending a letter (remember that TCP is like a phone call). You write on the envelope the address of the receiver (here, the remote IP and port) and your address (here, local IP and port) and send it (here, over the wires). You...