The Transmission Control Protocol (TCP) is a fantastic protocol, and TCP sockets provide a beautiful abstraction. They present discrete packets on an unreliable network as a reliable, continuous stream of data. To the programmer, sending and receiving data from a peer anywhere in the world is made nearly as easy as reading and writing to a file.
TCP works very well to hide network shortcomings. When a flaky network drops a few packets, TCP faithfully sorts out the mess and retransmits as needed. The application using TCP receives the data in perfect order. The application doesn't even know there was a network problem, and it certainly doesn't need to address the problem.
With this abstraction, like all abstractions, comes some inherent risk. TCP tries very hard to make networks look reliable. It usually succeeds, but sometimes, abstractions leak. What happens if your network cable is cut? What happens if the application you are connected to crashes? TCP isn't magic. It can...
