Java™ Network Programming and Distributed Computing

1.3. Communication across Layers

The concept of layers was introduced to acknowledge and address the complexity of networking theory. The most popular approach to network layering is the Open Systems Interconnection (OSI) model, created by the International Standards Organization (ISO). This model groups network operations into seven parts, from the most basic physical layer through to the application layer, where software applications such as Web clients and e-mail servers communicate.

Under the OSI model, each of the seven layers into which communication is grouped can be referred to by a number or by a descriptive name. Generally, when network programmers refer to a particular layer (e.g., Layer n), they are referring to the nth layer of the ...