In the Beginning…

At the very heart of Java networking (and most other internetworking) is TCP/IP (Transmission Control Protocol and Internet Protocol). TCP/IP is a protocol suite (i.e., a set of rules for exchanging information) that sits between an application and a network that enables an application (object) on one node of a network to pass information back and forth to another application (object) residing on another node of the network. The approach used by TCP/IP to do this is to arrange the protocol into layers of subprotocols that each have their own specific function(s) that, when used together, provide a rich functionality and an orderly approach to data communications.

In many ways TCP/IP is very similar to other software-based protocols (i.e., protocols that are "on the wire" protocols like Ethernet, NETBIOS, NETBUI, SNA). The major difference is the way that TCP/IP was developed: Rather than being a protocol based on one manufacturer's view of networking and its relation to corporate profitability, TCP/IP developed out of the idea of "Open Systems." Open Systems are systems whose specifications are developed "out in the open" rather than behind closed doors; as long as a software developer implements the specification faithfully, the developed system is an Open System.